Effects of a single footshock followed by situational reminders on HPA axis and behaviour in the aversive context in male and female rats

Psychoneuroendocrinology. 2006-01-01; 31(1): 92-99
DOI: 10.1016/j.psyneuen.2005.05.014

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Gender is an important factor in the vulnerability to develop psychopathologies.
At the biological level, stress-related pathologies such as depression or
post-traumatic stress disorder (PTSD) are associated with profound disturbances
of the hypothalamo-pituitary-adrenal (HPA) axis. The aim of the present study was
to assess sex-differences in the long-term effect of an intense stressful
procedure on HPA function and behaviour in the aversive context in rats. Female
and male rats experienced an aversive procedure consisting in an electric
footshock (2mA, 10s) in a dark chamber followed by 3 weekly situational reminders
(SR, 2min in the white chamber close to the footshock chamber). Our results
indicate that 41 days after the end of the aversive procedure, female rats showed
an increase of the corticosterone negative feedback in response to restraint
stress, whereas such effect was not observed in males. Despite this change in the
hormonal response, glucocorticoid receptors mRNA expression in the hippocampus
was not affected in shocked females. In contrast, a significant increase of the
mineralocorticoid receptors mRNA was observed in the CA2 of the hippocampus in
shocked males. Finally, CRH mRNA levels in the paraventricular nucleus of the
hypothalamus (PVN) were decreased in both female and male animals exposed to the
aversive procedure. Behavioural observation revealed that shocked males and
shocked females showed a high level of avoidance. However, the latency to visit
the shock box was lower in females, which spent also more time in this area than
males. In conclusion, our results suggest that gender might be a key factor
impacting the direction of the effects induced by an intense stress.
Interestingly, only females exhibited an increased negative feedback of the HPA
axis response to stress, which could parallel endocrine changes of PTSD.

DOI: 10.1016/j.psyneuen.2005.05.014
PMID: 16081221 [Indexed for MEDLINE]

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