[D2-subtype of dopaminergic receptors is involved in anxiety behavior in ovariectomized rats]

To compare the role of D2-subtype dopaminergic receptors in mechanisms of anxiety behavior in adult intact female rats during ovary cycle and ovariectomized (OVX) female rats, influence of chronic administration of D2-dopaminergic receptors agonist--quinperole (0.1 mg/kg) and D2-dopaminergic receptors antagonist--sulpiride (10.0 mg/kg) injected separately or in combination with 17beta-es-tradiol (0.5 mcg for each animal) within 14 days on behavioral status of adult intact and ovariectomized (OVX) female rats was investigated. The level of anxiety was assessed in the elevated plus maze, behavior of the animals was estimated in the open field test. It was established that chronic administration of sulpiride to intact rats resulted in anxiogenic behavior in the elevated plus maze in all phases of ovary cycle except proestrous. Quinperole administration to the intact rats had an anxiolytic action on behavior in the elevated plus maze in the metestrous, diestrous and proestrous. Chronic quinperole administration alone or in combination with 17beta-estradiol in OVX rats resulted in an anxiolytic effect on behavior in the elevated plus maze. On the contrary, sulpiride administration alone in OVX rats failed to modify an anxiety level, while in its combination with 17beta-estradiol an anxiolytic effect of the hormone drug was com-pletely blocked. In the open field test quinperole administration to OVX rats increased horizontal locomotor activity, exploratory and grooming behavior. Thus, the results obtained suggest a modulating role of D2-subtype dopaminergic receptors in the mechanisms of anxiety behavior in imbalance of estrogen.