Glucocorticoïde | EPFL Graph Search

Les glucocorticoïdes sont des corticoïdes qui ont une action sur le métabolisme protidique et glucidique. Ils s'opposent aux minéralocorticoïdes. En pratique courante, le terme corticoïde, sans précision, désigne les glucocorticoïdes. Les glucocorticoïdes naturels sont la cortisone et le cortisol. Les glucocorticoïdes de synthèse sont soit à effets courts (la prednisone), soit à effets intermédiaires (paraméthasone), soit à effets prolongés (bétaméthasone). Les médicaments s'appellent anti-inflammatoires stéroïdiens quand ils sont employés à cet effet. Classification

Les glucocorticoïdes naturels sont sécrétés par l'organisme humain à faibles doses et à un rythme circadien (70 % étant sécrétés entre 2 et 8 heures du matin). La cortisone et le cortisol (ou hydrocortisone) — sont utilisés essentiellement dans l’hormonothérapie de substitution des insuffisances surrénales.L’hémisuccinate d’hydrocortisone a un effet très rapide et doit donc être réservé aux problèmes d

Genetic selection for low glucocorticoid responsiveness recapitulates PTSD-related phenotypes: a behavioral, neuroimaging and sleep-physiology study

Silvia Monari

Humans show inter-individual differences in vulnerability to develop post-traumatic stress disorder (PTSD) following exposure to trauma. Several critical biobehavioral features have been consistently described in PTSD patients, including blunted cortisol levels, smaller hippocampal size, sleep disturbances. However, because of the delay between trauma exposure and the onset of symptoms characteristic of PTSD, only a few longitudinal studies have tried to dissect whether these features constitute pre-trauma risk factors or consequences of the trauma. Enormous effort in animal and human studies has been dedicated to understanding mechanisms of conditioned fear and fear extinction, processes that are at the core of PTSD. However, the same progress has not been translated into psychiatric practice for PTSD. Deepening our understanding of the contribution of key factors to PTSD-related alterations can serve to develop effective treatments.In particular, with regard to low cortisol levels in PTSD pathophysiology, a causative role for blunted glucocorticoid responsiveness in PTSD has not been demonstrated yet.Here, we have addressed this question in lines of Wistar rats genetically-selected for their differential habituation of glucocorticoid responses to stress (LOW-, INTER-, HIGH-CORT Responder rats) and focused on fear extinction, a hallmark of PTSD symptomology, as one of the key features. As a first step, we looked whether divergent trajectories of glucocorticoid responsiveness were associated with brain volume abnormalities, prompted by the influential role of glucocorticoid in brain development. Notably, rats with low or high corticosterone responsiveness exhibit smaller hippocampi, regardless of trauma exposure, compared to rats with normative corticosterone levels. Similarly, the distribution of corticosteroid receptors in the hippocampus presented similarities between the LOW-CR and the HIGH-CR rats with higher mineralocorticoid receptors (MR) and less glucocorticoid receptors (GR). Although LOW- and HIGH-CR rats displayed a similar hippocampal profile at the structural and molecular levels, only LOW-CR male rats exhibited strong deficits in extinction consolidation compared to rats with 'normative' glucocorticoid responses (INTER-CR rats), and showed higher fear response both at few days and at several weeks after trauma exposure. We next tested the causal involvement of corticosterone in the fear extinction consolidation, and found that post-extinction corticosterone treatment markedly prevented the deficits in extinction memory and attenuated fear relapse. In addition, pharmacological inhibition of corticosterone levels during extinction memory consolidation, but not during training, in the INTER-CR rats led to extinction deficits at retrieval one day later. These results indicate that blunted corticosterone levels contribute to confer major vulnerability than having a small hippocampus, and that consolidation processes following extinction are mainly affected by low corticosterone levels.It is well known that glucocorticoids play an important role in memory consolidation processes and that sleep disturbances are a diagnostic criterion of PTSD. Therefore, we investigated in greater detail the sleep architecture in undisturbed condition and during the consolidation period of the extinction phase, which is known to be supported by sleep-dependent processes. In polysomnographic recordings, we found that rats with blunted corticos

EPFL2022

Implication of individual differences in glucocorticoid responsiveness to stress in the development of psychopathology-like behaviour and underlying neurobiology

Sophie Elizabeth Walker

The period around puberty is a critical window in development. It is a time of neuroendocrine and neuroanatomical lability, rendering individuals highly sensitive to stress. Indeed, early adversity increases risk for psychopathology. The mechanisms via which this vulnerability is differentially translated between individuals are not yet understood. Wistar rats exposed to psychogenic stressors around puberty show increased psychopathology-like behaviors at adulthood. Like humans, not all rats exposed to this stress develop in the same way, particularly with regard to aggression. The actions of glucocorticoids, the end product of hypothalamic-pituitary-adrenal (HPA) axis activations, mediate some alterations induced by peripuberty stress (PPS). Here we thus focused on assessing if individual differences in glucocorticoid responsiveness to stress influenced outcome following stress. We exposed male rats to PPS and later measured socio-affective behaviors and brain structure with magnetic resonance imaging. By applying a profiling approach we discerned two distinct neurodevelopmental trajectories arising from PPS. One led to the development of pathological aggression and reduced mean diffusivity in infralimbic cortex, amygdala and hippocampus. The other led to increased anxiety-like behavior and reduced sociability, with no evidence of alterations in brain structure. We assessed glucocorticoid responsiveness to PPS across the protocol and found that impaired habituation was associated with a more aggressive profile. Impaired habituation of glucocorticoid responses, shown by â35% of people, is heritable and associated with self-report of psychopathology-related indices. Considering this and our findings, we asked if constitutive differences in habituation to repeated stress were implicated in vulnerability to psychopathology. To answer this question, we developed a new animal model. We selectively bred lines of rats, enriching for stress habituation (âlow-lineâ) and lack of stress habituation (âhigh-lineâ). Once the lines were established, we assessed socio-affective behaviors and neuroendocrine phenotype of the rats. High-line rats displayed more aggression, anxiety-like, and depression-like behaviors. High-line rats had a distinct neuroendocrine phenotype, with enhanced corticosterone reactivity to acute stress, but no evidence for general HPA axis hyperactivity, and altered expression of several HPA axis related genes. Finally, we studied the interaction of the two risk factors in the development of behavioral alterations. Low- and high-line rats were exposed to PPS, and socio-affective behaviors and basal activation of the brain were later assessed. Both factors enhanced levels of anxiety-like and aggressive behavior, as well as increasing activity across the prefrontal cortex in a manner that was associated with increased behavioral inhibition. PPS had a differential impact on the lines, enhancing aggression in the stress-habituating low-line but not in the already high-aggressive, high-line rats. In summary, we established incidence of differential neurobehavioral trajectories following PPS, trajectories associated with differential glucocorticoid responsiveness across the stress. Constitutively impaired stress habituation increased psychopathology-like behavior in its own right, and this was not enhanced by exposure to PPS. In contrast, constitutively strong habituation enhanced sensitivity to the programming effects of PPS.

EPFL2016

Role of the HPA axis in the long-term programming of social behaviors by peripuberty stress

Vandana Veenit

Stress during childhood and adolescence enhances the risk of psychopathology later in life. In fact, exposure to stress during this period is known to predispose individuals to the development of psychopathologies such as depression and anxiety disorders later in life. Similarly, individuals subjected to fearful experiences or abuse during childhood and puberty exhibit violent behaviors in adulthood, as revealed in both human literature and animal studies. Previous work from our laboratory has shown that exposing peripuberty rats to fear experiences (such as synthetic fox odor and exposure to an elevated platform) following an unpredictable schedule, on a range of 7 specific days across P28 to P42 in male Wistar rats leads to reduced sociability, increased aggression, anxiety- and depression-like behaviors in adulthood. The hypothalamic pituitary adrenal (HPA) axis is one of the main physiological stress systems and various components of the HPA axis like corticotropin releasing hormone (CRH), glucocorticoids are modulated in response to early life experience. We therefore sought to investigate the role of HPA axis in long term programming of social and emotional behaviors as a result of peripuberty stress(PPS). We addressed this by manipulating (i) glucocorticoid system by two approaches, and, (ii) corticotropin releasing hormone (CRH) system. First, using male Wistar rats, we evaluated the consequences of administration of corticosterone following the same experimental schedule as for stress administration in our peripuberty stress paradigm (without actual stress exposure) on play behavior on postnatal day 44 (P44) and on behavioral tests of anxiety, aggression, sociability and depression in adulthood. Corticosterone response to novelty was also measured in adulthood. Our results show that, as compared to vehicle-, corticosterone-treated animals exhibit higher aggressive play behavior during adolescence, and escalated aggressive behavior in adulthood, while reduced sociability and decreased corticosterone response to novelty in adulthood. No differences were observed between groups on anxiety- and depression-like behavior tested later in life. Next, we examined whether pharmacological blockade of glucocorticoid receptor 30 minutes prior to peripuberty stress would prevent the consequences of peripuberty stress on emotional, social behavior and dysregulated gene expression. Our findings showed that administration of glucocorticoid receptor antagonist on days of peripuberty stress prevents the effects of peripuberty stress on behaviors related to the domain of aggression and sociability in adulthood without producing any effect on anxiety- and depression-like behavior tested later in life. Interestingly, administration of GR antagonist in PPS animals also reversed the effects of PPS on increased expression of GR and Trpc5 genes in central nucleus of amygdala. We also observed increased Crhr1 expression in limbic areas in peripuberty stressed animals which was not reversed by administration of GR antagonist in peripuberty stressed animals. Subsequently, we sought to evaluate the consequences of counteracting CRHR1 activation during early post-stress period on long-term behavioral consequences of peripuberty stress in tests for anxiety- and depression-like behaviors. Our results showed that administration of CRHR1 antagonist post peripuberty stress rescued the effects of peripuberty stress on depression-like behavior and to some extent on anxiety- like behavior. Taken together, our studies show that corticosterone administration during peripuberty largely mimics the behavioral alterations observed in peripuberty stressed animals in social realm, administration of glucocorticoid receptor antagonist on days of peripuberty stress prevents the effects of peripuberty on social domain and on increased expression of GR and Trpc5 genes in central nucleus of amygdala, and administration of CRHR1 antagonist post peripuberty stress rescued the effects of PPS on depression-like behavior and to some extent on anxiety-like behavior.

EPFL2013