| Summary: | 碩士 === 國立臺灣師範大學 === 生命科學系 === 103 === Type II diabetes is one of the most epidemic metabolic syndrome. It was predicted that people with T2DM would rise to 366 million in 2030. Guava (Psidium guajava) has been reported to provide anti-oxidation, anti-inflammation, and anti-diabetes. Besides, it protected β cells from the damage of oxidative stress in type I DM rats. However, there were few studies which report the mechanism between the edible proportion of guava and the T2DM. Therefore, we utilized guava juice to investigate its effect on T2DM. To improve the palatability, we added one kind of sugar, trehalose. Trehalose is a disaccharide, which has been used in cryopreservation of cells. In addition, it was found to avoid β-amyloid formation and polyglutamine (polyQ) in Alzheimer disease and Huntington’s disease indicating its protective function. This study is to discover the protective mechanism of guava juice (40%) combination with trehalose (5%) on the pathophysiology of kidney and pancreas in T2DM rats.
T2DM was induced in female Wistar rats by intraperitoneal administration of nicotinamide and streptozotocin and combination with high fructose diets for 8 weeks. After successful induction (> 230 mg/dL), the rats were divided into 6 groups, CON, DM, T1, T2, T5, B1, and were fed with different dosage of guava juice combination with or without trehalose for 4 weeks (Dose: T1, T2, T5: 4, 8, 20 ml/kg BW guava juice with 5% trehalose; B1: 4 ml/kg BW guava juice without trehalose).OGTT, plasma insulin, HbA1c, Homeostasis model assessment of IR (HOMA-IR, an indicator of insulin resistance) and HOMA-β (an index of the function of β cell in pancreas and insulin secretion) were determined. We also measured the kidney reactive oxygen species (ROS) in vivo. The oxidative and inflammatory degrees were measured by immunohistochemistry stain, fluorescent stain, serum free radical value and western blotting. We also measured the active component of guava juice with LC/MS analysis.
We found high content of quercetin existing in the guava juice. Quercetin and guava juice could scavenge H2O2 and HOCl, whereas trehalose can selectively reduce H2O2, not HOCl in the in vitro study. The results showed that the rats in group DM had elevated the degree of oxidative stress and inflammatory levels. In contrast, rats treated with oral intake of trehalose and guava juice in group T1, T2, T5 showed less expression of oxidative and inflammatory indicators, such as IL-1β, Caspase 3 and 4-HNE compared to DM group. Consistently, in the measurement of serum free radical levels, we found that rats in T1, T2 and T5 have significantly (P < 0.05) lower free radicals counts than B1 and DM groups. The results of immunohisotchemic and fluorescent stain also showed that oral intake of guava juice with trehalose in T1, T2, T5 rats had less (P < 0.05) oxidative damage, autophagy and apoptosis in the kidney and pancreas than B1 rats.
In conclusion, trehalose supplement seems to provide the additively protective effect of guava juice in T2DM. Combination with trehalose and guava juice not only increases palatability, but also protects pancreas and kidney against oxidative and proinflammatory damages in T2DM.
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