Effect of ovine prolactin administration on glucose metabolism and plasma insulin levels in the dog.

Abstract

Uniformly labeled 14C-glucose was infused intravenously in intact unanesthetized dogs to determine the effect of ovine prolactin administration on glucose release by the liver and on glucose uptake and oxidation by the tissues. The intravenous injection of prolactin (1 mg/kg) had no immediate (first 5 hr) discernible effects on plasma glucose concentration or on glucose release and uptake. Continued administration of prolactin (1 mg/kg/day) for 3 to 7 days resulted in a small rise in plasma glucose concentration and a marked increase in glucose release and glucose uptake. Plasma insulin concentration was not changed. Determination of respiratory 14CO2 expired during the 14C-glucose experiments revealed that the amount of plasma glucose carbon oxidized to CO2 was also increased during the prolactin regimen; the fraction of glucose carbon taken up which was oxidized to CO2 was not affected by prolactin, nor was the total CO2 production. Infusion of insulin intravenously for 1 hr in prolactin-treated dogs re...