Function of the hypothalamo-pituitary-adrenocortical system during ontogenesis in rats with inherited stress-induced arterial hypertension.

The functional activity of the hypothalamo-pituitary-adrenocortical system (HPAS) during the development of rats with inherited stress-induced arterial hypertension (HSIAH rats) was compared with that in normotensive Wistar rats. In rats aged 2, 3, 4, 6, 8, 10, 12, and 18 weeks, competitive protein binding assays were used to estimate peripheral blood plasma corticosterone levels at rest and after 1 h of restricted mobility in mesh cylinders. Basal corticosterone levels and HPAS responses to stress were lower during ontogenesis in hypertensive rats than in Wistar rats of the same age. The exception was rats aged four weeks, when HSIAH rats started to develop hypertension and their HPAS was more sensitive to emotional stress than was the case in Wistar rats, this being associated with the greater reaction of the adrenals to ACTH. Decreased reactions of the HPAS to emotional stress in adult HSIAH rats is not associated with loss of adrenal ACTH sensitivity.