| Abstract: | Chronic experiments were made on intact rabbits and rabbits with destroyed paraventricular and ventromedial nuclei of the hypothalamus to explore the hydrocortisone-induced inhibition of the stressor response of the pituitary-adrenocortical system. Intravenous injection of hydrocortisone in a dose of 100 micrograms/kg 5 minutes before immobilization stress led to inhibition of corticosteroid elevation induced by immobilization of the animals. Inhibition of the stressor reaction was maximal in intact animals, less in rabbits with destroyed ventromedial nuclei, and further less in animals with destroyed paraventricular nuclei. The paraventricular and ventromedial nuclei of the hypothalamus are necessary for inhibition of the pituitary-adrenocortical system by the feedback mechanisms. |
