Regulation of locomotor activity by metabotropic glutamate receptors in the nucleus accumbens and ventral tegmental

Glutamatergic innervation of the ventral tegmental area (VTA) and the nucleus accumbens (NA) regulates locomotor activity. The present study was designed to evaluate the involvement of metabotropic glutamate receptors (mGluRs) in motor activity. Agonists selective for each of the three subgroups of mGluRs were microinjected into the VTA or NA, and motor activity was monitored. The group I agonist (S)-3,5-dihydroxyphenylglycine elicited a dose-dependent elevation in motor activity after mi-croinjection into either the VTA or NA. The effect in the NA was blocked by the mGluR1-specific antagonist 7-(hydroxyimi-no)cyclopropa[b]chromen-1a-carboxylate ethyl ester. The group II agonist (2S,29R,39R)-2-(29,39-dicarboxycyclopropyl)glycine also elicited a short-duration motor activation after microinjec-tion into either structure. The dose response in the VTA wa