Adrenocortical Activity in Hypophysectomized Dogs

Abstract

The pituitary gland was removed in normal mongrel dogs. Following this operation low or zero plasma levels of 17-hydroxycorticosteroids (17-OHCS) were seen as early as 12 hours postoperatively. Dogs completely hypophysectomized from 15 to 30 days exhibited no increase in plasma 17-OHCS subsequent to the ‘stress’ of sodium pentobarbital anesthesia and cannulation of the femoral artery, and adrenal venous levels of 17-OHCS were very low in hypophysectomized dogs subjected to the ‘stress’ of laparotomy. Between the 15th and 30th day following hypophysectomy a normal removal of intravenously administered cortisol was found. However, at this time after hypophysectomy an inferior response in plasma 17-OHCS was demonstrated following the intravenous administration of ACTH. The oral administration of adrenal hormones to normal dogs for 15 days led to a similar impairment in the responsiveness of adrenocortical tissue to ACTH injection. It has thus been shown that lack of pituitary function for 15–30 days will rapidly result in a functional atrophy of the canine adrenal cortex. The data further demonstrate that intravenously administered cortisol is removed or ‘utilized’ at a normal rate in animals lacking pituitary function. Small remnants of anterior pituitary tissue appear to maintain a reduced but measurable adrenocortical capacity in the dog.