Neurotensin-polyplex-mediated brain-derived neurotrophic factor gene delivery into nigral dopamine neurons prevents nigrostriatal degeneration in a rat model of early Parkinson's disease.

Nancy G Hernandez-Chan,Daniel Martinez-Fong,Refugio García-Villegas,Jose L Gongora-Alfaro,Juan Armendáriz-Borunda,Carlos E Orozco-Barrios,Sergio Zamudio,Fidel De La Cruz,David Reyes-Corona,Michael J Bannon,Yazmin M Flores-Martínez,Lourdes Escobedo,Maria E Hernandez-Gutierrez,Lenin Pavón,Armando J Espadas-Alvarez,Rasajna Nadella,Jose Ayala-Davila

doi:10.1186/s12929-015-0166-7

Abstract

BackgroundThe neurotrophin Brain-Derived Neurotrophic Factor (BDNF) influences nigral dopaminergic neurons via autocrine and paracrine mechanisms. The reduction of BDNF expression in Parkinson’s disease substantia nigra (SN) might contribute to the death of dopaminergic neurons because inhibiting BDNF expression in the SN causes parkinsonism in the rat. This study aimed to demonstrate that increasing BDNF expression in dopaminergic neurons of rats with one week of 6-hydroxydopamine lesion recovers from parkinsonism. The plasmids phDAT-BDNF-flag and phDAT-EGFP, coding for enhanced green fluorescent protein, were transfected using neurotensin (NTS)-polyplex, which enables delivery of genes into the dopaminergic neurons via neurotensin-receptor type 1 (NTSR1) internalization.ResultsTwo weeks after transfections, RT-PCR and immunofluorescence techniques showed that the residual dopaminergic neurons retain NTSR1 expression and susceptibility to be transfected by the NTS-polyplex. phDAT-BDNF-flag transfection did not increase dopaminergic neurons, but caused 7-fold increase in dopamine fibers within the SN and 5-fold increase in innervation and dopamine levels in the striatum. These neurotrophic effects were accompanied by a significant improvement in motor behavior.ConclusionsNTS-polyplex-mediated BDNF overexpression in dopaminergic neurons has proven to be effective to remit hemiparkinsonism in the rat. This BDNF gene therapy might be helpful in the early stage of Parkinson’s disease.

Highlights

The neurotrophin Brain-Derived Neurotrophic Factor (BDNF) influences nigral dopaminergic neurons via autocrine and paracrine mechanisms
We showed that in a 6-OHDA-induced early hemiparkinsonism, surviving DA neurons conserve the expression of neurotensin-receptor type 1 (NTSR1) on cell bodies and neurites that enabled gene transfection by NTS-polyplex
Residual DA neurons conserve NTSR1 in early hemiparkinsonism One week after the 6-OHDA lesion, a reverse transcription-polymerase chain reaction (RT-PCR) analysis showed the expression of NTSR1 mRNA in the substantia nigra (SN) with 6-OHDA lesion and in the positive controls, but not in the negative controls (L929 cells and PCR reagents without cDNA) (Fig. 1a)

Summary

Introduction

The neurotrophin Brain-Derived Neurotrophic Factor (BDNF) influences nigral dopaminergic neurons via autocrine and paracrine mechanisms. The reduction of BDNF expression in Parkinson’s disease substantia nigra (SN) might contribute to the death of dopaminergic neurons because inhibiting BDNF expression in the SN causes parkinsonism in the rat. The brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family that is expressed by dopamine (DA) neurons along with its high-affinity receptor TrkB (tropomyosin related kinase B) [1, 2]. Inhibiting BDNF expression by antisense oligonucleotide infusion causes loss of nigral DA neurons and mimics parkinsonism in adult rats [8]. In Parkinson’s disease (PD), the significant reduction of BDNF and TrkB in the substantia nigra (SN) might contribute to the death of DA neurons worsening the neurodegeneration [9,10,11]. Reinforcing BDNF expression in DA neurons might rescue the nigrostriatal DA pathway from neurodegeneration

Objectives

Methods

Results

Discussion

Conclusion