Previous exposure to immobilisation and repeated exposure to a novel environment demonstrate a marked dissociation between behavioral and pituitary–adrenal responses

Gagliano, Humberto; Fuentes, Sílvia; Nadal, Roser; Armario, Antonio

doi:10.1016/j.bbr.2007.09.006

Cited by 53 publications

(42 citation statements)

References 39 publications

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“…There was however no effect of CR or SR on the corticosterone response to acute noise. Similar discrepancies between pituitary and adrenal responses to stress have been previously described (Gagliano et al 2008) and may be related to the modulation of adrenal response to ACTH via adrenal sympathetic innervation (Engeland & Arnhold 2005).…”

Section: Discussionsupporting

confidence: 75%

Effect of vasopressin 1b receptor blockade on the hypothalamic–pituitary–adrenal response of chronically stressed rats to a heterotypic stressor

Spiga¹,

Harrison²,

MacSweeney³

et al. 2008

Journal of Endocrinology

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Exposure to chronic restraint (CR) modifies the hypothalamicpituitary-adrenal (HPA) axis response to subsequent acute stressors with adaptation of the response to a homotypic and sensitization of the response to a heterotypic stressor. Since vasopressin (AVP) activity has been reported to change during chronic stress, we investigated whether this was an important factor in HPA facilitation. We therefore tested whether vasopressin 1b receptor (AVPR1B) blockade altered the ACTH and corticosterone response to heterotypic stressors following CR stress. Adult male rats were exposed to CR, single restraint, or were left undisturbed in the home cage. Twentyfour hours after the last restraint, rats were injected with either a AVPR1B antagonist (Org, 30 mg/kg, s.c.) or vehicle (5% mulgofen in saline, 0 . 2/kg, s.c.) and then exposed to either restraint, lipopolysaccharide (LPS) or white noise. CR resulted in the adaptation of the ACTH and corticosterone response to restraint and this effect was not prevented by pretreatment with Org. Although we found no effect of CR on LPS-induced ACTH and corticosterone secretion, both repeated and single episodes of restraint induced the sensitization of the ACTH, but not corticosterone response to acute noise. Pretreatment with Org reduced the exaggerated ACTH response to noise after both single and repeated exposure to restraint.

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Section: Discussionsupporting

confidence: 75%

Effect of vasopressin 1b receptor blockade on the hypothalamic–pituitary–adrenal response of chronically stressed rats to a heterotypic stressor

Spiga¹,

Harrison²,

MacSweeney³

et al. 2008

Journal of Endocrinology

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“…This was accompanied by increased corticosterone plasma levels after FC and EXT training in animals that were exposed to IMO vs handled controls. A potential explanation for these findings may be hormonal sensitization after a stressful experience when animals were previously exposed to IMO (Belda et al, 2008a(Belda et al, , b, 2012Gagliano et al, 2008). Of note, our data suggest that hormonal sensitization was also found in response to exposure to the FC chamber in the absence of shocks.…”

Section: Discussionsupporting

confidence: 54%

Dexamethasone Treatment Leads to Enhanced Fear Extinction and Dynamic Fkbp5 Regulation in Amygdala

Sawamura

Klengel

Armario

et al. 2015

Neuropsychopharmacol

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Posttraumatic stress disorder (PTSD) is both a prevalent and debilitating trauma-related disorder associated with dysregulated fear learning at the core of many of its signs and symptoms. Improvements in the currently available psychological and pharmacological treatments are needed in order to improve PTSD treatment outcomes and to prevent symptom relapse. In the present study, we used a putative animal model of PTSD that included presentation of immobilization stress (IMO) followed by fear conditioning (FC) a week later. We then investigated the acute effects of GR receptor activation on the extinction (EXT) of conditioned freezing, using dexamethasone administered systemically which is known to result in suppression of the HPA axis. In our previous work, IMO followed by tone-shockmediated FC was associated with impaired fear EXT. In this study, we administered dexamethasone 4 h before EXT training and then examined EXT retention (RET) 24 h later to determine whether dexamethasone suppression rescued EXT deficits. Dexamethasone treatment produced dose-dependent enhancement of both EXT and RET. Dexamethasone was also associated with reduced amygdala Fkbp5 mRNA expression following EXT and after RET. Moreover, DNA methylation of the Fkbp5 gene occurred in a dose-dependent and time course-dependent manner within the amygdala. Additionally, we found dynamic changes in epigenetic regulation, including Dnmt and Tet gene pathways, as a function of both fear EXT and dexamethasone suppression of the HPA axis. Together, these data suggest that dexamethasone may serve to enhance EXT by altering Fkbp5-mediated glucocorticoid sensitivity via epigenetic regulation of Fkbp5 expression.

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“…However, the magnitude of the effect is dependent on the severity and length of exposure to the stressors (see Armario et al, 2008 for a review). Results from our lab show that after an acute exposure to IMO a long-term endocrine and/or behavioural sensitization to novel environments can develop, but both phenomena appear to be dissociated (Belda et al, 2008(Belda et al, , 2012Gagliano et al, 2008;Muñoz-Abellán et al, 2008).…”

Section: Endocrine Responsementioning

confidence: 84%

Sex differences in the behavioural and hypothalamic–pituitary–adrenal response to contextual fear conditioning in rats

Daviu

Andero

Armario

et al. 2014

Hormones and Behavior

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SummaryIn recent years, special attention is being paid to sex differences in susceptibility to disease. In this regard, there is evidence that male rats present higher levels of both cued and contextual fear conditioning than females. However, little is known about the concomitant hypothalamicpituitary-adrenal (HPA) axis response to those situations which is critical in emotional memories.Here, we studied the behavioural and HPA responses of male and female Wistar rats to context fear conditioning using electric footshock as the aversive stimulus. Fear-conditioned rats showed a much greater ACTH and corticosterone response than those merely exposed to the fear conditioning chamber without receiving shocks. Moreover, males presented higher levels of freezing whereas HPA axis response was greater in females. Accordingly, during the fear extinction tests, female rats consistently showed less freezing and higher extinction rate, but greater HPA activation than males. Exposure to an open-field resulted in lower activity/exploration in fear-conditioned males, but not females, suggesting greater conditioned cognitive generalization in males than females. It can be concluded that important sex differences in fear conditioning are observed in both freezing and HPA activation, but the two set of variables are affected in the opposite direction: enhanced behavioural impact in males, but enhanced HPA responsiveness in females. Thus, the role of sex differences on fear-related stimuli may depend on the variables chosen to evaluate it, the greater responsiveness of the HPA axis in females perhaps being an important factor to be further explored.

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Previous exposure to immobilisation and repeated exposure to a novel environment demonstrate a marked dissociation between behavioral and pituitary–adrenal responses

Cited by 53 publications

References 39 publications

Effect of vasopressin 1b receptor blockade on the hypothalamic–pituitary–adrenal response of chronically stressed rats to a heterotypic stressor

Effect of vasopressin 1b receptor blockade on the hypothalamic–pituitary–adrenal response of chronically stressed rats to a heterotypic stressor

Dexamethasone Treatment Leads to Enhanced Fear Extinction and Dynamic Fkbp5 Regulation in Amygdala

Sex differences in the behavioural and hypothalamic–pituitary–adrenal response to contextual fear conditioning in rats

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