De nombreuses pathologies psychiatriques, telles que la schizophrénie, les troubles bipolaires ou la dépression majeure, bien que très différentes, ont en commun une dysfonction du système de récompense et de motivation en lien avec une altération de la transmission dopaminergique. Par ailleurs, ces pathologies s’accompagnent de modifications du métabolisme lipidique et en particulier d’une diminution des taux en acide docosahexaenoic (DHA), le principal acide gras polyinsaturé (AGPI) n-3 dans le système nerveux central. Cependant, bien que certaines études cliniques décrivent des effets bénéfiques de supplémentations en AGPI n-3 sur certains symptômes psychiatriques, ces résultats restent controversés, et l’implication de la modification du statut lipidique dans l’étiologie de ces pathologies reste très peu étudiée. Le but de ce travail a été d’établir s’il existe un lien causal entre une déficience en AGPI n-3 et certains endophénotypes neurobiologiques et comportementaux caractéristiques de pathologies psychiatriques. En particulier, nous avons fait l’hypothèse que la déficience en AGPI n-3 pourrait conduire à un dysfonctionnement de la transmission dopaminergique mésolimbique. Dans cette étude, des tâches de conditionnement opérant chez la souris nous ont permis de mettre en évidence un déficit motivationnel à l’âge adulte induit par une déficience développementale en AGPI n-3 qui est partiellement prévenu par une supplémentation en AGPI n-3 à la naissance, mais pas au sevrage. Ce déficit motivationnel s’accompagne d’une altération de la transmission dopaminergique comme le suggère la réduction de la sensibilité au psychostimulant, l’amphétamine. Plus précisément, nous avons pu montrer que la déficience en AGPI n-3 conduit à une dysfonction des propriétés électrophysiologiques des neurones épineux moyens (medium spinyneurons ou MSN) dans le noyau accumbens (NAc), population neuronale centrale pour la modulation de la motivation. En effet la carence en AGPI n-3 induit une réduction de l’excitabilité des MSNs de la voie directe (dMSNs) qui expriment le récepteur dopaminergique de type D1, associée à une augmentation de la transmission inhibitrice reçue par ces neurones. Ces modifications sont restaurées par l’application de l’agoniste des récepteurs dopaminergiques D2 (RD2), le quinpirole. Ces données nous ont amené à faire l’hypothèse que la diminution d’excitabilité des dMSNs sous déficience en AGPI n-3 résulte de l’augmentation de la transmission GABA issue des MSNs de la voie indirecte (iMSNs) exprimant le RD2. En accord avec ces résultats, par utilisation d’un transgène Cre-dépendant permettant l’expression de l’acide gras désaturase FAT1, nous démontrons que la normalisation des taux d’AGPI dans les iMSN sélectivement, est suffisante pour restaurer les propriétés électrophysiologiques des dMSNs. Par ailleurs, l’expression de la FAT1 dans les neurones exprimant le D2R – mais pas ceux exprimant le D1R - est suffisante pour normaliser le déficit motivationnel en situation de carence. Nos résultats montrent donc un lien causal entre des modifications de taux d’AGPI dans une sous-population neuronale spécifique et une altération comportementale. Par ailleurs, notre étude suggère que la diminution des taux d’AGPI décrite dans plusieurs pathologies psychiatriques pourrait directement participer à l’expression de certains symptômes tels que l’avolition ou l’apathie. / Various, though distinct psychiatric disorders, such as Schizophrenia, bipolar disorder or major depression are associated with a dysfunction of the reward system linked to an alteration of dopamine transmission. Furthermore, these pathologies are also accompanied by changes in lipid metabolism and in particular a decrease in the brain content of docosahexaenoic acid (DHA), the main n-3 polyunsaturated fatty acid (PUFA) in the nervous system. However, despite that n-3 PUFA supplementation seems to improve or prevent some psychiatric symptoms, these results are still controversial and the implication of brain lipid composition in the etiology of psychiatric endophenotypes has been overlooked. The aim of this study was to investigate a potential causal link between n-3 PUFA deficiency and common neurobiological and behavioral endophenotypes of psychiatric disorders. In particular, the hypothesis was that n-3 PUFA deficiency could lead to dysfunctions of mesolimbic dopamine transmission and associated behaviors. Using operant conditioning tasks in mice, we showed that developmental n-3 PUFA deficiency leads to a motivational deficit at adulthood, that is partially reversed by n-3 PUFA supplementation starting at birth, but not at weaning. This motivational deficit was associated with an alteration of dopaminergic transmission as revealed by the reduced sensitivity to the psychostimulant amphetamine. More precisely, we showed that n-3 PUFA deficiency leads to alterations in electrophysiological properties of medium spiny neurons (MSNs) in the nucleus accumbens (NAc), main actors in motivational processes. Indeed, MSNs from the direct pathway (dMSNs), that express dopaminergic D1 receptors, displayed a decrease in neuronal excitability in parallel with an increase of inhibitory input onto these neurons. These alterations were reversed by the dopaminergic D2 receptor (D2R) agonist quinpirole. These data led us to hypothesize that the decreased dMSN excitability induced by n-3 PUFA deficiency could result from an increase of the inhibitory input of MSNs from the indirect pathway (iMSNs that expresses D2R), called lateral inhibition. Accordingly, using a transgenic approach that allows the expression of the fatty acid desaturase FAT1 in a credependent manner, we showed that rescuing appropriate PUFA levels in D2R-expressing neurons selectively (including iMSNs), was sufficient to reverse alterations in electrophysiological properties of MSNs induced by n-3 PUFA deficiency. Moreover, the selective expression of FAT1 in D2-expressing neurons – but not in D1-expressing neurons – reversed the motivational deficit observed in n-3 PUFA deficient mice. We demonstrated the existence of a causal link between modifications in PUFA levels in a discrete neuronal population and behavioral alterations. Overall, this study suggests that altered PUFA levels, observed in some psychiatric disorders, could directly participate in the development of symptoms such as avolition or apathy.

Dietary N-3 PUFA plays a key role in brain maturation, development, stress response and cognitive abilities (Weiser et al., 2016; Devarshi et al., 2019). As adolescent’s prefrontal cortex is maturating, the period becomes sensitive to external factors such as environment, nutrition, and stress (Petrovich et al., 2001; Calabro et al., 2020). In this thesis, we aim to expand our knowledge of the influence of external factors, such as dietary omega-3 supplementation and enriched environment, during this critical maturation period. By designing four distinct studies, we tested the hypothesis that visible sex-specific alterations would arise from adolescence targeted diet n-3 PUFA supplementation and enriched environment, which would act to modify physiological and stress responses, as well as socio-emotional and cognitive performance. Our first study characterized the impact n-3 PUFA and n-6 PUFA regimen on corticosterone secretion and behavioural responses in adolescent male rodents. Additionally, it assessed the effects of delivery method (gavage versus restricted feeding) during this sensitive maturation period to ensure using a method with limited stress-mediated outcomes. This study highlighted gavage to induce reduced effects on corticosterone (CORT) secretion, regardless of the provided supplementation. On the last day of feeding, CORT secretion was diminished in fish oil (FO) fed rats exposed to restricted feeding, suggesting FO diet to promote physiological adjustments. Data also demonstrated that FO and soybean (CSO) rich diets were able to reduce anxiety-like behaviour compared to a high-fat diet intake (Hydrogenated Vegetal Fat - HVF), highlighting the role of n-3 PUFA dietary supplementation during adolescence on stress regulation. Our second study assessed sex-specific impact of adolescence targeted dietary supplementation on brain Docosahexaenoic Acid (DHA), Arachidonic Acid (AA) and Linolenic acid (LA) concentrations immediately following supplementation and during adulthood. Our findings demonstrated overall elevated DHA, AA and LA brain tissue concentrations in female compared to male rats, regardless of dietary supplementation. Benefit of supplementation were most apparent in adolescent males, where FO led to higher DHA concentrations compared to soybean oil supplementation, supporting a positive influence of FO dietary supplementation in males during intensive hormonal fluctuation and brain maturation. However, adolescent male rats showed reduced ability to extract nutrient essential fatty acids compared to female counterparts. Our third study characterized sex-specific coping strategies, socioemotional responses, and glucocorticoid regulation following an n-3 PUFA rich diet and enriched environment (EE) during the adolescent period. While basal CORT secretions were not significantly altered by supplementation in males, a gradual increase in CORT was observed during supplementation, peaking at DAY21. Passive coping strategies was preferred in the FST in RC (Regular Cage)- housed females exposed to FO while RC-housed CSO-fed males opted for an active climbing coping strategy. Increase locomotion and anxiolytic behaviour were observed in CSO-supplemented males (exposed to EE), while CSO by itself promoted social recognition in males. In contrast, sociability was improved in FO EE exposed females, indicating possible synergic effects. Adulthood hippocampal GR-ir expression was reduced at the hippocampal CA3 region in FO/RC and CSO/EE rat groups, which could have influenced memory consolidation and stress resilience. Overall, results from this study provided insights on positive effects associated with short-term adolescent n-3 PUFA supplementation in females, while male appeared to most benefited from soybean diet supplementation. Our fourth and last study assessed age- and sex-dependent influences of dietary supplementation on cognitive performance in the Barnes Maze Test. Our results showcase a gradual decrease in latencies to the escape box, as well as progressive decrease in working memory errors (WME) in adult compared to adolescent rats. Over the testing period, the FO females and CSO males showed improved performance through reduction of WMEs on specific days, which could subtend sex-related effects of dietary supplementations. However, while discrete effects of n-3 PUFA were more apparent in female rats, short-term supplementation appeared insufficient to promote consistent enhancement of visuospatial performance or cognitive flexibility that could be observed throughout the testing period. In conclusion, our findings support the importance of studying single and combined factors to understand overall impact. We were able to consistently demonstrate beneficial effects on coping strategies, stress reactivity, sociability, and cognitive performance of adolescence-targeted fish oil supplementation, especially in female rodents.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O óleo de peixe é rico em ácidos graxos poli-insaturados (AGPI) n-3 e vem sendo apontado como anti-inflamatório associado à melhora de diversas doenças de natureza inflamatória. No presente estudo, objetivou-se avaliar a influência do óleo de peixe sobre a inflamação pulmonar e hiper-reatividade em camundongos ativamente sensibilizados desafiados com ovoalbumina (OVA). Camundongos A/J machos foram alimentados com dieta standard-chow (SC) ou dieta rica em óleo de peixe (Px) durante 8 semanas. Após 4 semanas do início da dieta, cada grupo foi subdividido aleatoriamente para ser desafiado com salina (SC-SAL e PX-SAL) ou ovoalbumina (SC-OVA e PX-OVA). A função pulmonar (resistência e elastância) foi avaliada através de pletismografia invasiva, na condição de aerolização ou não com metacolina 24 horas após o último desafio antigênico. Foi realizado lavado broncoalveolar (LBA) para contagem de leucócitos e quantificação de eotaxina-2. A deposição de muco e de matriz peribronquiolar e o infiltrado de eosinófilos foram quantificados no tecido pulmonar. Foram avaliados interleucina (IL)-13 através de imunohistoquímica e NFκB, GATA-3 e PPARγ, por western-blotting. O desafio com OVA resultou em aumento da infiltração de eosinófilos, elevada produção de citocinas inflamatórias, remodelamento pulmonar, produção de muco e hiper-reatividade das vias aéreas. Detectou-se aumento na expressão dos fatores de transcrição NFκB e GATA-3 nos camundongos do grupo sensibilizado e desafiado com OVA em comparação aos controles. Todas essas alterações foram atenuadas nos camundongos que receberam dieta com óleo de peixe. Expressão elevada de PPARγ foi detectada nos pulmões dos camundongos dos grupos alimentados com óleo de peixe. Em conclusão, nossos resultados mostram que a ingestão de óleo de peixe atenuou as características clássicas do quadro asmático através da modulação da síntese de mediadores inflamatórios, via regulação negativa de NFκB e GATA-3 e regulação positiva de PPARγ. O óleo de peixe parece ser uma terapia alternativa para o controle e tratamento da asma. / Fish oil (FO) is rich in n-3 polyunsaturated fatty acids (PUFA), which have been suggested to be anti-inflammatory and are associated with improvement of several inflammatory diseases. In this study, we investigated the influence of FO on allergen-induced lung inflammation and airway hyperreactivity in mice. Male A/J mice were fed either a standard-chow (SC) or a FO diet (FO) for 8 weeks. After 4 weeks, each group was further randomized for ovalbumin (SC-OVA and FO-OVA) or saline (SC-SAL and FO-SAL) challenge. Resistance and elastance were measured at baseline and after aerosolized methacholine, 24h after the last challenge. Bronchoalveolar lavage (BAL) was performed for leukocyte counts and eotaxin-2 quantification. Lung tissue mucus deposition, peribronchiolar matrix deposition and eosinophil infiltration were quantified. Interleukin-13 expression was evaluated by immunohistochemistry and nuclear factor kappa B (NFκB), GATA-3 and peroxisome proliferator-activated receptor gamma (PPARγ) expression was measured by Western blot. OVA challenge resulted in increased eosinophil infiltration, increased inflammatory cytokine production, peribronchiolar matrix and mucus deposition and airway hyperreactivity to aerosolized methacholine. Elevated lung NFκB and GATA-3 expression was noted in OVA-challenged mice, which was attenuated in FO diet-fed mice. Higher PPARγ expression was also detected in the lungs from the FO-fed groups. In conclusion, FO intake attenuated classical asthma features by reducing inflammatory mediator production via GATA-3 and NFκB down-regulation and PPARγ up-regulation. Thus, FO might be an alternative therapy for asthma prevention and control.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O óleo de peixe é rico em ácidos graxos poli-insaturados (AGPI) n-3 e vem sendo apontado como anti-inflamatório associado à melhora de diversas doenças de natureza inflamatória. No presente estudo, objetivou-se avaliar a influência do óleo de peixe sobre a inflamação pulmonar e hiper-reatividade em camundongos ativamente sensibilizados desafiados com ovoalbumina (OVA). Camundongos A/J machos foram alimentados com dieta standard-chow (SC) ou dieta rica em óleo de peixe (Px) durante 8 semanas. Após 4 semanas do início da dieta, cada grupo foi subdividido aleatoriamente para ser desafiado com salina (SC-SAL e PX-SAL) ou ovoalbumina (SC-OVA e PX-OVA). A função pulmonar (resistência e elastância) foi avaliada através de pletismografia invasiva, na condição de aerolização ou não com metacolina 24 horas após o último desafio antigênico. Foi realizado lavado broncoalveolar (LBA) para contagem de leucócitos e quantificação de eotaxina-2. A deposição de muco e de matriz peribronquiolar e o infiltrado de eosinófilos foram quantificados no tecido pulmonar. Foram avaliados interleucina (IL)-13 através de imunohistoquímica e NFκB, GATA-3 e PPARγ, por western-blotting. O desafio com OVA resultou em aumento da infiltração de eosinófilos, elevada produção de citocinas inflamatórias, remodelamento pulmonar, produção de muco e hiper-reatividade das vias aéreas. Detectou-se aumento na expressão dos fatores de transcrição NFκB e GATA-3 nos camundongos do grupo sensibilizado e desafiado com OVA em comparação aos controles. Todas essas alterações foram atenuadas nos camundongos que receberam dieta com óleo de peixe. Expressão elevada de PPARγ foi detectada nos pulmões dos camundongos dos grupos alimentados com óleo de peixe. Em conclusão, nossos resultados mostram que a ingestão de óleo de peixe atenuou as características clássicas do quadro asmático através da modulação da síntese de mediadores inflamatórios, via regulação negativa de NFκB e GATA-3 e regulação positiva de PPARγ. O óleo de peixe parece ser uma terapia alternativa para o controle e tratamento da asma. / Fish oil (FO) is rich in n-3 polyunsaturated fatty acids (PUFA), which have been suggested to be anti-inflammatory and are associated with improvement of several inflammatory diseases. In this study, we investigated the influence of FO on allergen-induced lung inflammation and airway hyperreactivity in mice. Male A/J mice were fed either a standard-chow (SC) or a FO diet (FO) for 8 weeks. After 4 weeks, each group was further randomized for ovalbumin (SC-OVA and FO-OVA) or saline (SC-SAL and FO-SAL) challenge. Resistance and elastance were measured at baseline and after aerosolized methacholine, 24h after the last challenge. Bronchoalveolar lavage (BAL) was performed for leukocyte counts and eotaxin-2 quantification. Lung tissue mucus deposition, peribronchiolar matrix deposition and eosinophil infiltration were quantified. Interleukin-13 expression was evaluated by immunohistochemistry and nuclear factor kappa B (NFκB), GATA-3 and peroxisome proliferator-activated receptor gamma (PPARγ) expression was measured by Western blot. OVA challenge resulted in increased eosinophil infiltration, increased inflammatory cytokine production, peribronchiolar matrix and mucus deposition and airway hyperreactivity to aerosolized methacholine. Elevated lung NFκB and GATA-3 expression was noted in OVA-challenged mice, which was attenuated in FO diet-fed mice. Higher PPARγ expression was also detected in the lungs from the FO-fed groups. In conclusion, FO intake attenuated classical asthma features by reducing inflammatory mediator production via GATA-3 and NFκB down-regulation and PPARγ up-regulation. Thus, FO might be an alternative therapy for asthma prevention and control.

As exposições precoces às diferentes intervenções, como dietas e estresse, estão associadas a persistentes alterações sobre aspectos neuroquímicos e comportamentais, podendo este ser considerado um gatilho de transtornos psiquiátricos na vida adulta. O presente trabalho objetivou determinar se estas intervenções neonatais poderiam interagir com uma dieta deficiente em ácidos graxos poliinsaturados n-3 (n-3 PUFA), aplicados durante o desenvolvimento, com foco nos níveis centrais (hipocampo) e séricos do fator neurotrófico derivado do encéfalo (BDNF), bem como sobre a atividade enzimática e aspectos morfológicos (e.g. massa, potencial) mitocondriais do hipocampo de ratos machos adultos. Em nossa abordagem experimental animal, as ninhadas foram distribuídas aleatoriamente nos grupos intactos, manipulados neonatalmente [MN, separação mãe-filhote durante 10min/dia, entre o 1° e o 10° dia pós-natal (DPN)] e separado maternalmente [SM, separação mãe-filhote durante 3h/dia, entre o 1° e o 10° DPN]. No DPN 35, os filhotes machos foram agrupados em dieta n-3 PUFA adequada ou deficiente, por 17 semanas de tratamento. O peso e o consumo de ração foram aferidos semanalmente. Após este tratamento, soro e hipocampo foram coletados. Kits comerciais foram utilizados para a medição dos níveis hipocampais e séricos de BDNF (ELISA), bem como a atividade dos complexos da cadeia respiratória mitocondrial (método enzimático, análise espectrofotométrica), massa e potencial mitocondriais (MitoTracker, citometria de fluxo). A expressão gênica de BDNF no hipocampo também foi medido por RT-qPCR. Os testes estatísticos utilizados foram ANOVA de duas vias ou de medidas repetidas. Os níveis de significâncias foram fixados em p<0,05. A dieta deficiente em n-3 PUFA, associada aos estressores neonatais deste estudo (MN, SM) foram capazes de alterar o peso corporal e a ingestão de alimentos de um modo específico, uma vez que os níveis mais elevados destes parâmetros foram encontrados em animais submetidos a SM. Animais submetidos a MN alimentados com uma dieta n-3 PUFA deficiente exibiram uma maior atividade exploratória em resposta a um psicoestimulante (dietilpropiona). Embora os níveis proteicos séricos e hipocampais de BDNF permaneceram inalterados pelos tratamentos aplicados, fomos capazes de demonstrar a redução de sua expressão gênica em animais alimentados com uma dieta n-3 PUFA deficiente. Considerando os padrões mitocondriais e parâmetros de estresse oxidativo, as atividades das enzimas antioxidantes glutationa peroxidase (GPx) e catalase (CAT), bem como a produção de espécies reativas de oxigênio (EROs) se encontraram aumentadas no hipocampo de animais submetidos a uma deficiência crônica em n-3 PUFA. Esta deficiência mostrou interações com o fator estresse neonatal em alguns destes parâmetros (e.g. atividade da GPx, produção de EROs), indicando um possível sinergismo entre estressores neonatais e a deficiência em n-3 PUFA. Os níveis de tióis foram significativamente menores nos grupos estressados (MN, SM), sendo a dieta n-3 PUFA deficiente capaz de aumentar a quantidade de tiol no hipocampo. Por outro lado, animais estressados tratados cronicamente com uma dieta deficiente em n-3 PUFA apresentaram níveis mais elevados de tiol. Contudo, a MN per se foi capaz de diminuir o potencial mitocondrial hipocampal. Adicionalmente, um estudo com humanos teve como objetivo correlacionar os níveis de BDNF periféricos ao consumo de n-3 PUFA em adolescentes. Para este estudo, 137 adolescentes de uma amostra enriquecida para psicopatologias de ansiedade foram submetidos a um questionário de frequência alimentar (QFA), para uma análise quantitativa do consumo de macronutrientes e micronutrientes de n-3 PUFA. As correlações de Spearman foram realizadas para avaliar possíveis associações entre o consumo de n-3 PUFA e os níveis periféricos de BDNF. As amostras de sangue foram coletadas entre 7 a 10h após o período de 10-12h de jejum, sendo o soro armazenado para medir os níveis de BDNF. Todas as análises de BDNF foram realizadas no mesmo dia por ELISA, utilizando anticorpos monoclonais específicos para o BDNF, de acordo com as instruções do fabricante. Os efeitos de possíveis confundidores (e.g. consumo total de gordura, idade, sexo e medida de ansiedade) foram examinados por modelos de regressões lineares. Apesar de algumas limitações apresentadas (e.g. o tamanho reduzido da amostra, alta incidência de adolescentes ansiosos), o que poderia limitar a validade externa deste resultado, fomos capazes de detectar uma correlação entre o consumo de n-3 PUFA e os níveis séricos de BNDF em adolescentes. Como conclusão geral, esta tese demonstra que a manipulação neonatal e separação materna, associada com uma deficiência em n-3 PUFA, são capazes de alterar parâmetros comportamentais e neuroquímicos na idade adulta. Este sinergismo foi capaz de diminuir a expressão gênica de BDNF no hipocampo, embora não apresentando qualquer alteração deste parâmetro perifericamente. A correlação entre os níveis consumidos de n-3 PUFA, em uma população de adolescentes em idade escolar, com os níveis séricos de BDNF também foi encontrada. Ainda, as alterações nas atividades enzimáticas mitocondriais observadas no hipocampo destes animais reforçam a importância da participação desta estrutura, além de sua possível relação com o desenvolvimento de desordens psiquiátricas e de humor. Considerando-se a nossa abordagem metodológica em ratos, a mesma pode ser um protocolo útil para se estudarem as interações entre o ambiente precoce e a nutrição ao curso de vida em diferentes desfechos neuroquímicos. / Early exposure to different interventions, as diets and stress, are associated with persistent alterations in neurochemistry and behavior, and can be considered a trigger of psychiatric disorders in adulthood. This study investigated whether neonatal interventions interact with a diet deficient in n-3 polyunsaturated fatty acids (n-3 PUFA) applied during development, focusing on central (hippocampus) and serum brain-derived neurotrophic factor (BDNF), as well as mitochondrial enzymatic activity and morphology (e.g. mass, potential) in adult male rats. In our animal study, litters were randomized into non-handled (NH), handled [H, mother-offspring separation for 10min/day from 1st-10th postnatal day (PND)] and separated (S, separation for 3h/day from the 1st-10th PND) groups. On PND 35, male pups were randomized into adequate or deficient diet in n-3 PUFA for 17 weeks. The weight and food intake were measured weekly. Serum and hippocampi were collected after this n-3 PUFA treatment. Commercial kits were used for measuring hippocampal and serum BDNF (ELISA), as well as mitochondrial chain respirator complexes (enzymatic method, spectrophotometric analysis), mitochondrial mass and potential (MitoTracker, flow citometry). Hippocampal BDNF gene expression was also measure by RT-qPCR. Statistical testes used were Two-Way or repeated measures ANOVA. Significance levels were set at p<0.05. A n-3 PUFA deficient diet, in association with neonatal stressors used in this study (H, MS) were able to alter body weight and food intake in a specific way, since higher levels of these parameters were found in animals subjected to MS. Animals subjected to H fed an n-3 PUFA deficient diet displayed enhanced exploratory activity in response to a psychostimulant (diethylpropion). Although serum protein levels and hippocampus BDNF remained unchanged by the treatments applied, we were able to demonstrate its gene expression reduction in the hippocampus of animals fed an n-3 PUFA deficient diet. Considering mitochondrial and oxidative stress parameters, the activities of antioxidant enzymes glutathione peroxidase (GPx) and catalase (CAT) and the production of reactive oxygen species (ROS) were increased in the hippocampus of rats subjected to a deficiency n-3 PUFA. This deficiency displayed interactions with neonatal stress factor in some of these parameters (e.g. GPx activity, ROS), indicating a possible synergism between neonatal stressors and n-3 PUFA deficiency. Thiol levels were significantly decreased by neonatal stressors (H and MS), and the n-3 PUFA deficient diet was able to increase its total amount in hippocampus. On the other hand, chronically stressed animals treated with an n-3 PUFA deficient diet showed higher thiol levels. However, H per se was able to decrease mitochondrial potential in hippocampus. Additionally, a clinical study aimed to correlate peripheral BDNF levels and n-3 PUFA consumption in adolescents. For this study, 137 adolescents from a sample enriched for psychopathology of anxiety were subjected to a food frequency questionnaire (FFQ), in order for measuring the quantitative analysis of n-3 PUFA macronutrients and micronutrients consumption. Spearman correlations were performed to assess the association between n-3 PUFA consumption and serum BDNF levels. Blood samples were collected between 7 and 10h after fasting period of 10-12h, and serum was stored in order to measure BDNF levels. All BDNF measurements were performed in the same day by sandwich-ELISA using monoclonal antibodies specific for BDNF, according to the manufacturer’s instructions. Effects of potential confounders (e.g. total fat consumption, age, gender, anxiety) were examined using linear regression models. Although some limitations were presented (e.g. small sample size with high incidence of eager teenagers), which could limit the external validity of this result, we were able to detect a correlation between the consumption of n-3 PUFA and BDNF serum levels in adolescents. As a general conclusion, this thesis reports that neonatal handling and maternal separation, associated with a nutritional deficiency in n-3 PUFA, were able to change behavioral and neurochemical parameters in adulthood. This synergism was able to decrease BDNF gene expression in the hippocampus, while not presenting any change of this parameter peripherally. A correlation between the consumption levels of n-3 PUFA, in a population of schoolchildren with BDNF serum levels was also found. Still, changes in mitochondrial enzymatic activities observed in the hippocampus of these animals reinforce the importance of this structure participation and its relation to the development of psychiatric and mood disorders. Considering our rat methodological approach, it can be a useful tool for studying the interactions between early life environment and life-course nutrition on different neurochemical outcomes.

As exposições precoces às diferentes intervenções, como dietas e estresse, estão associadas a persistentes alterações sobre aspectos neuroquímicos e comportamentais, podendo este ser considerado um gatilho de transtornos psiquiátricos na vida adulta. O presente trabalho objetivou determinar se estas intervenções neonatais poderiam interagir com uma dieta deficiente em ácidos graxos poliinsaturados n-3 (n-3 PUFA), aplicados durante o desenvolvimento, com foco nos níveis centrais (hipocampo) e séricos do fator neurotrófico derivado do encéfalo (BDNF), bem como sobre a atividade enzimática e aspectos morfológicos (e.g. massa, potencial) mitocondriais do hipocampo de ratos machos adultos. Em nossa abordagem experimental animal, as ninhadas foram distribuídas aleatoriamente nos grupos intactos, manipulados neonatalmente [MN, separação mãe-filhote durante 10min/dia, entre o 1° e o 10° dia pós-natal (DPN)] e separado maternalmente [SM, separação mãe-filhote durante 3h/dia, entre o 1° e o 10° DPN]. No DPN 35, os filhotes machos foram agrupados em dieta n-3 PUFA adequada ou deficiente, por 17 semanas de tratamento. O peso e o consumo de ração foram aferidos semanalmente. Após este tratamento, soro e hipocampo foram coletados. Kits comerciais foram utilizados para a medição dos níveis hipocampais e séricos de BDNF (ELISA), bem como a atividade dos complexos da cadeia respiratória mitocondrial (método enzimático, análise espectrofotométrica), massa e potencial mitocondriais (MitoTracker, citometria de fluxo). A expressão gênica de BDNF no hipocampo também foi medido por RT-qPCR. Os testes estatísticos utilizados foram ANOVA de duas vias ou de medidas repetidas. Os níveis de significâncias foram fixados em p<0,05. A dieta deficiente em n-3 PUFA, associada aos estressores neonatais deste estudo (MN, SM) foram capazes de alterar o peso corporal e a ingestão de alimentos de um modo específico, uma vez que os níveis mais elevados destes parâmetros foram encontrados em animais submetidos a SM. Animais submetidos a MN alimentados com uma dieta n-3 PUFA deficiente exibiram uma maior atividade exploratória em resposta a um psicoestimulante (dietilpropiona). Embora os níveis proteicos séricos e hipocampais de BDNF permaneceram inalterados pelos tratamentos aplicados, fomos capazes de demonstrar a redução de sua expressão gênica em animais alimentados com uma dieta n-3 PUFA deficiente. Considerando os padrões mitocondriais e parâmetros de estresse oxidativo, as atividades das enzimas antioxidantes glutationa peroxidase (GPx) e catalase (CAT), bem como a produção de espécies reativas de oxigênio (EROs) se encontraram aumentadas no hipocampo de animais submetidos a uma deficiência crônica em n-3 PUFA. Esta deficiência mostrou interações com o fator estresse neonatal em alguns destes parâmetros (e.g. atividade da GPx, produção de EROs), indicando um possível sinergismo entre estressores neonatais e a deficiência em n-3 PUFA. Os níveis de tióis foram significativamente menores nos grupos estressados (MN, SM), sendo a dieta n-3 PUFA deficiente capaz de aumentar a quantidade de tiol no hipocampo. Por outro lado, animais estressados tratados cronicamente com uma dieta deficiente em n-3 PUFA apresentaram níveis mais elevados de tiol. Contudo, a MN per se foi capaz de diminuir o potencial mitocondrial hipocampal. Adicionalmente, um estudo com humanos teve como objetivo correlacionar os níveis de BDNF periféricos ao consumo de n-3 PUFA em adolescentes. Para este estudo, 137 adolescentes de uma amostra enriquecida para psicopatologias de ansiedade foram submetidos a um questionário de frequência alimentar (QFA), para uma análise quantitativa do consumo de macronutrientes e micronutrientes de n-3 PUFA. As correlações de Spearman foram realizadas para avaliar possíveis associações entre o consumo de n-3 PUFA e os níveis periféricos de BDNF. As amostras de sangue foram coletadas entre 7 a 10h após o período de 10-12h de jejum, sendo o soro armazenado para medir os níveis de BDNF. Todas as análises de BDNF foram realizadas no mesmo dia por ELISA, utilizando anticorpos monoclonais específicos para o BDNF, de acordo com as instruções do fabricante. Os efeitos de possíveis confundidores (e.g. consumo total de gordura, idade, sexo e medida de ansiedade) foram examinados por modelos de regressões lineares. Apesar de algumas limitações apresentadas (e.g. o tamanho reduzido da amostra, alta incidência de adolescentes ansiosos), o que poderia limitar a validade externa deste resultado, fomos capazes de detectar uma correlação entre o consumo de n-3 PUFA e os níveis séricos de BNDF em adolescentes. Como conclusão geral, esta tese demonstra que a manipulação neonatal e separação materna, associada com uma deficiência em n-3 PUFA, são capazes de alterar parâmetros comportamentais e neuroquímicos na idade adulta. Este sinergismo foi capaz de diminuir a expressão gênica de BDNF no hipocampo, embora não apresentando qualquer alteração deste parâmetro perifericamente. A correlação entre os níveis consumidos de n-3 PUFA, em uma população de adolescentes em idade escolar, com os níveis séricos de BDNF também foi encontrada. Ainda, as alterações nas atividades enzimáticas mitocondriais observadas no hipocampo destes animais reforçam a importância da participação desta estrutura, além de sua possível relação com o desenvolvimento de desordens psiquiátricas e de humor. Considerando-se a nossa abordagem metodológica em ratos, a mesma pode ser um protocolo útil para se estudarem as interações entre o ambiente precoce e a nutrição ao curso de vida em diferentes desfechos neuroquímicos. / Early exposure to different interventions, as diets and stress, are associated with persistent alterations in neurochemistry and behavior, and can be considered a trigger of psychiatric disorders in adulthood. This study investigated whether neonatal interventions interact with a diet deficient in n-3 polyunsaturated fatty acids (n-3 PUFA) applied during development, focusing on central (hippocampus) and serum brain-derived neurotrophic factor (BDNF), as well as mitochondrial enzymatic activity and morphology (e.g. mass, potential) in adult male rats. In our animal study, litters were randomized into non-handled (NH), handled [H, mother-offspring separation for 10min/day from 1st-10th postnatal day (PND)] and separated (S, separation for 3h/day from the 1st-10th PND) groups. On PND 35, male pups were randomized into adequate or deficient diet in n-3 PUFA for 17 weeks. The weight and food intake were measured weekly. Serum and hippocampi were collected after this n-3 PUFA treatment. Commercial kits were used for measuring hippocampal and serum BDNF (ELISA), as well as mitochondrial chain respirator complexes (enzymatic method, spectrophotometric analysis), mitochondrial mass and potential (MitoTracker, flow citometry). Hippocampal BDNF gene expression was also measure by RT-qPCR. Statistical testes used were Two-Way or repeated measures ANOVA. Significance levels were set at p<0.05. A n-3 PUFA deficient diet, in association with neonatal stressors used in this study (H, MS) were able to alter body weight and food intake in a specific way, since higher levels of these parameters were found in animals subjected to MS. Animals subjected to H fed an n-3 PUFA deficient diet displayed enhanced exploratory activity in response to a psychostimulant (diethylpropion). Although serum protein levels and hippocampus BDNF remained unchanged by the treatments applied, we were able to demonstrate its gene expression reduction in the hippocampus of animals fed an n-3 PUFA deficient diet. Considering mitochondrial and oxidative stress parameters, the activities of antioxidant enzymes glutathione peroxidase (GPx) and catalase (CAT) and the production of reactive oxygen species (ROS) were increased in the hippocampus of rats subjected to a deficiency n-3 PUFA. This deficiency displayed interactions with neonatal stress factor in some of these parameters (e.g. GPx activity, ROS), indicating a possible synergism between neonatal stressors and n-3 PUFA deficiency. Thiol levels were significantly decreased by neonatal stressors (H and MS), and the n-3 PUFA deficient diet was able to increase its total amount in hippocampus. On the other hand, chronically stressed animals treated with an n-3 PUFA deficient diet showed higher thiol levels. However, H per se was able to decrease mitochondrial potential in hippocampus. Additionally, a clinical study aimed to correlate peripheral BDNF levels and n-3 PUFA consumption in adolescents. For this study, 137 adolescents from a sample enriched for psychopathology of anxiety were subjected to a food frequency questionnaire (FFQ), in order for measuring the quantitative analysis of n-3 PUFA macronutrients and micronutrients consumption. Spearman correlations were performed to assess the association between n-3 PUFA consumption and serum BDNF levels. Blood samples were collected between 7 and 10h after fasting period of 10-12h, and serum was stored in order to measure BDNF levels. All BDNF measurements were performed in the same day by sandwich-ELISA using monoclonal antibodies specific for BDNF, according to the manufacturer’s instructions. Effects of potential confounders (e.g. total fat consumption, age, gender, anxiety) were examined using linear regression models. Although some limitations were presented (e.g. small sample size with high incidence of eager teenagers), which could limit the external validity of this result, we were able to detect a correlation between the consumption of n-3 PUFA and BDNF serum levels in adolescents. As a general conclusion, this thesis reports that neonatal handling and maternal separation, associated with a nutritional deficiency in n-3 PUFA, were able to change behavioral and neurochemical parameters in adulthood. This synergism was able to decrease BDNF gene expression in the hippocampus, while not presenting any change of this parameter peripherally. A correlation between the consumption levels of n-3 PUFA, in a population of schoolchildren with BDNF serum levels was also found. Still, changes in mitochondrial enzymatic activities observed in the hippocampus of these animals reinforce the importance of this structure participation and its relation to the development of psychiatric and mood disorders. Considering our rat methodological approach, it can be a useful tool for studying the interactions between early life environment and life-course nutrition on different neurochemical outcomes.

As exposições precoces às diferentes intervenções, como dietas e estresse, estão associadas a persistentes alterações sobre aspectos neuroquímicos e comportamentais, podendo este ser considerado um gatilho de transtornos psiquiátricos na vida adulta. O presente trabalho objetivou determinar se estas intervenções neonatais poderiam interagir com uma dieta deficiente em ácidos graxos poliinsaturados n-3 (n-3 PUFA), aplicados durante o desenvolvimento, com foco nos níveis centrais (hipocampo) e séricos do fator neurotrófico derivado do encéfalo (BDNF), bem como sobre a atividade enzimática e aspectos morfológicos (e.g. massa, potencial) mitocondriais do hipocampo de ratos machos adultos. Em nossa abordagem experimental animal, as ninhadas foram distribuídas aleatoriamente nos grupos intactos, manipulados neonatalmente [MN, separação mãe-filhote durante 10min/dia, entre o 1° e o 10° dia pós-natal (DPN)] e separado maternalmente [SM, separação mãe-filhote durante 3h/dia, entre o 1° e o 10° DPN]. No DPN 35, os filhotes machos foram agrupados em dieta n-3 PUFA adequada ou deficiente, por 17 semanas de tratamento. O peso e o consumo de ração foram aferidos semanalmente. Após este tratamento, soro e hipocampo foram coletados. Kits comerciais foram utilizados para a medição dos níveis hipocampais e séricos de BDNF (ELISA), bem como a atividade dos complexos da cadeia respiratória mitocondrial (método enzimático, análise espectrofotométrica), massa e potencial mitocondriais (MitoTracker, citometria de fluxo). A expressão gênica de BDNF no hipocampo também foi medido por RT-qPCR. Os testes estatísticos utilizados foram ANOVA de duas vias ou de medidas repetidas. Os níveis de significâncias foram fixados em p<0,05. A dieta deficiente em n-3 PUFA, associada aos estressores neonatais deste estudo (MN, SM) foram capazes de alterar o peso corporal e a ingestão de alimentos de um modo específico, uma vez que os níveis mais elevados destes parâmetros foram encontrados em animais submetidos a SM. Animais submetidos a MN alimentados com uma dieta n-3 PUFA deficiente exibiram uma maior atividade exploratória em resposta a um psicoestimulante (dietilpropiona). Embora os níveis proteicos séricos e hipocampais de BDNF permaneceram inalterados pelos tratamentos aplicados, fomos capazes de demonstrar a redução de sua expressão gênica em animais alimentados com uma dieta n-3 PUFA deficiente. Considerando os padrões mitocondriais e parâmetros de estresse oxidativo, as atividades das enzimas antioxidantes glutationa peroxidase (GPx) e catalase (CAT), bem como a produção de espécies reativas de oxigênio (EROs) se encontraram aumentadas no hipocampo de animais submetidos a uma deficiência crônica em n-3 PUFA. Esta deficiência mostrou interações com o fator estresse neonatal em alguns destes parâmetros (e.g. atividade da GPx, produção de EROs), indicando um possível sinergismo entre estressores neonatais e a deficiência em n-3 PUFA. Os níveis de tióis foram significativamente menores nos grupos estressados (MN, SM), sendo a dieta n-3 PUFA deficiente capaz de aumentar a quantidade de tiol no hipocampo. Por outro lado, animais estressados tratados cronicamente com uma dieta deficiente em n-3 PUFA apresentaram níveis mais elevados de tiol. Contudo, a MN per se foi capaz de diminuir o potencial mitocondrial hipocampal. Adicionalmente, um estudo com humanos teve como objetivo correlacionar os níveis de BDNF periféricos ao consumo de n-3 PUFA em adolescentes. Para este estudo, 137 adolescentes de uma amostra enriquecida para psicopatologias de ansiedade foram submetidos a um questionário de frequência alimentar (QFA), para uma análise quantitativa do consumo de macronutrientes e micronutrientes de n-3 PUFA. As correlações de Spearman foram realizadas para avaliar possíveis associações entre o consumo de n-3 PUFA e os níveis periféricos de BDNF. As amostras de sangue foram coletadas entre 7 a 10h após o período de 10-12h de jejum, sendo o soro armazenado para medir os níveis de BDNF. Todas as análises de BDNF foram realizadas no mesmo dia por ELISA, utilizando anticorpos monoclonais específicos para o BDNF, de acordo com as instruções do fabricante. Os efeitos de possíveis confundidores (e.g. consumo total de gordura, idade, sexo e medida de ansiedade) foram examinados por modelos de regressões lineares. Apesar de algumas limitações apresentadas (e.g. o tamanho reduzido da amostra, alta incidência de adolescentes ansiosos), o que poderia limitar a validade externa deste resultado, fomos capazes de detectar uma correlação entre o consumo de n-3 PUFA e os níveis séricos de BNDF em adolescentes. Como conclusão geral, esta tese demonstra que a manipulação neonatal e separação materna, associada com uma deficiência em n-3 PUFA, são capazes de alterar parâmetros comportamentais e neuroquímicos na idade adulta. Este sinergismo foi capaz de diminuir a expressão gênica de BDNF no hipocampo, embora não apresentando qualquer alteração deste parâmetro perifericamente. A correlação entre os níveis consumidos de n-3 PUFA, em uma população de adolescentes em idade escolar, com os níveis séricos de BDNF também foi encontrada. Ainda, as alterações nas atividades enzimáticas mitocondriais observadas no hipocampo destes animais reforçam a importância da participação desta estrutura, além de sua possível relação com o desenvolvimento de desordens psiquiátricas e de humor. Considerando-se a nossa abordagem metodológica em ratos, a mesma pode ser um protocolo útil para se estudarem as interações entre o ambiente precoce e a nutrição ao curso de vida em diferentes desfechos neuroquímicos. / Early exposure to different interventions, as diets and stress, are associated with persistent alterations in neurochemistry and behavior, and can be considered a trigger of psychiatric disorders in adulthood. This study investigated whether neonatal interventions interact with a diet deficient in n-3 polyunsaturated fatty acids (n-3 PUFA) applied during development, focusing on central (hippocampus) and serum brain-derived neurotrophic factor (BDNF), as well as mitochondrial enzymatic activity and morphology (e.g. mass, potential) in adult male rats. In our animal study, litters were randomized into non-handled (NH), handled [H, mother-offspring separation for 10min/day from 1st-10th postnatal day (PND)] and separated (S, separation for 3h/day from the 1st-10th PND) groups. On PND 35, male pups were randomized into adequate or deficient diet in n-3 PUFA for 17 weeks. The weight and food intake were measured weekly. Serum and hippocampi were collected after this n-3 PUFA treatment. Commercial kits were used for measuring hippocampal and serum BDNF (ELISA), as well as mitochondrial chain respirator complexes (enzymatic method, spectrophotometric analysis), mitochondrial mass and potential (MitoTracker, flow citometry). Hippocampal BDNF gene expression was also measure by RT-qPCR. Statistical testes used were Two-Way or repeated measures ANOVA. Significance levels were set at p<0.05. A n-3 PUFA deficient diet, in association with neonatal stressors used in this study (H, MS) were able to alter body weight and food intake in a specific way, since higher levels of these parameters were found in animals subjected to MS. Animals subjected to H fed an n-3 PUFA deficient diet displayed enhanced exploratory activity in response to a psychostimulant (diethylpropion). Although serum protein levels and hippocampus BDNF remained unchanged by the treatments applied, we were able to demonstrate its gene expression reduction in the hippocampus of animals fed an n-3 PUFA deficient diet. Considering mitochondrial and oxidative stress parameters, the activities of antioxidant enzymes glutathione peroxidase (GPx) and catalase (CAT) and the production of reactive oxygen species (ROS) were increased in the hippocampus of rats subjected to a deficiency n-3 PUFA. This deficiency displayed interactions with neonatal stress factor in some of these parameters (e.g. GPx activity, ROS), indicating a possible synergism between neonatal stressors and n-3 PUFA deficiency. Thiol levels were significantly decreased by neonatal stressors (H and MS), and the n-3 PUFA deficient diet was able to increase its total amount in hippocampus. On the other hand, chronically stressed animals treated with an n-3 PUFA deficient diet showed higher thiol levels. However, H per se was able to decrease mitochondrial potential in hippocampus. Additionally, a clinical study aimed to correlate peripheral BDNF levels and n-3 PUFA consumption in adolescents. For this study, 137 adolescents from a sample enriched for psychopathology of anxiety were subjected to a food frequency questionnaire (FFQ), in order for measuring the quantitative analysis of n-3 PUFA macronutrients and micronutrients consumption. Spearman correlations were performed to assess the association between n-3 PUFA consumption and serum BDNF levels. Blood samples were collected between 7 and 10h after fasting period of 10-12h, and serum was stored in order to measure BDNF levels. All BDNF measurements were performed in the same day by sandwich-ELISA using monoclonal antibodies specific for BDNF, according to the manufacturer’s instructions. Effects of potential confounders (e.g. total fat consumption, age, gender, anxiety) were examined using linear regression models. Although some limitations were presented (e.g. small sample size with high incidence of eager teenagers), which could limit the external validity of this result, we were able to detect a correlation between the consumption of n-3 PUFA and BDNF serum levels in adolescents. As a general conclusion, this thesis reports that neonatal handling and maternal separation, associated with a nutritional deficiency in n-3 PUFA, were able to change behavioral and neurochemical parameters in adulthood. This synergism was able to decrease BDNF gene expression in the hippocampus, while not presenting any change of this parameter peripherally. A correlation between the consumption levels of n-3 PUFA, in a population of schoolchildren with BDNF serum levels was also found. Still, changes in mitochondrial enzymatic activities observed in the hippocampus of these animals reinforce the importance of this structure participation and its relation to the development of psychiatric and mood disorders. Considering our rat methodological approach, it can be a useful tool for studying the interactions between early life environment and life-course nutrition on different neurochemical outcomes.

Background Iron deficiency (ID) is the world‟s most prevalent micronutrient deficiency and predominantly affects developing countries, also South Africa. In areas with low fish consumption and high n-6 PUFA vegetable oil intake, there is a risk for having inadequate n-3 PUFA status. Both iron and n-3 PUFA play important roles in the immune response, and supplementation is a strategy to alleviate deficiencies. However, little is known about potential interactive effects between concurrent iron and n-3 PUFA supplementation on the immune system. This is also important in the context that iron supplementation may be unsafe and may increase morbidity and mortality. Aim The overall aim of this thesis was to assess the effects of iron and docosahexaenoic (DHA)/eicosapentaenoic acid (EPA) supplementation, alone and in combination, on the immune system of ID children. More specifically, these effects were investigated on the occurrence and duration of illness and school-absenteeism due to illness, peripheral blood mononuclear cell (PBMC), red blood cell (RBC) and plasma total phospholipid fatty acid composition, iron status, fatty acid-derived immune modulators and targeted PBMC gene expression. Furthermore, association of PBMC, RBC and plasma total phospholipid fatty acid composition with allergic disease, were also examined. Design In a 2-by-2 factorial, randomised, double-blind, placebo-controlled trial, South African children (n = 321, aged 6–11 y) were randomly assigned to receive oral supplements of either 1) iron (50 mg as ferrous sulphate) plus placebo; 2) DHA/EPA (420/80 mg) plus placebo; 3) iron plus DHA/EPA (420/80 mg); or 4) placebo plus placebo for 8.5 mo, four times per week. Absenteeism and illness symptoms were recorded and biochemical parameters for compliance as well as parameters fundamental to immune function were assessed at baseline and endpoint. Furthermore, in a cross-sectional design, associations of allergic disease with baseline fatty acid composition of PBMC, RBC and plasma were examined. Results The combination of iron and DHA/EPA significantly attenuated respiratory illness caused by iron supplementation. DHA/EPA supplementation alone improved respiratory symptoms at school, but increased headache-related absenteeism. DHA/EPA and iron supplementation individually tended to increase and decrease anti-inflammatory DHA and EPA-derived mediators, respectively. Furthermore the anti-inflammatory DHA-derived immune mediator, 17HDHA was higher in the DHA/EPA plus placebo and iron plus DHA/EPA groups than in the iron plus placebo group. Also, the pro-inflammatory arachidonic acid (AA)-derived modulators (5- and 15-hydroxyeicosapentaenoic acid) were significantly lower in the iron plus DHA/EPA group compared to the placebo plus placebo groups. In the study population, 27.2% of the children had allergic disease and AA in PBMC phospholipids was significantly lower in the allergic children than in the non-allergic children. In RBC phospholipids dihomo-gamma-linolenic acid (DGLA) and the ratio of DGLA: linoleic acid (LA) correlated negatively and the n-6:n-3 PUFA ratio positively with total immunoglobulin E (tIgE). Furthermore, trans-C18:1n-9, tended to be higher in the allergic group. Conclusion DHA/EPA prevented respiratory illness caused by iron supplementation and although DHA/EPA on its own reduced respiratory morbidity when the children were present at school, surprisingly it increased the likelihood of being absent with headache and fever. The biochemical findings compliment the clinical results and support previous observations about DHA/EPA supplementation to reduce inflammation, but add to the current knowledge base that a relatively high oral dose of non-haem iron modulates circulating lipid-derived immune modulators and related gene expression. Furthermore, when supplementing with iron and DHA/EPA combined, in this ID population with low fish intake, the anti-inflammatory effect of DHA/EPA is maintained concurrently with attenuation of respiratory morbidity. This finding support the notion that excess iron (probably as non-transferrin bound iron) becomes available for pathogens and is probably why we found that iron increased respiratory infectious morbidity. The improved clinical outcome with combined supplementation seems to be related to increased lipid-mediator synthesis gene expression and the availability of DHA/EPA, leading to a more pro-resolving profile and enhanced immune competence. Overall these results give better insight into immune function and infectious morbidity in relation to n-3 PUFA and iron status and treatment, as well as the possible association of fatty acid status with allergic disease in young South-African school children. / PhD (Nutrition), North-West University, Potchefstroom Campus, 2015

Background Iron deficiency (ID) is the world‟s most prevalent micronutrient deficiency and predominantly affects developing countries, also South Africa. In areas with low fish consumption and high n-6 PUFA vegetable oil intake, there is a risk for having inadequate n-3 PUFA status. Both iron and n-3 PUFA play important roles in the immune response, and supplementation is a strategy to alleviate deficiencies. However, little is known about potential interactive effects between concurrent iron and n-3 PUFA supplementation on the immune system. This is also important in the context that iron supplementation may be unsafe and may increase morbidity and mortality. Aim The overall aim of this thesis was to assess the effects of iron and docosahexaenoic (DHA)/eicosapentaenoic acid (EPA) supplementation, alone and in combination, on the immune system of ID children. More specifically, these effects were investigated on the occurrence and duration of illness and school-absenteeism due to illness, peripheral blood mononuclear cell (PBMC), red blood cell (RBC) and plasma total phospholipid fatty acid composition, iron status, fatty acid-derived immune modulators and targeted PBMC gene expression. Furthermore, association of PBMC, RBC and plasma total phospholipid fatty acid composition with allergic disease, were also examined. Design In a 2-by-2 factorial, randomised, double-blind, placebo-controlled trial, South African children (n = 321, aged 6–11 y) were randomly assigned to receive oral supplements of either 1) iron (50 mg as ferrous sulphate) plus placebo; 2) DHA/EPA (420/80 mg) plus placebo; 3) iron plus DHA/EPA (420/80 mg); or 4) placebo plus placebo for 8.5 mo, four times per week. Absenteeism and illness symptoms were recorded and biochemical parameters for compliance as well as parameters fundamental to immune function were assessed at baseline and endpoint. Furthermore, in a cross-sectional design, associations of allergic disease with baseline fatty acid composition of PBMC, RBC and plasma were examined. Results The combination of iron and DHA/EPA significantly attenuated respiratory illness caused by iron supplementation. DHA/EPA supplementation alone improved respiratory symptoms at school, but increased headache-related absenteeism. DHA/EPA and iron supplementation individually tended to increase and decrease anti-inflammatory DHA and EPA-derived mediators, respectively. Furthermore the anti-inflammatory DHA-derived immune mediator, 17HDHA was higher in the DHA/EPA plus placebo and iron plus DHA/EPA groups than in the iron plus placebo group. Also, the pro-inflammatory arachidonic acid (AA)-derived modulators (5- and 15-hydroxyeicosapentaenoic acid) were significantly lower in the iron plus DHA/EPA group compared to the placebo plus placebo groups. In the study population, 27.2% of the children had allergic disease and AA in PBMC phospholipids was significantly lower in the allergic children than in the non-allergic children. In RBC phospholipids dihomo-gamma-linolenic acid (DGLA) and the ratio of DGLA: linoleic acid (LA) correlated negatively and the n-6:n-3 PUFA ratio positively with total immunoglobulin E (tIgE). Furthermore, trans-C18:1n-9, tended to be higher in the allergic group. Conclusion DHA/EPA prevented respiratory illness caused by iron supplementation and although DHA/EPA on its own reduced respiratory morbidity when the children were present at school, surprisingly it increased the likelihood of being absent with headache and fever. The biochemical findings compliment the clinical results and support previous observations about DHA/EPA supplementation to reduce inflammation, but add to the current knowledge base that a relatively high oral dose of non-haem iron modulates circulating lipid-derived immune modulators and related gene expression. Furthermore, when supplementing with iron and DHA/EPA combined, in this ID population with low fish intake, the anti-inflammatory effect of DHA/EPA is maintained concurrently with attenuation of respiratory morbidity. This finding support the notion that excess iron (probably as non-transferrin bound iron) becomes available for pathogens and is probably why we found that iron increased respiratory infectious morbidity. The improved clinical outcome with combined supplementation seems to be related to increased lipid-mediator synthesis gene expression and the availability of DHA/EPA, leading to a more pro-resolving profile and enhanced immune competence. Overall these results give better insight into immune function and infectious morbidity in relation to n-3 PUFA and iron status and treatment, as well as the possible association of fatty acid status with allergic disease in young South-African school children. / PhD (Nutrition), North-West University, Potchefstroom Campus, 2015