title: 5-Methoxy-N,N-dimethyltryptamine-induced analgesia is blocked by alpha-adrenoceptor antagonists in rats.
abstract: The effects of the alpha-adrenoceptor antagonists prazosin, phentolamine and yohimbine upon 5-methoxy-N,N-dimethyltryptamine (5-MeODMT)-induced analgesia were tested in the hot-plate, tail-flick and shock-titration tests of nociception with rats. Intrathecally injected yohimbine and phentolamine blocked or attenuated the analgesia produced by systemic administration of 5-MeODMT in all three nociceptive tests. Intrathecally administered prazosin attenuated the analgesic effects of 5-MeODMT in the hot-plate and tail-flick tests, but not in the shock titration test. Intrathecal yohimbine showed a dose-related lowering of pain thresholds in saline and 5-MeODMT-treated animals. Phentolamine and prazosin produced normal dose-related curves in the hot-plate test and biphasic effects in the shock titration and tail-flick tests. These results demonstrate a functional interaction between alpha 2-adrenoceptors and 5-HT agonist-induced analgesia at a spinal level in rats.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000700:Analgesics; D000818:Animals; D008297:Male; D008732:Methoxydimethyltryptamines / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects; D010646:Phentolamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D012701:Serotonin / Q000031:analogs & derivatives*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000317:Adrenergic alpha-Antagonists; D000700:Analgesics; D008732:Methoxydimethyltryptamines; D015016:Yohimbine; D012701:Serotonin; D011224:Prazosin; D010646:Phentolamine