title: Intracerebroventricular injection of trazodone produces 5-HT receptor subtype mediated anti-nociception at the supraspinal and spinal levels.
abstract: Serotonin (5-HT) mediated anti-nociceptive effects induced by an anti-depressant, trazodone, are related to 5-HT(1A) receptor activities at the supraspinal level. 5-HT(3) receptor activation via the descending anti-nociceptive pathways may contribute to the trazodone mediated anti-nociception at the spinal level. Intracerebroventricular (i.c.v.) injection of trazodone dose-dependently impaired nociceptive responses in the formalin test in mice. Six and 15 microg of trazodone inhibited the early (P<0.05 or 0.01) and the late phases of the formalin test (P<0.05 or 0.01), while 3 microg had no effect. We examined the effects of a selective 5-HT(1A) receptor antagonist, WAY-100635, a single injection of which induced hyperalgesia (P<0.05), and blocked the anti-nociceptive effects of trazodone (P<0.01) when the two were simultaneously injected i.c.v. Intrathecal (i.t.) injection of a selective 5-HT(3) receptor antagonist, 3-tropanylindole-3-carboxylate hydrochloride, blocked the anti-nociceptive effects of i.c.v. trazodone (P<0.01), while WAY-100635 (i.t.) did not impair trazodone mediated anti-nociception. Trazodone mediated anti-nocicepton is related to serotonergic activity at both the supraspinal and the spinal level.
authors.affiliation: Department of Physiology, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan.
authors.forename: Rihui
authors.initials: R
authors.lastname: Zhang
authors.forename: Tomonari
authors.initials: T
authors.lastname: Nagata
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hayashi
authors.forename: Mariko
authors.initials: M
authors.lastname: Miyata
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Kawakami
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007276:Injections, Intraventricular / Q000379:methods; D007278:Injections, Spinal / Q000379:methods; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D010879:Piperazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D014196:Trazodone / Q000494:pharmacology*
chemical_list: D010879:Piperazines; D011725:Pyridines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017367:Selective Serotonin Reuptake Inhibitors; D014196:Trazodone; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide