Adrenal Sensitivity to ACTH as a Function of Time after Hypothalamic Lesion and after Hypophysectomy.

Abstract

The adrenocortical response to injected adrenocorticotropic hormone (ACTH) USP Standard was studied as a function of time in rats after hypophysectomy or placement of a lesion in the median eminence of the hypothalamus. Adrenocortical response to ACTH is measured by variations of plasma free corticosterone levels rather than adrenal ascorbic acid depletion. There is an exponential decrease in sensitivity to ACTH of the adrenal gland as a function of time in both the hypothalamic and hypophysectomized rat. This can be observed in the presence of large adrenal glands in animals bearing hypothalamic lesions. The progressive decrease of adrenal sensitivity to ACTH in the lesioned animal makes it desirable to use only an acute preparation as a test for CRF.