FOS PROTEIN EXPRESSION IN THE NUCLEUS OF THE SOLITARY TRACT IN RESPONSE TO INTESTINAL NUTRIENTS IN AWAKE RATS

Nutrients in the intestine inhibit food intake via an action on the va gal afferent pathway. The aim of the present study was to use immunoch emical detection of Fos protein-like immunoreactivity (FLI) in the bra instem to trace the neuronal pathways activated by intestinal nutrient s. Perfusion of the intestine of awake rats via an indwelling duodenal catheter with iso-osmotic mannitol, hydrochloric acid or casein hydro lysate had no effect on the number of FLI neurons in the nucleus of th e solitary tract (NTS). Lipid emulsion (20%) and 2.7 M glucose signifi cantly increased the number of immunopositive cells in the NTS. There was a significant increase in the number of immunopositive cells from caudal to rostral NTS. Nutrients effective at decreasing food intake ( carbohydrate and fat) produced significant increases in Fos-like immun opositive cells in the NTS.