Involvement of CGRP, substance P and blood circulation in aggravating mechanism of absolute ethanol-induced antral lesions by capsaicin treatment in rats.

The effects of capsaicin-sensitive nerve degeneration (capsaicin-treatment) on the corpus and the antrum was investigated in the absolute ethanol-induced lesion model in rats. The gastric lesion in the antrum were significantly aggravated by the capsaicin-treatment, while those in the corpus were not affected. To clarify the different susceptibility between the antrum and the corpus, the effects on gastric mucosal blood flow (GMBF), mucus secretion and levels of calcitonin gene-related peptide (CGRP) or substance P (Sub P), were investigated by the hydrogen gas clearance method, histochemical methods and immunohistochemical methods, respectively. The GMBF in the antrum was significantly decreased by the capsaicin-treatment, but that in the corpus was not. Moreover, capsaicin-treatment increased the mucus secretion in the antrum, but not in the corpus. Capsaicin-treatment significantly decreased CGRP- and Sub P-immunoreactive substances in the vascular smooth muscle in the antrum, but not in the corpus. On the 4th day after absolute ethanol, antral ulcers were observed. From the above results, it was suggested that capsaicin-treatment decreased the gastroprotective ability in the antrum to a greater extent than in the corpus and this may be caused by the decrease of GMBF through the decrease of CGRP- and Sub P-immunoreactive substances.