Effect Of Rice Bran Antioxidant Peptides On Mitochondria Damage In Aging Mice Induced By D-galactose

To observe the protective effect of rice bran antioxidant peptides on mitochondria in aging mice induced by D-galactose(D-gal), and explore the possible mechanism preliminarily.Sixty Kunming mice were randomly divided into five groups(12 mice per group), namely young control group, aging control group, low dose, medium dose and high dose of rice bran antioxidant peptides-treated groups. Mice in aging control group and three peptides-treated groups were daily given subcutaneous injection of 100 mg/(kg·bw) D-gal on the nape back, young control group were given saline of the same volume. Mice in three peptides-treated groups were daily perfused respectively with the dose of 100 mg/(kg-bw), 200 mg/(kg-bw) and 500mg/(kg-bw) of rice bran antioxidant peptides, the two control groups were perfused saline of the same volume for 6 weeks continuously. The body characteration was observed, and body weight was measured in each week. The liver cell and mitochondria ultrastructure was observed under transmission electron microscopy(TEM). The content of malonadehide(MDA), activities of manganese-superoxide dimutase(Mn-SOD), glutathione peroxidase(GSH-Px), catalase(CAT), total anti-oxidation capacity(T-AOC) in heart, brain and liver mitochondria, and respiratory chain complexsⅠ,ⅡandⅤin heart and brain mitochondria were measured by UV spectrophotometer. The deletion mutation of mitochondria DNA(mtDNA) in brain was determined by polymerase chain reaction(PCR) and photodensity scan. The results are as follows:1. Liver mitochondria ultrastructure in aging control group showed typical injury signs: the mitochondria was swelling and disorderly, had bubble and deformity, the number was decreased, outer membrane and cristae were blurred and disappeared partly. The mitochondria appearance of mice in rice bran peptides groups were much better, the effect of high dose 500mg/(kg·bw) is better than medium and low dose.2. Compared with young control group, the activities of Mn-SOD,GSH-Px,CAT and T-AOC decreased apparently (P<0.01), MDA content increased markedly (P<0.01). The results suggestied that D-gal induced the increasing of oxygenic free radicals (OFR) which aggravated the lipid peroxidation. But the activities of all antioxidases and T-AOC of rice bran antioxidant peptides groups improved much better than that of aging control group, and MDA content was also decreased apparently (P<0.05), the effect of 500mg/mg/(kg-bw) was best. This indicated that rice bran antioxidant peptides could enhance antioxidation and alleviate mitochondrial lipid peroxidation injury in aging mice induced by D-gal.3. Compared with young control group, the activities of respiratory chain complexsⅠ,ⅡandⅤin heart and brain mitochondria of mice in aging control group were decreased markedly (P<0.01), deletion mutation of mtDNA in brain was increased apparently (P<0.01). Compared with aging control group, the rice bran antioxidant peptides of medium and high dose can raise the activities of respiratory chain complexsⅠ,ⅡandⅤgreatly (P<0.01 or P<0.05), and decrease depletion of brain mtDNA significantly(P<0.01). The results imply that rice bran antioxidant peptides have obvious protective effect on mitochondria respiratory chain complexs and mtDNA in senile mice induced by D-gal, which provides it the possibility of anti-aging effect from the molecular level.With age increasing, endogenesis free radical are increased, the activities of antioxidationase are decreased, and the structure and function of mitochondria in mice were damaged. Rice bran antioxidant peptides have abilities of enhancing free radical cleaning ability, improving the mitochondria conformation, raising the activities of Mn-SOD, GSH-Px, CAT, T-AOC, respiratory chain complexsⅠ,ⅡandⅤ, decreasing the MDA content and depletion of DNA in mitochondria to delay aging.