Nrf2/ARE Antioxidant Signaling Pathways Activated In The Role Of Glial Cell Mediated Neuroprotection

Parkinson’s disease (PD) is an age-related neurodegenerative disease. At present, we still lack effective means for the treatment of Parkinson’s disease, but symptomatic treatment is mostly usd to improve symptoms in the clinical. These treatments cannot prevent the progression of PD, and the symptoms will gradually worse over time. The lack of treatment reflects our poor understanding of the mechanism, so researching on the mechanism of PD pathogenesis and progression is vital.The effect of glial cells, especially the antioxidant effect of astrocytes is of great importance in the development of PD. In addition, many studies have also shown that Nrf2 (NF-E2-related factor 2) is the key factor in cell oxidative stress reaction, the Nrf2/ARE antioxidant signaling pathway have important nerve protective effect in the nervous system diseases. In this study, we evaluated Nrf2 expression in the PD rat models. After treated the PD model with CDDO-Me, the agonist of Nrf2/ARE signaling pathways, we investigated its influence on the improvement of the neurodegenerative of PD Drosophila and PD rats. Also we studied the improvement of neurodegenerative in PD Drosophila, after overexpressing Nrf2 in neurons and glial cells respectively in models, then discussing its neuroprotective effects of Nrf2/ARE signaling pathways in astrocytes in PD.Objective:The aim of this research is to investigate the expression and cellular location of Nrf2 and the expression of downstream target genes in the rat model of PD. We treated the PD models with Nrf2/ARE signaling pathway agonist CDDO-Me, then investigated its influence on the improvement of the symptoms of PD rats. And we studied the influence on the improvement of the symptoms of PD rats after expressing Nrf2 in neurons and glial cells respectively, then discussed its neuroprotective effects in PD, and studyed the effect of Nrf2/ARE signaling pathways on the PD.Methods:Male Sprague-Dawley rats were randomly divided into three groups: 6-OHDA group, control group and 6-OHDA+CDDO-Me group. The models of PD were established by injecting 6-OHDA and 6-OHDA+CDDO-Me respectively in the right medial forebrain bundle of rats. The expression of Nrf2 and GCLC in the striatum and substantia nigra were examined by Western blot. Immunohistochemistry was performed to identify the location of Nrf2 in the control and PD rats. We established the mutant a-Synuclein genetically modified PD drosophila model, and established the rotenone PD drosophila. After activating the Nrf2/ARE signaling pathways and overexpressing the Nrf2 protein, we detected the expression of Nrf2 and GCLC, and observed the improvement of their life cycle and movement ability.Results:The typical rotations over 210 in 30 minutes were occurred in the second week after the 6-OHDA damaging.88% neurons of the right substantia nigra compacta (SNc) in lesioned side of the rat model of PD were not seen by TH immuno fluorescence staining. Western blot analysis demonstrated that the expression of Nrf2 in the striatum and substantia nigra of PD was higher than control rats. The GCLC expression in the striatum was higher than normal rats, but in the substantia nigra the expression level was lower than normal rats. Immunohistochemical detection showed that Nrf2 mainly expressed in neurons in the substantia nigra of normal rats, and astrocytes rarely expressed, but Nrf2 mainly expression in astrocytes in the substantia nigra of PD. After the mutant a-Synuclein genetically modified PD drosophila model treated with agonist CDDO-Me, we observed it extended the life cycle,and improved athletic ability. Western blot results showed that the expression of Nrf2 and GCLC protein content increased, GAL4/UAS positioning of heterologous gene expression system makes Nrf2 respectively expression in neurons and glial cells, We observed the same improvement, and Nrf2 gene expression in glial cells showed higher biological activities than neurons, and the higher suppression of the mutation a-Synuclein neurodegenerative changes. In the rotenone model, the GAL4/UAS positioning of heterologous gene expression system makes the Nrf2 respectively express in neurons and glial cells, we observed that effectively prolonged the life of PD flies, improved their exercise capacity.Conclusions:The expression of Nrf2 and GCLC protein in normal rats and PD rats changing suggest that Nrf2/ARE signaling pathways in the development process of PD was activated, and mainly in astrocytes.In PD drosophila model, Nrf2 gene expression in glial cells showed higher biological activities than neurons, and astrocytes is the largest number of glial cells, the most widely function cells, and has a close relationship with neurons, Nrf2/ARE signaling pathways activated in astrocytes has major neuroprotective effects, and it has clinical value to find new PD treatment targets and prevent progression of PD.