Opioid receptors and the initiation of migrating myoelectric complexes in dogs. Am J Physiol 1989 Jan;256(1 Pt 1):G72-7
Date
01/01/1989Pubmed ID
2563201DOI
10.1152/ajpgi.1989.256.1.G72Scopus ID
2-s2.0-0024586366 (requires institutional sign-in at Scopus site) 14 CitationsAbstract
The role of endogenous opioids and opioid receptors in the control of migrating myoelectric complexes (MMCs) was studied in conscious dogs implanted with silver-silver chloride electrodes. In normal fasted dogs, MMC cycle times were 103 +/- 7 min in the duodenum. During naloxone infusion (1-2 mg/kg iv, then 0.2-1.0 mg.kg-1.h-1 iv) cycle times increased to 219 +/- 29 min (P less than 0.01). Naloxone (2 mg/kg iv, then 1 mg.kg-1.h-1 iv) had no effect on the response of the small intestine to bethanecol (5 mg sc) or to feeding. Pretreatment with naloxone (2 mg/kg iv) 5 min before the administration of motilin (400-500 micrograms/kg iv) did not block the initiation of MMCs by motilin. In separate experiments, animals were pretreated with the positive or negative isomer of the opioid receptor antagonist WIN-44,441 (0.2 mg/kg iv) 5 min before morphine administration. The negative isomer binds to opioid receptors whereas the positive isomer does not. The negative but not the positive isomer antagonized all effects of morphine on intestinal myoelectric activity. These studies suggest that endogenous opioids and opioid receptors may play a role in control of the initiation of MMCs and that motilin and exogenous opioids act via different mechanisms to initiate MMCs.
Author List
Telford GL, Condon RE, Szurszewski JHMESH terms used to index this publication - Major topics in bold
AnimalsAzocines
Bethanechol
Bethanechol Compounds
Digestive System
Digestive System Physiological Phenomena
Dogs
Duodenum
Electrophysiology
Food
Gastrointestinal Motility
Ileum
Morphine
Motilin
Naloxone
Narcotic Antagonists
Receptors, Opioid
Stereoisomerism
Stomach
