抄録
Recently, we showed that luminal glutamate triggered the vagal afferent activation via NO and 5-HT transduction pathways in the rat gastric mucosa (Uneyama et al., Am. J. Physiol: 2006, 291: G1163-1170). In the present experiment, we examined the existence of the functional couplings of NO and vagal nerve endings in the rat gastric mucosa. Male Sprague-Dawley rats were anesthetized with urethane and the afferent nerve discharges from nerve bundle of the left gastric were monitored. Blood pressure and body temperature were also continuously monitored during experiments. Gastric vagal afferent nerve was activated both by luminal and intra-vascular applications of NO donors such as sodium nitroprusside (SNP). SNP-evoked gastric afferent nerve discharges were abolished by pre- and post-treatment with serotonin type3 antagonist, granisetron. The SNP-evoked afferent nerve discharge was depressed by the treatment with a mucosal serotonin depletor, p-chlorophenylalanine. With receptor pharmacology using specific 5-HT receptor subtypes, it is revealed that the 5-HT receptor subtype of the gastric vagal nerve endings is dominantly type3. These results strongly indicate that a chemical perception pathway of NO-triggered 5-HT release to the vagus exists in the rat gastric mucosa. [J Physiol Sci. 2007;57 Suppl:S242]
