Effect of vagotomy on expression of neuropeptides and histamine in rat oxyntic mucosa

The effect of vagotomy and pyloroplasty on the density of nerve fibers containing bombesin/gastrin-releasing peptide (GRP), calcitonin gene-related peptide (CGRP), and galanin as well as histamine-, 5-hydroxytryptamine (5-HT)-, and somatostatin-containing cells in the oxyntic mucosa of the rat stomach was studied. Ten days after vagotomy and pyloroplasty the density of histamine-containing cells in the oxyntic mucosa was increased by 70% (P < 0.05), and these cells were larger and showed more extensive cell processes than in control animals. The density of 5-HT-immunoreactive (IR) cells and somatostatin-IR cells were not affected. A marked decrease in the density of CGRP-IR nerve fibers and a slighter decrease in the density of GRP-IR nerve fibers was observed in the mucosal layer, while only a minor reduction of CGRP-IR fibers, and no reduction of GRP-IR fibers was seen in the muscular layer. The density of galanin-IR nerve fibers was not affected. The height of the oxyntic mucosa was reduced by about 25% (P < 0.05). Thus, a striking effect on the histamine-IR cells was seen, supporting the view that these cells are regulated by the vagus nerve. The study also indicates that a major portion of the CGRP-IR nerve fibers, and part of the GRP-IR nerve fibers, in the mucosal layer of the fundic region are of vagal origin or regulated by normal vagus nerve activity.