The Impact Of Dietary-restriction-reduced Autophagy On The Aged Rats' Life Expectancy

PartⅠRelationship between the plasmas concentration of essential amino acid and the level of autophagyObjective:To explore the effects of the concentration of essential amino acid in plasmas on the level of autophagy.Methods:Aged rats were randomly assigned into three groups with 10 rats in each:A group (normal diet), B group (1-day free diet and 1-day fasting), C group (5-day free diet and 2-day fasting). Five months later in vivo state 1mm3 liver tissues were taken and stored at 4℃. Blood samples were taken from rats hearts, then anticongulated, centrifuged and deproteinized, finally, the supernates were saved at-70℃.The amount of autophagosomes of hepatic cells was detected by transmission electron microscope(TEM); The contents of essential amino acids in plasma were detected using high-performance liquid chromatography(HPLC);Spearman rank correlation were used to analyze the correlation relationship between them.Results:Concentration of valine was in the maximum correlation with the level of autophagy(r=-0.779,P<0.001), while lysine's was in the minimum (r=-0.517,P<0.01), the level of autophagy was negatively correlated with leucine,meth and phenylalanine (r=-0.566,-0.527, and-0.531, P<0.01). There was no correlation between the concentration of other essential amino acids and the level of autophagy.Conclusion:The concentration of some essential amino acids in plasma was negatively correlated with the extent of autophagy. Among them, valine, phenylalanine, methionine, leucine and lysine concentrations can influence the extent of autophagy significantly. To regulate the level of autophagy by amino acids in plasma will be an important aspect in the clinical application of autophagy. PartⅡAn investigation the role of autophagy in anti-ageing by dietary restrictionObjective:The role of autophagy in anti-ageing by dietary restrictions was explored by observing of the autophagy level of hepatocytes and survival time of aged rats which are with different dietary restrictions.Methods:The approach of group as mentioned, three months later, samples were taken to detect the plasma essential amino acids by HPLC(high-performance liquid chromatography), the amount of autophagosomes in hepatic cells by TEM (transmission electron microscopy), and the MAP1-LC3 mRNA by RT-PCR.Then the survival time of rats were recorded, survival curves were drawn.Results:Compared with Group A, Group B and Group C had the following statistically significant differences:the plasma concentrations of five EAA (essential amino acids) were reduced significantly; the autophagy in liver cells was enhanced significantly; the survival times was prolonged obviously. While there was no statistical significance between Group B and Group C. Correlation analysis showed that there had a highly positive correlation between the survival times of rats and the level of autophagy in hepatic cells (r=0.842,P<0.01).Conclusion:To enhance the degree of autophagy by reducing the plasma concentrations of amino acid may be a mechanism for anti-ageing by dietary restriction. To provide experimental evidence for a new healthy diet.