MPEP, an mGlu5 receptor antagonist, reduces the development of l-DOPA-induced motor complications in de novo parkinsonian monkeys: Biochemical correlates

► Chronic treatment with MPEP of one month reduces the expression of LID. ► MPEP maintained the duration of the antiparkinsonian effect of l-DOPA. ► Dyskinesias are positively correlated with mGlu5 receptor levels in the putamen. ► mGlu5 receptor levels only increased in the putamen of l-DOPA-treated MPTP monkeys.