Expression of Sirt1 and Sirt2 in injured optic retina of calorie restricted rats.

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 eyes 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 statistically-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.