Growth Hormone Secretion in the Unanesthetized Rhesus Monkey in Response to Noxious Stimuli1

Serial blood samples, taken from conscious, lightly restrained rhesus monkeys bearing indwelling venous catheters or chronically implanted intracardiac catheters, were assayed for growth hormone (GH) concentration by a radioimmunologic procedure. It was found that sudden perturbations in the environment and painful stimuli were associated with abrupt increases in plasma GH levels. Hemorrhage as well as the administration of histamine, epinephrine, chlorpromazine and, on occasion, of pentobarbital led to precipitous elevations in plasma GH concentration. Arousal from pentobarbital anesthesia was accompanied by marked increases in circulating GH levels. These findings coupled with earlier observations that large doses of vasopressin also cause rapid increases in plasma GH concentration lead to the conclusion that a variety of otherwise unrelated stimuli, all known to augment ACTH secretion, similarly activate the release of GH from the pituitary. (Endocrinology80:163,1967)