The present invention pertains to the field of genomics and nanotechnology, specifically to the in vivo gene expression technologies and their application in gene therapy. It consists of the performance of the NTS-polyplex nanocomplex, which can carry nucleic acids to the neurons, involving neurotrophic therapy to treat neurodegenerative diseases. In particular, the present invention addresses the treatment of Parkinsons disease by the regulated expression of the BDNF neurotrophin.