STIMULATION OF LUTEINIZING-HORMONE SECRETION BY FOOD-INTAKE - EVIDENCE AGAINST A ROLE FOR INSULIN

In adult male rhesus monkeys, 1 day of fasting leads to a profound sup pression of LH secretion that is rapidly reversed with refeeding. To t est the hypothesis that changes in insulin secretion during fasting an d refeeding mediate the changes in LH secretion, blood samples for LH measurement were obtained between 0900-2400 h from adult male rhesus m onkeys (n = 9) on 1) a day when monkeys were refed their normal meal a fter a day of fasting, and 2) a day when monkeys were refed their norm al meal, but endogenous insulin secretion was suppressed. Diazoxide (7 .5-9.5 mg/kg . h) caused a 40-99% suppression of postmeal insulin secr etion. However, no significant differences in LH pulse frequency, puls e amplitude, or mean serum LH levels were detected between control and diazoxide trials, even in animals in which insulin was markedly suppr essed. Further, no correlation existed between the degree of insulin s uppression and the magnitude of the meal-induced stimulation of LH. We conclude that meal-induced insulin secretion does not provide the sti mulus mediating the meal-induced increase in LH secretion.