Vago-sympathetic modulation of gastric mechanoreceptors: effect of distention and nutritional state

Abstract

Unit discharge evoked in gastric afferents by tactile stimulation of the frog's stomach was inhibited by electrical stimulation of gastric vagi and facilitated by cervical sympathetic stimulation. The inhibition or the facilitation of the evoked response depended on the mode and parameters of stimulation used. The tactually-evoked activity was also inhibited by gastric distention in well-fed animals (Type-I). This inhibition was released by gastric vagotomy, while cervical sympathectomy had no appreciable effect on the evoked inhibitory response. In Type-II animals (animals kept on chronic food deprivation) the tactually-evoked activity was facilitated, rather than inhibited, by coupling tactile stimulation with gastric distention. This facilitation was abolished by cervical sympathectomy, but was not significantly affected by gastric vagotomy. It appears that the differential modulating control of gastric mechanoreceptor activity is biased by the state of energy balance and is brought about by a dual efferent control system mediated through autonomic nerves, gastric vagal fibers being inhibitory, and cervical sympathetic nerves being facilitatory to the tactile response.