Effect of denervation on initiation and coordination of gastroduodenal motility in turkeys

The effect of total extrinsic denervation of the stomach on the rhythmicity and coordination of the gastroduodenal cycle was determined in domestic turkeys. The vagus and two gastric branches of the sympathetic nerve were sectioned at the level of the glandular stomach. Motilities of the glandular stomach, proximal duodenum, and caudal thin muscle of the muscular stomach were monitored via implanted strain gauge transducers for 1 h every other day. Denervation had no significant effect on initiation of contractions or frequency of gastric contractions in fed birds, but fasted birds whose stomachs were extrinsically denervated exhibited significantly slower contractions than controls. In addition, denervation uncoupled the coordination of the duodenal and gastric contractions in the gastroduodenal cycle. Moreover, birds with extrinsically denervated stomachs exhibited a cephalic phase of gastric motility that was significantly delayed in onset compared with controls. These results suggest the existence of both a neural and endocrine component in the avian gastric response to the sight of food. Extrinsic input seems to be an important modulator of gastric motility in birds and is essential for the normal coordination of the gastroduodenal contraction cycle.