Central action of narcotic analgesics. VI. Further studies on the participation of serotonin in the action of analgesics.
The effects of agents changing the cerebral serotonin (5-HT) level on the action of morphine, codeine, fentanyl and pentazocine were tested in rats with the tests of catalepsy and analgesia (hot plate). In addition, the effect of analgesics of the level and turnover of cerebral 5-HT was studied. Depression of the cerebral level of 5-HT usually antagonized the behavioral effects of analgesics, but the effect varied with the agent depressing the 5-HT level. The serotonergic influences in catalepsy seem to be more pronounced than in analgesia. An increase in the cerebral level of 5-HT may potentiate the analgesic and prolonged the cataleptogenic effects of some drugs (morphine and pentazocine), not affecting the effect of others (fentanyl, codeine). The potentiation by morphine of the turnover of cerebral 5-HT in rats is not a common property of analgesics agents.
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D001923:Brain Chemistry / Q000187:drug effects; D002375:Catalepsy / Q000139:chemically induced; D010134:Fenclonine / Q000494:pharmacology; D006801:Humans; D008297:Male; D051381:Rats; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*
D000701:Analgesics, Opioid; D012701:Serotonin; D006916:5-Hydroxytryptophan; D010134:Fenclonine