Capsaicin and its analogue resiniferatoxin inhibit gastric acid secretion in pylorus-ligated rats.

The effect of capsaicin and its analogue resiniferatoxin on gastric acid secretion was studied in conscious pylorus-ligated rats. Capsaicin administered intragastrically (i.g.) in very low concentrations inhibited gastric acid secretion (GAS) in a dose-dependent manner. The effect was most pronounced in the first hour. Resiniferatoxin administered in low concentrations like capsaicin produced a similar dose-dependent inhibition of GAS. The antisecretory action of both compounds was not present in rats desensitized with capsaicin applied i.g. in high concentration or in rats depleted of somatostatin by pretreatment with cysteamine. The results suggest that stimulation of capsaicin-sensitive primary afferents inhibits gastric acid secretion in rats and this effect is likely to be mediated by the release of neuropeptides.