title: Further studies on the dose-dependent stimulus properties of 5-methoxy-N,N-dimethyltryptamine.
abstract: Twenty-two rats were trained to discriminate either 1.5 mg/kg of 5-methoxy-N,N-dimethyltryptamine (5-OMe DMT) from saline in a standard two-lever operant procedure. Once responding was stable, various doses of several serotonin (5-HT) antagonists, i.e., cyproheptadine (CYP), methysergide (UML), cinanserin (CIN), and methergoline (MCE), were administered in combination with 5-OMe DMT, to assess the ability of each antagonist to attenuate each 5-OMe DMT-stimulus. The 5-OMe DMT-stimulus at 1.5 mg/kg was completely antagonized by CYP, and was partially attenuated by CIN and MCE. UML had negligible effects on 5-OMe DMT-appropriate responding. In the 3.0 mg/kg 5-OMe DMT-trained rats, UML and MCE partially blocked the 5-OMe DMT-stimulus; CYP and CIN had no significant effect on 5-OMe DMT-appropriate responding. The results suggest that until the in vivo effects and mechanism of action of 5-OMe DMT and certain 5-HT antagonists are better understood, caution is advised when conclusions are drawn from studies employing these agents.
mesh_terms: D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008297:Male; D008732:Methoxydimethyltryptamines / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000031:analogs & derivatives*; D012702:Serotonin Antagonists / Q000494:pharmacology
chemical_list: D008732:Methoxydimethyltryptamines; D012702:Serotonin Antagonists; D012701:Serotonin