title: The role of central serotonergic mechanisms on head-twitch and backward locomotion induced by hallucinogenic drugs.
abstract: Head-twitch induced by lysergic acid diethylamide, mescaline and 2,5-dimethoxy-4-methylamphetamine (DOM) was significantly increased by medial raphe (m-R) lesions, but dorsal raphe (d-R) lesions did not produce any changes. Hallucinogen-induced head twitch was inhibited by methysergide and tended to be increased by PCPA. These results suggest that 5-HT receptors innervated with the ascending 5-HT pathway originating in the m-R play a vital role in the manifestation of hallucinogen-induced head-twitch. That is, increase of head-twitch is ascribed to supersensitivity of 5-HT receptors. On the other hand, DOM-induced backward locomotion was inhibited by m-R or both dorsal and medial raphe lesions and methysergide, and was reversed to forward locomotion, differently from the hallucinogen-induced head-twitch. A reversion of backward locomotion was not obtained with d-R lesions or PCPA treatment.
mesh_terms: D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine / Q000494:pharmacology; D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000502:physiology*; D013759:Dronabinol / Q000494:pharmacology; D005260:Female; D006213:Hallucinogens / Q000494:pharmacology*; D006801:Humans; D008238:Lysergic Acid Diethylamide / Q000494:pharmacology; D008635:Mescaline / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects; D011903:Raphe Nuclei / Q000502:physiology; D051381:Rats; D012701:Serotonin / Q000502:physiology*; D013239:Stereotyped Behavior / Q000187:drug effects
chemical_list: D006213:Hallucinogens; D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine; D012701:Serotonin; D013759:Dronabinol; D008238:Lysergic Acid Diethylamide; D006916:5-Hydroxytryptophan; D008635:Mescaline