Systemic administration of an mGluR5 antagonist, but not unilateral subthalamic lesion, counteracts L-DOPA-induced dyskinesias in a rodent model of Parkinson's disease

Altered glutamatergic neurotransmission is central to the expression of Parkinson's disease (PD) symptoms and may underlie L-DOPA-induced dyskinesias. Drugs acting on glutamate metabotropic receptors (mGluR) of group 1 can modulate subthalamic nucleus (STN) overactivity, which plays a pivotal role in these phenomena, and may counteract dyskinesias. To address these issues, we investigated the effects of a 3-week treatment with mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP), or of a subthalamic lesion, on abnormal involuntary movements (AIMS) and associated striatal expression of transcription factor FosB/Delta FosB caused by chronic L-DOPA administration, in rats with a nigrostriatal lesion. MPEP virtually abolished AIMS and reduced, dramatically, striatal expression of FosB/Delta FosB. Reduced FosB/Delta FosB expression, coupled with nonsignificant reduction of AIMS, was also observed in STN-lesioned rats. Our data confirm the role of glutamatergic neurotransmission in the pathogenesis of dyskinesias and the potential of mGluR5 antagonists in the treatment of L-DOPA-induced dyskinesias. (c) 2007 Elsevier Inc. All rights reserved.