Open AccessDifferential involvement of Ras‐GRF1 and Ras‐GRF2 in L‐DOPA‐induced dyskinesia
Author(s) -
Bido Simone,
Solari Nicola,
Indrigo Marzia,
D'Antoni Angela,
Brambilla Riccardo,
Morari Michele,
Fasano Stefania
Publication year - 2015
Publication title -
annals of clinical and translational neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.824
H-Index - 42
ISSN - 2328-9503
DOI - 10.1002/acn3.202
Subject(s) - medicine , dyskinesia , differential (mechanical device) , pharmacology , parkinson's disease , disease , engineering , aerospace engineering
Objective Recent findings have shown that pharmacogenetic manipulations of the Ras‐ERK pathway provide a therapeutic means to tackle l ‐3,4‐dihydroxyphenylalanine ( l ‐DOPA)‐induced dyskinesia (LID). First, we investigated whether a prolonged l ‐DOPA treatment differentially affected ERK signaling in medium spiny neurons of the direct pathway (dMSNs) and in cholinergic aspiny interneurons (ChIs) and assessed the role of Ras‐GRF1 in both subpopulations. Second, using viral‐assisted technology, we probed Ras‐GRF1 and Ras‐GRF2 as potential targets in this pathway. We investigated how selective blockade of striatal Ras‐GRF1 or Ras‐GRF2 expression impacted on LID (induction, maintenance, and reversion) and its neurochemical correlates. Methods We used both Ras‐GRF1 knockout mice and lentiviral vectors (LVs) delivering short‐hairpin RNA sequences (shRNAs) to obtain striatum‐specific gene knockdown of Ras‐GRF1 and Ras‐GRF2. The consequences of these genetic manipulations were evaluated in the 6‐hydroxydopamine mouse model of Parkinson's disease. Escalating doses of l ‐DOPA were administered and then behavioral analysis with immunohistochemical assays and in vivo microdialysis were performed. Results Ras‐GRF1 was found essential in controlling ERK signaling in dMSNs, but its ablation did not prevent ERK activation in ChIs. Moreover, striatal injection of LV‐shRNA/Ras‐GRF1 attenuated dyskinesia development and ERK‐dependent signaling, whereas LV‐shRNA/Ras‐GRF2 was without effect, ruling out the involvement of Ras‐GRF2 in LID expression. Accordingly, Ras‐GRF1 but not Ras‐GRF2 striatal gene‐knockdown reduced l ‐DOPA‐induced GABA and glutamate release in the substantia nigra pars reticulata, a neurochemical correlate of dyskinesia. Finally, inactivation of Ras‐GRF1 provided a prolonged anti‐dyskinetic effect for up to 7 weeks and significantly attenuated symptoms in animals with established LID. Interpretation Our results suggest that Ras‐GRF1 is a promising target for LID therapy based on Ras‐ERK signaling inhibition in the striatum.