Central action of narcotic analgesics. IX. Participation of serotonin in the development of tolerance to cataleptogenic effects of morphine in rats.
Subcutaneous implantation of morphine-base (75 mg) pellets over a period of 72 h caused the development of tolerance ot cataleptogenic action of morphine in rats. The development of morphine tolerance was inhibited by p-chlorophenylalanine (pCPA) or reserpine, drugs which decrease the content of brain serotonin (5-HT). Administration of 5-hydroxytryptophan (5-HTP(, which protected 5-HT stores against depleting action of reserpine, prevented the above of reserpine on the development of morphine tolerance in rats. Blockade of 5-HT neurotransmission by pizotifen or cyproheptadine inhibited the development of morphine tolerance, while the increase of it by imipramine did not alter the development of this tolerance . The Obtained results have shown that serotonergic system plays an important role in the development of tolerance to cataleptogenic effects of morphine.
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D002375:Catalepsy / Q000139:chemically induced*; D004347:Drug Interactions; D004361:Drug Tolerance; D010134:Fenclonine / Q000494:pharmacology; D006801:Humans; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012110:Reserpine / Q000494:pharmacology; D012701:Serotonin / Q000502:physiology*
D012701:Serotonin; D009020:Morphine; D012110:Reserpine; D006916:5-Hydroxytryptophan; D010134:Fenclonine