ACTION OF ENKEPHALINASE (EC-3.4.24.11) INHIBITION ON THE PREPRANDIAL AND POSTPRANDIAL ELECTROMYOGRAPHIC PATTERNS OF COLON IN RATS

Endogenous opioids are an important regulatory factor for the digestive tract and specially for its motility pattern. Enkephalin degradation includes an enkephalinase (EC 3.4. 24. 11) and the effects on the colic electromyographic profile of its inhibition by acetorphan has been investigated in the unrestrained rat. Electromyogram consisted of Long Spike Bursts (LSB). In fasted state, they propagated indifferently in both aboral or oral directions from any point of the colon, Feeding privileges LSB which start near the cecal junction and propagated aborally to the distal colon. The acetorphan treatment (A) increases the percentage of LSB propagating aborally on the entire colon in fasted state and (B) reinforces the increased percentage of LSB which propagated down on the entire colon induced by feeding. All the actions of acetorphan on colic motility pattern disappear after inhibition of opioid receptors by naloxone. That may account for involvement of enkephalins in acetorphan properties on the pattern of the colic electrical activity.