INSULIN SENSITIVITY AND ADRENOCORTICAL FUNCTION IN GUINEA-PIGS WITH HYPOTHALAMIC LESIONS

Abstract

ABSTRACT Insulin hypersensitivity was displayed by adult, male guinea-pigs with bilateral, electrolytic lesions in the anterior and middle hypothalamus. The increased hypoglycaemic response to a single intraperitoneal injection of insulin (0.5 U/kg) was followed by marked hypoglycaemia unresponsiveness compared with preoperative control values. The most effective lesions were those centered in and about the ventromedian and dorsomedian hypothalamic nuclei, either ablating a portion of the anterior median eminence or leaving it entirely intact. Animals with both types of lesions had lower fasting blood sugar levels and marked adrenal regression as evidenced by reduced adrenal weights and decreased levels of 17-hydroxycorticosteroid excretion. It is postulated that lesions in the ventromedian and dorsomedian hypothalamus which interfere with adrenocortical function correspond in anatomic site to those which render the guinea-pig more sensitive to insulin.