Purpose: We determined whether sirtuins (SIRT1-SIRT7) are expressed in the zebrafish retina, evaluated the modulatory effect of resveratrol in the normal retina, and examined N-Methyl-D-aspartic acid (NMDA)-induced zebrafish retinal damage associated with mitochondrial sirtuins and mitochondrial fusion and fission mediators, OPA1 and Fis1.
Methods: Sirtuins, OPA1, and Fis1 mRNA expression was analyzed by RT-PCR and quantitative real time PCR (qPCR) in adult zebrafish (AB type) retina and liver. qPCR showed an effect of resveratrol on SIRTs (SIRT1, 3, 4, 5) and OPA1 and Fis1 in low and high concentrations (5 and 50 mg/L) at different time points (0, 1, 24, and 48 hours) in the retina. Western blots were performed to examine the expression of SIRTs and OPA1 proteins under high concentrations of resveratrol for 24 hours. Hematoxylin and eosin staining, qPCR and mitochondrial copy number, and DNA damage assays then were used to confirm the protective effects of resveratrol on NMDA-induced retinal damage.
Results: The seven sirtuins and OPA1 were highly expressed in zebrafish retina compared to the liver. Treatment with resveratrol promoted SIRT1, mitochondrial sirtuins, and OPA1 gene and protein expression, and improved mitochondrial DNA repair in adult zebrafish retina. Interestingly, the effect of resveratrol on SIRT4 gene and protein expression was significantly higher in the zebrafish retina. Importantly, resveratrol offered protection against NMDA-induced retinal damage by activating the SIRT1 gene and subsequent protein expression. Mitochondrial sirtuins and OPA1 genes likely had a role in regulating mitochondrial dynamics.
Conclusions: To our knowledge, our study is the first composite analysis of sirtuins in adult zebrafish retina and provides sufficient evidence that resveratrol, as an activator of SIRT1, protects NMDA-induced zebrafish retinal damage by potentially mediating mitochondrial sirtuins and OPA1 genes.