Study on the effect of polysaccharide from stigma maydison on ATP synthesis in renal mitochondria and its mechanism in D-galactose-induced aging mice / 中华老年医学杂志

ABSTRACT

Objective:To investigate the effect of Stigma Maydis Palysaccharide(SMPS)on ATP synthesis in kidney mitochondria of D-galactose-induced aging mice, and to clarify its possible mechanism.Methods:The aging mouse model was established by subcutaneous injection of D-galactose solution in the back of the neck.The 48 SPF male mice were randomly divided into normal control group(control group), D-galactose model group(D-Gal group), SMPS low-dose group and SMPS high-dose group(n=12 for each). The control group was subcutaneously injected with 150 mg/kg normal saline on the back of the neck every day, while the other three groups were subcutaneously injected with 150 mg/kg of D-gal solution on the back of the neck every day.SMPS-L and-H dose groups were given 30 mg/kg and 60 mg/kg of SMPS solution by gavage at the same day of D-Gal injection.The control group and D-GAL group were given the same volume of normal saline daily by gavage for 42 days.Blood samples were collected from the eyeball under general anesthesia after 42 days of intervention for the detection of serum levels of superoxide dismutase(SOD), glutathione peroxidase(GSH-Px)and MDA.After harvesting the kidney tissue, various tests were used to detect ATP content, the mRNA expression levels and protein expression levels in kidney.Luciferase assay was used to detect ATP content in renal tissue.Real-time fluorescent quantitative PCR was used to detect the mRNA expression levels of succinate dehydrogenase(SDH)of complex Ⅱ, cytochrome C reductase(Cycs)of complex Ⅲ, complex Ⅳ(COXⅣ)and ATP5b in ATP synthase in mitochondrial oxidative respiratory chain.Western blot was used to detect the expression levels of mitochondrial fusion protein 2(MFN2), dynamin-related protein1(DRP1)and mitochondrial autophagy related protein P62 in renal tissues of each group.Results:Compared with control group, the activities of serum of SOD(116.53±10.01)U/mg and GSH-Px(127.58±8.74)μmol/L were significantly decreased in D-GAL group(both P< 0.01), and serum MDA content(15.42±0.91)μmol/L increased significantly in D-GAL group( P<0.01). Compared with D-GAL group, the activities of SOD(152.80±9.29)U/mg and GSH-Px(274.07±10.73)μmol/L were significantly increased in SMPS intervention group( P< 0.01), while the MDA content(8.10±0.66)μmol/L decreased significantly in SMPS intervention group( P< 0.01). Compared with control group, the content of ATP(178±4)10 -4 μmol in D-gal group was significantly decreased( P<0.01), the mRNA expression levels of SDH, Cycs and COXⅣ were not significantly changed in D-gal group, and the mRNA expression level of ATP5b(0.67±0.01)was down-regulated in D-gal group( P<0.01), the expression of MFN2 protein(0.29±0.02)was significantly decreased in D-gal group( P<0.01), and the expression of DRP1 and P62 protein(0.31±0.02 and 0.21±0.01)was significantly increased in D-gal group(both P<0.01). Compared with the D-gal group, the ATP content(193±1)10 -4 μmol in the kidney tissue of the mice was significantly increased in SMPS intervention group( P< 0.01), and the ATP5b mRNA expression and MFN2 protein expression(0.87±0.05 and 0.71±0.08)were significantly increased in SMPS intervention group(both P< 0.01), DRP1 and P62 protein expressions(0.20±0.01 and 0.10±0.01)were significantly down-regulated in in SMPS intervention group(both P< 0.01). Conclusions:SMPS can improve the mitochondrial dynamic homeostasis disorder in aging mice by increasing the activity of antioxidant enzymes, up-regulating the expression of ATP5b mRNA and MFN2 protein, down-regulating the expression of DRP1 and P62 protein, and promoting the generation of mitochondrial ATP in D-gal-induced aging mice kidney tissue.