Effect of syringin on insulin resistance

• Main Authors: Wen-Ching Ko, 柯文清
• Other Authors: Feng-Lin Hsu Ph.D
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/20641672131019353152

碩士 === 臺北醫學大學 === 生藥學研究所 === 93 === There are two types of diabetes mellitus(DM): Type 1 DM is IDDM( insulin dependent DM) that is due to failure of insulin secretion of the pancreatic β-cell. Type 2 DM is NIDDM( non-insulin dependent DM) that can be characterized by a diminished ability of insulin sensitivity. Type II DM is so-called adult-type DM because the disease usually develops in the patients elder than 40 years old, but it can develop in the young persons. The ability of insulin secretion is normal in most Type 2 DM patients ; besides, it always accompanies with insulin resistance. The key feature of insulin resistance is oversecretion of pancreatic β-cell, leading to hyperinsulinemia that can diminish insulin sensitivity in target tissues, such as skeletal muscle, fatty tissue and liver. Therefore, it shows a significant decrease of glucose uptake and leads to hyperglycemia. Eleutherococcus senticosus that has the physiologic effect of treating hyperglycemia has been reported in the literature.In order to understand the mechanisms of treating hyperglycemia of Eleutherococcus senticosus and it’s effect of treating insulin resistance, we use one of the major component of Eleutherococcus senticosus “ Syringin” to carry out our experiments. Syringin was obtained for glucose tolerance tests and evaluated the effects of glucose-insulin index.In fructose-induced insulin resistance rats, we found that syringin can lower the plasma glucose and insulin level in the association of dose dependence. Besides, the higher concentrations of the syringin was added , the lower glucose-insulin index was obtained. Therefore, we can concluded that syringin has the physiologic effect to treat insulin resistance in fructose-induced insulin resistance rats. The lowered glucose-insulin index will be blocked when we give naloxone (antagonist of opioid β-receptor). The results presented that activation of opioid β-receptor can diminish the effect of insulin resistance. In order to realize the possible mechanisms, Western blotting was employed to detect the amounts of IRS-1( Tyr ), PI-3 kinase( p85α ), and Akt( Ser473 ) phosphorylation to nuderstand the insulin signal pathways.The results showed that syringin can elevate the protein expression of IRS-1( Tyr ), PI-3 kinase( p85α ), and Akt( Ser473 ) phosphorylation in fructose-induced insulin resistance rats. We selected mouse myoblast cell line C2C12 to undergo the test of glucose uptake.We found that the more concentration of Syringin was added, the stronger effect of glucose uptake of the C2C12 cell line was obtained. However, the effect disappeared when we pretreated the C2C12 cell line with naloxone or naloxonazine. When we added syringin in TNF-α induced insulin resistance C2C12 cell line, glucose uptake level increased markedly. However, the effect disappeared when we pretreat the C2C12 cell line with naloxone or naloxonazine. Syringin can elevate the protein expression of IRS-1( Tyr ), PI-3 kinase( p85α ), and Akt( Ser473 ) phosphorylation in insulin resistant C2C12 cell. Besides, syringin can increase protein expression of GLUT4. Thus, the present study found that syringin can improve insulin resistance both in vivo or in vitro.