Effects of stimulation and blockade of d(2) receptor on depression-like behavior in ovariectomized female rats.

The aim of the present study was to explore the hedonic effects of D(2) receptor agonist, quinpirole and D(2) receptor antagonist, and sulpiride alone or in combination with a low dose of 17β-E(2)-estradiol (17β-E(2)) in the adult ovariectomized female rats (OVX). OVX rats of Wistar strain were used in all experiments. Two weeks after surgery rats were chronically treated with vehicle, a low dose of 17β-E(2) (5.0 μg/rat), quinpirole (0.1 mg/kg), sulpiride (10.0 mg/kg), quinpirole plus 17β-E(2), or sulpiride plus 17β-E(2) for 14 days before the forced swimming test. We found that sulpiride significantly decreased immobility time in the OVX females. A combination of sulpiride with a low dose of 17β-E(2) induced more profound decrease of immobility time in the OVX rats compared to the rats treated with sulpiride alone. On the contrary, quinpirole failed to modify depression-like behavior in the OVX rats. In addition, quinpirole significantly blocked the antidepressant-like effect of 17β-E(2) in OVX rats. Thus, the D(2) receptor antagonist sulpiride alone or in combination with a low dose of 17β-E(2) exerted antidepressant-like effect in OVX female rats, while the D(2) receptor agonist quinpirole produced depressant-like profile on OVX rats.