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

Abstract

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). 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.