Effect of denervation of the myenteric plexus on gastroduodenal motility in turkeys

Abstract

The effect of denervation of portions of the myenteric plexus on initiation and coordination of gastric and duodenal contractions was examined in domestic turkeys. Three areas of the muscular stomach (MS), the isthmus between the glandular stomach (GS) and MS, and the pylorus were denervated by application of 1% benzalkonium chloride. Motor activity of the gastroduodenal organs was monitored for 1 h every other day for 13 days using strain gauge transducers implanted at selected sites. Denervation of the isthmus reduced the frequency of MS and duodenal contractions by 50% and abolished GS contractions. Pyloric denervation did not affect the frequency of GS or MS contractions but abolished duodenal contractions. These results suggest that 1) a driving pacemaker for the gastroduodenal cycle is located in the isthmus, and 2) the myenteric plexus is essential for conduction from the pacemaker to the GS and to the duodenum. Denervation of the medial commissure of the myenteric plexus of the MS significantly impaired the function of the ventral half of the MS. It caused atrophy of the underlying medial thick muscle and significantly decreased contraction amplitude. Denervation at this site also caused an enlargement and impaction of the adjacent caudal thin muscle with food and a significant decrease in contraction amplitude. In contrast, denervation of the lateral commissure enlarged the underlying lateral thick muscle and significantly increased its contraction amplitude. Denervation of the cranial thin muscle delayed contractions of that muscle, causing an asynchronization of thin muscle pair.(ABSTRACT TRUNCATED AT 250 WORDS)