| Summary: | 碩士 === 中山醫學大學 === 營養學研究所 === 102 === Objectives：The study has two main goals. The first was to determine whether the long-term subcutaneous (s.c.) injection of D-galactose could induce the aging cardiovascular dysfunction in Balb/c male mice. The second is to determine effects of dietary supplement of konjac glucomannan (KGM), fructo-oligosaccharide (FOS) or vitamin E on the D-galactose-induced dysfunction and the underlying mechanisms.
Materials and Methods： The twelve-week-old male Balb/c mice were divided into control group, D-galactose group (DG group), D-galactose-konjac glucomannan group (DG+K group, 5% w/w), D-galactose-fructo-oligosaccharide group (DG+FO group, 5% w/w), D-galactose-KGM-FOS group (DG+KFO group, 2.5% w/w each), D-galactose-vitamin E group (DG+E group, 0.04% w/w as a antioxidant control). The control group was given 0.9% saline (s.c.) while the other groups were injected with D-galactose (s.c., 1.2 g/kg BW) for 49 days. Another natural aging group (NA group) did not receive any injection and were killed at 56 weeks old. The ECG was determined a week before the end of the experiment. Mice were anaesthetized with CO2 after 18 h fasting and a midline incision was made to collect blood from the inferior vena cava, and to dissect the heart and aorta. Analysis of the project includes ECG, left ventricular thickness, cardiac TUNEL stain, Masson trichrome stain, western blot, aortic elastin stain, RT-PCR, plasma total cholesterol, triglyceride and malondialdehyde.
Result：D-galactose and natural aging groups had similar cardiovascular dysfunction. The heart rate of DG group was significantly lower than that of the control group. Based on the ECG, the RR interval and QTc was greater in the DG than the control group. In addition, the left ventricular thickness, cardiac TUNEL stain level, and the cardic protein levels of Bid, Bax, Cytochrome c was significantly greater in the NA group and DG group than the control group, respectively. Supplementation of KGM, FOS or vitamin E could ameliorate the D-galactose-induced alterations in the heart rate, cardiac TUNEL stain and apoptosis-related proteins. In the aorta, the elastic fiber nicks and the thickness of smooth muscle layer of NA or DG group was significantly greater than those of the control group. The LOX gene expression of the aorta was significantly lower in the NA and DG groups than that of the control group. Supplementation of KGM, FOS or vitamin E could diminish the D-galactose-induced vascular alteration in the morphology and the LOX gene expression. The plasma MDA, total cholesterol, and triglyceride in the NA and DG groups were significantly greater than that in the control group. Supplementation of KGM, FOS or vitamin E effectively decreased these alterations.
Conclusion：Supplementation of KGM, FOS and vitamin E effectively decreased the alterations caused by the D-galactose in the heart and aorta. These effects was likely to be mediated by the antioxidative and lipid-lowering effects of dietary fiber, which subsequently ameliorate the oxidatie stress-related intracellular apoptotic pathway, and increased the related gene expression of elasticity of blood vessels.
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