Influence of corticostriatal δ-opioid receptors on abnormal involuntary movements induced by L-DOPA in hemiparkinsonian rats

► δ-Opioid receptors and l-DOPA-induced dyskinesias in a model of Parkinson's disease. ► DPDPE, a δ-opioid agonist, increased the expression of l-DOPA-induced dyskinesias. ► Naltrindole, a δ-opioid antagonist reduced the number of l-DOPA-induced dyskinesias. ► A cortical lesion decreased the number of δ-opioid receptors. ► A cortical lesion prevented the stimulant effect of DPDPE on dyskinesias.