Rat pups provide a useful developmental model for the study of feeding behavior. By nine days of age, feeding behavior in rat pups is altered by nutritive stimuli. Pups given glucose preloads have reduced intake compared to pups that received saline preloads. By fifteen days of age, pups respond specifically to postgastric nutritive cues; duodenal infusions of glucose significantly reduce intake. Further studies have shown that the anesthetic tetracaine hydrochloride attenuates these inhibitory nutritive effects in preweanling pups, suggesting that the response to infused nutrients, especially glucose, is preabsorptive. I propose to examine preweanling rat pups to determine if duodenal infusions of the non-nutritive sweetener, sodium saccharin, can produce feeding inhibition in rat pups.

Near the beginning of a 24 hour deprivation period, 1 5-day-old rat pups had infusion cannulas installed in the proximal duodenum. After deprivation, pups were duodenally infused with distilled water, 0.6M glucose, isotonic saline, 0.5%, 1%, or 2% sodium saccharin over an eight minute period at the beginning a 30 minute feeding test. In addition, the pups' levels of activity, mouthing, and grooming were recorded for ten second periods at two minute intervals for the entire length of the test. After recording the behavioral observations, intake and stomach contents were determined as a percentage of pre-test body weight.

The 0.5%, 1%, and 2% sodium saccharin infusions did not have significant effects on intake or stomach contents. The sodium saccharin infusions also demonstrated no significant effects on activity, mouthing, or grooming during the feeding test.

Sodium saccharin's failure to induce feeding inhibition runs counter to my initial hypothesis; however, this lack of effect may be due to small sample size, pups' low body weights, or reflux of infused solutions. In future studies, duodenal cannulas should be placed further down the duodenum and infusion time increased to allow intestinal receptors greater exposure to duodenally infused solutions.