| Aging,a complex physiological process,is accompanied with decline of function and aging-related diseases.The further researches on aging have found a number of aging biomarkers,such as genetic instability,mitochondrial dysfunction and oxidative stress.The theory of oxidative stress hold that elevated level of reactive oxygen species(ROS)results in aging due to causing damage to biological macromolecules and mitochondria.The annual fish genus Nothobranchius with relatively short lifespan and accelerated growth is becoming a novel animal model in aging research.Metformin,a biguanide compound originally derived from a guanidine derivative found in the plant Galega officinalis,is the most widely used as type ? diabetes treatment drug.It is confirmed that metformin have effects of extending lifespan and anti-aging as well as regulating metabolism and mitochondrial function in many model animals.Metformin can activate AMPK and SIRT1 in vitro.AMPK can promote mitochondrial biogenesis as well as down-regulating the level of ROS and keeping redox balance by phosphorylating PGC-1? and FoxO3 a respectively.SIRT1,a deacetylase relative to aging can acetylate PGC-1? and FoxO3 a.In the previous studies of our laboratory,it has been found that metformin could extend lifespan and reduce the accumulation of lipofuscin in liver of N.guentheri.Here,we use N.guentheri as animal model to reseach the mechanism.We investigated the histological structure and ultrastructure as well as the mitochondrial membrane potential of liver,oxidative stress-related markers and expression of related proteins(AMPK,SIRT1,FoxO3 a and PGC-1?)in liver to explore whether metformin resist oxidative damage to anti-aging of N.guentheri.In this study,130 fishes were randomly divided into two groups at 3-months.The fishes of control group were fed with standard food without metformin,and the experimental group was fed with food supplemented metformin.At the age of 6,9 and12 months old(young,middle-age and old),the fishes were acrificed on ice for experiment.Our results showed:1.Compared with histological structure of liver at 6 months old,at the age of 9month histological structure of liver displayed some irregularity shaped hepatocytes,decrease of sinusoid structure and an alteration of normal architecture in the form of hepatocellular cords.As aging,loss of sinusoid structure and architecture in the form of hepatocellular cords,all irregularity shaped hepatocytes,larger nucleus most vacuolated hepatocytes and inflammatory cell infiltration were observed in liver of 12 months old.Metformin-treatment improved the decline of liver histological structure with age.And the ultrastructural of liver in N.guentheri at 9 months old revealed a decrease number of mitochondrial number and a reduction in that of lipid droplets.Metformin-treatment improved the ultrastructural in liver of N.guentheri at 9 months old.2.Mitochondrial membrane potential of liver decreased gradually with age,while the levels of ROS,protein oxidation and lipid peroxidation increasing gradually with age.The long-term treatment of metformin significantly increased the mitochondrial membrane potential in liver,and significantly reduced the level of oxidative damage of N.guentheri.3.For researching the deep molecular mechanism,the expression of AMPK,SIRT1,PGC-1? and FoxO3 a in liver of 12 months old N.guentheri were analyzed by immunohistochemical staining.The results showed that metformin-treated up-regulated expression of proteins relative with oxidative stress in liver of 12 months old N.guentheri.In summary,metformin-treated improved histological structure as well as increasing mitochondrial membrane potential of liver and reduced oxidative stress with upregulating expression of oxidative stress related proteins in N.guentheri.In combination with the previous results of our laboratory,we hypothesized thatmetformin might resist mitochondrial oxidative damage by increasing expression of AMPK,SIRT1,PGC-1? and FoxO3 a resulting in anti-aging of N.guentheri. |
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