β-arrestin2 alleviates L-dopa-induced dyskinesia via lower D1R activity in Parkinson's rats

The cause of the L-dopa-induced dyskinesia (LID) has been ascribed to G-protein coupled receptor (GPCR) supersensitivity and uncontrolled downstream signaling. It is now supposed that β-arrestin2 affects GPCR signaling through its ability to scaffold various intracellular molecules. We used the rAAV (recombinant adeno-associated virus) vectors to overexpress and ablation of β-arrestin2. L-dopa-induced changes in expression of signaling molecules and other proteins in the striatum were examined by western blot and immunohistochemically. Our data demonstrated that via AAV-mediated overexpression of β-arrestin2 attenuated LID performance in 6-OHDA-lesioned rodent models. β-arrestin2 suppressed LID behavior without compromising the antiparkinsonian effects of L-dopa. Moreover, we also found that the anti-dyskinetic effect of β-arrestin2 was reversed by SKF38393, a D1R agonist. On the contrary, the rat knockdown study demonstrated that reduced availability of β-arrestin2 deteriorated LID performance, which was counteracted by SCH23390, a D1R antagonist. These data not only demonstrate a central role for β-arrestin2/GPCR signaling in LID, but also show the D1R signal pathway changes occurring in response to dopaminergic denervation and pulsatile administration of L-dopa.