title: Synergy between glutathione peroxidase-1 and astrocytic growth factors suppresses free radical generation and protects dopaminergic neurons against 6-hydroxydopamine.
abstract: The degeneration of dopaminergic neurons in the course of Parkinson disease is largely blamed on oxidative damage in the brain. This study examined the potency of glutathione peroxidase-1 (GPX-1) to protect dopaminergic neurons against toxicity induced by the parkinsonian neurotoxin 6-hydroxydopamine (6-OHDA). We generated pLV-GPX1, a recombinant lentivirus vector carrying the coding sequence for human GPX-1, into the SK-N-MC neuroblastoma cell line. The pLV-GPX1-infected neurons showed an over 3-fold increase in enzyme expression and a 2.6-fold increase in enzyme activity compared to the pLV-EGFP-infected control cells. In the pLV-GPX1-infected cells, we also detected significantly increased neuronal survival and resistance to 6-OHDA-mediated toxicity compared to our controls (75 ± 4% versus 51 ± 7%, p < 0.001). To maximize this protection, the neurons were treated with conditioned medium taken from growing primary astrocytes (astro-CM). We found the treated pLV-GPX1-infected neurons even more significantly resistant to 6-OHDA toxicity compared to their untreated counterparts (86 ± 5% versus 75 ± 4%, p < 0.001). Concomitant with increased neuroprotection, co-presence of overexpressed GPX-1 and astro-CM significantly increased glutathione (GSH) levels compared to when either of the two was present (p < 0.001). Further analysis showed nearly 2.7-fold reduction, in the presence of astro-CM, of hydrogen peroxide (H(2)O(2)) levels released from the pLV-GPX1-infected neurons compared to control groups (p < 0.001). Finally, regression analysis between H(2)O(2) levels and cell viability showed that co-presence of GPX-1 and astro-CM reduced 33% of cell death rate (p < 0.05). These data highlight the antioxidant properties of GPX-1 in protecting dopaminergic neurons and further emphasize the capacity of astrocytes in pumping growth-inducing factors that may synergize with GPX-1 to accelerate neuroprotection.
authors.affiliation: Department of Molecular Genetics, National Institute of Genetic Engineering and Biotechnology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Mossa65@nigeb.ac.ir
authors.forename: Mossa
authors.initials: M
authors.lastname: Gardaneh
authors.forename: Mostafa
authors.initials: M
authors.lastname: Gholami
authors.forename: Nader
authors.initials: N
authors.lastname: Maghsoudi
mesh_terms: D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D002470:Cell Survival; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism*; D005609:Free Radicals / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006801:Humans; D006892:Hydroxydopamines / Q000633:toxicity; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000378:metabolism / Q000494:pharmacology*; D000094765:Glutathione Peroxidase GPX1
chemical_list: D005609:Free Radicals; D006892:Hydroxydopamines; D036341:Intercellular Signaling Peptides and Proteins; D018696:Neuroprotective Agents; D005979:Glutathione Peroxidase; D004298:Dopamine; D000094765:Glutathione Peroxidase GPX1; C000722067:GPX1 protein, human