Abstract

In this experiment, I examined the nervous system responses to duodenal infusions of 0.8 M glucose in comparison to isotonic saline in l5-day-old rat pups. In two variations of this experiment, pyloric nooses were used to restrict infusions to the intestine or nooses were not used. However, significant differences between infusion effects were seen only in the groups without nooses. After being infused with either of the two solutions, the pups' brains were analyzed using c-fos immunocytochemistry in regions shown previously to be activated by feeding in adults (the area postrema, AP , and the nucleus of the tractus solitarius, NTS). The region of the NTS caudal to AP showed a significantly higher number of activated cells in the brains of the glucose-infused animals in comparison with the brains of the saline-infused animals. The regions of the NTS rostral to AP , at AP , and within AP itself, did not show significant differences between the c-fos expression of the two groups, but glucose-infused animals tended to show greater expression of c-fos in all of these areas. These results support the postnatal development of a postgastric, nutritive control system of satiety in rats.