Group III and subtype 4 metabotropic glutamate receptor agonists: Discovery and pathophysiological applications in Parkinson's disease

► We discuss group III mGluRs as targets in the treatment of Parkinson's disease (PD). ► We present recent improvements of group III mGluR agonists and positive modulators. ► We review the symptomatic effects of group III mGluR agonists. ► We discuss the effect of LSP1-2111 in PD l-DOPA induced dyskinesia. ► We discuss the neuroprotective effect of group III mGluR activation on DA neurons.