Influence of lesions of the limbic-hypothalamic system on adrenocortical responses to daily repeated heat exposures in rabbits.

The effects of lesions in the basal medial hypothalamus and limbic structure upon the responses of adrenocorticoids formation in adrenal slices of rabbits to daily repeated heat exposures has been investigated. (1) The adrenocortical responses to heat exposure on the 1st day were decreased by lesions in the periventricular arcuate nucleus (ARC), ventromedial hypothalamus (VMH), stria terminalis (ST) and dorsal fornix (FX). (2) There were no effects of heat exposure on the 10th day upon the adrenocorticoid formation in either the sham-lesioned rabbits or the rabbits with the lesions of ARC, VMH and ST. (3) In rabbits with the FX lesions, the adrenocorticoids formation was significantly increased by heat exposure on the 10th day. (4) These results suggested that the basal medial hypothalamus, amygdala (AMYG)-ST system and dorsal hippocampus (HPC)-FX system participated in the mechanisms of adrenocortical responses to heat exposure on the 1st day, but only the HPC-FX system played some roles in complete disappearance process of adrenocortical responses to heat exposure by repetition of exposures.