High Protein Intake Increases Sirtuin 1 mRNA Expression in Rat Liver

Background: The relationship between aging or disease and diets, as in the relationship between the intake of calories and disease, has been studied. Appropriate protein intake is im-portant for disease, frailty, and the life span. However, little is knew regarding to protein diet on any disease and lifespan. So we analyze the effects of high protein diets on rat liver oxidative stress and tumor marker. Methodology: Rats were separated into three groups: LPD with 5% protein, SPD with 20% protein, and HPD with 40% protein, administered over 4 weeks. The qRT-PCR method was used for measuring mRNA expression levels. as the expression of the an-ti-aging-related enzyme Sirtuin 1, superoxide dismutase (SOD), CuZn-SOD, EC-SOD, endothelial nitric oxide synthase (eNOS), tumor suppressor protein p53, and nuclear respiratory factor 1 (NRF-1). Results: A significant difference (p = 0.03853) was observed between the LPD and SPD groups for Sirtuin 1 and also between the LPD and HPD groups (p = 0.004914). There were signif-icant differences in CuZn-SOD and EC-SOD between the LPD and SPD groups (CuZn-SOD: p = 0.02062, EC-SOD: p = 0.01906). A significant difference (p = 0.01359) between the LPD and SPD groups was also observed for eNOS. Conclusions: A significant difference in Sirtuin 1 expression was observed between the LPD and SPD, and between the LPD and HPD groups, indicates that high protein intake promotes Sirtuin 1 and prevents aging. As for CuZn-SOD, EC-SOD, and eNOS, the significant difference between the SPD and LPD groups indicates that low protein intake lowers the production of SOD and increases reactive oxygen species (ROS). An appropriate amount of protein is necessary for the prevention of aging, lifestyle-related diseases, and arteriosclerotic diseases caused by oxidative stress and to extend the life span.