C-fos expression in the brainstem after voluntary ingestion of sucrose in the rat.

Neurons showing activity after sweet taste stimulation, were detected with c-fos immunocytochemistry, to identify brainstem nuclei involved in processing taste information. The distribution of the evoked expression of c-fos was visualized in the rat brainstem after voluntary ingestion of sucrose. Sucrose-taste-specific c-fos immunoreactive neurons were found within the medial part of the nucleus of the solitary tract, the dorsal motor nucleus of the vagus at caudal levels, the paratrigeminal nucleus and the lateral and medial part of the parabrachial nucleus. These nuclei are known to be involved in the processing of information related to ingestive behavior such as information about taste quality. The present study has shown that c-fos is a useful anatomical marker for activated neurons in the rat brainstem, and that the above-mentioned brainstem areas are involved in the processing of sweet taste information.