IN-VIVO INHIBITION OF VERATRIDINE-EVOKED RELEASE OF STRIATAL EXCITATORY AMINO-ACIDS BY THE GROUP-II METABOTROPIC GLUTAMATE-RECEPTOR AGONISTLY354740 IN RATS

In vivo microdialysis in freely moving rats was used to investigate th e presynaptic mechanisms by which LY354740, a novel, potent, selective , and systemically active agonist for group II metabotropic glutamate receptors (mGluRs), alters glutamate neuronal transmission. Basal leve ls of glutamate and aspartate in striatal dialysates of LY354740 (10 m g/kg i.p.)-treated animals were not significantly different from the s aline-treated control animals. In the saline treated controls, veratri dine (100 mu M) induced a 6-fold increase in glutamate and 9-fold incr ease in aspartate. However, following LY354740 administration the vera tridine-evoked release of glutamate and aspartate was completely preve nted. These data demonstrate that LY354740 blocks the evoked release o f endogenous excitatory amino acids, and indicate a role for group II mGluRs in presynaptic modulation of glutamate neuronal transmission in vivo. (C) 1997 Elsevier Science Ireland Ltd.