Effects of venlafaxine given repeatedly on α1-adrenergic, dopaminergic and serotonergic receptors in rat brain

✍ Scribed by J. Maj; M. Dziedzicka-Wasylewska; Z. Rogóż; R Rogoż; W. Margas

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 180 KB
• Volume: 14
• Category: Article
• ISSN: 0885-6222
• DOI: 10.1002/(sici)1099-1077(199907)14:5<333::aid-hup104>3.0.co;2-2

✦ Synopsis

Venlafaxine (VEN), a representative of a new class of antidepressants (serotonin and noradrenaline reuptake inhibitors, SNRI), administered repeatedly aects Ð as was demonstrated by us previously Ð the behavioural responsiveness of a 1 -adrenergic, dopaminergic (D 2 and D 3 ) and serotonergic systems to their agonists. In the present study we aimed to ®nd out whether parallel changes in the binding to the respective receptors also occurred. The experiment was carried out on male Wistar rats. VEN was administered in a dose of 10 mg/kg once or repeatedly (14 days, twice daily). The obtained results showed that VEN did not change the binding (B max and K D ) of a 1 -adrenergic receptors to [ 3 H]-prazosin in the cerebral cortex, having increased only its displacement by phenylephrine. The binding (B max and K D ) to D 1 and D 2 receptors in the limbic forebrain and the striatum was not aected by repeated venlafaxine when [ 3 H]-SCH 23390 and [ 3 H]-spiperone, respectively, were used as ligands. When [ 3 H]-quinpirole was used as a ligand, the binding was enhanced in the striatum, the nucleus accumbens (shell and core) and islands of Calleja. VEN also increased the binding of [ 3 H]-7-OH-DPAT to D 3 receptors in islands of Calleja and the nucleus accumbens (shell). In the serotonergic system, a decrease in the density of 5-HT 1A receptors was observed in the hippocampus, whereas no changes occurred in the binding of 5-HT 2 receptors in the cortex. Thus VEN given repeatedly enhanced the binding (of the ligands that are agonists) to dopamine D 2 and D 3 receptors. Weaker eects were observed in the a 1 -adrenergic and the serotonergic systems.