Investigation Of Anti-aging Effect Of Dietary Restriction In Female Aged Rats

Objective:To observe the discrepancy of autophagy in female aged rats with different dietary, to explore the effect of dietary restriction on the superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in serum of female aged rats, to analyze experimental animal's natural life-spans and survival curves, and to inquire into the anti-aging effect and mechanism of dietary restriction.Methods:Forty-five female 24-month aged SD rats were randomly and evenly divided into 3 groups :control group, EOD group (every-other-day ad libitum feeding rats, which spend one day of their time fed and the next day in the state of fasting) and sustained two-day fasting group (rats spend five days of their time fed and the next two days in the state of fasting). Then dietary intervention in different ways were implemented and samples were taken after 3 months. Autophagosomes were observed with Transmission Electron Microscopy, while serum SOD and MDA were measured with reagent kits. In addition, survival curves were drawn for survival analysis. At last, correlation analysis between survival time and experimental indexes (autophagic activity, serum SOD and MDA) were investigated.Results:Proportions of autophagosome to the total area of cytoplasm in EOD group and sustained two-day fasting group were significantly higher(p<0.01) than that in control group, but no significant difference between the two groups (p>0.05). Activity of SOD in EOD group was significantly higher (p<0.01) and in sustained two-day fasting group was significantly higher (p<0.05) than that in control group ,and contents of MDA were significantly lower(p<0.01). Survival analysis showed that there was difference among three groups survival curves. Specifically, survival rates of EOD group and sustained two-day fasting group were significantly higher than that of control group(p<0.01),whereas no statistical difference between the two groups (p>0.05).The result of correlation analysis(rs=0.903) between survival time and autophagic activity indicated that survival time positively correlated with autophagic activity, which between survival time and serum SOD(rs=0.717) indicated that survival time positively correlated with SOD activity, which between survival time and serum MDA (rs=-0.745) indicated that survival time negatively correlated with MDA content.Conclusions:Autophagic activity at high level may be benefit for extension of life-span in female rats. Dietary restriction led to increasing of life expectancy, which may be associate with autophagy. Dietary restriction of aged rats can increase the activity of SOD, and decrease the content of MDA, resulting into the attenuation of oxidative stress. Dietary restriction can increase autophagy and decrease oxidative stress, through which DR can retard the progress of aging.