Gastric emptying of glucose loads in rats: effects of insulin-induced hypoglycemia.

Previous work has established that the increased food intake of rats in response to insulin-induced hypoglycemia can be inhibited by the intravenous infusion of fructose, a sugar that cannot cross the blood-brain barrier and nourish cerebral chemoreceptors, and that this effect of fructose is abolished by hepatic vagotomy. The present series of experiments examined the effects of these treatments on gastric emptying of various glucose solutions in rats. Gastric emptying of the administered loads decreased in proportion to increasing concentration of glucose solution but not by enough for caloric delivery to be regulated precisely. Insulin-induced hypoglycemia increased the rate at which the glucose solutions emptied from the stomach. This enhanced emptying was suppressed by infusion of fructose, and that suppression was eliminated by hepatic vagotomy. These and other findings support previous proposals that food intake is controlled in part by satiety signals reflecting the nutrient content of the stomach and in part by satiety signals related to the delivery of utilizable calories to the liver.