SUBDIAPHRAGMATIC VAGOTOMY DOES NOT ATTENUATE C-FOS INDUCTION IN THE NUCLEUS OF THE SOLITARY TRACT AFTER CONDITIONED TASTE-AVERSION EXPRESSION

After acquisition of a conditioned taste aversion (CTA) against sucros e, intraoral infusions of sucrose induce c-Fos-like immunoreactivity ( c-FLI) in the medial intermediate nucleus of the solitary tract (iNTS) of the rat. In order to determine if c-FLI expression in the iNTS dep ends on subdiaphragmatic vagal afferent input to the NTS secondary to gastrointestinal symptoms during CTA expression (e.g. diarrhea), we qu antified the induction of c-FLI in the iNTS by sucrose infusions after total subdiaphragmatic vagotomy in rats with a previously acquired CT A against sucrose. Rats were conditioned against intraoral infusions o f sucrose by pairing sucrose infusions with toxic LiCl injections. Aft er CTA acquisition, rats underwent bilateral subdiaphragmatic vagotomy or were sham-vagotomized. One week after surgery, rats received an in traoral infusion of sucrose. One hour after the test infusion, rats we re perfused and processed for c-FLI. Vagotomy had no apparent effect o n the behavioral expression of the previously acquired CTA, because bo th vagotomized and sham-vagotomized rats rejected all of the test intr aoral infusion of sucrose. There was also no significant difference be tween vagotomized and sham-vagotomized rats in the number of c-FLI-pos itive cells in the iNTS after CTA expression. We conclude that c-FLI i nduction correlated with CTA expression is not dependent on subdiaphra gmatic vagal efferent output or afferent input.