Excitatory stimulation of neurons in the arcuate nucleus inhibits gastric acid secretion via vagal pathways in anesthetized rats

It is well established that autonomic control of gastrointestinal function is modulated by central autonomic neuro trans mission. In this context it h as been shown that gastrointestinal motility and secretion can be modulated by exogenous neuropeptides microinjected into the paraventricular nucleus of the hypothalamus (PVN). Furthermore, there is considerable evidence sugg esting that neurons projecting from the arcuate nucleus (Arc) to the PVN ma y be the source of endogenous neuropeptide release in the PVN. This poses t he question whether stimulation of neurons in the arcuate nucleus, e.g. by an excitatory amino acid, alters gastrointestinal function. In the present study, we investigated the effect of an excitatory amino acid, kainate, mic roinjected into the arcuate nucleus on gastric acid secretion in urethane-a nesthetized rats. Kainate (140 pmol/rat) bilaterally microinjected into the Arc induced an significant inhibition of pentagastrin (PG) stimulated (16 mg/kg per h) gastric acid secretion throughout an observation period of 120 min after microinjection. Microinjection of kainate into hypothalamic area s outside the arcuate nucleus did not modify gastric secretion. Bilateral c ervical vagotomy blocked the effect of kainate injected into the Arc on PG- stimulated gastric acid secretion. These data show that gastric secretory f unction can be modulated by stimulation of neuronal activity in the Arc via efferent vagal pathways. The results suggest that the arcuate nucleus is a forebrain area involved in the CNS regulation of gastrointestinal function . (C) 2001 Elsevier Science B.V. All rights reserved.