Effects of hypothalamic deafferentations on adrenocortical responses in the rat following hippocampal stimulation

Adrenocortical responses, as expressed by changes in plasma corticosterone levels, following ether stress and dorsal hippocampal stimulation, were studied in intact rats and in rats with complete, anterior of posterior hypothalamic deafferentations. Ether stress produced normal responses in all experimental groups. In the three groups with hypothalamic deafferentations, the adrenocortical response following hippocampal stimulation was completely blocked, when compared to intact animals. The results suggest that the hippocampal signal enters the hypothalamus anteriorly, but that caudal propagation and posterior re-entry into the hypothalamus are also essential for the adrenocortical activation by the hippocampus.