C-FOS INDUCTION IN THE RAT NUCLEUS OF THE SOLITARY TRACT CORRELATES WITH THE RETENTION AND FORGETTING OF A CONDITIONED TASTE-AVERSION

Recently, we have described a potential neuronal correlate of the beha vioral expression of a conditioned taste aversion (CTA) against sucros e at the level of c-Fos expression, Intraoral infusions of sucrose ind uce c-Fos-Like immunoreactivity (c-FLI) in the intermediate nucleus of the solitary tract (iNTS) after a CTA has been acquired for sucrose, Sucrose infusions do not induce c-FLI in the iNTS of unconditioned rat s or in conditioned rats after extinction of the CTA, Here, we describ e persistence of altered responsiveness of the iNTS in rats with CTAs against sucrose by intraorally infusing sucrose 2 days, 3 months, or 6 months after acquisition of the CTA, Sucrose infusions induced c-FLI in the iNTS 6 months after conditioning, The behavioral expression of the CTA was attenuated at 6 months but not at 3 months; the number of c-FLI positive cells in the iNTS was proportional to the magnitude of the expression of the CTA, This evidence strengthens our hypothesis th at c-FLI in the iNTS is a neuronal correlate of the expression of a CT A.