Effects Of Vitamin B₂ Supplementation On Nutritional Metabolism After Acute Hypoxia Exposure In Mice

ObjectiveTo observe the effects of vitamin B2 supplementation on vitamin B2 nutritional status and nutritional metabolism after acute hypoxia exposure in mice. The metabonomic technique was also applied to investigate the metabonomic changes after vitamin B2 supplementation in order to explore the mechanisms possibly involved.Methods1. Male Kunming mice were fed vitamin B2 supplemented diets for two weeks. The acute hypoxia exposure was simulated at 6000m in an animal chamber.2. The plasma and hepatic vitamin B2 contents were measured with a HPLC method. The blood glutathione reductase activity coefficient was also determined in order to assess vitamin B2 status indirectly.3. The contents of plasma glucose, lactate and urea were determined on an Hitachi automatic analyzer. The contents of plasma pyruvate, free fatty acids and muscular and hepatic glycogen were analysed spectrophotometrically. The plasmaβ-hydroxybutyrate content was measured with a commercial ELISA kit.4. 1H NMR technique was used to assay the metabonomic changes in plasma.Results1.The plasma vitamin B2 content did not change significantly while the hepatic vitamin B2 content decreased after acute hypoxia exposure. The vitamin B2 supplementation increased both plasma and hepatic vitamin B2 contents remarkably at high dosages. The blood glutathione reductase activity coefficient was increased in response to the acute hypoxia exposure and decreased after vitamin B2 supplementation.2. The contents of plasma pyruvate, lactate,β-hydroxybutyrate and urea were increased after acute hypoxia exposure. The contents of plasma pyruvate andβ-hydroxybutyrate were decreased while the contents of plasma lactate and urea were not changed after vitamin B2 supplementation. The plasma carnitine content was decreased after acute hypoxia exposure and increased after vitamin B2 supplementation. The plasma content of free fatty acids did not change significantly after acute hypoxia exposure and decreased after vitamin B2 supplementation at high dosage. The muscular glycogen content showed no significant change after acute hypoxia exposure and increased after vitamin B2 supplementation.3. After acute hypoxia exposure, the plasma metabolic pattern showed a significant change and recovered after vitamin B2 supplementation. The lipids, lactate, alanine, NAC, glutamate, choline, taurine, glucose, carnitine and glycine were among the components that contributed remarkably to the changes in metabolic pattern.Conclusion1. The vitamin B2 status was decreased after acute hypoxia exposure and improved after vitamin B2 supplementation.2. Vitamin B2 supplementation was effective in improving carbohydrate and lipid metabolism in acute hypoxia exposured mice. The carnitine played an important role in improving lipid metabolism after vitamin B2 supplementation.3. The results of metabonomic analysis confirmed the improvement of carbohydrate and lipid metabolism in acute hypoxia exposured mice after vitamin B2 supplementation. It was indicated that metabolism of some amino acids was also changed significantly.