Anxiolytic-like activity of MGS0039, a selective group II mGlu receptor antagonist, is serotonin-and GABA-dependent

In the present study, we examined the anxiolytic-like effects of (1R,2R,3R,5R,6R)-2-amino-3-(3,4-dichlorobenzyloxy)-6fluorobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (MGS0039), a mGluR2/3 antagonist, in the Vogel conflict drinking test in rats. MGS0039 administered at the doses of 1 and 2 mg/kg ip (yet not at 3 mg/kg) produced anxiolytic-like effects in this test. Diazepam (2.5-10 mg/kg) was used as a reference drug. In the second part of our experiment, MGS0039 was tested at an effective dose of 2 mg/kg after a mixed injection with ritanserin (5-HT2A/C receptor antagonist) and WAY100635 (5-HT1A receptor antagonist) or flumazenil (benzodiazepine receptor antagonist), and all of the compounds were found to attenuate the effect of MGS0039. The above results indicate that the mGluR2/3 antagonist MGS0039 may play a role in the therapy of anxiety and that its action may be mediated by serotonin and the GABAergic systems.