title: Blockade of cannabinoid CB1 and CB2 receptors does not prevent the antipruritic effect of systemic paracetamol.
abstract: Cannabinoid CB1 receptors have been shown to mediate the antinociceptive, but not the hypothermic, action of the worldwide used analgesic, paracetamol. Since itch and pain sensations share many similarities, the purpose of the present study was to investigate whether blockade of cannabinoid CB1 and CB2 receptors participates in the antipruritic activity of paracetamol in mice. Scratching behavior was induced by intradermal serotonin injection into the rostral part of the back of the mice. After serotonin administration, scratching of the injected site by the hind paws were videotaped and counted for 30 min. Serotonin-induced scratching behavior was attenuated with high-dose paracetamol (300 mg/kg). The CB1 receptor antagonist, AM-251 (1 mg/kg), and the CB2 receptor antagonist, SR-144528 (1 mg/kg), did not alter the anti-scratching behavioral effect of paracetamol. Our results indicate that, in contrast to its antinociceptive action, but similar to its hypothermic effect, cannabinoid receptors are not involved in the antipruritic activity of paracetamol.
authors.affiliation: Department of Medical Pharmacology, Faculty of Medicine, Trakya University, 22030, Edirne, Turkey.
authors.forename: Gulis
authors.initials: G
authors.lastname: Saglam
authors.forename: Ozgur
authors.initials: O
authors.lastname: Gunduz
authors.forename: Ahmet
authors.initials: A
authors.lastname: Ulugol
mesh_terms: D000082:Acetaminophen / Q000627:therapeutic use*; D000818:Animals; D000982:Antipruritics / Q000627:therapeutic use*; D001892:Camphanes / Q000627:therapeutic use; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D010880:Piperidines / Q000627:therapeutic use; D011537:Pruritus / Q000139:chemically induced / Q000188:drug therapy*; D011720:Pyrazoles / Q000627:therapeutic use; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D043885:Receptor, Cannabinoid, CB2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012701:Serotonin / Q000633:toxicity
chemical_list: D000982:Antipruritics; D001892:Camphanes; D010880:Piperidines; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; C110630:SR 144528; D012701:Serotonin; D000082:Acetaminophen; C103505:AM 251