Feeding pattern of rabbits following intraduodenal glucose infusion as a function of caloric load, fasting interval, and vagal denervation

Abstract

Several meal parameters were evaluated during the 3-h period following intraduodenal infusion (3.3 ml/kg BW) of 5%, 10%, or 20% d-glucose, infusion of isotonic saline, or no infusion. Bilateral subdiaphragmatically vagotomized and sham-operated rabbits with chronic intraduodenal cannulas received all infusion treatments following both a 24-h fast and a period of free feeding. When infusions were given after free feeding, cumulative food intake was significantly decreased and latency to initiate feeding significantly increased by infusion of 5% glucose in the sham-operated rabbits, but not by infusion of 10% or 20% glucose. Cumulative food intake and latency were not affected by glucose infusion in the fasted sham-operated rabbits, or in the vagotomized rabbits following fasting or free feeding. The absence of glucose-induced satiety for the higher concentrations indicates that vagotomy does not merely shift the threshold for satiety, but appears to render vagotomized rabbits insensitive to the satiating effects of glucose. Both vagal denervation and a 24-h pretest fast produced dramatic effects on several short-term meal parameters. The nonmonotonic relation between the intraduodenal glucose load and subsequent feeding in sham-operated, free-feeding rabbits may result from the interaction of several factors, including activation of visceral satiety mechanisms, secretion of gut hormones, and visceral malaise.