Monoamine oxidase and head-twitch response in mice. Mechanisms of alpha-methylated substrate derivatives
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Updated: Aug 29, 2026

Development of a Unilaterally-lesioned 6-OHDA Mouse Model of Parkinson's Disease
Published on: February 14, 2012
Osamu Nakagawasai1, Yuichiro Arai, Shin-etsu Satoh
1Department of Pharmacology, Tohoku Pharmaceutical University, Sendai 981-8558, Japan. osamun@tohoku-pharm.ac.jp
Abstract:
It is well known that head-twitch response (HTR) in mice represents hallucinations, since administration of lysergic acid diethylamide (LSD) produces hallucinations in humans, and the HTR in mice is induced by administration of LSD as a hallucinogen. The HTR is produced by excitation of 5-hydroxytryptamine (5-HT)2A receptors. In this paper, we review the mechanisms of HTR induced by various drugs such as 5-HT precursor, 5-HT receptor agonist, 5-HT releaser, hallucinogenic compounds, benzodiazepins and cannabinoid. The response induced by HTR-inducers is significantly enhanced by combined treatment with a non-selective form of monoamine oxidase (MAO) inhibitor. Thus, the relationship between MAO activity and HTR caused by these drugs (especially, alpha-methylated analogous compounds which 5-fluoro-alpha-methyltryptamine, 6-fluoro-alpha-methyltryptamine and p-hydroxyamphetamine) is presented in detail.
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