| Summary: | 碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 102 === Advanced glycation end products (AGEs) are produced from the Maillard reaction and present in food and biological systems. The present studies show that high levels of circulating AGEs are associated with diabetic complications, such as nephropathy, retinopathy and atherosclerosis.It is worth noting that male diabetic patients may also have reproductive dysfunction, and this dysfunction may result from the oxidative stress induced by AGE-mediated the receptor for AGEs (RAGE) activation. Sustained intake of food rich in AGEs may lead to an increase in endogenous AGEs and chronic oxidative damage. Taken together, it is interesting to clarify the effect of AGE diet on function of testes, kidney and pancreas in normal and diabetic anamals. Silymarin is a flavonoid with hepatoprotective characteristics and powerful antioxidant activity.Therefore, the other section of study was further investigated to clarify the biological actions of silymarin in animals fed an AGE diet. Our study is divided into two sections as follows:
In part 1, we assessed the effect of different formula of AGE diet on testes, kidney and pancreas in male BALB/c mice and Sprague-Dawley rats, respectively, and the effect of the biological actions of silymarin. The results showed that AGE diet may lead to accumulation of AGEs in vivo, resulting in oxidative damage of testes and epididymis as well as a decrease
in sperm count and motility. To investigate the intervention effect of silymarin, we found that silymarin had potential for prevention of AGE
diet-induced oxidative damage. Based on the results of first part, AGE diet
was shown to cause accumulation of AGEs. Because the circulating AGEs
are closely related to the progression of diabetic complications, it is
speculated that diabetic damage of testes and epididymis may be augmented by AGE diet. In part 2, we investigated the effect of AGE diet on STZ-induced type 1 diabetes mellitus (DM) SD rat as well as the intervention effect of silymarin. The results showed that DM-induced oxidative damage led to a decrease of sperm count and motility, and AGE diet may aggravate related lesions, such as an increase of abnormal sperm rate. However, silymarin elevated activity of antioxidant enzymes of testes and ameliorated the lipid peroxidation in pancreas. Silymarin showed the potential for improving DM-induced oxidative damage in vivo; however, it did not significantly improve the STZ and AGE diet-induced decline of sperm count and diffuse spermatic degeneration/necrosis of epididymis. We speculate that the related damage of animals may be difficult to restore; thus, we cannot observe the expected results in related analyses.
In conclusion, diversity and preparation method of diet, experimental models, and animal strain might be the reasons why partial results are inconsistent. Based on all results, we summerize that AGE diet-induced oxidative stress are closely related to abnormalities of sperm in rodents. Additionally, administration of silymarin indeed significantly promoted antioxidant actions within testes, kidney and pancreas in rodents, suggesting that silymarin has potential to inhibit the generation of lipid peroxides and improvement of oxidative damage in vivo.
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