CAUDAL HINDBRAIN PARTICIPATION IN THE SUPPRESSION OF FEEDING BY CENTRAL AND PERIPHERAL BOMBESIN

We have previously demonstrated that bombesin (BBS) infused into the f ourth cerebral ventricle in rats suppressed feeding at doses 10-1,000 times less than those required after lateral ventricular administratio n. These results suggest that centrally administered BBS acts in the c audal hindbrain to suppress food intake. To investigate the participat ion of caudal hindbrain structures in fourth-ventricular BBS-induced s uppression of feeding, we made lesions that destroyed the following: 1 ) area postrema (AP) and 2) AP and medial nucleus of the solitary trac t (NST). Additionally, we examined the role of the AP/NST in the suppr ession of food intake after peripheral BBS administration. Our experim ents revealed that lesions of the AP/NST abolished the suppression of food intake by fourth-ventricular BBS and attenuated the suppression o f food intake by peripheral BBS. Lesions restricted to the AP attenuat ed the suppression of food intake by fourth-ventricular BBS but had no effect on suppression of intake by peripherally administered BBS. The se results suggest that the NST may be a common neural substrate for t he inhibition of food intake by both centrally and peripherally admini stered BBS.