Role of Cholinergic Innervation of Sphincter of Oddi in Dogs. Experimental Study Using Botulinum Toxin.

Abstract

The role of cholinergic nerves in the regulation of the motility of the sphincter of Oddi (SO) has been investigated by cholinergic stimulation and blockade, but their result may be a composite of effects on multiple cholinergic neural and neuromuscular transmissions and reflex pathways. We used botulinum toxin that selectively blocks cholinergic nerves within the area of local injections to study the role of its cholinergic innervation. Four conscious dogs with a duodenal cannula underwent manometry of the common bile duct, SO, and duodenum. After baseline recording, each dog had intrasphincteric injections of saline or botulinum toxin, and the manometry was repeated on day 7. The injections of botulinum toxin caused a significant decrease in the mean SO basal pressure from 6.6±0.1 mmHg to 3.6±0.2 mmHg (p<0.0001) and amplitude from 47±2.5 mmHg to 29.2±1.6 mmHg (p<0.0001), but no change in the frequency of the SO phasic contractions and temporal coordina-tion of SO cyclic motility and the duodenal migrating motor complex. The saline injections had no effect on the SO basal pressure, amplitude, frequency, and cyclic motility. These results indicate that cholinergic nerves play an important role in maintaining the SO basal pressure and amplitude but do not contribute to the cyclic changes in its motility in phase with the duodenal migrating motor complex. Botulinum toxin would be a useful tool to study the effect of the cholinergic innervation. Key words: sphincter of Oddi, migrating motor complex, botulinum toxin, cholinergic innervation.