O estudo da expressão circadiana de genes de relógio tem sugerido hormônios como potenciais agentes sincronizadores. A regulação da ritmicidade de relógios periféricos é, aparentemente, mais um dentre os diferentes efeitos fisiológicos atribuídos aos glicocorticoides (GCs), que se constituem como candidatos a zeitgeber dado ao fato de que seus níveis circulantes apresentam padrões diários robustos e são uma das principais eferências do relógio central em mamíferos. Entretanto, em outros vertebrados, o papel dessa classe hormonal em relação a este aspecto ainda é pouco explorado e se a regulação é direta ou indireta, quais suas consequências e de que maneira ela ocorre são indagações a serem respondidas. Empregando a técnica do PCR quantitativo, avaliamos o perfil de expressão dos genes da alça negativa do núcleo da maquinaria molecular do relógio, per1b e cry1b, em células ZEM-2S do teleósteo Danio rerio expostas ao regime fotoperiódico 12:12 CE ou mantidas em escuro constante (EE) e mantidas em EE, mas condicionadas a trocas diárias de meio de cultura ou a pulsos diários de dexametasona a 10-7 M (DEXA), agonista sintético de glicocorticoide. Em 12:12 CE, ambos os genes apresentaram variação temporal, com picos de expressão observados na fase clara do ciclo. Em EE, per1b mostrou um perfil oscilatório de amplitude atenuada, enquanto para cry1b, não foi detectada oscilação ao longo das 24 h. Trocas de meio em EE alteraram significativamente o padrão de expressão de per1b e cry1b, no entanto, os pulsos diários de DEXA promoveram uma oscilação temporal muito mais pronunciada para per1b, modulando positiva ou negativamente sua expressão nos diferentes pontos temporais. O emprego do antagonista RU 486 na concentração de 10-5 M aboliu o pico de expressão detectado no ZT 16, porém, na concentração de 10-6 M, a expressão gênica foi aumentada em cerca de 3 vezes comparado ao tratamento apenas com DEXA. O gene cry1b, por sua vez, não se apresentou suscetível aos pulsos diários de DEXA. Estes resultados permitem confirmar as células ZEM-2S como modelo de relógios periféricos em cultura dada a fotossensibilidade intrínseca das mesmas, reafirmando o papel do ciclo CE como principal agente sincronizador. Os glicocorticoides certamente exercem modulação de per1b por meio da via genômica direta, sem, no entanto excluir uma possível ação via receptor de membrana, tendo em vista a atividade agonista de RU 486, podendo se constituir em um dos fatores que regulam o complexo funcionamento da maquinaria molecular do relógio biológico de zebrafish / Studies on the circadian expression of clock genes have suggested hormones as potential synchronizing agents. Regulation of rhythmicity of peripheral clocks is among the various physiological effects of glucocorticoids (GCs), which are candidate to zeitgeber, since their circulating levels present robust daily patterns and are one of the major outputs of the mammalian central pacemaker. However, in other vertebrates, such a feature has yet to be clarified as well as if the hormonal regulation is direct or indirect, what are its mechanisms and consequences. Applying qPCR technique, we evaluated the gene expression profile of per1b and cry1b, negative feedback loop members of the molecular machinery of biological clock, in ZEM-2S cells of the teleost Danio rerio. The cells were exposed to photoperiod regimen of 12:12 LD; kept in constant darkness (DD); kept in DD but subject to medium changes or treated with daily pulses of 10-7 M dexamethasone (10-7 M DEXA), a glucocorticoid synthetic analogue. In 12:12 LD, both genes presented temporal variation, with peaks of expression in the light phase. In DD, per1b showed an oscillatory profile with attenuated amplitude, whereas cry1b did not oscillate throughout 24 h. DEXA-free medium changes in constant DD conditions altered significantly per1b and cry1b expression profiles. Nevertheless, DEXA daily pulses promoted a temporal oscillation much more pronounced for per1b, modulating positively or negatively its expression at different time points, whereas cry1b was not susceptible to the hormone. RU 486 at 10-5 M abolished the peak of expression of per1b previously observed at ZT 16. On the other hand, RU 486 at 10-6 M increased the gene expression around 3-fold in comparison to just DEXA treatment. These results confirm ZEM-2S cells as a model of peripheral clocks in culture due to their intrinsec photosensitivity, emphasizing the light/dark cycle as a major synchronizing agent. The glucocorticoid modulates per1b expression, probably through a direct genomic pathway, without excluding however its possible action through membrane receptors, since RU 486 exerted agonistic activity. Glucocorticoids could, therefore, be one of the factors that regulate the complex molecular machinery of zebrafish biological clock

No description available.

Life-history is the study of all the different stages of life that affect reproductive success and survival between the birth and death of an organism. The reproductive output of an organism is constrained by many things including time, resource, disease agents and environmental conditions. In addition, lineage-specific traits and the limitations of the physiological systems can limit how an organism responds to ecological processes, and thus constrains the variation of life histories represented in nature. Central to the theory of life history are the trade-offs that organisms make during their lifetime to maximise their reproductive potential. In this thesis, I focus on the effect of haemosporidian blood parasites on host life history, in relation to the glucocorticoid response and environmental conditions. The host study species is a population of collared flycatchers (Ficedula albicollis), a species that provides bi-parental care, located in the south of Gotland. We show that nestling condition predicts parasite infection and that parasite-mediated selection can start early on in the birds’ life. We also found a link between Lower levels of glucocorticoids and parasite infection, which might indicate a trade-off between immunity and reproductive effort. Adult birds’ upregulated glucocorticoids in response to an increase in reproductive effort and a predictable change in energy demand during reproduction. I also show that glucocorticoids respond to changing environmental conditions. These results together accentuate the importance of the plasticity of the glucocorticoid response to reproductive success. Moreover, higher levels of hormone during reproduction predicted survival to the next breeding season. In nestlings, glucocorticoid levels increased as a consequence of parent infection status and an increase in reproductive effort. Overall, our results indicate that the glucocorticoid response is context dependent. Finally, female collared flycatchers might pay a fitness cost as a consequence of parasite infection, but can still reproduce successfully suggesting that they can tolerate the parasite. To further our understanding of costs related to parasite infection, we must understand better the mechanisms that enable the host to tolerate infection. This study indicates that glucocorticoids provide a useful tool to detect how wild birds respond to predictable and unpredictable challenges.

Glucocorticoid excess is associated with adverse effects on a number of physiological parameters, leading to obesity, dysfunction of the hypothalamic-pituitary- adrenal (HPA) axis and behavioural changes such as anxiety and impaired learning and memory. Circulating and local tissue glucocorticoid levels are tightly controlled by the HPA axis but an additional level of control exists in tissues such as brain, liver and adipose tissue. In these structures, enzymes including 5α-reductase 1 (5αR1), catalyse the conversion of corticosterone to A-ring reduced metabolites, which have a different spectrum of activities. This thesis investigates the role of 5αR1 in regulating central glucocorticoid actions which control HPA axis function and behaviour in a mouse model with genetic disruption of 5αR1 (5αR1-KO). Preliminary data showed 5αR1-KO mice were susceptible to developing insulin resistance and obesity and had reduced HPA axis responses to acute stress. Additionally, male 5αR1-KO mice were more prone to obesity than wild-type (WT) when fed a high-fat diet whilst female 5αR1-KO mice gained more weight than WT even on a normal chow diet. Intriguingly, female 5αR1-KO mice subjected to social isolation stress lost this extra weight and became comparable to WT controls. This study tested the hypothesis that 5αR1-KO mice are less able to inactivate glucocorticoids in the periphery and within tissues, resulting in a predisposition to metabolic disturbances and behavioural alterations. These were hypothesised to include hyperphagia, weight gain, impaired stress responses, anxiety (exacerbated by environmental stress) and cognitive deficits. It was also thought that many of these features would be more pronounced in female vs. male mice. The main aims of this study were to determine if 5αR1-KO induced weight gain and if this was correlated to altered gene expression of key hypothalamic neuropeptides which regulate appetite, to determine the central mechanisms which underpin attenuated HPA axis responses to acute stress and to determine whether behaviours such as anxiety and learning and memory ability are affected by global 5αR1 loss. It was hypothesised that female 5αR1-KO mice have increased appetite and reduced locomotor activity compared with WT and male 5αR1-KOs. However, male 5αR1- KO mice (on a mixed genetic background, C57Bl/6j/SvEv/129) were hyperphagic on a normal chow diet but did not gain extra weight, while female 5αR1-KO mice gained more weight vs. WT despite hypophagia. Free ambulatory activity was unaffected by genotype in either sex. Male 5αR1-KO mice appeared less anxious but responses of female 5αR1-KO mice in tests of anxiety did not differ from WT controls. Mice lacking 5αR1 generally had a poorer metabolic profile with impaired glucose tolerance and hyperinsulinaemia; with hepatic steatosis evident in female mice. There was evidence of compensatory changes in hypothalamic orexigenic and anorexigenic peptides. Phenotypes were sexually dimorphic such that male mice had a poorer metabolic profile vs. females, which was particularly marked in male 5αR1- KO animals. 5αR1-KO mice were previously shown to have attenuated HPA axis responses to acute stress and it was hypothesised that disruption of 5αR1 would result in altered expression of genes related HPA axis regulation with a view to increased negative feedback. Here, male and female 5αR1-KO mice demonstrated altered corticosteroid receptor expression within the hippocampus and the pituitary, two key structures in the HPA cascade. In situ hybridisation showed reduced mRNA for MR in the hippocampus and for Crh in the hypothalamus of 5αR1-KO mice. These modifications along with decreased Crhr-1 mRNA (CRH‘s main receptor) may be due to a lack of corticosterone metabolism within the brain resulting in enhanced negative feedback and reduced HPA axial drive. In order to study behaviour in detail and also to test whether potential central glucocorticoid excess may predispose to cognitive decline with ageing, a separate cohort of female 5αR1-KO backcrossed onto a uniform C57Bl/6j background was studied both when young (6 months) and when aged (14-15 months). Additionally, mice were housed in either groups or singly (social isolation) to investigate the potentially additive effects of environmental stress. It was hypothesised that local glucocorticoid increases in the brains of 5αR1-KO mice would be associated with anxiety and cognitive deficiencies and that these phenotypes would be exaggerated by the stress of social isolation as well as ageing. Behavioural differences were not observed at 6 months of age. However aged, 5αR1-KO mice housed singly showed increased anxiety and had higher plasma corticosterone levels than group-housed mice. Moreover, aged mice lacking 5αR1 performed less well than WT in tests of memory and had a marginally greater cognitive decline when learning ability at 14- 15 months old was compared to that of the same animals tested at 6 months old. Overall, mice with global 5αR1 loss appeared susceptible to anxiety as well as some degree of age-associated cognitive impairment, but only when subjected to social isolation stress which is a known chronic stressor. The final set of experiments aimed to determine the effect of mouse strain on 5αR1- KO phenotypes. It was hypothesised that glucocorticoid clearance would be attenuated to a lesser degree in 5αR1-KO mice bred onto a congenic C57Bl/6j strain compared to those of the mixed strain and that this would manifest as less disruption of metabolism and less suppression of HPA axis stress responses. Although social isolation again induced weight-loss in female mice and more so in 5αR1-KO animals, mice on the C57Bl/6j background strain did not show dampened HPA axis responses to acute stress as seen previously. It was subsequently shown in adrenalectomised mice that animals bred on the C57Bl/6j strain cleared active corticosterone from plasma and liver faster than mixed strain mice. This may have rendered mixed strain 5αR1-KO mice more susceptible to excessive corticosterone levels producing a more exaggerated phenotype in this group. In conclusion, these data suggest a role for the enzyme 5αR1 in modifying glucocorticoid concentrations in the brain and liver, influencing not only metabolic and peripheral effects such as weight gain and insulin resistance, but also in modifying cognition, appetite stimulation and affective behaviours. It has been highlighted that outside factors such as housing and age can modify these phenotypes and are important considerations for future studies. This study has also highlighted the importance of choosing an appropriate genetic background for genetically modified animals since phenotypes can be enhanced or attenuated depending on strain. Finally, 5αR inhibitors are used to treat disorders such as benign prostatic hyperplasia in men, and it is important to consider that these drugs may have a wide array of associated side effects both systemically and in the central nervous system.

No description available.

La libération d'hormones glucocorticoïdes (GC), en réponse au stress, est un mécanisme important du contrôle de la neurogenèse chez l'adulte. Une question non résolue est de savoir si ces hormones agissent directement sur les précurseurs neuronaux (NPCs) ou indirectement, en agissant sur d'autres types cellulaires, modifiant la libération de facteurs de croissance ou l'activité de réseaux neuronaux. Afin de répondre à cette question, nous avons développé un modèle murin dans lequel le gène du récepteur des GC (GR) est invalidé, de façon inductible, dans les précurseurs neuraux adultes. Nous avons montré qu'en présence ou en absence du GR, un traitement chronique avec des GC affecte de façon similaire la différentiation et la survie des neurones nés chez l'adulte. L'effet connu des GC sur la suppression de la neurogenèse adulte n'est donc pas du à une action directe de ces hormones sur les NPCs. L'absence du GR n'affecte pas non plus le comportement des souris mutantes lorsque les GC circulent à un niveau de base. En revanche, un traitement chronique avec des GC induit chez les animaux contrôles un phénotype anxieux (observé dans les tests de novelty-suppressed feeding, light/dark box, and elevated O-maze) alors que les animaux mutés sont préservé de ce changement comportemental. De façon similaire, un traitement chronique avec des GC facilite l'apprentissage des souris contrôles lors d'un test d'apprentissage par la peur. L'invalidation du gène GR dans les NPC bloque cet effet. L'apprentissage des souris. Ces résultats précisent le rôle du GR dans le contrôle de la neurogenèse dans l'hippocampe adulte et dans la modulation des comportements de type anxieux. / Stress hormones are known as one of the strongest and most ecologically relevant mediators of adult neurogenesis. A lingering question in adult neurogenesis is whether these hormones, known as glucocorticoids (CG), act directly on neural progenitor cells (NPCs), or indirectly through secreted factors or changes in network activity. To address these unknowns, we generated a transgenic mouse model whose GC receptors (GRs) could be inducibly inactivated specifically in NPCs. We investigated the effect of this cell-specific GR knockout model on hippocampal survival and differentiation and found them to be similarly affected by chronic GC treatment compared to controls. This implies that GC-suppressed neurogenesis and its impact on morphology is indirect, and GR in other cells may be mediating the effects. Furthermore, mice with GR inactivation in newborn neurons behaved similarly to controls in all tasks observed under basal levels of GC. When mice were chronically treated with GC, however, controls exhibited an anxious phenotype, whereas transgenic mice behaved like untreated control groups in all anxiety measures except latency to feed in NSF. Neither GC nor inactivation of GR in adult-born neurons altered depression-like behaviors in the forced swim test, nor percent freezing in contextual fear discrimination. Lastly, we found that GC increased the rate of learning in 1-trial contextual fear conditioning, an effect not mediated by reducing GR signaling in the neurogenic pool. These results highlight the functional contributions of adult neurogenesis as well as how their GRs mediate anxiety-relevant behaviors irrespective of suppressed neurogenesis.

L’obésité est devenue une véritable épidémie mondiale qui résulte principalement de la surnutrition mais peut également avoir une origine iatrogène, par la prise au long cours de glucocorticoïdes (GC). Le but de ce travail a été d’identifier les mécanismes impliqués dans la survenue et dans le développement de l’obésité nutritionnelle et induite par les GC. Le modèle d’obésité induite par un régime hyperlipidique a permis de caractériser des perturbations intestinales associées: une capacité d’absorption des acides aminés élevée, un temps de transit ralenti et une perméabilité intestinale augmentée ainsi qu’une flore intestinale altérée qui pourraient concourir à moduler la balance azotée et énergétique.Parallèlement, le second modèle de diabète et d’obésité cortico-induits a révélé des effets différentiels des GCs selon les dépôts adipeux : une hyperplasie adipocytaire et une invasion précoce des macrophages spécifiquement au niveau viscéral ainsi qu’une polarisation macrophagique distincte entre les dépôts viscéraux et sous-cutanés. L’accumulation des macrophages viscéraux est responsable tout au moins partiellement de l’insulino-résistance induite par les GC. D’autre part, en terme d’homéostasie glucidique, le traitement par GC provoque des réponses différentes sur deux fonds génétiques distincts ce qui s’explique par une adaptation pancréatique souche-dépendante. L’ensemble de ce travail met en exergue différents mécanismes d’adaptation des organes périphériques à l’obésité. / Obesity becomes a worldwide epidemic due to over-nutrition, but also to drug treatments, particularly glucocorticoids (GCs). The aim of this work was to identify the mechanisms involved in obesity induced by high-fat diet or by GCs. High-fat diet-induced obesity model was used to characterize intestinal disturbances: an elevated amino acids absorption capacity, a delayed transit time and an increased intestinal permeability and an altered gut microbiota, which can further modulate nitrogen and energy balance. Meanwhile, GC-induced obesity model revealed differential effects of GCs on fat depots. Adipogenesis and an early increased macrophage infiltration were restricted to visceral adipose tissue with a differential macrophage polarization between visceral and subcutaneous fat pads. Visceral macrophage infiltration was responsible for GC-induced insulin resistance. Moreover, GC exposure resulted in opposite phenotypes of glucose metabolism in two distinct genetic murine backgrounds that could be explained by a strain-dependent pancreatic adaptation. Taken together, our work highlights adaptive mechanisms of peripheral organs during obesity.

In contrast to most teleost fish that are ammoniotelic, the gulf toadfish (Opsanus beta) is both facultatively ureogenic and ureotelic. In vivo pharmacological manipulations were used to show that lowering circulating cortisol levels or blocking glucocorticoid receptors (GR) enhanced both urea excretion and urea pulse size. These findings demonstrated that changes in pulsatile urea excretion in the toadfish are mediated by the permissive action of cortisol through GRs. Measurement of urea transport across isolated basolateral gill membranes revealed a cortisol-sensitive carrier mechanism. Cortisol infusion in vivo significantly reduced urea transport capacity, suggesting that cortisol inhibits the recruitment of urea transport proteins (UT) to the basolateral membrane to ultimately decrease the size of the urea pulse in toadfish. A 1.2 kb fragment of the upstream transcription start site for the toadfish urea transporter (tUT) gene was isolated and in silico analysis revealed the presence of several putative glucocorticoid response element (GRE) half sites. Toadfish provided with this regulatory sequence in a reporter gene construct showed increased reporter gene transcription driven by cortisol. The data indicated that cortisol-mediated upregulation of tUT mRNA by GREs may be necessary to maintain tUT activity. Four Rhesus (Rh) glycoproteins (Rhag, Rhbg, Rhcg1, Rhcg2) were isolated from toadfish; these sequences grouped with those of other vertebrates coding for membrane channels that transport ammonia. In vivo increases in circulating cortisol reduced branchial Rh glycoprotein expression and decreased ammonia excretion. These changes were accompanied by cortisol-induced increases in glutamine synthetase activity, an enzyme that captures ammonia for urea synthesis. Taken together, the data indicated that cortisol reduces the loss by branchial excretion of ammonia, instead favouring biochemical pathways that convert ammonia to urea. This thesis confirms that nitrogen excretion in toadfish is controlled and regulated in fashions unlike those in other teleosts. The results demonstrate the importance of the GR signaling pathway in mediating changes in both urea and ammonia transport through molecular mechanisms. As a whole, the data provide a new understanding of branchial nitrogen excretion in the gulf toadfish and enhance our evolutionary perspective of the integrated biological systems involved in nitrogen excretion in fish.

Le récepteur des glucocorticoïdes (GR) est un facteur de transcription, activé par la libération de glucocorticoïdes (GCs) en réponse à un stress. Il est impliqué dans la modulation des comportements influencés par le stress tels que les émotions, les comportements sociaux et l’addiction. L’invalidation du GR dans les neurones dopaminoceptifs (GRD1Cre) entraine une diminution des réponses à la cocaïne. Afin d’identifier les gènes cibles du GR, une analyse comparative du transcriptome de souris contrôles et GRD1Cre, en conditions basales, suite à un traitement à la cocaïne ou aux GCs, a été réalisée. Le GR agit principalement comme activateur de la transcription dans les neurones dopaminoceptifs, quelque soit le traitement. De plus, une corrélation entre les gènes régulés par le GR suite à un traitement aux GCs et ceux régulés suite à un traitement à la cocaïne existe. Le GR contrôle l’expression de ses gènes par des mécanismes variés dont certains impliquent le recrutement du complexe de remodelage de la chromatine SWI/SNF. Ce complexe est composé d’une ATPase catalytique qui peut être soit Brahma (BRM), soit BRG1 (Brahma-Releated Gene 1), deux protéines qui partagent un haut degré d’homologie. Nos résultats montrent que le GR interagit avec l’une et l’autre dans le striatum, structure clé dans l’addiction. En utilisant des souris invalidées pour BRM (BRM-/-) et/ou spécifiquement pour BRG1 (BRM-/-BRG1D1Cre et BRG1D1Cre), un rôle différentiel de BRM et BRG1 a été mis en évidence. Alors que BRM n’est pas nécessaire aux réponses à la cocaïne, BRG1 dans les neurones dopaminoceptifs est essentiel aux réponses à cette drogue. BRG1 est également impliqué dans les réponses locomotrices à la morphine. De manière différente, BRG1 et BRM se compensent dans les comportements émotionnels. / The glucocorticoid receptor (GR) is a transcription factor involved in the stress response, activated by glucocorticoids (GCs). Inactivation of GR in dopaminoceptive neurons (GRD1Cre) induces a decrease of behavioral and cellular responses to cocaine. In order to identify the GR target genes, we performed thorough transcriptome analyses using controls and GRD1Cre mice under basal conditions, after treatment of cocaine or GCs. We highlighted that GR acts predominantly as a transcriptional activator within dopaminoceptive neurons. We then identified a closed link between genes induced in responses to an acute stress and in response to cocaine. GR controls expression of its target genes by numerous mechanisms. We examined the putative contribution of the SWI/SNF chromatin remodeler complexes. This multi-subunit complex contains either BRM (Brahma) or BRG1 (Brahma-related gene 1) as central ATPase subunit. We detected an interaction between GR and BRG1, and between GR and BRM in the striatum. To understand the role of BRM and BRG1 proteins, we developed animals with a constitutive BRM inactivation (BRM-/-) and/or with a specific deletion of BRG1 in dopaminoceptive neurons (BRM-/-BRG1D1Cre, BRG1D1Cre mice). A differential role of theses two proteins has been highlighted. While BRM is not required for behavioral responses to cocaine, BRG1 within dopaminoceptive neurons is essential. BRG1 is also involved in locomotor responses to morphine. Nevertheless, inactivation of either BRM or BRG1 gene in dopaminoceptive neurons did not change anxiety-like behaviors.

Epidemiological studies show that offspring subjected to maternal undernutrition during early pregnancy are prone to developing obesity and other diseases in adulthood. The hypothalamic energy regulating pathway may be altered in these offspring, with epigenetic changes as a core mechanism. Therefore, this thesis aimed to determine if epigenetic changes are present in this pathway in the hypothalami from offspring subjected to maternal undernutrition. The investigations are focused on the glucocorticoid receptor (GR) as an inhibitor of the anorexigenic neuropeptide pro-opiomelanocortin (POMC), with potential modifications leading to increased food intake and the development of obesity. To achieve this, an established sheep model developed by our collaborators was used, during which maternal ewes were undernourished periconceptionally to produce a 10-15% decrease in body weight. We found that hypothalami from fetal offspring had greater epigenetic modifications when this reduction in maternal body weight was maintained from 60 days before conception until 30 days into pregnancy, with lower levels of POMC and GR promoter methylation. This was associated with increased GR mRNA expression. Other regions of the brain that also express POMC and GR, did not exhibit these epigenetic modifications. This study revealed that maternal undernutrition induces tissue specific epigenetic changes in fetal hypothalami which may contribute to disease in later life. Twins have been shown to have similar phenotypic characteristics as maternally undernourished offspring and therefore it has been suggested that they may also be programmed, but by intrauterine growth restriction. Consequently, extensive methylation and histone analysis of GR and POMC promoter regions was carried out in twin fetal hypothalami and compared to maternally undernourished groups. Interestingly, the decreased POMC and GR methylation of our amplicons in the maternally undernourished fetal hypothalami was also observed in twin fetal hypothalamic. This was concomitant with histone modifications and alterations in overall DNA methyltransferase activity. However, it was found that there were no changes in the POMC and GR mRNA expression levels in twin fetuses, but we postulate that this may occur later in life. To determine if changes in the fetal epigenetic status of hypothalamic GR and POMC impacted the adult progeny, tissues were obtained from adult offspring of maternally undernourished ewes. Epigenetic changes in the hypothalamic GR promoter observed in the fetal group persisted into adulthood, with concurrent increases in GR mRNA and GR protein expression. Of these groups the undernourished adult male offspring had decreased hypothalamic POMC expression and increased fat mass, changes that are consistent with an obese phenotype. The epigenetic and expression status of GR in the hippocampus and pituitary were modified, but in a tissue and sex specific manner. POMC epigenetic changes in the brain were complex, with various levels of epigenetic and expression changes. Overall periconceptional undernutrition induces hypothalamic specific changes in the epigenetic status of the GR gene which is known to regulate energy balance. Hypothalamic changes were persistent from the fetal stage into adulthood, with modifications in other tissues occurring after birth. These adaptations have the potential to increase the offspring’s propensity to develop obesity and altered stress regulation in later life.