Capsaicin-sensitive sensory neurons in healing gastric lesions induced by HCl in rats.

The role of capsaicin-sensitive sensory neurons in the healing of HCl-induced gastric lesions was investigated in rats. Rats fasted for 18 hr were given 0.6 N HCl orally for induction of gastric lesions, and they were fed normally from 1 hr later. On various days after HCl treatment, area of lesions, acid secretion, mucosal H+ permeability, and blood flow responses were measured. Functional ablation of capsaicin-sensitive sensory neurons was performed two weeks before the experiment by subcutaneous injections of high-dose capsaicin. Sensory deafferentation did not affect the development of gastric damage in response to HCl but significantly delayed the healing of these lesions. The mucosa damaged by HCl secreted less acid but showed significant rise in H+ permeability, resulting in acid back-diffusion accompanied by an increase of mucosal blood flow. Sensory deafferentation had no effect on acid secretion and mucosal permeability changes in the damaged stomach but completely blocked the hyperemic response caused by acid back-diffusion. Capsaicin-sensitive sensory neurons may contribute to healing of gastric lesions, probably by mediating the mucosal hyperemic responses associated with acid back-diffusion and by facilitating acid disposal in the mucosa.