Neuroendocrine Reactions to Intracerebroventricular Injections of Arginine-Vasopressin in Prenatally Stressed Rats

We studied the effect of central vasopressinergic stimulation on the functions of the hypothalamo-pituitary-adrenal and hypothalamo-pituitary-gonadal axes in mature offsprings of female rats stressed during the last week of pregnancy (daily immobilization for 1 h). Experiments were carried out on unanesthetized rats; the blood samples were taken 20 and 40 min after intracerebroventricular injections of arginine-vasopressin (AVP). Twenty minutes after infusion of 0.5 ng of this neuropeptide dissolved in 2 µl of isotonic NaCl solution into the III cerebral ventricle, the adrenocortical reaction in prenatally stressed males was 50% smaller than that in normal animals; on the 40th min, it continued to develop but remained weaker. In prenatally stressed females, the adrenocortical reaction to central vasopressinergic stimulation was weakened. Arginine-vasopressin-induced increases in the level of corticotropin in the blood were nearly identical in both prenatally stressed and normal rats (males and females). The level of testosterone in the blood of prenatally stressed and normal males dropped sharply 20 min after intracerebroventricular injection of AVP and, on the 40th min, remained significantly lower than the basal level in males of both studied groups; prenatal stress did not influence these alterations. Our data show that vasopressinergic control is weakened in prenatally stressed male rats, and this is a significant probable reason for the decrease in the stress reactivity of the hypothalamo-pituitary-adrenal system in these animals.