抄録
Neuronal activity in the parabrachial nucleus (PBN) of rats was examined using Fos-like immunoreactivity (FLI) in retention and after extinction of conditioned taste aversion (CTA) to NaCl. In experiment 1, intraorally infused NaCl induced significantly greater FLI in the external lateral (els) and central medial subnuclei (cms) in the CTA group that had acquired CTA than in the sham-conditioned control group. Addition of the epithelial sodium channel blocker, amiloride, to NaCl solution severely reduced FLI in the cms but not in the els in both groups. In experiment 2, effects of decerebration after the acquisition of CTA on FLI in the PBN were examined. Decerebration completely eliminated the elevated FLI in the els and cms in the CTA group that was observed in experiment 1. In experiment 3, FLI in the PBN of rats in which CTA had been behaviorally extinguished (EXT group) was examined. FLI in the cms in the EXT group was significantly smaller than in the CTA group, and greater than in the control group. These results suggest that the els and cms are functionally different and that forebrain structures critically contribute to gustatory information processing in the PBN. [Jpn J Physiol 54 Suppl:S187 (2004)]
