Involvement of the dopamine D1 receptor system in the anxiolytic effect of cedrol in the elevated plus maze and light-dark box tests.

Cedrol, mainly derived from Juniperus virginiana L. essential oil, has been demonstrated the anxiolytic effect, although its mechanism of action is still not fully established. In the present study, male ICR mice were submitted to the elevated plus maze (EPM) and light-dark box (LDB) tests to investigate the putative mechanism of anxiolytic effect. WAY100635 (5-HT_1A receptor antagonist), flumazenil (benzodiazepine receptor antagonist), SCH23390 (dopamine D₁ receptor antagonist) or sulpiride (dopamine D₂/D₃ receptor antagonist) were used in the behavioral experiment to determine the mechanism of action of cedrol. Subsequently, the monoamine neurotransmitter levels were evaluated after behavioral tests. The data suggest that no significant effect in behavioral parameters were observed after sole intraperitoneal (i.p.) injection of antagonists compared to saline group. The anxiolytic effect of cedrol in behavioral procedures was blocked by either WAY100635 or flumazenil. The anxiolytic effect of cedrol (1200 mg/kg) was effectively antagonized by SCH23390 (0.125 mg/kg). Furthermore, cedrol decreased the DA and NE levels in hippocampus, striatum and hypothalamus. The present findings suggest that the dopaminergic system (D₁ receptor) rather than serotoninergic or GABAergic system may potentially be involved in the modulation of cedrol-induced anxiolytic-like behaviors in mice.