Nitronergic regulation of gastric motility and emptying

This review focuses on recent developments regarding the potential role of nitric oxide (NO) in the regulation of gastric motility and emptying. The nonadrenergic noncholinergic inhibitory motor neurons in the stomach containing NO synthase were found to project in the aboral direction and the cholinergic excitatory motor neurons in the oral direction up to a mean distance of about 1 mm. The implications of this polarization in the spatial organization of gastric contractions and gastric emptying are discussed. It seems that NO synthesis in the brain may also modulate gastric motor activity through the vagus nerves. In addition, some of the central peptides may modulate gastric motor activity by the release of NO from the enteric neurons. This modulation also occurs through the vagal efferents. It is ironic that the systemic administration of both NO donors and NO synthase inhibitors delay gastric emptying. The delay in gastric emptying by the two opposing classes of agents may, however, be due to the stimulation or inhibition of different parameters of gastropyloroduodenal contractions.