Effects of lateral hypothalamic stimulation on medulla oblongata and gastric vagal neural responses

Abstract

Recordings were made of neural activity in the medial to lateral region of the dorsal nucleus of the vagus in the medulla oblongata (NDV), and from the gastric branch of the vagal nerve (gastric vagus) in rats. Gastric acid secretion following lateral hypothalamic (LHA) stimulation was observed, and NDV neurons were identified by stimulation of the peripheral end of the gastric vagus. NDV-neurons responded to LHA stimulation with latencies of about 5 msec, and about 6.5 msec to the peripheral stimulation of the gastric vagus. Out of 274 NDV neurons, which were located by their spontaneous discharge, 186 (67.9%) responded to LHA stimulation. Gastric acid secretion (with either short or long latency) occurred in 8.6% (16/186) of these cases. These 16 neurons were considered to be 'gastric secretory' neurons and are discussed as such. The results imply that some LHA neurons, which are either concerned with or directly control gastric acid secretion, communicated by at least one path (probably polysynaptic) to the medulla oblongata and then via the vagus to the oxyntic cells of gastric glands.