Abstract

Accumulating evidence suggests that neuroinflammation and oxidative stress in cardiovascular center contribute to the pathological processes underlying hypertension. Microglia activation triggers the inflammation and oxidative stress. Melatonin is a documented potent anti-inflammatory regent and antioxidant, the underlying roles of melatonin in regulating microglia activation via mitochondria remain unclear. In present study, we investigated the protective role of melatonin in decreasing M1 phenotype switching via attenuating mitochondrial oxidative damage in dependence on uncoupling protein 2 (UCP2) pathway in microglia. Prorenin (20 nmol/L; 24 hr) was used to induce inflammation in cultured microglia. Mitochondrial morphology was detected by transmission electron microscope. The reactive oxygen species (ROS) production by using DCFH-DA fluorescence imaging and mitochondrial membrane potential (MMP, ΔΨm) was evaluated by JC-1 staining. The indicator of the redox status as the ratio of the amount of total NADP+ to total NADPH, and the expression of 6 subunits of NADPH oxidase is measured. The pro-inflammatory cytokines releasing was measured by qPCR. UCP2 and activated AMPKα (p-AMPKα) expression were examined by immunoblot. Melatonin (100 μM) markedly alleviated the M1 microglia phenotype shifting and abnormal mitochondria morphology. Melatonin attenuated prorenin-induced ΔΨm increasing and ROS overproduction. Melatonin decreased the redox ratio (NADP+/NADPH) and the p47phox and gp91phox subunits of NADPH oxidase expression in prorenin-treated microglia. These effects were reversed in the presence of UCP2 siRNA. Our results suggested that the protective effect of melatonin against prorenin-induced M1 phenotype switching via attenuating mitochondrial oxidative damage depending on UCP2 upregulation in prorenin-treated microglia.

Highlights

  • Accumulating evidence suggests that neuroinflammation [1,2,3] and oxidative stress [4] in cardiovascular center contribute to the pathological processes underlying sustained high blood pressure, and microglia activation have been proposed to play an important role in the progression of neuroinflammation and oxidative stress

  • Prorenin-induced M1 phenotype switching and increased proinflammatory cytokines (PICs) releasing, while melatonin reversed these effects which depended on uncoupling protein 2 (UCP2)

  • Our results suggested that the protective effect of melatonin against prorenin-induced M1 phenotype switching via attenuating mitochondrial oxidative damage depending on UCP2 upregulation in prorenin-treated microglia

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Summary

Introduction

Accumulating evidence suggests that neuroinflammation [1,2,3] and oxidative stress [4] in cardiovascular center contribute to the pathological processes underlying sustained high blood pressure, and microglia activation have been proposed to play an important role in the progression of neuroinflammation and oxidative stress. We hypothesize that the protective role of melatonin in decreasing M1 phenotype switching depends on uncoupling protein 2 (UCP2) pathway in prorenin-treated microglia. We first examined the protective effects of melatonin against prorenin-induced M1 activation in rat primary cultured microglia.

Results
Conclusion
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