title: Effects of an enkephalin analog on motility of the small and large intestine in the cat.
abstract: In order to study the effects of naturally occurring opioids on intestinal motility we exposed the unanesthetized cat to different doses of methionine (Met)-enkephalin analog DAMME. DAMME 10(-10) and 10(-9) M/kg body weight inhibited spike activity in the small intestine 20-50 min after injection, whereas in the colon doses as low as 10(-11) M/kg stimulated spiking. Transit of a radiopaque marker infused into duodenal and cecal catheters was delayed both in the small and large bowel. The enkephalin effect was inhibited by the opiate antagonist naloxone 10(-8) and 10(-7) M/kg in the colon, but only at 10(-7) M/kg in the small intestine. Atropine suppressed the enkephalin effect in the small, but not in the large bowel. DAMME caused central nervous side effects. It is concluded that the Met-enkephalin analog suppresses myoelectrical activity in the small intestine probably via cholinergic nervous pathways, and it stimulates spiking and segmenting contractions in the colon probably via a myogenic action. Opiate antagonists may be useful in the treatment of constipation if endogenous opioids are involved.
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002415:Cats; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D007420:Intestine, Large / Q000187:drug effects*; D007421:Intestine, Small / Q000187:drug effects*; D008297:Male; D009270:Naloxone / Q000494:pharmacology
chemical_list: D009270:Naloxone; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; D001285:Atropine