Evidence for serotonergic system involvement in the effect of morphine on gastrointestinal motility in the rat.
1. Intestinal motility was measured by the transit of charcoal meal through the small intestine of the rat. 2. Morphine given subcutaneously induced a reduction in the gastrointestinal transit (GIT), and the response was dose-dependent (0.1-2.5 mg/kg). 3. The inhibitory effect of morphine was antagonized by prior subcutaneous administration of naloxone (1 mg/kg). 4. Depletion of serotonergic neurons by para-chlorophenylalanine (100 mg/kg, ip, 3 days) completely abolished the inhibitory action of morphine. 5. Methysergide (5 mg/kg, sc) and ketanserin (5 mg/kg, sc) also reduced the morphine effect. 6. Destruction of serotonergic neurones by intracerebroventricular injection of 5,7-dihydroxytryptamine (20 mu/kg) abolished the effect of morphine. 7. These observations provide some evidence for the involvement of a central serotonergic system in the effect of morphine on gastrointestinal motility.
Pourgholami
M H
MH
Department of Pharmacology, Faculty of Medicine, Medical Sciences University of Shahid-Beheshti, Evin, Tehran, Iran.
Goshadrou
F
F
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D002490:Central Nervous System / Q000187:drug effects; D002606:Charcoal; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D010134:Fenclonine / Q000494:pharmacology; D005277:Fenfluramine / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects*; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000502:physiology*
D002606:Charcoal; D005277:Fenfluramine; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D009270:Naloxone; D009020:Morphine; D007650:Ketanserin; D010134:Fenclonine