Highlights in basic autonomic neurosciences: Diet-induced enteric, vagal and brainstem dysfunction.

Abstract

Vagally-dependent reflexes are critical to the control and regulation of appropriate gastrointestinal (GI) functions, including early satiety and the regulation of food intake. Visceral sensory information is relayed to the central nervous system via the afferent vagus nerve, the central terminals of which enter the brainstem via the tractus solitarius and terminate on neurons of the nucleus tractus solitarius (NTS). These second-order NTS neurons assimilate and integrate this vast volume of sensory information with inputs received from other brainstem and higher CNS centers involved in the regulation of autonomic homeostatic functions. The integrated signal is then relayed to the adjacent dorsal motor nucleus of the vagus (DMV) which contains the preganglionic parasympathetic motoneurons that transfer the appropriate output response back to the upper GI tract via the efferent vagus nerve. While the enteric nervous system (ENS) is capable of a significant degree of autonomy of GI functions, the stomach and upper GI tract in particular, are more dependent upon extrinsic neural inputs, particularly through the vagus nerve.