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Intrastriatal injections of KN-93 ameliorates levodopa-induced dyskinesia in a rat model of Parkinson’s disease

Authors Yang X, Wu N, Song L, Liu Z

Received 19 March 2013

Accepted for publication 20 May 2013

Published 19 August 2013 Volume 2013:9 Pages 1213—1220

DOI https://doi.org/10.2147/NDT.S45422

Checked for plagiarism Yes

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Xinxin Yang, Na Wu, Lu Song, Zhenguo Liu

Department of Neurology, Xinhua Hospital affiliated with Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China

Background: Levodopa remains the most effective drug for the treatment of Parkinson’s disease (PD). However, long-term levodopa treatment is associated with the emergence of levodopa-induced dyskinesia (LID), which has hampered its use for PD treatment. The mechanisms of LID are only partially understood. A previous study showed that KN-93, a Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor, could be used to ameliorate LID in rats. However, the precise mechanisms by which KN-93 acts as an antidyskinetic are not fully understood.
Methods: In the present study, a rat model of PD was induced by 6-hydroxydopamine (OHDA) injections. Then, the successfully lesioned rats were intrastriatally administered with a different dose of KN-93 (1 µg, 2 µg, or 5 µg) prior to levodopa treatment. Abnormal involuntary movements (AIMs) scores and apomorphine-induced rotations were measured in PD rats. Phosphorylated levels of GluR1 at Serine-845 (pGluR1S845) levels were determined by western blot. Arc and Penk levels were measured by real-time polymerase chain reaction (PCR).
Results: We found that both 2 µg and 5 µg KN-93 treatment lowered AIMs scores in levodopa priming PD rats without affecting the antiparkinsonian effect of levodopa. In agreement with behavioral analysis, KN-93 treatment (2 µg) reduced pGluR1S845 levels in PD rats. Moreover, KN-93 treatment (2 µg) reduced the expression of Gad1 and Nur77 in PD rats.
Conclusion: These data indicated that intrastriatal injections of KN-93 were beneficial in reducing the expression of LID by lowering the expression of pGluR1S845 via suppressing the activation of CaMKII in PD rats. Decreased expression of pGluR1S845 further reduced the expression of Gad1 and Nur77 in PD rats.

Keywords: Parkinson’s disease, levodopa-induced dyskinesia, KN-93

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