[Effects of stimulation and blockade of D2-dopaminergic receptors on behavior In gonadectomized male rats]

The present study aims to perform the comparative assessment of stimulation and blockade for D2-dopaminergic receptors in depression-like behavior in male rats with deficiency of androgen hormones. Two weeks after surgery, GDX rats began 14 days of treatment with vehicle, a low dose of testosterone propionate (0.5 mg/kg, s.c.), quinpirole (0.1 mg/kg, i.p.), sulpiride (10.0 mg/kg, i.p.), quinpirole plus testosterone propionate or sulpiride plus testosterone propionate. The animals were then tested in forced swimming test (FST) and the open field test (OFT). Quinpirole administered alone or in a combination with a low dose of testosterone propionate resulted in antidepressant-like effect in GDX rats in the FST. Repeated treatment of quinpirole and testosterone propionate profoundly increased antidepressant-like effect of the single substances they exert per se. Application of neither quinpirole nor quinpirole plus testosterone propionate led to any changes of behavioral reactions in GDX rats in the OFT, except increased grooming behavior. On the contrary, sulpiride treatment failed to alter depression-like behavior in GDX rats in the FST. In addition, sulpiride blocked the antidepressant-like effect of testosterone propionate in GDX rats and its combination with a low dose of testosterone propionate induced prodepressant-like effect in GDX rats. Co-administration of sulpiride with testosterone propionate or its single application increased frequency of rearing and grooming in GDX rats in the OFT. In summary, the results of the present study suggest that stimulation of D2-dopaminergic receptors results in antidepressant-like effect at androgen deficiency in male rats, while blockade of D2-dopaminergic receptors resulted in prodepressant-like effect.