title: Sex differences and serotonergic mechanisms in the behavioural effects of psilocin.
abstract: Psilocybin has recently attracted a great deal of attention as a clinical research and therapeutic tool. The aim of this paper is to bridge two major knowledge gaps regarding its behavioural pharmacology - sex differences and the underlying receptor mechanisms. We used psilocin (0.25, 1 and 4 mg/kg), an active metabolite of psilocybin, in two behavioural paradigms - the open-field test and prepulse inhibition (PPI) of the acoustic startle reaction. Sex differences were evaluated with respect to the phase of the female cycle. The contribution of serotonin receptors in the behavioural action was tested in male rats with selective serotonin receptor antagonists: 5-HT1A receptor antagonist (WAY100635 1 mg/kg), 5-HT2A receptor antagonist (MDL100907 0.5 mg/kg), 5-HT2B receptor antagonist (SB215505 1 mg/kg) and 5-HT2C receptor antagonist (SB242084 1 mg/kg). Psilocin induced dose-dependent inhibition of locomotion and suppression of normal behaviour in rats (behavioural serotonin syndrome, impaired PPI). The effects were more pronounced in male rats than in females. The inhibition of locomotion was normalized by 5-HT1A and 5-HT2B/C antagonists; however, PPI was not affected significantly by these antagonists. Our findings highlight an important issue of sex-specific reactions to psilocin and that apart from 5-HT2A-mediated effects 5-HT1A and 5-HT2C/B receptors also play an important role. These findings have implications for recent clinical trials.
authors.affiliation: aNational Institute of Mental Health, Klecany bThird Medical Faculty, Charles University in Prague, Prague, Czech Republic.
authors.forename: Filip
authors.initials: F
authors.lastname: Tylš
authors.forename: Tomáš
authors.initials: T
authors.lastname: Páleníček
authors.forename: Lukáš
authors.initials: L
authors.lastname: Kadeřábek
authors.forename: Michaela
authors.initials: M
authors.lastname: Lipski
authors.forename: Anna
authors.initials: A
authors.lastname: Kubešová
authors.forename: Jiří
authors.initials: J
authors.lastname: Horáček
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D006213:Hallucinogens / Q000008:administration & dosage / Q000494:pharmacology*; D008124:Locomotion / Q000187:drug effects; D008297:Male; D011562:Psilocybin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D013216:Reflex, Startle / Q000187:drug effects; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology; D012737:Sex Factors
chemical_list: D006213:Hallucinogens; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D011562:Psilocybin; D012701:Serotonin; C009105:psilocin