Effects of gustation and gastric loading on rapid calorie metering in rats

On gustation/intubation of nutritive sucrose or glucose solution, both ad lib and meal-time rats reduced their subsequent 1 hr calorie intake via stock diet. But gustation/intubation of calorically-inert water had no effect on 1 hr calorie intake of either group of rats. In contrast, on tasting calorically-inert but sweet saccharin, the 1 hr intake of meal-time rats was reduced, though not the intake of ad lib rats. However, on intubation of saccharin solution no reduction in 1 hr intake was shown by either meal-time or ad lib rats. Quinine also showed differential effects on calorie intake. On intubation, but not on gustation of quinine, both ad lib and meal-time rats evidenced increase in their 1 hr calorie intake. Daily (24 hr) calorie intake via stock diet of ad lib rats, in contrast to 1 hr intake was unaffected by gustation/intubation of any test solution, including nutritive sucrose and glucose. Meal-time rats daily (3 hr) intake, on the other hand, was similar to 1 hr calorie intake following test solution treatment. It was reduced on gustation/intubation of calorically-rich solution as well as on tasting the sweet, but calorically-inert saccharin. Taste/intubation of quinine did not cause any change in daily calorie intake of either ad lib or meal-time rats.