Expression of Sirt1 and Sirt2 in the Injured Optic Retina of Calorie-Restricted Rats

R774; Purpose:To investigate retinal ganglion cell (RGC) survival after optic nerve injury in calorie-restricted (CR) rats,and analyze the potential role of Sirtuins.Methods:Ten-month old male Sprague-Dawley rats (n=14)were divided into calorie restricted (CR) and ad libitum (AL)groups.In the CR group (n=7),the rats were denied access to food every other day.Animals in the AL group (n=7) had had free access to food.PN-ON grafting was carried out on the right eye of all subjects after 5 months of feeding.Three weeks postoperatively,retina samples were collected,half of which were fixed in 4％ paraformaldehyde (PFA) and subjected to standard immunofluorescence staining for TUJ-1.The remaining samples were subjected to total RNA analysis and RT-PCR for Sirt1 and 2 expression.Results:Comparing the amount of TUJ-1 staining between the groups,the mean density and the total number of RGCs showed no significant difference.RT-PCR results indicated that mRNA expression of Sirtuin2 in the CR group was significantly lower than that in the AL group,whereas no statisti cally significant difference was observed between the two groups regarding the mRNA expression of Sirt1.Conclusion:Calorie restriction had no impact on the survival of injured RGCs.The down-regulated mRNA expression of Sirt2 in the CR group may indicate an improved capacity for regeneration among these animals,but more work is needed to explore this possibility.( Eye Science 2011 ; 26:221-224 )