O estresse é um fenômeno conservado e observado evolutivamente, que tem como objetivo assegurar a sobrevivência do indivíduo. Porém quando o organismo perde a capacidade de se autorregular, torna-se uma ameaça. Algumas psicopatologias, como ansiedade e depressão, sugerem o envolvimento dos sistemas CRF e noradrenérgico e de níveis elevados de GCs. Avaliamos nesse trabalho algumas alterações morfofisiológicas e comportamentais decorrentes da exposição do estresse crônico imprevisível (EI) em ratos machos. Avaliados 24 h após o último estímulo estressor, os animais submetidos ao EI apresentaram níveis elevados de corticosterona plasmática, de RNAm de CRF2 e expressão de GR em regiões encefálicas (LSi e VmH e LSi, CeA, BST e PVH, respectivamente). Essas alterações morfofisiológicas foram, em parte, decorrentes da ação de GCs e de NE. Não foram observadas alterações comportamentais quanto à anedonia e ansiedade. Dessa maneira, podemos dizer que o EI utilizado nesse estudo, foi capaz de induzir algumas alterações morfofisiológicas, porém não comportamentais. / While acute stress initiates neuronal responses that prepare an organism to adapt to challenges, chronic stress may lead to maladaptative responses that could result in diseases. Evidence suggests the involvement of CRF system and high corticosterone levels in stress-related psychiatric disorders such as anxiety and major depressive disorders. The aim of this work was to investigate whether chronic unpredictable stress (CUS) could modulate de CRF system, GR expression in the CNS and behavior in male rats. Results showed an increase in corticosterone plasmatic levels, CRF2 mRNA and GR expression in specific regions of the CNS (LSi e VmH e LSi, CeA, BST e PVH, respectively), associated with the limbic system at 24 h after the last stress session. The chronic treatment with an inhibitor of GCs synthesis (metyrapone) and adrenergic receptor antagonists (atenolol and phentolamine) prevented the CUS effects in CRF2 mRNA levels and GR expression. No anxiety or depression-like behavior was observed in rats submitted to CUS. We conclude that CUS cause biochemical alterations since the increase CRF2 mRNA levels and GR expression in limbic region, but these changes were not able to cause behavioral changes.

O objetivo do presente estudo foi avaliar os perfis de metabólitos de glicocorticóides fecais através de radioimunoensaio em cachorros-vinagre (Speothos venaticus) mantidos em cativeiro e suas possíveis implicações na função reprodutiva. Duas fêmeas e quatro machos adultos, após período de condicionamento, foram marcados e tiveram suas fezes recolhidas durante 45 dias. Estes animais recebiam diariamente marcadores (corantes e miçangas) para a devida identificação das amostras fecais. O desafio com ACTH foi realizado em uma das fêmeas e mostrou o perfil reativo esperado, validando a técnica do ponto de vista fisiológico. As concentrações de metabólitos de glicocorticóides fecais para o grupo em geral variaram de 2,32 a 65,09 μ/g de fezes secas, com média e desvio-padrão de 18,11±11,33 μ/g de fezes secas, respectivamente. Quatro animais apresentaram um pico cada um, porém aparentemente, sem relação com qualquer evento estressante em particular. Não se verificou diferença significativa nos perfis de glicocorticóides fecais entre machos e fêmeas, nem entre a fêmea dominante e os outros indivíduos. Tais resultados sugerem que os animais estão bem adaptados à condição do cativeiro e provavelmente isentos ou minimamente afetados pelo estresse. A dosagem dos glicocorticóides fecais é uma ferramenta útil no monitoramento não-invasivo para avaliar a condição de estresse do cachorrovinagre, demonstrando se aspectos de manejo e fatores ambientais interferem de modo importante ou não no bem-estar animal e no potencial reprodutivo, sendo de interesse para a manutenção e conservação da espécie. / The aim of this study was to evaluate the fecal glucocorticoid metabolite profiles by radioimmunoassay in captive bush dog (Speothos venaticus) and its possible role in the reproductive function. Six adult animals (two females and four males), after training, were marked and their fecal samples were collected during 45 days. Every day the animals received markers (dye and colored plastic beads) for the appropriate identification of each sample. One female was used to the ACTH challenge and showed the expected classical response, with a significant peak one day after stimulation, therefore confirming the physiological validation. The overall fecal glucocorticoid metabolite concentrations for the whole group, ranged from 2,32 to 65,09 μ/g of dried feces, with an average and standard deviation of 18,11±11,33 μ/g of dried feces, respectively. Four animals revealed one individual peak during the observation period, however they could not be correlated with any stressful event. The fecal glucocorticoid metabolite concentrations did not show significant differences between males and females neither between the dominant female and the other animals in the study. The results suggest that the animals are well adapted to the captive conditions and likely without or minimally affected by stress. The fecal glucocorticoid metabolite dosage is a useful non-invasive tool to evaluate the bush dog stress situation and to monitor local management and environmental factors that could possibly influence the well being and reproductive success, considered both key factors for the specie maintenance and conservation.

A utilização do corticosteróide antenatal objetivando induzir artificialmente a maturação fetal e garantir a sobrevivência de neonatos críticos é bem estabelecido e rotineiramente utilizado em Medicina. Por outro lado, a utilização pós-natal de corticóide, como garantia de melhores condições clínicas do neonato, ainda figura como expressivo desafio tanto em neonatologia humana quanto veterinária. Deste modo, este estudo tem como objetivo avaliar a eficácia da corticoterapia pré ou pós-natal em cordeiros prematuros extremos na melhora da condição clínica, pulmonar, metabólica e hemodinâmica; necessidade de assistência ventilatória e na garantia de sobrevivência neonatal. Para tal, cordeiros prematuros, nascidos aos 135 dias de gestação, foram aleatoriamente alocados nos grupos: corticoterapia materna pré-natal (CORT PRÉ; n=8), corticoterapia pós-natal (CORT PÓS; n=9) e controle (CONT; n=5). A corticoterapia foi realizada com betametasona em dose única de 0,5 mg/Kg, por via de aplicação intra muscular, aos 133 dias de gestação ou aos 10 minutos após o nascimento para os grupos CORT PRÉ e CORT PÓS, respectivamente. O parto foi induzido utilizando-se o fármaco aglepristona às 49 horas prévias à data estimada para o parto. Os neonatos foram avaliados quanto ao escore Apgar, condição clínica geral (freqüência cardíaca, freqüência respiratória, tônus muscular e irritabilidade reflexa), temperatura corpórea, hemogasometria arterial, glicemia, lactatemia, concentrações séricas das enzimas antioxidantes (superoxido dismutase SOD e glutationa peroxidase GPx) e marcador do estresse oxidativo (TBARS) em 10 momentos pontuais durante os 3 dias subsequentes ao parto. Para os cordeiros destinados ao suporte ventilatório, avaliamos o tempo (em minutos) necessário para o início do protocolo ventilatório a partir do nascimento e o tempo de permanência na ventilação. Os dados foram analisados por meio de testes paramétricos e não-paramétricos, com nível de significância de 95%. As variáveis também foram submetidas ao teste de correlação de Spearman. Como resultados, observamos melhor condição de vitalidade e tônus muscular nos neonatos tratados em relação ao grupo controle. Quanto à avaliação cardiogênica, a betametasona pré-natal apresentou efeito bradicárdico, enquanto a administração pós-natal resultou em efeito taquicárdico. Tanto os resultados de frequência respiratória como temperatura corpórea foram estatisticamente superiores nos neonatos tratados em relação ao controle. Todos os cordeiros nasceram bradicárdicos e bradipneicos, com valores normais atingidos a partir de 10 minutos. Observamos hiperglicemia nos grupos tratados, com valor estatisticamente superior no grupo CORT PÓS. O valor de lactato foi estatisticamente superior no grupo CORT PÓS em relação ao controle. Quanto aos componentes do equilíbrio ácido-básico, os neonatos do grupo CORT PRÉ tiveram valores significativamente maiores de bicarbonato, enquanto menores pressões de CO2 foram observadas a partir de 60 minutos, embora sem diferença quanto ao pH e BE. Os tratamentos não determinaram alterações nos valores de PO2 e SO2. Entretanto, os diferentes protocolos corticoterápicos influenciaram no perfil hematológico neonatal, com valores significativamente maiores de hematócrito no grupo CORT PÓS, seguido pelo grupo CORT PRÉ. Observamos também atuação do tratamento pós-natal nos valores de SOD e correlação positiva com os valores de hematócrito e hemoglobina. Comparando-se o percentual de cordeiros submetidos à assistência ventilatória, verificou-se maior necessidade no grupo controle. Os neonatos do grupo CORT PRÉ permaneceram por tempo menor sob assistência ventilatória, em relação ao grupo controle Com base nos resultados obtidos, concluímos que a corticoterapia pós-natal ou pré-natal favorece a condição clínica neonatal (vitalidade, tônus muscular e funções vitais), a função pulmonar (trocas gasosas e compensação aos desequilíbrios ácido-básicos) e a atividade metabólica (controle glicêmico). O tratamento pós-natal aumentou a atividade da enzima SOD, reduzindo os riscos de danos pulmonares. Ainda, o tratamento com betametasona pós-natal ou materna pré-natal diminui a necessidade de assistência ventilatória em cordeiros prematuros extremos / The use of corticosteroid aiming artificially fetal lung maturation and survival of critical neonates is used as a routine in medicine. On the other hand, the postnatal steroid therapy used to improve clinical conditions of the newborn, It\'s still a therapeutic challenge both in human as veterinary neonatology. Thus, the aims this study is to assess the effectiveness of corticosteroid, used in the pre or postnatal period, in extremely preterm lambs to improve clinical, pulmonary, metabolic and hemodynamic condition; the need for ventilatory support and neonatal survival rate. For it, preterm lambs, born with 135 days of gestation, were randomly allocated into three groups: prenatal maternal corticosteroid therapy (CORT PRE; n = 8), postnatal corticosteroid therapy (CORT POST; n = 9) and control (CONT; n = 5). The steroid therapy was performed with betamethasone in a single dose of 0.5 mg/ kg, by intramuscular route of administration, at 133 days of pregnancy our after 10 minutes from the birth in the groups CORT PRÉ and CORT PÓS, respectively. The labor was induced with aglepristone administrated 49 hours prior to the estimated date of birth. Newborns were assessed by Apgar score, general medical condition (heart rate, respiratory rate, muscle tone and reflex irritability), body temperature, blood gas analysis, blood glucose, blood lactate concentration, serum concentrations of antioxidant enzymes (superoxide dismutase - SOD and glutathione peroxidase - GPx) and marker of oxidative stress (TBARS). The assessments were performed in 10 moments during the three days from delivery. For ventilated newborns, we assessed the needed time (in minutes) between birth and the beginning of ventilatory protocol, as well as length of stay on ventilatory support. Data were analyzed using parametric and nonparametric tests, with 95% of significance level. The variables were assessed from Spearman correlation test. As results, we noted better condition of vitality and muscle tone in newborns treated when compared with control group. Regarding cardiogenic values, antenatal betamethasone resulted in bradycardic effect, while its postnatal administration was related with tachycardia. Both results of respiratory and body temperature rates were significantly higher in newborns treated compared to the control. All lambs born whith bradycardia and bradypnea, reached normal values from 10 minutes of life. Hyperglycemia was observed in the treated groups, with statistically higher values in CORT PÓS group. The lactate value was statistically higher in CORT PÓST group compared to the control. Concerning the components of the acid-base balance, the CORT PRÉ showed significantly higher values of bicarbonate, while lower pressures of CO2 were observed from 60 minutes, although there were no differences in pH and BE values. The treatments did not determine changes in PO2 and SO2 values. However, the different protocols of steroid therapy influenced on neonatal blood profile, with significantly higher hematocrit values in CORT POST group, followed by CORT PRÉ. We also observed influence of postnatal treatment in SOD values as well as positive correlation between SOD and the hematocrit and hemoglobin values. Comparing the percentage of lambs submitted to mechanical ventilation, there were most ventilated neonates in the control group. Lower ventilation time was observed in the CORT PRÉ group. Then we conclude that, the postnatal or antenatal steroids improve neonatal clinical condition (vitality, muscle tone and vital functions), lung function (gas exchange and compensation to acid-base imbalances) and metabolic activity (glycemic control). The postnatal treatment increased the activity of SOD by reducing the risks of pulmonary damage. Moreover, treatment with postnatal betamethasone or prenatal maternal reduces the need for mechanical ventilation in extremely preterm lambs

Les hormones ovariennes sont impliquées dans le développement du cancer du sein des femmes porteuses de mutations du gène BRCA1. L’étude du tissu mammaire normal de femmes mutées et non mutées nous a permis de montrer des altérations de la signalisation de l’estradiol et la progestérone dans un modèle de greffes chez la souris. Ces dérégulations concernent l’activité proliférative et l’expression des récepteurs hormonaux, et sont hétérogènes d’une patiente mutée à l’autre. De plus, une diminution de l’expression de la forme phosphorylée en sérine 211 du récepteur des glucocorticoïdes a été mise en évidence dans le tissu muté BRCA1. Ces observations posent la question de la place d’unantiprogestatif/anti-glucocorticoïde tel que l’ulipristal acétate (UPA) dans le traitement préventif des femmes mutées pour BRCA1. Les effets de l’UPA ont été caractérisés in vitro dans les cellules mammaires normales pour préciser les conséquences de son utilisation sur le sein. Son action a ensuite été examinée sur les xénogreffes de sein de patientes mutées et non mutées. Nous montrons que l’UPA est capable d’inhiber la prolifération du tissu muté lorsqu’elle est induite par la progestérone. Ce résultat encourage son utilisation dans la prévention tumorale mais indique une spécificité d’action en fonction des dérégulations hormonales associées au tissu muté. / Ovarian hormones, estradiol and progesterone, are known to promote breast carcinogenesis in BRCA1 mutated women. Using normal mammary gland xenografted in mice, we found that hormonal responses were deregulated in a heterogeneous fashion within BRCA1 mutation carriers. These observations raise the question of a potential use ofantiprogestin treatment as ulipristal acetate (UPA) to prevent breast tumorigenesis in BRCA1mutated women. Studies with this experimental model and epithelial normal breast cells in vitro, revealed that UPA alone had no proliferative activity on breast tissue but was efficient to inhibit proliferative activity when induced by progesterone treatment in mutated tissue. UPAcould be a promising treatment to prevent breast tumorigenesis for some mutated women. In addition, we observed a severe decrease of the phosphorylated Serine 211 glucocorticoid receptor isoform in BRCA1 carriers compared to non mutated tissue. This observation suggests that the glucocorticoid receptor expression and activation should be taken intoaccount in BRCA1 carriers.

Este estudo investigou se o tratamento com glicocorticoide durante a gestação altera o metabolismo energético, hormonal e molecular materno, a função das ilhotas pancreáticas e mudanças correlativas sobre miRNAs. Foram utilizadas 80 ratas dividas em dois grupos de 40 animais, sendo um grupo destinado para envelhecimento até um ano após o desmame da prole, e o seguinte grupo destinado para experimentação no 20º dia de gestação, ambos dispostos em: CTL - controle, CTL-Dex - controle tratadas com dexametasona por 6 dias, P - prenhes e P-Dex - prenhes tratadas com dexametasona do 14º-19º dia de gestação. A expressão de miRNA das ilhotas foram analisadas em larga escala. Os genes alvos foram rastreados em banco de dados e confirmados. Por fim, investigou-se o mecanismo de modulação da homeostasia glicêmica. Inúmeras modificações resultaram da terapia com DEXA na gestação concluindo que a associação do tratamento ao período gravídico modula positivamente membros da família miRNA-29 ocasionando um desequilíbrio na homeostasia glicêmica por meio de falha na maquinaria exocitótica em longo prazo, desencadeado pela modulação negativa de progesterona e seu receptor promovendo prejuízo no processo de remodelação da ilhota pancreática na fase final da gestação. / This study investigated whether treatment with glucocorticoids during pregnancy alters the energetic, hormonal and molecular maternal metabolism, function of pancreatic islets and correlative changes of miRNAs. Were used 80 rats divided into two groups of 40 animals, one group designed to aging up one year after weaning, and the next group destined to experimentation at 20th day of gestation, both arranged: CTL - control, CTL-Dex - control treated with dexamethasone for 6 days, P - pregnant rats and P-Dex - pregnant rats treated with dexamethasone from 14th to 19th day of pregnancy. Pancreatic islets were collected for large-scale analysis of miRNA expression. The target genes were screened and confirmed by qPCR. Finally it was investigated the mechanism of modulation of glucose homeostasis through qPCR and Western Blot. We can be observed numerous changes resulting from therapy with DEXA in pregnancy concluded that the association of treatment to the pregnancy period modulates members of the miRNA-29 family causing an imbalance in glucose homeostasis through long-term failure in exocytotic machinery, triggered by the downregulation of the progesterone and its receptor promoting injury in the pancreatic islet remodeling process in late pregnancy.

O objetivo do presente estudo foi avaliar os perfis de metabólitos de glicocorticóides fecais através de radioimunoensaio em cachorros-vinagre (Speothos venaticus) mantidos em cativeiro e suas possíveis implicações na função reprodutiva. Duas fêmeas e quatro machos adultos, após período de condicionamento, foram marcados e tiveram suas fezes recolhidas durante 45 dias. Estes animais recebiam diariamente marcadores (corantes e miçangas) para a devida identificação das amostras fecais. O desafio com ACTH foi realizado em uma das fêmeas e mostrou o perfil reativo esperado, validando a técnica do ponto de vista fisiológico. As concentrações de metabólitos de glicocorticóides fecais para o grupo em geral variaram de 2,32 a 65,09 μ/g de fezes secas, com média e desvio-padrão de 18,11±11,33 μ/g de fezes secas, respectivamente. Quatro animais apresentaram um pico cada um, porém aparentemente, sem relação com qualquer evento estressante em particular. Não se verificou diferença significativa nos perfis de glicocorticóides fecais entre machos e fêmeas, nem entre a fêmea dominante e os outros indivíduos. Tais resultados sugerem que os animais estão bem adaptados à condição do cativeiro e provavelmente isentos ou minimamente afetados pelo estresse. A dosagem dos glicocorticóides fecais é uma ferramenta útil no monitoramento não-invasivo para avaliar a condição de estresse do cachorrovinagre, demonstrando se aspectos de manejo e fatores ambientais interferem de modo importante ou não no bem-estar animal e no potencial reprodutivo, sendo de interesse para a manutenção e conservação da espécie. / The aim of this study was to evaluate the fecal glucocorticoid metabolite profiles by radioimmunoassay in captive bush dog (Speothos venaticus) and its possible role in the reproductive function. Six adult animals (two females and four males), after training, were marked and their fecal samples were collected during 45 days. Every day the animals received markers (dye and colored plastic beads) for the appropriate identification of each sample. One female was used to the ACTH challenge and showed the expected classical response, with a significant peak one day after stimulation, therefore confirming the physiological validation. The overall fecal glucocorticoid metabolite concentrations for the whole group, ranged from 2,32 to 65,09 μ/g of dried feces, with an average and standard deviation of 18,11±11,33 μ/g of dried feces, respectively. Four animals revealed one individual peak during the observation period, however they could not be correlated with any stressful event. The fecal glucocorticoid metabolite concentrations did not show significant differences between males and females neither between the dominant female and the other animals in the study. The results suggest that the animals are well adapted to the captive conditions and likely without or minimally affected by stress. The fecal glucocorticoid metabolite dosage is a useful non-invasive tool to evaluate the bush dog stress situation and to monitor local management and environmental factors that could possibly influence the well being and reproductive success, considered both key factors for the specie maintenance and conservation.

Tanto hormônios glicocorticóides (GCs) como o gene supressor de tumor TP53, medeiam a resposta celular a uma diversidade de condições fisiológicas de estresse, sendo reguladores fundamentais do processo de vida/morte de diversos tipos celulares. A interação funcional entre estes fatores vem sendo explorada, recentemente, revelando que GCs exercem um efeito dual sobre p53. O modelo celular ST1/P7 de glioma de rato é particularmente interessante para investigar o papel de p53 na ação de GCs, já que estas linhagens apresentam respostas distintas a GCs. O tratamento com Hidrocortisona (Hy) leva as células ST1 a uma complexa reversão fenotípica tumoral→normal, enquanto as células P7 são altamente resistentes ao tratamento. Foi possível observar que a ativação de p53 por Hy ocorre apenas em células ST1, mas não em P7. Esta ativação é mediada pela indução de fosforilação da Ser15 de p53 e seu acúmulo nuclear, o que resulta no aumento de sua ligação a elementos responsivos a p53 no DNA e na sua capacidade de transativação de p53, levando a um aumento da expressão de alguns de seus genes-alvo. Contudo, o bloqueio de p53 através de siRNA não foi suficiente para alterar a resposta de células ST1 a GCs, indicando que a regulação positiva de p53 por GCs pode ser um evento secundário, mas não essencial, para a resposta anti-tumoral exercida por estes hormônios em células ST1. / Both glucocorticoid hormones (GCs) and the TP53 tumor suppressor gene mediate cellular responses to a diversity of physiological stress conditions, acting as crucial regulators of the life/death process in a wide variety of cell types. The ST1/P7 rat glioma model cell system is particularly interesting to investigate the role of p53 in the action of GCs, since these cell lines display opposite responses to GCs. Treatment with Hydrocortisone (Hy) leads ST1 cells to a complete tumoral→normal phenotypic reversion, while P7 cells are highly resistant to this treatment. It was possible to observe that activation of p53 by Hy occurs only in ST1 cells, but not in GC-resistant P7 cells. This activation is mediated by induction of phosphorylation of the Ser15 residue of p53 and its accumulation in the nucleus, resulting in increased binding of p53 to its responsive elements on the DNA and in activation of its transactivating potential, leading to increased expression of some of its target genes. However, blocking of p53 through siRNA was not sufficient to alter ST1 cells response to GCs, indicating that the positive regulation of p53 by GCs may be a secondary, non-essential, event for the anti-tumor response exerted by these hormones in ST1 cells.

L'inflammation chronique relayée par la glie activée contribue à la dégénérescence des neurones dopaminergiques (ND) au cours de la maladie de Parkinson (MP). L'étendue des dégâts cellulaires provoqués par la réaction inflammatoire dépend de l'efficacité des mécanismes régulateurs de l'inflammation. Les glucocorticoïdes endogènes sont des régulateurs puissants de l'inflammation agissant via le récepteur des glucocorticoïdes (GR). Notre équipe a récemment montré le rôle central du GR microglial dans la régulation de la mort neuronale dont la sévérité est corrélée à l'intensité et la durée de l'inflammation. Mon projet de thèse a été d'étudier le rôle des GR microglial et astrocytaire dans la régulation des réponses inflammatoires au cours de la dégénerescence des ND. Dans la première partie de ma thèse, nous avons effectué une analyse transcriptomique comparative de microglie ex vivo isolée de souris traitées au MPTP (modèle de parkinsonisme) et avons identifié des gènes régulés par le GR microglial, potentiellement impliqués dans l'inflammation chronique. Dans la deuxième partie de ma thèse, nous avons mis en évidence la régulation par le GR microglial de la mort neuronale induite par l'activation de TLR9. L'ADN mitochondrial endogène peut engendrer la mort neuronale en activant le TLR9, en cas de dysfonction du GR microglial. Dans la troisième partie de mon travail, nous avons démontré que le GR astrocytaire régule la survie des ND en modulant l'expression de gènes pro-inflammatoires et l'activité excessive des hémicanaux à connexine 43. Globalement, les GR microglial et astroglial jouent des rôles essentiels dans la régulation de l'inflammation aigue et chronique. / Chronic inflammation, mounted by activated glia, contributes to dopamine neuron (DN) loss, a major hallmark of Parkinson’s disease. It can be postulated that the extent of DN injury inflicted by inflammation is affected by the efficacy of regulatory mechanisms. The activation of hypothalamic–pituitary–adrenal axis results in release of glucocorticoids, which activate glucocorticoid receptor (GR). GR exerts adaptive responses including resolution of inflammation to restore the homeostatic state. We previously demonstrated the role of microglial GR in regulating the intensity and duration of inflammation, which influences DN survival. My thesis was centered on dissecting the roles of microglial and astrocytic GR during DN degeneration in experimental Parkinsonism. In the first part of my thesis, we conducted comparative transcriptome experiments of ex vivo microglia acutely isolated from mice treated with MPTP (model of parkinsonism) and identified genes and pathways in microglia regulated by GR, potentially involved in chronic inflammation in PD. In the second part of my thesis, we found that microglial GR regulates Toll-Like Receptor 9-induced DN loss by regulating the lysosomal compartment and demonstrated that diminished sensitivity of GR in microglia creates a permissive environment for TLR9 activation by endogenous mitochondrial DNA to become lethal for DNs. In the third part of my work, we showed that during DN degeneration, astrocytic GR regulates inflammatory gene expression and prevents connexin-43 hemichannel activity that contributes to DN loss. Overall, both microglial and astrocytic GR play essential roles in regulating chronic and acute inflammation.

<p>Persistent environmental pollutants were examined for their interaction with the glucocorticoid hormone system. The focus was placed on interference with the glucocorticoid synthesis and the glucocorticoid-signalling pathway in various <i>in vitro</i> test systems.</p><p>Several aryl methyl sulphones competitively inhibited CYP11B1 activity in mouse adrenocortical Y1 cells. The DDT metabolite, 3-methylsulphonyl-2,2’-bis(4-chlorophenyl)-1,1’-dichloroethene (3-MeSO₂-DDE) had a higher affinity to the enzyme than the endogenous substrate, 11-deoxycorticosterone. In fact, 3-MeSO₂-DDE (K_i 1.6 μM) was almost as potent as the drug metyrapone (K_i 0.8 μM), a well-known inhibitor of the enzyme. 3-MeSO₂-DDE inhibited CYP11B1 activity in human adrenocortical H295R carcinoma cells, and at higher concentrations the CYP21 activity. The human H295R cell line seems to be a useful test system for studies of enzyme activities and could be used to screen endocrine disrupting chemicals interfering with the glucocorticoid hormone synthesis.</p><p>Several chiral PCB methyl sulphones and the fungicide tolylfluanid proved to be antagonists to the glucocorticoid receptor (GR) in rat hepatoma cells and/or Chinese hamster ovary cells stable transformed with a human GR and a responsive reporter vector. The 4-methylsulphonyl-2,3,6,2’,4’,5’-hexachlorobiphenyl (4-MeSO₂-CB149) enantiomers had similar antagonistic effect on the GR. Co-exposure of substances led to additive inhibitory effects on glucocorticoid-regulated protein synthesis in rat hepatoma cells. In general, 4-substituted but not 3-substituted methylsulphonyl-PCBs interacted with the glucocorticoid hormone system.</p><p>In the environment, humans and wildlife are constantly exposed to a wide range of chemicals. Considering the effects of these substances via mechanisms of actions described in this thesis, interference of xenobiotics with the glucocorticoid hormone system deserves further attention. In conclusion, environmental pollutants can interact with the glucocorticoid hormone system <i>in vitro</i>, yet the effects of the tested substances on this hormone system remain to be established <i>in vivo.</i></p>

<p>CYP27A1 and CYP7B1 are widely expressed in various human tissues and are two key enzymes involved in the pathways for conversion of cholesterol to bile acids. Also, CYP27A1 is involved in bioactivation of vitamin D3 and CYP7B1 plays a role in 7alpha-hydroxylation of dehydroepiandrosterone and other steroids. Both enzymes have been reported to be relevant to prostate cell proliferation. The current study examines the hormonal regulation of CYP27A1 and CYP7B1.</p><p>CYP7B1 was shown to be regulated by estrogens and androgens in human embryonic kidney HEK293 and prostate cancer LNCaP cells. Quantitation of CYP7B1 mRNA in adult and fetal human tissues showed markedly higher CYP7B1 mRNA levels in fetal tissues compared with the corresponding adult ones, except in the liver. This indicates a tissue-specific, developmental regulation of CYP7B1 and suggests an important function for this enzyme in fetal life. CYP7B1 regulation by estrogens may be of importance in fetal development and in other processes where CYP7B1 is involved, including cholesterol homeostasis, cellular proliferation, and CNS function. The regulation of CYP7B1 by sex hormones also suggests an important role for CYP7B1 in balancing prostate hormone levels in human cells. </p><p>Results show that CYP27A1 can be regulated by dexamethasone, growth hormone, IGF-1, PMA, estrogens and androgens in liver-derived HepG2 cells. Dexamethasone, growth hormone and IGF-1 stimulated the promoter and endogenous activity of CYP27A1, whereas thyroid hormones and PMA inhibited CYP27A1. The regulatory effects of estrogens and androgens are different depending on the cell types. Thus, the results imply that human CYP27A1 gene is a target for estrogens and androgens, and the expression of CYP27A1 may be affected by endogenous sex hormones and pharmacological compounds with estrogenic or androgenic effects. </p><p>The mechanism for the dexamethasone-induced effect on the human CYP27A1 promoter was examined. A GRE was identified important for GR-mediated regulation of CYP27A1 transcriptional activity. </p>