Since previous have shown that mGluR5 might be involved in mediating the toxic effects of Aβ [30,38-42], and mGluR5 deficient mice or mice treated with mGluR5 inhibitors are protected from MPTP-induced toxicity in models of parkinsonism [25,34,43], we tested the role of mGluR5 in mediating toxicity in our system. This evidence concerns the gene GRM5 and Parkinson disease.