Purpose Sirtuin1(Sirt1) activation protects nerves from oxidative stress injury. In previous study, we applied caloric restriction rats, however, Sirt1 didn’t show evaluation as we expected at 3 weeks after injury. In this study, we applied young rats optic nerve injury model to analyze the change of Sirt1 at different time point. To better understand the role of Sirt1 during optic nerve injury.

Materials and methods
Surgery: 12 week old adult male F344 rats were used (total n=36). All surgery was carried out under anaesthesia of a 1:1 mixture (1.5ml/kg) of ketamine (100mg/mL) and xylazine (20mg/mL). Rats were divided into two groups randomly. One group underwent optic nerve cut and the other group underwent peripheral nerve-optic nerve graft (PN-ON graft). Under the anesthesia mentioned above, a 1.5-cm segment of peroneal nerve on the left leg was dissected out and sutured onto newly cut ON stump (transaction site at 1.5mm behind eye ball). The distal end of the PN segment was secured onto connective tissue on the skull. On cut group was underwent 1.5mm ON cut. At the time point of 1 day, 3 day, 1week, 2 week and 4week, the retina of both eyes were removed and total RNA was extracted. Followed by real-time PCR SYBR Green. The target gene expression was normalized by house-keeping gene beta-actin. The CT value was introduced into SPSS 11.0 and EXCEL to analyze. RNA isolation and real-time PCR: Total RNA was extracted from retina of both eyes and first-strand cDNA was synthesized. PCR was performed with an IQ5 (Bio Rad) and 2 × qPCR MasterMix (stratagene) according to the manufacturers’ instructions. All PCR reactions were run in duplicate and were performed with 40 cycles, including a negative control consisting of PCR-grade water. Quantitative real-time PCR analysis was carried out using the 2-^ΔΔCt method.

Results The quantitative real time PCR profile suggested that Sirt1 had time period after optic injury. The highest Sirt1 expression was found at 2 week after ON-cut. The level was nearly 11times more than the contra-lateral eye. Afterwards Sirt1 was decreased and fell to low levels at 4 week. In PN-ON eye, the peak expression of Sirt1 showed at 1 week after injury, which were 2 more times than the contra-lateral eye.

Conclusion The expression of Sirt1 has fluctuation after optic nerve injury and in optic nerve cut had different pattern with PN-On graft. These results indicated that Sirt1 participate in optic nerve injury, while play less role in optic nerve regrowth.