Adrenocortical Function in Monkeys After Forebrain Removal or Pituitary Stalk Section

Abstract

Previous studies in dogs with isolated pituitaries have shown unexplained, persistent hypersecretion of adrenocortical steroids for up to 5 days. Since hypothalamic participation has been generally regarded as necessary for pituitary ACTH secretion, it was considered important to establish whether the isolated pituitary phenomenon occurs in a primate. Left adrenal vein and femoral or carotid artery cannulae were placed in rhesus monkeys before one of the following brain operations was performed: forebrain removal with pituitary isolation or with hypophysectomy, or pituitary stalk section (with a barrier). Secretion of 11-hydroxycorticoids fell from an average of 4.2 μg/min immediately after hypophysectomy to an average of 0.9 μg/min by 4 hr after operation and to an average of 0.3 μg/min by 8 hr after operation. After forebrain removal leaving only an isolated pituitary or after acute pituitary stalk section, 11-hydroxycorticoid secretion exceeded 1 μg/ min 4 or 8 hr later. In some instances the secretion rate was above 5 μg/min 8 or more hr following isolation of the pituitary. In chronically stalk-sectioned animals, peripheral plasma 11- hydroxycorticoids returned to preoperative levels by 3–10 days following and never were below the normal range despite insertion of a barrier to prevent regrowth of the pituitary stalk. It is concluded that in the rhesus monkey pituitary ACTH secretion may persist temporarily following brain operations regardless of whether the hypothalamus is present or is removed. The cause of the continued ACTH secretion after brain removal has not been established. (Endocrinology84: 686, 1969)