title: Carbidopa-based modulation of the functional effect of the AAV2-hAADC gene therapy in 6-OHDA lesioned rats.
abstract: Progressively blunted response to L-DOPA in Parkinson's disease (PD) is a critical factor that complicates long-term pharmacotherapy in view of the central importance of this drug in management of the PD-related motor disturbance. This phenomenon is likely due to progressive loss of one of the key enzymes involved in the biosynthetic pathway for dopamine in the basal ganglia: aromatic L-amino acid decarboxylase (AADC). We have developed a gene therapy based on an adeno-associated virus encoding human AADC (AAV2-hAADC) infused into the Parkinsonian striatum. Although no adverse clinical effects of the AAV2-hAADC gene therapy have been observed so far, the ability to more precisely regulate transgene expression or transgene product activity could be an important long-term safety feature. The present study was designed to define pharmacological regulation of the functional activity of AAV2-hAADC transgene product by manipulating L-DOPA and carbidopa (AADC inhibitor) administration in hemi-parkinsonian rats. Thirty days after unilateral striatal infusion of AAV2-hAADC, animals displayed circling behavior and acceleration of dopamine metabolism in the lesioned striatum after administration of a low dose of L-DOPA (5 mg/kg) co-administered with 1.25 mg/kg of carbidopa. This phenomenon was not observed in control AAV2-GFP-treated rats. Withdrawal of carbidopa from a daily L-DOPA regimen decreased the peripheral L-DOPA pool, resulting in almost total loss of L-DOPA-induced behavioral response in AAV2-hAADC rats and a significant decline in striatal dopamine turnover. The serum L-DOPA level correlated with the magnitude of circling behavior in AAV2-hAADC rats. Additionally, AADC activity in homogenates of lesioned striata transduced by AAV2-AADC was 10-fold higher when compared with AAV2-GFP-treated control striata, confirming functional transduction. Our data suggests that the pharmacological regulation of circulating L-DOPA might be effective in the controlling of function of AAV2-hAADC transgene product in PD gene therapy.
authors: Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United State of America.
authors: Agnieszka
authors: A
authors: Ciesielska
authors: Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United State of America.
authors: Nitasha
authors: N
authors: Sharma
authors: Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United State of America.
authors: Janine
authors: J
authors: Beyer
authors: Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United State of America.
authors: John
authors: J
authors: Forsayeth
authors: Department of Neurological Surgery, University of California San Francisco, San Francisco, California, United State of America.
authors: Krystof
authors: K
authors: Bankiewicz
mesh_terms: D000818:Animals; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001522:Behavior, Animal / Q000187:drug effects*; D002230:Carbidopa / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D003342:Corpus Striatum / Q000378:metabolism; D000229:Dependovirus / Q000235:genetics*; D004298:Dopamine / Q000031:analogs & derivatives / Q000032:analysis; D055664:Electrochemical Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007980:Levodopa / Q000097:blood / Q000494:pharmacology; D008297:Male; D017072:Neostriatum / Q000378:metabolism / Q000473:pathology; D016627:Oxidopamine / Q000633:toxicity*; D010300:Parkinson Disease / Q000209:etiology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D007980:Levodopa; D016627:Oxidopamine; D001142:Aromatic-L-Amino-Acid Decarboxylases; C000595218:DDC protein, human; D002230:Carbidopa; D004298:Dopamine