Abdominal pathways and central origin of rat vagal fibers that stimulate gastric acid.

The brainstem location and peripheral course of the vagal preganglionic fibers that stimulate gastric acid secretion were identified using electrical stimulation combined with retrograde (True Blue; Dr. K. G. Illing, Gross Umstadt, Germany) and anterograde (Dil; Molecular Probes) fluorescent neural tracers in rats with various selective vagotomies. Animals with only one or both gastric branch(es) spared had normal, large gastric acid responses to electrical stimulation of the ipsilateral cervical vagus and showed an abundance of Dil-labeled vagal fibers and terminals in the gastric myenteric plexus. Rats with only the unpaired hepatic branch spared had a much smaller but significant gastric acid response and a few labeled vagal profiles in the antral region of the stomach. In contrast, rats with only one or both celiac branch(es) intact had neither a gastric acid response, nor evidence for Dil transport to the stomach. Retrograde transport of True Blue through the spared vagal axons to the brainstem indicated that the cell bodies of the preganglionics that send their axons through the acid-positive gastric and hepatic branches occupy the medial longitudinal columnar subnuclei of the dorsal motor nucleus. It is concluded that besides the long-recognized gastric branches, which are the major access route to the parietal cells, the hepatic branch contains a small number of fibers that most likely reach the antrum through the right gastroepiploic artery along the greater curvature and/or the right gastric artery.