Adrenocortical responses in dexamethasone-treated rats with septal, preoptic and combined hypothalamic lesions.

To elucidate the role of limbic structures in the negative feedback regulation of corticoids of adrenocortical function, the effect of dexamethasone on adrenocortical responses to ether stress was studied in intact and lesioned rats. In animals with septal and preoptic lesions the degree of the feedback of dexamethasone on adrenocortical responses was similar to that in intact rats. In animals with bilateral medial forebrain bundle lesions the feedback influence was enhanced, but this was reversed by a subsequent posterior hypothalamic deafferentation, which if produced separately diminished the feedback effect. This would indicate that though the septum and preoptic area do not play a significant role in the feedback of dexamethasone, there is a mutual interaction between closely situated facilitatory and inhibitory systems in the feedback control of adrenal function.