Effect of neonatal ovariectomy and estradiol treatment on corticosterone release in response to stress in the adult female rat

Abstract

Although organizational effects of sex hormones in early life on hypothalamic–pituitary–adrenal function have been reported for males, the findings are mixed for females, likely the result of not controlling for adult gonadal status. In experiment 1, females were ovariectomized (OVX) either on postnatal day 1 or as adults and given estradiol benzoate (EB) and progesterone implants or not as adults. Corticosterone release in response to restraint stress was responsive to hormonal replacement irrespective of timing of OVX: without replacement, both OVX groups had lower corticosterone concentrations after restraint stress than did OVX groups with replacement and gonadally intact females. Thus, neonatal OVX did not alter the activational effects of sex hormones in adulthood. In a second experiment, females administered a dose of EB on postnatal day 1 had a more rapid decline of corticosterone concentrations after restraint as adults compared to oil-treated females, irrespective of whether they were OVX as neonates or as adults (all groups were given estradiol replacement as adults). Thus, evidently there are organizational effects of the sex hormonal milieu of the neonatal female, although this is a modest effect compared to previous reports in males.