Innervation of the gastric mucosa

A plethora of neuronal messengers ("classical" transmitters, gaseous messen gers, amino acid transmitters, and neuropeptides) are capable of mediating or modulating gastric functions. Accordingly, the stomach is richly innerva ted. Gastric nerves are either intrinsic to the gastric wall, i.e., they ha ve their cell bodies in the intramural ganglia and thus belong to the enter ic nervous system, or they reach the stomach from outside, originating in t he brainstem, in sympathetic ganglia, or in sensory ganglia. Topographicall y, the nerve fibers in the stomach reach all layers from the most superfici al portions of the gastric glands to the outer smooth muscle layer. This wi de distribution implies that virtually all different cell types may be reac hed by neuronal messengers. Within the gastric mucosa endocrine and paracri ne cells (e.g., gastrin cells, ECL cells, somatostatin cells), exocrine cel ls (parietal cells, chief cells, mucous cells), smooth muscle cells, and st romal cells are regulated by neuronal messengers. The sensory innervation, responding to capsaicin, plays an important role in mucosal protection, and in ulcer healing. Presumably also other nerves are involved and a plastici ty in the neuropeptide expression has been demonstrated at the margin of ga stric ulcers. Taken together, available data indicate a complex interplay b etween hormones, paracrine messengers and neuronal messengers, growth facto rs and cytokines in the regulation of gastric mucosal activities such as se cretion, local blood flow, growth, and restitution after damage. (C) 2000 W iley-Liss, Inc.