PDYN and drug-induced dyskinesia: In the striatum, chronic D1R stimulation in both healthy and parkinsonian animals also leads to robust upregulation of dynorphin and prodynorphin (pDyn) levels.1,61,62 Increased pDyn levels are also highly correlated with dyskinesia severity.40,61,63 Accordingly, greater D1R expression in TRAPed neurons might lead to greater downstream signaling.