Site-specific formation of gastric ulcers by the electric stimulation of the left or right gastric branch of the vagus nerve in the rat.

The present study was conducted to investigate the role of the parasympathetic nervous system innervating the stomach in gastric ulcer formation, with special reference to its neuroanatomic characteristics in rats. First, the effects of electric vagal stimulation on the gastric mucosa were examined. The electric stimulation of the left or right gastric branch of the vagus nerve caused gastric mucosal lesions to develop. Interestingly, however, gastric lesions were found on the anterior wall in the rats that had received electric stimulation to the left gastric branch of the vagus nerve and on the posterior wall in the rats that had received stimulation to the right gastric branch. Next, the cells of origin projecting to the left or right gastric branch of the vagus nerve were identified by means of a horseradish peroxidase retrograde tracer method. The left and right gastric branches were found to be innervated by the left and right dorsal motor nuclei of the vagus nerve in the medulla oblongata, respectively. It has been reported that the left and right dorsal motor nuclei of the vagus nerve separately innervate the anterior or posterior gastric wall. The present results, therefore, suggest that the long-lasting excitation of neurons in the dorsal motor nucleus facilitates the site-specific formation of gastric ulcers through the left or right gastric branch of the vagus nerve.