Lentiviral nigral delivery of GDNF does not prevent neurodegeneration in a genetic rat model of Parkinson's disease

Viral delivery of glial cell line-derived neurotrophic factor (GDNF) currently represents one of the most promising neuroprotective strategies for Parkinson's Disease (PD). However, the effect of this neurotrophic factor has never been tested in the newly available genetic models of PD based on the viral expression of mutated alpha-synuclein. In this study, we evaluated the ability of lentiviral vectors coding for GDNF (lenti-GDNF) to prevent nigral dopaminergic degeneration associated with the lentiviral mediated expression of the A30P mutant human alpha-synuclein (lenti-A30P). This virally based rat model develops a progressive and selective loss of dopamine neurons associated with the appearance of alpha-synuclein containing inclusions, thus recapitulating the major hallmarks of PD. Lenti-GDNF was injected in the substantia nigra 2 weeks before nigral administration of lenti-A30P. Although a robust expression of GDNF was observed in the whole nigrostriatal pathway due to retrograde and/or anterograde transport, lenti-GDNF did not prevent the alpha-synuclein-induced dopaminergic neurodegeneration in the lentiviral-based genetic rat model of PD. These results suggest that sustained GDNF treatment cannot modulate the cellular toxicity related to abnormal folded protein accumulation as mutated human alpha-synuclein.