title: The role of 5-HT receptor subtypes in the anxiolytic effects of selective serotonin reuptake inhibitors in the rat ultrasonic vocalization test.
abstract: We evaluated whether the anxiolytic effects of selective serotonin reuptake inhibitors (SSRIs) in the rat ultrasonic vocalization (USV) test are preferentially mediated by (indirect) activation of 5-HT1A, 5-HT1B/1D, 5-HT2A, 5-HT3 or 5-HT4 receptors. The SSRIs, paroxetine (ED50 in mg/kg, IP: 6.9), citalopram (6.5), fluvoxamine (11.7) and fluoxetine (> 30), dose dependently reduced shock-induced USV. The effects of paroxetine (3.0 mg/kg, IP) were not blocked by the selective 5-HT1A receptor antagonist, WAY-100635 (3.0 mg/kg, IP), the 5-HT1B/1D receptor antagonist, GR 127935 (30 mg/kg, IP), the nonselective 5-HT2A receptor antagonists, ritanserin (3.0 mg/kg, IP) and ketanserin (1.0 mg/kg, IP), the 5-HT3 receptor antagonist, ondansetron (0.1 mg/kg, IP), or the 5-HT4 receptor antagonist, GR 125487D (3.0 mg/kg, SC). In contrast, the selective 5-HT2A receptor antagonist, MDL 100,907 (0.1 mg/kg, IP), completely prevented the paroxetine-induced reduction of USV. Under similar conditions, WAY-100635 blocked the anxiolytic-like effects of the selective 5-HT1A receptor agonist, 8-OH-DPAT [(+/-)-8-hydroxy-2-(di-n-propylamino)tetralin, 1.0 mg/kg, IP], and ritanserin, ketanserin, and MDL 100,907 blocked the anxiolytic-like effects of the mixed 5-HT2A/2C receptor agonist, DOI [1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane, 3.0 mg/kg, IP]. WAY-100635 (1.0 mg/kg, IP) in combination with ritanserin (3.0 mg/kg, IP), but not ondansetron (0.1 mg/kg, IP), GR 125487D (3.0 mg/kg, SC), or GR 127935 (30 mg/kg, IP), attenuated the USV reducing effects of paroxetine. Although the results suggest that selective stimulation of 5-HT1A and 5-HT2A receptors produces a decrease of USV, we postulate that only 5-HT2A receptors play a pivotal role in the effects of SSRIs in this model of anxiety.
authors.affiliation: CNS Research, Troponwerke GmbH & Co. KG, Cologne, Germany. rudy.schreiber.rs@bayer-ag.de
authors.forename: R
authors.initials: R
authors.lastname: Schreiber
authors.forename: C
authors.initials: C
authors.lastname: Melon
authors.forename: J
authors.initials: J
authors.lastname: De Vry
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D014465:Ultrasonics; D014828:Vocalization, Animal / Q000187:drug effects*
chemical_list: D014151:Anti-Anxiety Agents; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017367:Selective Serotonin Reuptake Inhibitors