Neural network of glucose monitoring system.

Glucose-sensitive neural elements exist in the hypothalamus, the nucleus of the solitary tract (NTS) and autonomic afferents from visceral organs such as liver and gastrointestinal tract. Glucose affects neural activity through these central and peripheral chemosensors. Glucose is generally suppressive in the liver, the NTS and the lateral hypothalamic area (LHA), and generally excitatory in the small intestine and ventromedial hypothalamic nucleus (VMH). The hypothalamus is involved in the control of pancreatic hormone secretion through autonomic efferent nerves. Stimulation or lesion of the hypothalamus induces various changes in pancreatic autonomic nerve activity. The VMH, the dorsomedial hypothalamic nucleus and the paraventricular nucleus have inhibitory effects on vagal nerve activity and excitatory effects on splanchnic nerve activity. The LHA is excitatory to the vagal nerve, and both excitatory and inhibitory to the splanchnic nerve. These findings suggest that the neural network of the glucose monitoring system, which also analyzes and integrates information concerning other metabolites and peptides in the blood and cerebrospinal fluid, contributes to regulation of peripheral metabolism and endocrine activity as well as feeding behavior. The physiological function and input-output organization of this network are discussed.