Group II, but not group I, metabotropic glutamate receptors in the rat nucleus accumbens contribute to amphetamine-induced locomotion

Recently, it was reported that blocking metabotropic glutamate receptors (m GluRs) in the rat nucleus accumbens (NAcc) prevents the generation of locom otion by amphetamine (AMPH) in this site. In these studies, the non-selecti ve group I/group II mGluR antagonist (R,S)-alpha-methyl-4-carboxyphenylglyc ine [(R,S)-MCPG] was used. The present study used more selective receptor a ntagonists to examine the specific contribution of group I and group II mGl uRs to this effect. When co-injected bilaterally with AMPH into the NAcc, t he group II selective mGluR antagonist (2S)-alpha-ethylglutamic acid [EGLU; 0.5-5.0 nmole/side] dose-dependently blocked the locomotion and rearing pr oduced by AMPH. Equimolar concentrations of the group I selective antagonis t (R,S)-1-aminoindan-1,5-dicarboxylic acid [AIDA; 0.5-5.0 nmole/side] were without effect. As previously reported for (R,S)-MCPG, neither of these rec eptor antagonists produced locomotor effects when injected alone in these c oncentrations into the NAcc. These results suggest that group II, but not g roup I, mGluRs in the rat NAcc contribute importantly to the ability of AMP H to produce locomotor activation. (C) 2000 Elsevier Science Ltd. All right s reserved.