[Maternal deprivation-induced stress responses in female rats].

Objective: To investigate the effect of maternal deprivation on the activity of hypothalamo-pituitary-adrenal (HPA) axis, acute stress response and the sex hormone receptors expression in hypothalamic paraventricular nucleus (PVN) in female rats.

Methods: Maternal deprivation model was induced in female Sprague-Dawley (SD) rats. Foot shock was given at different stages of estrus cycle during the adulthood. Plasma estradiol, testosterone and adrenocorticotropin (ACTH) levels were determined by radioimmunoassay; and plasma corticosterone level was measured by enzyme linked immunosorbent assay. The expression of androgen receptor (AR) and estrogen receptor (ER-β) in the hypothalamic PVN was detected by immunohistochemistry.

Results: Decreased plasma ACTH and corticosterone levels were found in the proestrus of female rats with maternal deprivation (P=0.012 and P=0.019, respectively). A significant down-regulation (P=0.008) of PVN-AR, but not PVN-ER-β expression was found in female rats with maternal deprivation.

Conclusion: Maternal deprivation may reduce the HPA axis activity in female SD rats, which is closely correlated with the fluctuation of the circulating sex hormones. The androgen in the hypothalamus seems to play a more important role than the estrogen in this procedure.