Neuronal control of esophageal function.

Esophageal peristalsis and sphincter function are controlled by the autonomic nervous system, with contributions from parasympathetic, sympathetic, and enteric divisions. Proximal regions, including the upper esophageal sphincter, are composed of striated muscle and are under direct (cholinergic) control of vagal motoneurons located in the nucleus ambiguus. Sequential peristaltic contraction is coordinated by a brainstem pattern generator circuit involving the nucleus of the solitary tract and modulated by vagal afferents. Distal esophageal regions including the lower sphincter are controlled by intramural enteric circuitry, with a poorly characterized contribution from vagal preganglionic fibers arising in the dorsal motor nucleus of the vagus. Peristaltic contraction depends on cholinergic (muscarinic) excitation and NO-mediated inhibition. Neurally-produced lower esophageal sphincter relaxation is mediated by NO, vasoactive intestinal polypeptide, or both.