Abstract
Purpose :
Increasing evidence suggests mitochondrial disorders and oxidative stress have been key contributors to the loss of retinal ganglion cells (RGCs) in glaucoma. Quercetin, a natural polyphenol flavonoid, has been reported to possess free radical scavenging as an antioxidant in many neurodegenerative diseases. However, little is known about its effect on the RGCs. This study is to investigate whether Quercetin prevents RGCs loss following the chronic ocular hypertension in rat and the underlying mechanisms.
Methods :
Episcleral vein cauterization (EVC) was performed in Wistar rats to induce chronic ocular hypertension. Quercetin was intravitreally injected to test its effects on RGC survival after ocular hypertension by the counting of retrograde FG-labeled RGCs. The RGCs were isolated by the magnetic cell sorter (MACS) method for further investigating the possible mechanisms of neuroprotective effects mediated by quercetin.
ROS level, activities of mitochondrial complex I and III in the RGCs were determined using biochemical methods. Expressions of PGC-1alpha, Nrf1, Nrf2, and Tfam examined using Western blotting and Real-time quantitative PCR, respectively. mtDNA copy number was measured by Real-time RT PCR.
Results :
Quercetin significantly reduced RGC loss 2 and 4 weeks after ocular hypertension. The loss of RGC in PBS-(used as a negative control) and quercetin-treated retinas was approximately 30.2% and 17.9% respectively at 4weeks, compared with control. Quercetin preserved 36.4% of RGCs which might be death in glaucomatous retinas. Western blot and qPCR results showed that quercetin obviously increased the activities of mitochondrial complex I and III, and reduced ROS level in RGCs, and up-regulated protein and mRNA expressions of PGC-1alpha, Nrf1, Nrf2, and Tfam. Finally, we found the mitochondrial copy number increased significantly in the quercetin-treated RGCs as compared to the control eyes.
Conclusions :
The present results first demonstrate that quercetin treatment reduced the loss of RGC in an experimental model of glaucoma. Quercetin may exert neuroprotective effects by enhancing mitochondrial biogenesis and reducing oxidative stress via up-regulating PGC-1alpha, Nrf1, Nrf2, and Tfam.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.