Hypothalamic Mediation of Growth Hormone and Adrenal Stress Response in the Squirrel Monkey

Hypothalamic lesions were produced in the squirrel monkey in order to identify the neural pathways by which the emotional stimulus of capture and the stress of ether anesthesia bring about growth hormone (GH) hypersecretion. Plasma GH levels were determined by human GH radioimmunoassay. As an index of pituitary-adrenal activation in these animals, plasma corticoids were measured by competitive binding assay. In unlesioned animals capture led to increased release of GH and to adrenal cortical activation. Chair restraint was followed by continued adrenal cortical hypersecretion unaccompanied Tjy GH discharge, while ether anesthesia induced GH discharge without a significant increase in adrenocortical secretion. Growth hormone responses to capture and ether anesthesia were blocked by relatively small lesions in either anterior or posterior median eminence, while adrenal responses to capture and chair restraint were blocked by lesions in the posterior median eminence in 3 animals. Lesions of the inferior third of the mammillary bodies blocked GH and adrenal responses to capture. GH responses to ether were greatly enhanced in 3 animals with midline optic chiasm lesions and in one animal with a mammillary body lesion, suggesting that structures in these regions may have an inhibiting effect on GH responses. (Endocrinology 89: 694, 1971)