O labirinto em cruz elevado (LCE) é um dos testes de ansiedade mais empregados na atualidade. Uma característica intrigante desse modelo é a abolição dos efeitos ansiolíticos dos benzodiazepínicos como resultado de uma única experiência prévia no labirinto. Este fenômeno, chamado “one-trial tolerance” (OTT), tem recebido considerável atenção e dentre as diversas hipóteses sugeridas para explicá-lo, podemos citar uma alteração no estado emocional do animal, perda do conflito motivacional e habituação do comportamento exploratório. A descoberta de que benzodiazepínicos reduzem a atividade de neurônios serotoninérgicos, associada a resultados obtidos em testes de conflito que mostram que antagonistas serotoninérgicos podem causar efeitos ansiolíticos comparáveis aos benzodiazepínicos, levaram à noção de que a serotonina (5-HT) é o principal neurotransmissor envolvido na ansiedade. No entanto, com o uso de outros modelos animais, o envolvimento da 5-HT tem sido questionado, ao mesmo tempo em que outras aminas biogênicas, como a noradrenalina (NA), têm sido implicadas na modulação da ansiedade. Nesse estudo procedemos uma análise etofarmacológica de ratos tratados com o antagonista serotoninérgico cetanserina e os antidepressivos fluoxetina e desipramina submetidos ao teste e reteste no LCE. Esses antidepressivos aumentam os níveis sinápticos de 5-HT e NA, respectivamente. Além disso, foram medidas as concentrações plasmáticas de corticosterona - considerada um índice confiável de medo e estresse - de ratos expostos à sessão única ou repetida no LCE. As drogas administradas antes da reexposição ao labirinto não produziram efeitos ansiolíticos, replicando o fenômeno da OTT comumente associado aos benzodiazepínicos. Por outro lado, a cetanserina administrada antes da primeira sessão produziu um efeito ansiolítico, mas o tratamento subcrônica com fluoxetina e desipramina não alterou o comportamento exploratório dos animais no LCE. Ratos submetidos à sessão única ou repetida no labirinto apresentaram um aumento similar dos níveis plasmáticos de corticosterona, indicando que a reexposição ao LCE apresenta propriedades aversivas e a OTT deve estar mais relacionada à uma alteração no estado emocional do animal do que à habituação do comportamento exploratório. / The elevated plus-maze (EPM) is currently one of the most used test of anxiety. An intriguing feature of this model is the abolition of the anxiolytic effect of benzodiazepines by a single previous experience with the maze. This phenomenon, termed one-trial tolerance (OTT), has received considerable attention and among the several hypotheses suggested to explain it, we can listed a shift in the animal emotional state, lack of motivational conflict and exploratory behavior habituation. The discovery that benzodiazepines reduce the activity of serotonergic neurons, associated with results obtained in conflict tests showing that serotonergic antagonists may cause anxiolitic-like effects comparable to the benzodiazepines, has led to the notion that the serotonin (5-HT) is the most important neurotransmitter involved in the anxiety. Nevertheless, with the use of other animal models, the 5-HT involvement has been questioned, at the same time that other biogenic amines, such as noradrenalin (NA), have been implicated in the anxiety modulation. In this study, we carried out an ethopharmacological analysis of rats under treatment with the serotonergic antagonist ketanserin and the antidepressants fluoxetine and desipramine submitted to the test and retest in the EPM. These antidepressants increase the synaptic levels of 5-HT and NA, respectively. Besides, plasma corticosterone concentrations - considered a reliable index of fear and stress - of rats exposed once or twice to the EPM were measured. The drugs injected before the retest in the EPM did not produce anxiolytic effects, replicating the OTT phenomenon generally associated with the benzodiazepines. On the other hand, ketanserin injected before the first session produced an anxiolytic effect but the subchronic treatment with fluoxetine and desipramine did not change the exploratory behavior of the animals in the EPM. Naive and experienced rats show a similar increase in the plasma corticosterone levels when submitted to the EPM, indicating that the retest to EPM has aversive properties and the OTT may be more related to a change in the emotional state of the animal than to a habituation of the exploratory behavior.

O estresse é uma realidade na produção avícola mundial. Sabe-se que ambientes estressores prejudicam o bem-estar, os parâmetros produtivos e a imunidade de frangos de corte. Sabe-se, também, que o estresse por calor diminui a atividade de macrófagos em frangos de corte e, que existem, inúmeros estressores ambientais que insidem sobre a produção animal e podem aumentar a susceptibilidade às doenças. A Salmonella spp. é uma das maiores zoonoses do mundo, causando mais de 1 bilhão de casos de infecção. Nesse sentido, o presente trabalho analisa os efeitos do estresse por calor (31±1°C) sobre os índices zootécnicos, a imunidade, a invasão bacteriana e a integridade intestinal em frangos de corte infectados com Salmonella enteritidis; os dados obtidos foram discutidos dentro de uma perspectiva neuroimune. Os frangos foram divididos em quatro grupos: 1) Controle (C); 2) Estresse por Calor a 31±1 °C (HS31°C); 3) Controle infectados com Salmonella enteritidis (Controle Positivo [PC]) e; 4) Estresse por calor a 31±1 °C e infectados com Salmonella (PHS31°C). Nossos resultados mostraram que o estresse por calor em uma situação de infecção experimental por Salmonella enteritidis (grupo PHS31°C) 1) diminuiu os índices zootécnicos; especificamente, diminuiu o ganho de peso, consumo de alimento e a conversão alimentar; 2) diminuiu os níveis plasmáticos de INF-γ e IgA; 3) diminuiu a expressão de, IL-6 e IL-12 em baço e diminui IL1- β, IL-10 e TGF-β em tonsila cecal; 4) diminuiu a expressão de AvBD-4 e AvBD-6 em tonsila cecal e; 5) diminuiu a expressão de TLR-2 em baço e tonsila cecal. Observamos, também, 6) aumento dos níveis séricos de corticosterona nos animais dos grupos HS31°C e PHS31°C e; 7) piora no quadro de enterite produzida pela Salmonella enteritidis, quando os animais foram estressados por calor, caracterizando-se uma enterite moderada ao longo de todo o intestino delgado. Finalmente, 8) observamos que o estresse por calor aumentou a migração de Salmonella enteritidis para baço das aves do grupo PHS31°C, porém esse aumento não foi observado no fígado; observamos, também, presença de Salmonella na medula osssea dos animais estressados e infectado com essa bactéria. Os dados obtidos sugerem que a somatória dos fatores estresse por calor e infecção por Samonella prejudicou os parâmetros produtivos, a integridade intestinal, a imunidade e, em especial a ativação e atividade de macrófagos, possibilitando um aumento da migração de Salmonella enteritidis para o baço e medula óssea dos frangos de corte. Neste sentido, o estresse por calor teria prejudicado a qualidade da barreira imune intestinal, via ativação do eixo HPA e aumento dos níveis de corticosterona, diminuindo a imunidade inata proporcionando a migração das bactérias patogênicas através da mucosa intestinal para o baço e a medula óssea das aves estressadas. / Stress is a reality in the world poultry production. Environmental stressors impair both welfare, performance parameters and immunity in broiler chickens. Heat stress decreases macrophage activity in broiler chickens and many environmental stressors that impact animal production increases animal\'s susceptibility to diseases. Samonella spp is one of the most endemic zoonotic diseases of the world, inducing more than 1 billion infection cases per year. In this way, we studied the effects of 31±1°C heat stress on performance parameters, immunity, bacteria invasion and intestinal integrity in broiler chickens experimentally infected with Salmonella enteritidis; the data were discussed under a neuroimmune perspective. The broiler chickens were divided into four different groups: 1) Control group (C); 2) 31±1 °C heat stressed group (HS31°C); 3) Control group infected with Salmonella enteritidis Positive control (PC) and; 4) 31±1 °C heat stressed and Salmonella enteritidis infected group (PHS31°C). We showed the heat stress applied in the course of Salmonella enteritidis infection (PHS31°C group) decreased poultry performance parameters; specifically, it decreased the body weight gain, the feed intake and the food conversion; 2) decresead INF-γ and IgA plasmatic levels; 3) decreased the mRNA expression of IL-6 and IL- 12 in spleen and the mRNA expression of IL1-β, IL-10 and TGF-β in cecal tonsil; 4) decreased the mRNA expression of AvBD-4 and AvBD-6 in cecal tonsil and; 5) decreased the mRNA expression of TLR-2 in spleen and cecal tonsil. We also observed 6) an increase in corticosterone serum levels in the animals of the HS31°C and the PHS31°C groups and, 7) more severe intestinal inflamation produced by Salmonella enteritidis in heat stressed chickens, characterized by a moderate enteritis throughout all the small intestine mucosa (PHS31°C group). Finally, 8) we showed that the heat stress increased splenic Salmonella enteritides invasion in PHS31°C broiler chickens; we also observed the presence of Salmonella in the bone marrow of stressed and infected broiler chickens. These data suggest that heat stress and Salmonella infection working together impair chicken\'s performance parameters, intestinal integrity and immunity (specially the macrophage activity), increasing ate the same time splenic and bone marrow Salmonella enteritidis invasion. Thus, heat stress could have impared the intestinal immunity barrier quality, via HPA axis activation and corticosterone serum levels release, decreasing the inate immunity and, providing pathogenic bacteria migration through the intestinal mucosa for spleen and bone marrow of the heat stressed chickens.

Influências de secreções endógenas e estímulos ambientais durante o período neonatal parecem ser determinantes para programar a atividade neuroendócrina e comportamental na vida adulta. O propósito do presente trabalho foi estudar a interação entre os hormônios gonadais e a manipulação durante o período neonatal sobre a concentração plasmática de corticosterona, gonadotrofinas (hormônios luteinizante e folículo estimulante), e hormônios gonadais (estradiol, progesterona e testosterona) em ratos adultos machos e fêmeas. Para alguns grupos experimentais, filhotes de ratos Wistar foram gonadectomizados, ou submetidos à cirurgia fictícia, antes de 6 horas após o nascimento, ou foram mantidos sem cirurgia. Metade destes animais foram estimulados diariamente, ou foram mantidos sem a manipulação neonatal, durante os primeiros 10 dias de vida. Para outros grupos experimentais, machos foram manipulados diariamente durante o período dos 10 primeiros e gonadectomizados aos 80 dias de vida. Somente a manipulação neonatal não provocou diferenças na concentração plasmática de corticosterona e gonadotrofinas, tanto em machos quanto em fêmeas, mas reduziu a secreção de hormônios gonadais em fêmeas. Enquanto a manipulação em fêmeas gonadectomizadas logo após o nascimento induziu um menor aumento na resposta de corticosterona comparada com às fêmeas não-manipuladas, em machos, a ausência de hormônios gonadais aboliu a redução da resposta ao estresse induzida pela gonadectomia neonatal no grupo não-manipulado. A manipulação aumentou a responsividade do feedback negativo para as gonadotrofinas em machos e fêmeas gonadectomizados no período neonatal. Mas a gonadectomia na idade adulta, em ratos machos manipulados no período neonatal induziu a um menor aumento no LH, comparado aos machos não-manipulados. Deve-se considerar que a castração realizada logo após o nascimento provoca a ausência dos hormônios gonadais durante todo o restante da vida do animal. Em fêmeas, a estimulação ambiental atuou sobre um sistema que não estava sob a influência dos hormônios gonadais. Mas em machos, além dos efeitos pré-natais dos esteróides gonadais, uma interação entre a estimulação neonatal e os efeitos destes hormônios durante o período neonatal provavelmente ocorreu. A estimulação ambiental durante o período neonatal e os hormônios gonadais interagem exercendo um profundo impacto a longo-prazo sobre a atividade do sistema de estresse hipotálamo-hipófise-adrenais e também sobre os mecanismos de controle neuroendócrino do sistema reprodutivo na vida adulta. / Endogenous hormones and environmental stimuli during the neonatal period appear to be determinant to program the behavioral and neuroendocrine profile in adult life. The purpose of the present study was to analyze the interaction between gonadal hormones and handling stimulation during the neonatal period on plasma corticosterone, gonadotrophins (luteinizing and follicle stimulating hormones), and gonadal hormones (estradiol, progesterone and testosterone) in adult male and female rats. For experimental groups, newborn Wistar pups were gonadectomized, or submitted to sham surgery or kept without surgery, at up to 6 hours after delivery. These pups were or stimulated daily by experimental handling, or kept without handling, during the first 10 postnatal days. For another experimental groups, males were stimulated daily on neonatal period (until 10 postnatal days) and gonadectomized at 80 days. Only neonatal handling shows no differences on plasma corticosterone and gonadotrophins, both in male or female rats, but reduced gonadal hormones in female rats. While handling in neonatal gonadectomized females induced a lesser increase in corticosterone response compared with the non-handled ones, in males, the absence of the gonadal hormones abolished the reduction of the stress response induced by neonatal gonadectomy in the non-handled group. Handling increased the negative feedback responsiveness to gonadotrophins of neonatal gonadectomized male and female rats. But, adult gonadectomy of neonatal handled males induced a lesser increase in LH compared with the non-handled ones. It is noteworthy that those castration performed just after birth, provoked the absence of the hormones occurred throughout the life of the animal. In females, early life environmental stimulation occurred upon a nervous system that has not been under the influence of gonadal hormones. In males, besides pre-natal effects of gonadal steroids, an interaction between environmental stimulation and hormonal effects during the neonatal period probably occurred. Environmental stimulation during the neonatal period and gonadal hormones interact and exert a profound long-lasting impact on the activity of the hypothalamic-pituitary-adrenal stress system and also on the reproductive neuroendocrine control mechanisms in adulthood.

O labirinto em cruz elevado (LCE) é um dos testes de ansiedade mais empregados na atualidade. Uma característica intrigante desse modelo é a abolição dos efeitos ansiolíticos dos benzodiazepínicos como resultado de uma única experiência prévia no labirinto. Este fenômeno, chamado “one-trial tolerance" (OTT), tem recebido considerável atenção e dentre as diversas hipóteses sugeridas para explicá-lo, podemos citar uma alteração no estado emocional do animal, perda do conflito motivacional e habituação do comportamento exploratório. A descoberta de que benzodiazepínicos reduzem a atividade de neurônios serotoninérgicos, associada a resultados obtidos em testes de conflito que mostram que antagonistas serotoninérgicos podem causar efeitos ansiolíticos comparáveis aos benzodiazepínicos, levaram à noção de que a serotonina (5-HT) é o principal neurotransmissor envolvido na ansiedade. No entanto, com o uso de outros modelos animais, o envolvimento da 5-HT tem sido questionado, ao mesmo tempo em que outras aminas biogênicas, como a noradrenalina (NA), têm sido implicadas na modulação da ansiedade. Nesse estudo procedemos uma análise etofarmacológica de ratos tratados com o antagonista serotoninérgico cetanserina e os antidepressivos fluoxetina e desipramina submetidos ao teste e reteste no LCE. Esses antidepressivos aumentam os níveis sinápticos de 5-HT e NA, respectivamente. Além disso, foram medidas as concentrações plasmáticas de corticosterona - considerada um índice confiável de medo e estresse - de ratos expostos à sessão única ou repetida no LCE. As drogas administradas antes da reexposição ao labirinto não produziram efeitos ansiolíticos, replicando o fenômeno da OTT comumente associado aos benzodiazepínicos. Por outro lado, a cetanserina administrada antes da primeira sessão produziu um efeito ansiolítico, mas o tratamento subcrônica com fluoxetina e desipramina não alterou o comportamento exploratório dos animais no LCE. Ratos submetidos à sessão única ou repetida no labirinto apresentaram um aumento similar dos níveis plasmáticos de corticosterona, indicando que a reexposição ao LCE apresenta propriedades aversivas e a OTT deve estar mais relacionada à uma alteração no estado emocional do animal do que à habituação do comportamento exploratório. / The elevated plus-maze (EPM) is currently one of the most used test of anxiety. An intriguing feature of this model is the abolition of the anxiolytic effect of benzodiazepines by a single previous experience with the maze. This phenomenon, termed one-trial tolerance (OTT), has received considerable attention and among the several hypotheses suggested to explain it, we can listed a shift in the animal emotional state, lack of motivational conflict and exploratory behavior habituation. The discovery that benzodiazepines reduce the activity of serotonergic neurons, associated with results obtained in conflict tests showing that serotonergic antagonists may cause anxiolitic-like effects comparable to the benzodiazepines, has led to the notion that the serotonin (5-HT) is the most important neurotransmitter involved in the anxiety. Nevertheless, with the use of other animal models, the 5-HT involvement has been questioned, at the same time that other biogenic amines, such as noradrenalin (NA), have been implicated in the anxiety modulation. In this study, we carried out an ethopharmacological analysis of rats under treatment with the serotonergic antagonist ketanserin and the antidepressants fluoxetine and desipramine submitted to the test and retest in the EPM. These antidepressants increase the synaptic levels of 5-HT and NA, respectively. Besides, plasma corticosterone concentrations - considered a reliable index of fear and stress - of rats exposed once or twice to the EPM were measured. The drugs injected before the retest in the EPM did not produce anxiolytic effects, replicating the OTT phenomenon generally associated with the benzodiazepines. On the other hand, ketanserin injected before the first session produced an anxiolytic effect but the subchronic treatment with fluoxetine and desipramine did not change the exploratory behavior of the animals in the EPM. Naive and experienced rats show a similar increase in the plasma corticosterone levels when submitted to the EPM, indicating that the retest to EPM has aversive properties and the OTT may be more related to a change in the emotional state of the animal than to a habituation of the exploratory behavior.

Cost and benefits of high individual growth rates are likely to vary across different environments leading to geographic differentiation in growth strategies. In ectotherms, habitats constrained by short growing seasons favour rapid growth and development leading to adaptive latitudinal clines in these traits. Geographic variation in growth strategies should be influenced by physiological variation as well as environmental factors, however many of these mechanisms remain largely unexplored. In my thesis, I studied hormonal correlates of growth strategies, and compensatory responses to phenological variation and environmental stress in anuran tadpoles. I tested the hypotheses that fast growing high latitude common frog Rana temporaria tadpoles have higher growth hormone (GH) expression, and low stress hormone (CORT) elevation in response to predator stress. I found no relationship between GH expression and latitude, but CORT response decreased with latitude after 24 hours of predator exposure. Lower CORT response at high latitude can be adaptive as it may enable the tadpoles to maintain high growth in time constrained habitats. I also found that breeding phenology affected latitudinal variation in growth, development and anti-predator strategies. Northern R. temporaria tadpoles were phenotypically more similar to southern tadpoles when breeding occurred early, suggesting that part of the latitudinal variation is plastic and affected by yearly variation in phenology. When time stress was manipulated by delaying hatching, tadpoles were able to compensate by increasing their development and growth during the larval stage, decreasing the cost of the delayed development. In the final study, I found that northern tadpoles showed stronger compensatory growth during the larval stage than southern tadpoles after being delayed by low food, however, temperature manipulation did not induce differences in the compensatory responses. In general, my results highlight the roles of both environmental and genetic variation in determining individual growth strategies. / Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 735

Stress promotes the use of methamphetamine and other recreational substances and is often implicated in relapse to stimulant use. Thus, it is of critical importance to examine the consequences of the co-occurance of stress and methamphetamine use. Activity of the glutamatergic N-methyl D-aspartate (NMDA) receptor system appears to be involved in the neurotoxic effects of both chronic stress and methamphetamine exposure. The current studies investigated the hypothesis that chronic pre-exposure to the stress hormone corticosterone (CORT) results in an increase of NMDA receptor activity and that this will potentiate the neurotoxic effects of methamphetamine (METH). Co-cultures of the ventral tegmental area, nucleus accumbens, and medial prefrontal cortex were pre-exposed to CORT (1 μM) for 5 days prior to co-exposure to METH (100 μM) for 24 hours to investigate the combined effects on neurotoxicity and protein density of NMDA receptor subunits. The combination of CORT and METH resulted in significant neurotoxicity within the medial prefrontal cortex compared to either CORT or METH alone. The CORT+METH-induced toxicity was attenuated by co-exposure to the NMDA receptor antagonist (2R)-amino-5-phosphonovaleric acid (APV; 50 μM) during the 24 hour CORT and METH co-exposure. Although CORT alone did not significantly alter the density of the NR1 and NR2B subunits of the NMDA receptor, METH exposure for 24 hours resulted in a significant loss of the polyamine sensitive NR2B subunit. Co-exposure to CORT and METH also resulted in decreased extracellular glutamate while not significantly altering extracellular dopamine. These results suggest an enhancement of NMDA receptor systems or downstream effectors in areas of the mesolimbic reward pathway following chronic pre-exposure to CORT, which leads to enhanced neuronal vulnerability to future excitotoxic insults. This may be of critical importance as use of psychostimulants such as METH and other drugs of abuse may produce excitotoxic events in these areas, thus further compromising neuronal viability.

Alcohol abuse disorders (AUD) represent a serious worldwide health problem with far reaching social, financial, and interpersonal implications. One of the most devastating facets of these disorders is the propensity to relapse following periods of abstinence. Ethanol withdrawal (EWD) is believed to promote relapse by increasing anxiety and craving, and may contribute to the development of cognitive decline associated with long-term dependence. Clinical data suggest that stress also plays a main role in both the development of AUD as well as relapse to drinking. As a physiological stressor, EtOH elevates levels of stress hormones (cortisol in humans, corticosterone (CORT) in the rat). Both CORT and EtOH have been shown to alter the composition, function, and activity of the N-methyl-D-aspartate (NMDA) receptor, and in particular, the NR2B subunit of this receptor. These alterations have been suggested to mediate EWD, which may negatively impact abstinence rates. This synergistic interaction between EtOH and CORT may present a therapeutic target for the treatment of EWD. In fact, data suggest that blocking the glucocorticoid receptor, which is a main target for CORT, with RU-486 could promote abstinence, as treatment with the drug has been shown to reduce consumption and the development dependence, as well as the severity of EWD and the cognitive deficits following EWD. However, these latter effects have not been validated in models of voluntary EtOH consumption. As there is considerable evidence that active versus passive intake can significantly impact neuroadaptations to ethanol this is an important consideration. These studies sought to characterize consumption and evaluate the development of dependence in a chronic voluntary model of intermittent access (IA) to EtOH. CORT plasma levels and protein expression of the glucocorticoid and NR2B receptors were measured during and/or following exposure. Finally, to assess the role of CORT in EtOH consumption and the development of dependence, the glucocorticoid receptor antagonist ORG-34517 was administered during access to EtOH. IA access to 20% EtOH produced varying levels of consumption (2.0-6.7g/kg/24hr exposure) and blood EtOH levels (6.3-116.9 mg/dl), but did not significantly affect food consumption or weight gain. Baseline CORT levels were found to be predictive of subsequent EtOH consumption and levels of consumption were sufficient to elevate CORT levels following one hour of EtOH exposure. Further, IA to EtOH was sufficient to produce dependence, as measured by elevations in the acoustic startle reflex following 26 hours and five days of withdrawal. No alteration in protein expression was observed regarding either the NR2B or glucocorticoid receptors and exposure to ORG-34517 had no effect on consumption or withdrawal.

Notre étude à pour but de déterminer l’implication de la corticostérone centrale sur l’activité du réseau hippocampe-cortex préfrontal (HPC-CPF) ainsi que son rôle dans l’émergence et le maintien d’altération de la mémoire de travail (MDT) durant l’alcoolisation chronique (12% durant 6 mois), ou bien après un sevrage aigu (1semaine) ou prolongé (6 semaines). Les effets du sevrage ont également été comparés à ceux résultant d’un stress chronique léger imprédictible (SCLI) modélisant la dépression. Nos données montrent que le sevrage et le SCLI, mais non l’alcoolisation, induisent des troubles de MDT, un déficit d’activation de pCREB (CPF et HPC) ainsi qu’une augmentation excessive des taux de corticostérone spécifiquement dans le CPF après un sevrage. Sur le plan pharmacologique, l’inhibition de la synthèse de la corticostérone restaure la MDT et l’activité de pCREB dans le CPF, chez les souris sevrées et SCLI. Nos résultats montrent également que l’augmentation de pCREB ou le blocage des récepteurs aux minéralocorticoïdes, dans le CPF, mais non dans l’HPC, restaure la MDT des souris sevrées. Ces résultats démontrent que la perturbation de taux de corticostérone dans le CPF joue un rôle clé dans l’émergence des troubles cognitifs et neuronaux après un sevrage. Nous avons également montré qu’un traitement chronique au Diazépam atténue ces altérations transitoirement. Notre étude suggère que des composés agissant sur l'activité de l’axe corticotrope peuvent constituer des stratégies alternatives pour prévenir l'émergence et le maintien des troubles cognitifs induits par le sevrage. / Our study was aimed to determine the involvement of central corticosterone on the activity of hippocampalprefrontal cortex (HPC-PFC) network and its role in the emergence of working memory (WM) alterations during chronic alcohol consumption (12% for 6 months), or after a short (1 week) or a prolonged (6 weeks) withdrawal periods. The alcohol-withdrawal effects were compared to those resulting from an unpredictable mild chronic stress (UCMS), modeling depression. Our data showed that withdrawal and UCMS, but not alcohol, induced WM disorders and deficits of CREB activation in both the PFC and HPC, and an excessive corticosterone increase specifically in the PFC of withdrawn animals. Pharmacological experiments showed that the inhibition of corticosterone synthesis restored pCREB activity in the PFC of both withdrawn and UCMS mice and improved WM. Furthermore, in withdrawn mice, the increase of pCREB or the blockade of the mineralo-corticoid receptor in the PFC, but not in the HPC, restored WM performance. These results demonstrated that corticosterone dysfunction into the PFC plays a key role in the long-lasting cognitive and neural activity disorders of alcohol-withdrawn mice. We also showed that chronic administration of diazepam reduced such alterations only transitorily. Thus, overall, our study suggests that compounds acting on the GCs activity may constitute alternative strategies to prevent the emergence and maintenance of cognitive disorders induced by alcohol withdrawal.

Influências de secreções endógenas e estímulos ambientais durante o período neonatal parecem ser determinantes para programar a atividade neuroendócrina e comportamental na vida adulta. O propósito do presente trabalho foi estudar a interação entre os hormônios gonadais e a manipulação durante o período neonatal sobre a concentração plasmática de corticosterona, gonadotrofinas (hormônios luteinizante e folículo estimulante), e hormônios gonadais (estradiol, progesterona e testosterona) em ratos adultos machos e fêmeas. Para alguns grupos experimentais, filhotes de ratos Wistar foram gonadectomizados, ou submetidos à cirurgia fictícia, antes de 6 horas após o nascimento, ou foram mantidos sem cirurgia. Metade destes animais foram estimulados diariamente, ou foram mantidos sem a manipulação neonatal, durante os primeiros 10 dias de vida. Para outros grupos experimentais, machos foram manipulados diariamente durante o período dos 10 primeiros e gonadectomizados aos 80 dias de vida. Somente a manipulação neonatal não provocou diferenças na concentração plasmática de corticosterona e gonadotrofinas, tanto em machos quanto em fêmeas, mas reduziu a secreção de hormônios gonadais em fêmeas. Enquanto a manipulação em fêmeas gonadectomizadas logo após o nascimento induziu um menor aumento na resposta de corticosterona comparada com às fêmeas não-manipuladas, em machos, a ausência de hormônios gonadais aboliu a redução da resposta ao estresse induzida pela gonadectomia neonatal no grupo não-manipulado. A manipulação aumentou a responsividade do feedback negativo para as gonadotrofinas em machos e fêmeas gonadectomizados no período neonatal. Mas a gonadectomia na idade adulta, em ratos machos manipulados no período neonatal induziu a um menor aumento no LH, comparado aos machos não-manipulados. Deve-se considerar que a castração realizada logo após o nascimento provoca a ausência dos hormônios gonadais durante todo o restante da vida do animal. Em fêmeas, a estimulação ambiental atuou sobre um sistema que não estava sob a influência dos hormônios gonadais. Mas em machos, além dos efeitos pré-natais dos esteróides gonadais, uma interação entre a estimulação neonatal e os efeitos destes hormônios durante o período neonatal provavelmente ocorreu. A estimulação ambiental durante o período neonatal e os hormônios gonadais interagem exercendo um profundo impacto a longo-prazo sobre a atividade do sistema de estresse hipotálamo-hipófise-adrenais e também sobre os mecanismos de controle neuroendócrino do sistema reprodutivo na vida adulta. / Endogenous hormones and environmental stimuli during the neonatal period appear to be determinant to program the behavioral and neuroendocrine profile in adult life. The purpose of the present study was to analyze the interaction between gonadal hormones and handling stimulation during the neonatal period on plasma corticosterone, gonadotrophins (luteinizing and follicle stimulating hormones), and gonadal hormones (estradiol, progesterone and testosterone) in adult male and female rats. For experimental groups, newborn Wistar pups were gonadectomized, or submitted to sham surgery or kept without surgery, at up to 6 hours after delivery. These pups were or stimulated daily by experimental handling, or kept without handling, during the first 10 postnatal days. For another experimental groups, males were stimulated daily on neonatal period (until 10 postnatal days) and gonadectomized at 80 days. Only neonatal handling shows no differences on plasma corticosterone and gonadotrophins, both in male or female rats, but reduced gonadal hormones in female rats. While handling in neonatal gonadectomized females induced a lesser increase in corticosterone response compared with the non-handled ones, in males, the absence of the gonadal hormones abolished the reduction of the stress response induced by neonatal gonadectomy in the non-handled group. Handling increased the negative feedback responsiveness to gonadotrophins of neonatal gonadectomized male and female rats. But, adult gonadectomy of neonatal handled males induced a lesser increase in LH compared with the non-handled ones. It is noteworthy that those castration performed just after birth, provoked the absence of the hormones occurred throughout the life of the animal. In females, early life environmental stimulation occurred upon a nervous system that has not been under the influence of gonadal hormones. In males, besides pre-natal effects of gonadal steroids, an interaction between environmental stimulation and hormonal effects during the neonatal period probably occurred. Environmental stimulation during the neonatal period and gonadal hormones interact and exert a profound long-lasting impact on the activity of the hypothalamic-pituitary-adrenal stress system and also on the reproductive neuroendocrine control mechanisms in adulthood.

Influências de secreções endógenas e estímulos ambientais durante o período neonatal parecem ser determinantes para programar a atividade neuroendócrina e comportamental na vida adulta. O propósito do presente trabalho foi estudar a interação entre os hormônios gonadais e a manipulação durante o período neonatal sobre a concentração plasmática de corticosterona, gonadotrofinas (hormônios luteinizante e folículo estimulante), e hormônios gonadais (estradiol, progesterona e testosterona) em ratos adultos machos e fêmeas. Para alguns grupos experimentais, filhotes de ratos Wistar foram gonadectomizados, ou submetidos à cirurgia fictícia, antes de 6 horas após o nascimento, ou foram mantidos sem cirurgia. Metade destes animais foram estimulados diariamente, ou foram mantidos sem a manipulação neonatal, durante os primeiros 10 dias de vida. Para outros grupos experimentais, machos foram manipulados diariamente durante o período dos 10 primeiros e gonadectomizados aos 80 dias de vida. Somente a manipulação neonatal não provocou diferenças na concentração plasmática de corticosterona e gonadotrofinas, tanto em machos quanto em fêmeas, mas reduziu a secreção de hormônios gonadais em fêmeas. Enquanto a manipulação em fêmeas gonadectomizadas logo após o nascimento induziu um menor aumento na resposta de corticosterona comparada com às fêmeas não-manipuladas, em machos, a ausência de hormônios gonadais aboliu a redução da resposta ao estresse induzida pela gonadectomia neonatal no grupo não-manipulado. A manipulação aumentou a responsividade do feedback negativo para as gonadotrofinas em machos e fêmeas gonadectomizados no período neonatal. Mas a gonadectomia na idade adulta, em ratos machos manipulados no período neonatal induziu a um menor aumento no LH, comparado aos machos não-manipulados. Deve-se considerar que a castração realizada logo após o nascimento provoca a ausência dos hormônios gonadais durante todo o restante da vida do animal. Em fêmeas, a estimulação ambiental atuou sobre um sistema que não estava sob a influência dos hormônios gonadais. Mas em machos, além dos efeitos pré-natais dos esteróides gonadais, uma interação entre a estimulação neonatal e os efeitos destes hormônios durante o período neonatal provavelmente ocorreu. A estimulação ambiental durante o período neonatal e os hormônios gonadais interagem exercendo um profundo impacto a longo-prazo sobre a atividade do sistema de estresse hipotálamo-hipófise-adrenais e também sobre os mecanismos de controle neuroendócrino do sistema reprodutivo na vida adulta. / Endogenous hormones and environmental stimuli during the neonatal period appear to be determinant to program the behavioral and neuroendocrine profile in adult life. The purpose of the present study was to analyze the interaction between gonadal hormones and handling stimulation during the neonatal period on plasma corticosterone, gonadotrophins (luteinizing and follicle stimulating hormones), and gonadal hormones (estradiol, progesterone and testosterone) in adult male and female rats. For experimental groups, newborn Wistar pups were gonadectomized, or submitted to sham surgery or kept without surgery, at up to 6 hours after delivery. These pups were or stimulated daily by experimental handling, or kept without handling, during the first 10 postnatal days. For another experimental groups, males were stimulated daily on neonatal period (until 10 postnatal days) and gonadectomized at 80 days. Only neonatal handling shows no differences on plasma corticosterone and gonadotrophins, both in male or female rats, but reduced gonadal hormones in female rats. While handling in neonatal gonadectomized females induced a lesser increase in corticosterone response compared with the non-handled ones, in males, the absence of the gonadal hormones abolished the reduction of the stress response induced by neonatal gonadectomy in the non-handled group. Handling increased the negative feedback responsiveness to gonadotrophins of neonatal gonadectomized male and female rats. But, adult gonadectomy of neonatal handled males induced a lesser increase in LH compared with the non-handled ones. It is noteworthy that those castration performed just after birth, provoked the absence of the hormones occurred throughout the life of the animal. In females, early life environmental stimulation occurred upon a nervous system that has not been under the influence of gonadal hormones. In males, besides pre-natal effects of gonadal steroids, an interaction between environmental stimulation and hormonal effects during the neonatal period probably occurred. Environmental stimulation during the neonatal period and gonadal hormones interact and exert a profound long-lasting impact on the activity of the hypothalamic-pituitary-adrenal stress system and also on the reproductive neuroendocrine control mechanisms in adulthood.