Base teórica: O surgimento de bactérias multirresistentes levou a uma renovação no interesse de antigos antimicrobianos, como a polimixina B, medicamento que foi descartado no passado devido sua toxicidade. Nas últimas duas décadas, esse antimicrobiano tornou-se um dos mais importantes agentes terapêuticos para o tratamento de infecções causadas por bactérias multirresistentes; porém, ainda faltam estudos clínicos que avaliem a segurança da polimixina B, especialmente em altas doses. Objetivo: Avaliar eventos adversos graves relacionados à infusão e a falência renal nos pacientes que receberam altas doses de polimixina B intravenosa. Métodos: Realizamos um estudo de coorte retrospectivo, multicêntrico. Incluímos pacientes que receberam > 3mg/kg/ dia ou uma dose total ≥250mg/dia de polimixina B, no período de janeiro de 2013 a dezembro de 2015. Para a avaliação dos eventos relacionados a infusão, foram incluídos pacientes que receberam ≥ 1 dose de polimixina B e para avaliação de falência renal incluiu apenas os pacientes que receberam ≥ 48 horas de polimixina B. Os desfechos principais avaliados foram os eventos adversos graves relacionados à infusão de acordo com os Critérios de Terminologia Comuns para Eventos Adversos (CTCAE v4.0) e a falência renal, utilizamos os critérios RIFLE (Risk, Injury, Failure, Loss and End stage), para categorizar os diferentes graus de lesão renal aguda. As variáveis incluídas no estudo foram as variáveis demográficas (idade, sexo), as variáveis individuais (peso, comorbidades, escore de Charlson), os fatores de gravidade (internação em UTI, uso de vasopressor, uso de bloqueador neuromuscular), outras fármacos nefrotóxicas, dose de polimixina utilizada (total, média diária e em mg/kg/dia), associação com outros medicamentos, e características da infecção (sítio, isolamento microbiológico) foram avaliadas em análise bivariada. Variáveis com P≤0.2 foram incluídas uma a uma, em ordem crescente, em modelo de regressão de COX. Variáveis com P< 0.1 permaneceram no modelo final. Resultados: Foram incluídos 222 pacientes para análise de eventos graves relacionados à infusão. A dose média de polimixina B foi de 3.61± 0.97 mg/kg /dia (dose total media = 268 mg/kg). Ocorreram eventos adversos graves relacionados à infusão em dois pacientes, determinando uma incidência bruta de 0.9% (intervalo de confiança de 95%, 0.2-3.2): um 7 evento classificado como um risco ameaçador a vida (efeito adverso classe IV) ocorreu em um paciente, homem, de 40 anos, internado no Centro de Terapia Intensiva, com fibrose cística, que recebeu 3,3 mg / kg / dia de PMB e desenvolveu dor torácica súbita, dispnéia e hipoxemia, no quarto dia de tratamento e o outro evento adverso grave (classe III), ocorreu em um paciente, homem, 23 anos, internado na enfermaria, com linfoma, que recebeu 3,6 mg / kg / dia de PMB , que apresentou parestesia perioral, tonturas e dispnéia no primeiro dia de tratamento. A falência renal foi analisada em 115 pacientes que receberam ≥ 48 horas de polimixina B e que não estavam em diálise no início do tratamento com Polimixina B; Falência renal foi encontrada em 25 de 115 (21,7%) pacientes expostos as PMB. Nosso estudo identificou que 54 [47,0%] pacientes desenvolveram algum grau de lesão renal aguda, pelos critérios de RIFLE: risco, 15 (27,8%), injúria, 14 (25,9%) e falência, 25 (46,3%) dentro das categorias do RIFLE. Além disso, droga vasoativa, outros fármacos nefrotóxicos e clearance de creatinina foram fatores de risco independentes para falência renal. Nem a dose diária de polimixina B ajustada para o peso corporal, nem a dose diária total foram associadas a falência renal. A mortalidade intra-hospitalar foi de 60% (134 pacientes): 26% (57 pacientes) morreram durante o tratamento e nenhum óbito foi durante a infusão. Conclusão: Altas doses de polimixina B no tratamento de infecções por bactérias gramnegativo apresentaram incidência baixa de eventos adversos agudos no nosso estudo e incidência de nefrotoxicidade elevadas, mas semelhantes a alguns estudos prévios com doses usuais”. Portanto, doses elevadas podem ser testadas em ensaios clínicos, objetivando melhorar os desfechos dos pacientes gravemente doentes com infecções por bactérias multirresistentes e minimizar o surgimento da resistência a polimixina B. / Background: The emergence of multiresistant bacteria has led to a renewal in the interest of old antimicrobials, such as polymyxin B, a drug that has been discarded in the past due to its toxicity. However, at this time, this antimicrobial has become one of the most important therapeutic agents for the treatment of infections caused by multiresistant bacteria but there is still a lack of clinical studies that evaluate the safety of polymyxin B, especially in relation to the use of high doses. This strategy, high doses, may be necessary in the fight against Gramnegative bacteria with a high minimum inhibitory concentration. Patients and methods: A retrospective, multicenter cohort study; the period evaluated was from January 2013 to December 2015, included patients who received > 3mg/kg/day or a total dose of ≥250mg/day of polymyxin B. The study included the evaluation of infusion-related events, patients who received ≥ 1 dose of polymyxin B and patients who received ≥ 48 hours of PMB were included for evaluation of renal failure. Major outcomes were serious adverse events related to infusion according to the Common Terminology Criteria for Adverse Events (CTCAE v4.0) and categorized renal failure by the RIFLE criteria (Risk, Injury, Failure, Loss, End stage). Factors potentially related to nephrotoxicity or mortality in 30 days were: demographic variables (age, sex), individual variables (weight, comorbidities, Charlson score), severity factors (ICU admission, use of vasopressor, use of Neuromuscular blocker), nephrotoxicity (other nephrotoxic drugs), polymyxin dose (total, daily mean and mg / Kg / day), association of drugs and infection characteristics (site and microbiological isolate) were evaluated in bivariate analysis. Variables with P≤0.2 were included one by one, in ascending order, in a Cox regression model. Variables with P <0.1 remained in the final model. Results: Two of 222 patients presented a severe infusion-related adverse event during PMB infusion, resulting in a crude incidence of 0.9% (95% Confidence Interval [CI], 0.2-3.2); one was classified as life-threatening and one classified as severe (crude incidence of each adverse event, 0.45%; 95% CI, 0.08-2.5). The life-threatening adverse effect occurred in an ICU patient (crude incidence among ICU patients, 0.67%; 95% CI, 0.12-3.7), a 40-years old male with cystic fibrosis who used 3.3 mg/kg/day of PMB and developed sudden thoracic pain, dyspnea and hypoxemia, in the fourth day of treatment. The severe adverse effect occurred in a non-ICU patient (crude incidence among non-ICU patients, 1.3%; 95% CI, 0.2-7.2), a 23- years old male with lymphoma exposed to 3.6 mg/kg/day of PMB, who presented perioral 9 paresthesia, dizziness and dyspnea in the first day of treatment. Renal failure was analysed in 115 patients who received ≥48 hours of PMB and who were not previously in dialysis. A total of 54 [47.0%] patients developed any degree of AKI, categorised as Risk [27.8%]; Injury [25.9%] and Failure [46.3%]) and 25 of 115 (21.7%) patients presented renal failure Vasoactive drug, concomitant nephrotoxic drugs and baseline creatinine clearance were independent risk factors for renal failure. Neither PMB daily dose scaled by body weight nor total daily dose were associated with renal failure. In-hospital mortality was 60% (134 patients): 26% (57 patients) occurred during treatment and none during infusion. Conclusion: Results suggest that high dose regimens have similar safety profile of usual doses and could be further tested in clinical trials assessing strategies to improve patients’ outcomes and minimize the emergence of PMB resistance.

Neuropatia é a complicação mais comum e mais debilitante da Diabetes Mellitus, a longo prazo presente em mais de 50% dos pacientes que possuem a doença. A hiperglicemia induz estresse oxidativo nos neurônios de diabéticos acarretando a ativação de múltiplas vias bioquímicas, as quais são potenciais alvos terapêuticos para a neuropatia diabética. Está claro que compostos carbonil reativos são mediadores glicotóxicos do estresse oxidativo através da formação de produtos finais de glicação avançada como resultado direto da hiperglicemia. Metilglioxal e glicolaldeído são compostos carbonil reativos inevitavelmente produzidos pelo metabolismo, os quais são encontrados em maior quantidade em situações de hiperglicemia. Recentemente, tem sido dada muita atenção para o envolvimento de espécies reativas na toxicidade do metilglioxal e do glicolaldeído, e tem-se demonstrado que essas glicotoxinas têm potencial para induzir estresse oxidativo, parar o crescimento celular e promover morte por apoptose ou necrose. O metilglioxal e o glicolaldeído interagem com grupamentos sulfidril de moléculas de glutationa e de enzimas, inibindo sua atividade; entretanto, os mecanismos moleculares relacionados aos efeitos tóxicos dessas glicotoxinas e as vias pelas quais elas levam a formação de espécies reativas não estão completamente elucidados. Neste estudo nós buscamos esclarecer a relação entre o metabolismo do metilglioxal e do glicolaldeído e a produção de espécies reativas, e investigamos as possíveis rotas de morte celular envolvidas. Utilizamos a linhagem celular de neuroblastoma humano SH-SY5Y diferenciada, pois este é um modelo neuronal bem caracterizado para estudos de compostos neurotóxicos. Nós avaliamos a produção de espécies reativas induzida por metilglioxal e glicolaldeído através da técnica da diclorofluoresceína, e avaliamos, também, seus efeitos sob o conteúdo de glutationa celular. Além disso, investigamos a ativação das caspase-3, -8 e -9 e a contribuição de diferentes sistemas peroxidases (glutationa-redutase e a tioredoxina-redutase), na defesa neuronal contra essas glicotoxinas. Como resultados encontramos que o tratamento com ambas glicotoxinas rapidamente provocou um aumento na produção de espécies reativas e diminuição do conteúdo de glutationa, com concomitante ativação das caspases-8 e -9 e, posteriormente, também houve ativação da caspase-3 pelo tratamento com metilglioxal. Vimos que a tioredoxina-redutase possui um papel mais importante na defesa celular contra a toxicidade do metilglioxal do que contra o glicolaldeído, enquanto que a glutationa-redutase tem papel semelhante na defesa celular contra ambas glicotoxinas. Nossos resultados demonstraram que o estresse oxidativo é um importante mecanismo da toxicidade do metilglioxal e do glicolaldeído nas células diferenciadas SHSY5Y e, que enzimas redutoras de grupamentos sulfidril contribuem de diferentes formas na defesa celular contra cada uma dessas glicotoxinas. / Neuropathy is the most common and debilitating complication of Diabetes Mellitus present in more than 50% of the patients with long-standing disease. Hyperglycemia induces oxidative stress in neurons from diabetic patients and results in activation of multiple biochemical pathways. These activated pathways are a major source of damage and are potential therapeutic targets in diabetic neuropathy. A large body of evidence has implicated reactive carbonyl compounds as glycotoxic mediators of oxidative stress by forming advanced glycation endproducts as a direct result of hyperglycemia. Methylglyoxal and glycolaldehyde are reactive carbonil compounds inevitably produced by the metabolism, but they are found in increased rates under hyperglycemia condition. Recently, the attention has been focused on the involvement of reactive species in methylglyoxal and glycolaldehyde toxicities, resulting in oxidative stress and leading to cell growth arrest, apoptotic or necrosis death. These glycotoxins interact with sulfhydryl-groups of glutathione molecules enzymes, inhibiting their activity; however, the molecular mechanism underlying methylglyoxal and glycolaldehyde cytotoxic effects and reactive species generation are not fully understood. In this study we have pursued to establish the role of methylglyoxal and glycolaldehyde metabolisms and reactive species production, and have looked for the possible death routes involved with the toxic effects of these glycotoxins. Here we used the differentiated human neuroblastoma SH-SY5Y cells as neuronal experimental model to investigate the pathological effects of various neurotoxic compounds. We have evaluated the methylglyoxal and glycolaldehyde capacity to reactive species generation by dichlorofluorescein assay and their effects upon cellular glutathione content. Also, we have assessed the caspase-3, -8 and -9 activation and the contribution of different peroxidases systems (glutathione reductase and thioredoxin reductase) in the neuronal defense against methylglyoxal and glycolaldehyde cytotoxicities. We found that both glycotoxins promptly provoke reactive species generation and decrease the cell glutathione content, as well induce caspase-8 and -9 activation. Later caspase-3 activation was found in methylglyoxal treatment. We demonstrate that thioredoxin reductase has a most important role in cell defense against methylglyoxal toxicity than against glycolaldehyde, meanwhile there is no difference in the glutathione reductase role. Our results show that oxidative stress is an important mechanism in the methylglyoxal and glycolaldehyde toxicities and sulfhydryl reductases contributes differently in the cellular defense against these glycotoxins.

L'étude de l'impact des facteurs environnementaux sur les effets à long-terme des psychostimulants a montré que des facteurs négatifs, comme le stress, augmentent le risque de développer une addiction, alors que des facteurs positifs, comme l'exposition à des conditions stimulantes, le réduisent. Une partie de cette thèse a consisté à rechercher les mécanismes neurobiologiques et cellulaires qui sous-tendent cette influence environnementale. Ainsi, l'exposition d'animaux à un environnement enrichi (EE), qui procure des conditions stimulantes, diminue leur niveau d'anxiété, un effet qui serait en partie lié à la régulation de gènes appartenant au système cannabinoïde endogène (SCE) dans des régions impliquées dans la réactivité au stress (article 1). Par ailleurs, nos travaux ont mis en évidence des limites de l'exposition à l'EE : quand celle-ci est interrompue, ses effets bénéfiques sont perdus et la vulnérabilité à la cocaïne est même augmentée. Ceci s'expliquerait par l'apparition d'un état émotionnel négatif, associé à une activation du facteur CREB dans l'amygdale étendue, une région carrefour entre la récompense et le stress (article 2). Nous nous sommes aussi intéressés à la toxicité de la méthamphétamine et à sa modulation par le SCE, pour lequel des propriétés neuroprotectives avaient déjà été suggérées. Ainsi, une stimulation pharmacologique du SCE permet de prévenir la neurotoxicité dopaminergique induite par la méthamphétamine (article 3). Nos résultats soulignent la complexité d'utilisation des manipulations environnementales et mettent en lumière les capacités protectives du SCE contre la dépendance et la neurotoxicité engendrées par les psychostimulants. / Studies of the impact of environmental factors on the long-term effects of psychostimulants have shown that negative factors, such as stress, increase the risk of developing drug addiction, while positive factors, such as exposure to stimulating conditions, reduce it. The first aim of this thesis work was to look for the neurobiological and cellular mechanisms that underlie this environmental influence. We found that exposure of animals to stimulating enriched environments (EE) reduces anxiety levels, an effect that may be partly related to the regulation of genes belonging to the endogenous cannabinoid system (ECS) in regions involved in stress reactivity (Article 1). In addition, our work has highlighted some limitations of the exposure to EE since discontinuation of enrichment results not only in the loss of its beneficial effects but also in increased vulnerability to cocaine. This effect is associated with emotional distress associated and changes in the activity of the transcription factor CREB in the extended amygdala, an interface region between reward and stress processes (Article 2). We also investigated whether ECS, for which neuroprotective properties have already been suggested, could reduce the brain toxicity induced by methamphetamine. We found that pharmacological stimulation of ECS provides protection against the methamphetamine-induced dopaminergic neurotoxicity (Article 3). Our results highlight the complex consequences of environmental conditions on brain and behavior and highlight the protective role of ECS against both addiction and neurotoxicity induced by psychostimulants.

Les maladies neurodégénératives sont des pathologies progressives qui affectent le système nerveux, entraînant la mort des cellules nerveuses. Les plus connues et les plus fréquentes sont la maladie d’Alzheimer et la maladie de Parkinson, mais il en existe d’autres. Toutes ces maladies se caractérisent par la perte progressive de neurones dans des régions plus ou moins localisées du système nerveux, entraînant des complications cognitives, motrices ou perceptives. La maladie de Parkinson (MP) est causée par la dégénérescence de neurones dopaminergiques de la substance noire et de leurs terminaisons nerveuses qui normalement libèrent la dopamine dans le striatum. Les deux principaux facteurs de risque communs aux maladies neurodégénératives sont l’âge et le stress oxydant. Le stress oxydant joue un rôle central dans la physiopathologie de la MP, mais les mécanismes impliqués dans le contrôle de ce stress dans les cellules dopaminergiques ne sont pas totalement élucidés. De nombreuses études montrent que les sélénoprotéines jouent un rôle central dans le contrôle de l'homéostasie redox et la protection cellulaire, mais la contribution précise des membres de cette famille de protéines au cours des maladies neurodégénératives est encore peu connue. Des études antérieures de l’Unité ont permis de découvrir le rôle essentiel d’une nouvelle sélénoprotéine, la sélénoprotéine T (SelT) dans les processus de différenciation neuronale, mais le rôle de cette sélénoprotéine dans les processus neurodégénératifs n’était pas connu. Nous avons montré d'abord que la SelT dont l’invalidation génétique est létale pendant l'embryogenèse, exerce une puissante activité oxydoréductase de type thiorédoxine. Dans un modèle cellulaire de neurones dopaminergiques, représenté par les cellules de neuroblastome SH-SY5Y, la modification de l’expression de la SelT affecte le niveau du stress oxydant et la survie cellulaire. Le traitement de souris sauvages par des neurotoxines ciblant les neurones dopaminergiques telles que le 1-méthyl-4-phényl-1,2,3,6-tétrahydropyridine (MPTP) ou la roténone induit une expression massive de la SelT dans la voie nigro-striée, suggérant que la SelT pourrait protéger ces neurones dans les conditions de dégénérescence. En revanche, ce même traitement administré chez les souris invalidées pour la SelT dans le cerveau provoque un syndrome parkinsonien, avec apparition de symptômes moteurs confirmant donc que la présence de la SelT doit participer à la protection des neurones dopaminergiques dans des conditions mimant la MP. Les symptômes moteurs observés sont associés à un stress oxydant et une dégénérescence marquée des neurones dopaminergiques. De même, nous avons observé une diminution de la forme active de la tyrosine hydroxylase, ce qui se traduit par des taux de dopamine réduits dans le striatum des souris invalidées et traitées par les neurotoxines. Ces données montrent que la SelT est essentielle à la survie et à la fonctionnalité des neurones dopaminergiques in vitro et in vivo dans les conditions de neurodégénérescence mimant la MP. Enfin, chez les patients souffrant de la MP, nous avons observé une augmentation considérable de la SelT au niveau du caudate-putamen mais pas d’autres structures cérébrales. L’ensemble de ces résultats révèle l'activité d'une nouvelle enzyme de type thiorédoxine qui protège les neurones dopaminergiques contre le stress oxydant et empêche l’apparition précoce de symptômes moteurs sévères chez les modèles animaux de la MP. Nos données indiquent que des sélénoprotéines telles que la SelT dont les taux sont élevés chez des parkinsoniens, jouent un rôle crucial dans la protection des neurones dopaminergiques contre le stress oxydant et la mort cellulaire ouvrant ainsi la voie au développement de nouvelles stratégies de neuroprotection ciblant ces protéines dans la MP. / Neurodegenerative diseases are progressive pathologies that affect the nervous system, causing the death of nerve cells. The best known and most frequent are Alzheimer's and Parkinson's disease, but there are others. All these diseases are characterized by the progressive loss of neurons of the nervous system, leading to cognitive, motor or perceptual complications. Parkinson's disease (PD) is caused by the degeneration of dopaminergic neurons of the substantia nigra and their nerve endings that normally release dopamine into the striatum. The two main risk factors common to neurodegenerative diseases are age and oxidative stress. Oxidative stress plays a central role in the pathophysiology of PD, but the mechanisms involved in controlling this stress in dopaminergic cells are not fully elucidated. Many studies show that selenoproteins play a central role in the control of redox homeostasis and cell protection, but the precise contribution of members of this family of proteins during neurodegenerative diseases is still unknown. Previous studies performed in our laboratory have uncovered the essential role of a new selenoprotein, selenoprotein T (SelT) in the processes of neuronal differentiation, but the role of this selenoprotein in neuroprotection was not known. We first showed that SelT, whose gene knock-out is lethal during embryogenesis, exerts a potent thioredoxin-like oxidoreductase activity. In a cellular model of dopaminergic neurons, represented by SH-SY5Y neuroblastoma cells, modification of SelT expression affects the level of oxidative stress and cell survival. Treatment of wild-type mice by neurotoxins targeting dopaminergic neurons such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or rotenone induced massive expression of SelT in the nigro-striatal system, suggesting that SelT could protect these neurons under conditions of degeneration. On the other hand, this same treatment given in mice invalidated for SelT in the brain caused a parkinsonian syndrome with the appearance of motor symptoms, thus confirming that the presence of SelT must participate in the protection of dopaminergic neurons under conditions mimiking PD. The observed motor symptoms are associated with oxidative stress and marked degeneration of dopaminergic neurons. Similarly, we observed a decrease in the active form of tyrosine hydroxylase, resulting in reduced dopamine levels in the striatum of invalidated and neurotoxin-treated mice. These data show that SelT is essential for the survival and functionality of dopaminergic neurons in vitro and in vivo under the conditions of neurodegeneration mimicking PD. Finally, in patients with PD, we observed a considerable increase in SelT levels in the caudate-putamen but not in other cerebral structures. Together, these results uncovered the activity of a novel thioredoxin-like enzyme that protects dopaminergic neurons against oxidative stress and prevents the early onset of severe motor symptoms in animal models of PD. Our data indicate that selenoproteins such as SelT, whose levels are increased in PD play a crucial role in protecting dopaminergic neurons against oxidative stress and cell death, thus paving the way for the development of new neuroprotection strategies targeting these proteins in PD.

No description available.

The synthetic cathinones, 3,4- methylenedioxypyrovalerone (MDPV), 4-methylmethcathinone (mephedrone), and 3,4- methylenedioxymethcathinone (methylone), gained worldwide notoriety as the psychoactive components of ‘bath salts;’ a marketing term used to circumvent federal drug laws and permit their legal sale. Previous studies have shown that these drugs share pharmacological characteristics with cocaine and the amphetamines, however, descriptions of their neurotoxic properties are limited. Moreover, while forensic analysis has revealed that the most frequently abused bath salts ‘brands’ contain binary and ternary mixtures of MDPV, mephedrone, and methylone, the majority of preclinical research has focused on explicating the individual effects of these drugs. Therefore, the present dissertation aimed to address this limitation and characterize the acute and chronic effects of combined synthetic cathinone exposure on dopaminergic tone in mesolimbic and nigrostriatal brain regions. To accomplish this, male Swiss-Webster mice were administered MDPV, mephedrone, and methylone, individually or concomitantly, 1 time or 7 times over the course of two weeks and the corresponding effects of each treatment on mesolimbic and nigrostriatal brain tissue levels of dopamine (DA) and DA metabolites were analyzed using a high performance liquid chromatography – electrochemical detection (HPLC-ECD) assay. Additionally, motor-stimulant activity was evaluated after both dosing regimens using locomotor activity assays, while immunoblot and immunostaining techniques were used to evaluate the chronic effects of co-synthetic cathinone exposure on tissue levels of tyrosine hydroxylase (TH), dopamine transporter (DAT), monoamine oxidase B (MAO-B), catechol-O-methyltransferase (COMT), and glial fibrillary acidic protein (GFAP). Results from these studies provide evidence of a significant pharmacological interaction among major bath salt constituents, MDPV, mephedrone, and methylone. This was observed acutely as enhanced DA responses and chronically as functional toxicity at the DA synapse. Furthermore, such interactions may contribute to the deleterious effects reported by bath salt users. Together, these findings have shown that the composition of bath salts preparations can significantly influence their psychostimulant and toxic effects, substantiating the importance of modeling bath salts as drug mixtures.

No description available.

<p>  </p> <p>Perfluoroalkyl substances (PFAS) are synthetic chemicals that are composed of fluorinated aliphatic chains and are widely used in industrial and consumer products. These chemicals are very stable and persist in the environment. Due to concerns linked with longer chain PFAS, shorter chain chemicals are being used as replacements. There are limited human health data regarding the shorter chain chemicals. In addition, these alternatives are persistent in the environment similar to the longer chain PFAS. The main objective of this dissertation was to assess developmental toxicity of the shorter chain PFAS or shorter chain PFAS with chemical modifications represented by perfluorobutanoic acid (PFBA, C4), perfluorohexanoic acid (PFHxA, C6), perfluorobutane sulfonate (PFBS, C4), and perfluoro-2-proxypropanoic acid (GenX, C6). Overall, the results showed that chain length and functional group are determinants of toxicity of PFAS. All tested PFAS induced one or more developmental adverse outcome, but the effects of each chemical are unique, warranting further studies to address the toxicity of the replacement PFAS. </p>

Methamphetamine (MA) is a well-known, easily accessible and powerful psychostimulant, and its abuse has become a global problem. MA abuse affects millions of people worldwide and places an enormous burden on public healthcare resources. Documented consequences of MA abuse include cardiotoxic, neurotoxic and teratogenic effects, as well as long-term consequences of chronic abuse including affective disorders such as schizophrenia and major depressive disorder (MDD). MDD is a highly prevalent mood disorder in both adults and children, documented to contribute to approximately 850 000 suicides annually. This disorder is projected to become the 2nd leading disease of global burden by 2020, preceded only by ischemic heart disease. Depressive-like behaviour is documented as a symptom of chronic MA abuse and particularly during extensive MA withdrawal. Also, MA abuse during pregnancy is documented to cause neurodevelopmental changes that persist into later life. However, current understanding thereof is limited and warrants further investigation of the effects of early-life exposure to MA on outcome in adulthood, particularly in terms of mood disorders. The aim of the current study was to determine the effect of chronic exposure to MA on the depressive-like behaviour later in life in stress-sensitive (Flinders Sensitive Line) and control (Flinders Resistant Line) rats. Rats were exposed during one of the following natal day (ND) age groups: prenatal (ND-13 to ND+02), postnatal (ND+03 to ND+18), prepuberty (ND+19 to ND+34) or puberty (ND+35 to ND+50). These age groups represent different stages in neurodevelopment, as also seen in humans. For prenatal exposure, pregnant dams received 5 mg/kg daily subcutaneously (s.c.), and pups from postnatal, prepuberty and puberty age groups received an escalating dose regimen to simulate “binge-dosing” commonly seen in humans abusing MA. After MA exposure, rats were housed normally until behavioural testing on postnatal day 60 (ND+60), which included the novel object recognition test (NOR), open field test (OFT) and forced swim test (FST), measuring cognitive function, locomotor activity and depressive-like behaviour respectively. The FST data showed increased immobility behaviour of saline-treated FSL rats relative to that of FRL rats, in line with previous data validating FSL rats as a genetic rodent model of depression. Practically significant MA-induced increases in immobility behaviour were observed in all FSL and FRL treatment groups in the FST, reaching statistical significance in prenatally treated FRL rats, and in postnatally, prepuberty and puberty treated FSL rats. The data suggest that early-life MA exposure may alter neurodevelopment to predispose the rats to display depressive-like behaviour in early adulthood, and suggests that this detrimental effect of MA may be more expressed in stress-sensitive rats. Furthermore, all FSL groups plus prenatally and puberty treated FRL rats revealed practically and statistically significant decreases in swimming behaviour in the FST, whereas decreases in swimming behaviour in prepuberty treated FRL rats were practically significant but did not reach statistical significance. These data suggest that MA-induced depressive-like behaviour in FSL rats may be related to impaired serotonergic neurotransmission, and that this appears to be more robust in FSL rats. Climbing behaviour in the FST was generally not altered by early-life MA exposure, with a notable exception being a practically and statistically significant increase in puberty treated FRL rats. These data suggest that in general early-life MA exposure does not affect noradrenergic neurotransmission in early adulthood, except when normal rats were treated at puberty. The reason for the latter observation is not clear. The data from the NOR test revealed no discernible trends of MA-induced effects on memory and cognition, except for a small albeit practically significant increase in exploration time in prepuberty treated FRL rats and a practically and statistically significant decrease in exploration time in puberty-treated FRL rats. Lastly, locomotor activity in the OFT was mostly unaffected by MA treatments, except for practically significant decreases in locomotor activity in postnatally-and prepuberty-treated FRL rats and practically and statistically significant decreases in locomotor activity of prepuberty treated FSL rats. Altered locomotor activity is therefore not expected to explain any of the immobility results of the FST. In final conclusion, the study confirms that early-life MA exposure results in a depressogenic effect later in life in stress-sensitive (FSL) and control (FRL) rats, but appears to be more robust in stress-sensitive animals. Furthermore the data suggest that long-lasting MA-induced depressogenic effects may relate to impaired serotonergic neurotransmission. / MSc (Pharmacology), North-West University, Potchefstroom Campus, 2014

Methamphetamine (MA) is a well-known, easily accessible and powerful psychostimulant, and its abuse has become a global problem. MA abuse affects millions of people worldwide and places an enormous burden on public healthcare resources. Documented consequences of MA abuse include cardiotoxic, neurotoxic and teratogenic effects, as well as long-term consequences of chronic abuse including affective disorders such as schizophrenia and major depressive disorder (MDD). MDD is a highly prevalent mood disorder in both adults and children, documented to contribute to approximately 850 000 suicides annually. This disorder is projected to become the 2nd leading disease of global burden by 2020, preceded only by ischemic heart disease. Depressive-like behaviour is documented as a symptom of chronic MA abuse and particularly during extensive MA withdrawal. Also, MA abuse during pregnancy is documented to cause neurodevelopmental changes that persist into later life. However, current understanding thereof is limited and warrants further investigation of the effects of early-life exposure to MA on outcome in adulthood, particularly in terms of mood disorders. The aim of the current study was to determine the effect of chronic exposure to MA on the depressive-like behaviour later in life in stress-sensitive (Flinders Sensitive Line) and control (Flinders Resistant Line) rats. Rats were exposed during one of the following natal day (ND) age groups: prenatal (ND-13 to ND+02), postnatal (ND+03 to ND+18), prepuberty (ND+19 to ND+34) or puberty (ND+35 to ND+50). These age groups represent different stages in neurodevelopment, as also seen in humans. For prenatal exposure, pregnant dams received 5 mg/kg daily subcutaneously (s.c.), and pups from postnatal, prepuberty and puberty age groups received an escalating dose regimen to simulate “binge-dosing” commonly seen in humans abusing MA. After MA exposure, rats were housed normally until behavioural testing on postnatal day 60 (ND+60), which included the novel object recognition test (NOR), open field test (OFT) and forced swim test (FST), measuring cognitive function, locomotor activity and depressive-like behaviour respectively. The FST data showed increased immobility behaviour of saline-treated FSL rats relative to that of FRL rats, in line with previous data validating FSL rats as a genetic rodent model of depression. Practically significant MA-induced increases in immobility behaviour were observed in all FSL and FRL treatment groups in the FST, reaching statistical significance in prenatally treated FRL rats, and in postnatally, prepuberty and puberty treated FSL rats. The data suggest that early-life MA exposure may alter neurodevelopment to predispose the rats to display depressive-like behaviour in early adulthood, and suggests that this detrimental effect of MA may be more expressed in stress-sensitive rats. Furthermore, all FSL groups plus prenatally and puberty treated FRL rats revealed practically and statistically significant decreases in swimming behaviour in the FST, whereas decreases in swimming behaviour in prepuberty treated FRL rats were practically significant but did not reach statistical significance. These data suggest that MA-induced depressive-like behaviour in FSL rats may be related to impaired serotonergic neurotransmission, and that this appears to be more robust in FSL rats. Climbing behaviour in the FST was generally not altered by early-life MA exposure, with a notable exception being a practically and statistically significant increase in puberty treated FRL rats. These data suggest that in general early-life MA exposure does not affect noradrenergic neurotransmission in early adulthood, except when normal rats were treated at puberty. The reason for the latter observation is not clear. The data from the NOR test revealed no discernible trends of MA-induced effects on memory and cognition, except for a small albeit practically significant increase in exploration time in prepuberty treated FRL rats and a practically and statistically significant decrease in exploration time in puberty-treated FRL rats. Lastly, locomotor activity in the OFT was mostly unaffected by MA treatments, except for practically significant decreases in locomotor activity in postnatally-and prepuberty-treated FRL rats and practically and statistically significant decreases in locomotor activity of prepuberty treated FSL rats. Altered locomotor activity is therefore not expected to explain any of the immobility results of the FST. In final conclusion, the study confirms that early-life MA exposure results in a depressogenic effect later in life in stress-sensitive (FSL) and control (FRL) rats, but appears to be more robust in stress-sensitive animals. Furthermore the data suggest that long-lasting MA-induced depressogenic effects may relate to impaired serotonergic neurotransmission. / MSc (Pharmacology), North-West University, Potchefstroom Campus, 2014