Adrenocortical Activity in Hypophysectomized Dogs

¹ From the Departments of Biological Chemistry and Anatomy, University of Utah College of Medicine, Salt Lake City, Utah

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.