Increased c-fos expression in nucleus of the solitary tract correlated with conditioned taste aversion to sucrose in rats.

The pattern of neuronal activation in the rat nucleus of the solitary tract (NTS) in response to a standard gustatory stimulus was examined using c-Fos-like immunoreactivity (c-FLI) before and after conditioned taste aversion (CTA) formation. While unconditioned oral infusions of sucrose solution did not induce c-FLI in the NTS, after three pairings of sucrose with lithium chloride injections, sucrose induced c-FLI in the medial intermediate NTS 1 h after oral infusion. Extinction of the CTA by repeated infusions of sucrose alone reversed the induction of c-FLI.