title: Controlled-release levodopa methyl ester/benserazide-loaded nanoparticles ameliorate levodopa-induced dyskinesia in rats.
abstract: BACKGROUND
  Levodopa remains the most effective drug in the treatment of Parkinson's disease. However, long-term administration of levodopa induces motor complications, such as levodopa-induced dyskinesia. The mechanisms underlying levodopa-induced dyskinesia are not fully understood.
  
  
  METHODS
  In this study, we prepared levodopa methyl ester (LDME)/benserazide-loaded nanoparticles, which can release LDME and benserazide in a sustained manner. Dyskinesia was induced in rats by repeated administration of levodopa then treated with LDME plus benserazide or the same dose of LDME/benserazide-loaded nanoparticles. Apomorphine- induced rotations and abnormal involuntary movements (AIMs) were measured on treatment days 1, 5, 10, 15, and 20. In addition, the levels of phosphorylated dopamine- and cyclic adenosine monophosphate- regulated phosphoprotein of 32 kDa, extracellular signal-regulated kinases 1/2, and ΔfosB were determined by Western blot. Tau levels were determined by Western blot and immunohistochemistry. Dynorphin levels in the striatum and cortex of rats were measured using enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Over the course of levodopa treatment, the rats developed abnormal AIMs, classified as locomotive, axial, orolingual, and forelimb dyskinesia. The degree of reduction of apomorphine-induced rotations was comparable in dyskinetic rats treated with LDME plus benserazide or LDME/benserazide-loaded nanoparticles. The axial, limb, and orolingual (ALO) AIMs of dyskinetic rats treated with LDME/benserazide-loaded nanoparticles were 14 ± 2.5, 9 ± 2.0, and 10 ± 2.1 on treatment days 10, 15, and 20, respectively, which were significantly reduced compared with dyskinetic rats treated with LDME plus benserazide (25 ± 3.7, 27 ± 3.8, and 25 ± 3.5, respectively). The locomotive AIMs of dyskinetic rats treated with LDME/benserazide-loaded nanoparticles were 2.3 ± 0.42, 1.7 ± 0.35, and 1.6 ± 0.37 on treatment days 10, 15, and 20, respectively, which were also reduced compared with dyskinetic rats treated with LDME plus benserazide (4.4 ± 0.85, 4.7 ± 0.95 and 4.8 ± 0.37, respectively). Western blot showed that the levels of phosphorylated dopamine- and cyclic adenosine monophosphate-regulated phosphoprotein of 32 kDa, extracellular signal-regulated kinases 1/2, tau, and ΔfosB in dyskinetic rats treated with LDME/benserazide-loaded nanoparticles were 134.6 ± 14.1, 174.9 ± 15.1, 134.2 ± 19.3, and 320.5 ± 32.8, respectively, which were significantly reduced compared with those of dyskinetic rats treated with LDME plus benserazide (210.3 ± 19.7, 320.8 ± 21.9, 340.4 ± 27.1, and 620.7 ± 48.3, respectively). Immunohistochemistry indicated that the level of phosphorylated tau was (7.2 ± 1.1) × 10(4) in dyskinetic rats treated with LDME/benserazide-loaded nanoparticles. However, the tau level was only (14.6 ± 2.3) × 10(4) in LDME plus benserazide-treated dyskinetic rats. There was a significant difference between the two groups. Enzyme-linked immunosorbent assay showed that dynorphin levels in the striatum and cortex of dyskinetic rats treated with LDME/benserazide-loaded nanoparticles were 5.7 ± 1.2 and 4.8 ± 0.87, respectively, which were significantly reduced compared with LDME plus benserazide-treated dyskinetic rats (13.3 ± 2.1 and 8.1 ± 1.1 for the striatum and cortex, respectively).
  
  
  CONCLUSIONS
  Results suggest that LDME/benserazide-loaded nanoparticles can be used to reduce the expression of dyskinesia in dyskinetic rats.
authors.affiliation: Department of Neurology, Xinhua Hospital (affiliated to Shanghai Jiaotong University School of Medicine), Shanghai, People's Republic of China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Yang
authors.forename: Ruiyuan
authors.initials: R
authors.lastname: Zheng
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Cai
authors.forename: Meiling
authors.initials: M
authors.lastname: Liao
authors.forename: Weien
authors.initials: W
authors.lastname: Yuan
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000818:Animals; D000978:Antiparkinson Agents / Q000008:administration & dosage* / Q000009:adverse effects*; D001545:Benserazide / Q000008:administration & dosage*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000378:metabolism; D004337:Drug Carriers / Q000737:chemistry; D016503:Drug Delivery Systems; D004399:Dynorphins / Q000378:metabolism; D004409:Dyskinesia, Drug-Induced / Q000188:drug therapy* / Q000503:physiopathology; D007980:Levodopa / Q000008:administration & dosage / Q000009:adverse effects* / Q000031:analogs & derivatives*; D008297:Male; D008855:Microscopy, Electron, Scanning; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D050997:Nanomedicine; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D010316:Particle Size; D010766:Phosphorylation; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D016875:tau Proteins / Q000378:metabolism
chemical_list: D000978:Antiparkinson Agents; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004337:Drug Carriers; C483820:Fosb protein, rat; C489131:Mapt protein, rat; C497930:Ppp1r1b protein, rat; D016760:Proto-Oncogene Proteins c-fos; D016875:tau Proteins; D007980:Levodopa; D004399:Dynorphins; D001545:Benserazide; D020929:Mitogen-Activated Protein Kinase Kinases; C035420:levodopa methyl ester