Cloning and sequencing of human neuronal aromatic L-amino acid decarboxylase gene and its therapeutic effects on Parkinson's disease

doi:10.3321/j.issn:1673-8225.2004.19.021

Abstract：BACKGROUND: In Parkinson's disease, the activity of aromatic L-amino acid decarborJase (AADC) decreased greatly secondary to the degeneration of dopaminergic neurons within the substantia nigra pars compacta leads to a series of clinical symptoms occur. Furthermore, the fluctuation of AADC activity is one of the most important cause leading to some severe side-effects,such as "on-off" phenomenon and so on, following the chronic L-dopa administration.OBJECTIVE: To study the roles of AADC gene therapy for Parkinson' s disease and its action by coadministrated of exogenous L-dopa and to discuss the effectiveness of the approach of cationic liposome mediated gene transferring into the brain.DESIGN: 2 x 2 factorial design.SETTING and MATERIALS: Research was completed at Linbaixin Medical Research Center of the Second Affiliated Hospital of Sun Yat-sen University. Materials used mainly includes human pheochromocytoma, TRIzoleukaryotic expression vector pCDNA3, cationic liposome, 6-OHDA, apomorphine, AADC monoclone antibody, SD rats.INTERVENTIONS: pCDNA3-AADC complex were constructed using gene cloning and subcloning technics. Then either the pCDNA3-AADC-Liposome or pCDNA3-Liposome complexes were injected into the striatum of Parkinsonian SD rats of experimental and control groups respectively. Furthermore,exogenous L-dopa were given to each groups. The expression of AADC were assayed with immunohistochemical staining.therapy at a certain concentration on rotational behaviour of rats.complex improved the rotational behavior of Parkinsonian rats in some degree when its being observed at 3, 7, 14, 21 and 28 days( P ＜ 0.05), reached56.0%, 62.6%, 49.4% , 36. 3%, 27.4%, respectively, this improvement lasted for 4 weeks and disappeared at the 5th week, the maximum improveexogenous L-dopa( 10 mg/kg body mass) per day, the experimental groups reached much more obvious improvement than that in the controls at the same time points( P ＜ 0.05), the maximum improvement was also at the time of 1munohistochemical staining showed that the AADC were expressed stably in the striatum.CONCLUSION: Increase of AADC gene expression may improve the rotational behavior of Parkinsonian rats as well as elevate the curative effect of exogenous L-dopa therapy, suggesting that it should be helpful to maintain a long-term L-dopa theraputic effect at a much lower level. The technic of intracerebral gene transfer mediated by cationic liposome may be a new method for gene therapy of PD.