Influence of repeated cold exposures on adrenocorticoid formation in rabbits with lesioned limbic-hypothalamic system.

Abstract

Experiments were carried out in the rabbit, with view to elucidating the role of limbic-hypothalamic system in the adrenocortical responses to repeated cold exposures. In each sham-lesioned group, in the rabbit with lesioned in bilateral stria terminalis and dorsal fornix, the formation of adrenocorticoids in adrenal was markedly increased by 1st cold exposure (cold exposure on 1st day), with the adrenocortical responses to 1st cold exposure being nearly the same in these groups. The bilateral lesions in periventricular arcuate nucleus and ventromedial hypothalamus decreased the adrenocortical responses to 1st cold exposure. In each sham-lesioned group, and in the rabbits with lesioned in bilateral periventricular arcuate nucleus, ventromedial hypothalamus and dorsal fornix, there were no effects of 7th cold exposure (cold exposure on 7th day) on the formation of adrenocorticoids. However, in the rabbits with lesioned in bilateral stria terminalis, the formation of adrenocorticoids was markedly increased by the 7th cold exposure. From these results it might be suggested that periventricular arcuate nucleus and ventromedial hypothalamus participated to adrenocortical response to 1st cold exposure, and the amygdala-stria terminalis system played some role in the establishment of adaptation to repeated cold exposures in adrenocortical responses.