Study On Hypoglycemic Effect And Mechanism Of Enteromorpha's Polysaccharide

Objective To observe the biological effects of EP to the metabolism of glucose and lipid among the ALX-induced diabetic mice, and to explore the mechanism of its hypoglycemic effect.Methods The diabetic mice model was established by single intraperitoneal injection of ALX. Various doses of EP were given to animal subjects and the intake of water and food were recorded every day. FBG, TSOD, iNOS, TC, TG and LDL were measured after 28 days from initial intervention. Thymus, spleen and liver were removed, then the organ index was calculated and the liver glycogen level was obtained. The histological structure of spleen and liver were observed by using HE staining. As for the secretion of insulin, it was examined by immunohistochemistry. The expressions of MnSODmRNA, BaxmRNA and Bcl-2mRNA in pancreas were all evaluated by RT-PCR assay.Results 1. General activity, FBG, blood lipid and organ index: The animal subjects in EP intervention group showed better general activity and significant relief of polydipsia and polyphagia; Compared with normal group, the subjects in control group had increased FBG, TC, TG, LDL-C, the index of spleen and thymus, in contrast, the index of liver was lower. The all above-mentioned differences between two groups were all with significance (P<0.001 or P<0.05), indicating that the establishment of model was satisfactory. The EP intervention groups all had decreased level of FBG and blood lipid, higher spleen index(P<0.05 or P<0.01) and lower liver index (P<0.05 or P<0.01). However, the pancreas index has no significant difference between EP intervention groups and DM group. 2. Level of TSOD and iNOS: The activity of TSOD and iNOS were both decreased among the animal subjects of control group and had significance when compared with normal group (P<0.05). Medium dose of EP group and metformin group maintained elevated TSOD activity with significance( P<0.05); The activity of iNOS was significantly suppressed among the subjects of high dose of EP group and metformin group (P<0.01 or P<0.05). 3. Glycogen level and HE staining of liver: The level of liver glycogen was significantly reduced in control group(P<0.01), in opposite, the EP intervention groups and metformin group had elevated level with great significance (P<0.05). According to the result of HE staining, the control group showed disorder, additionally, cellular necrosis and enlarged cells were visualized, the pathological progress on EP intervention groups and metfromin group was relieved and dose-relationship was obtained. 4. HE staining and immunohistochemistry of pancreas: The HE staining demonstrated that EP could be involved in maintaining stable structure of pancreas; Compared with control group, Desity(mean)measured in low and medium dose of EP groups has significantly increased (P<0.05), and the significance went greater in high dose of EP group (P<0.01), however, we observed no significance when compared with metformin group (P>0.05). 5. The expression of MnSODmRNA, BaxmRNA and Bcl-2mRNA in pancreas: The expression of Bax was significantly suppressed among subjects in EP intervention groups and metformin group (P<0.05 and P<0.01) when compared with control group. The expression of Bcl-2 was up-regulated in high dose of EP group with significance (p<0.05); As for the expression of MnSOD, it was greatly increased in all doses of EP groups (P<0.001), identical change was also observed in metformin group (p<0.05).Conclusion:1. The application of EP on animal subjects indicated that it would lead to the improvement of food and water consumption among diabetic mice. Moreover, the blood glucose, TC, TG and LDL-C were reduced by the EP. So it was capable of lowering blood glucose and adjusting lipid metabolic disorder;2. EP was capable of increasing the index of spleen and decreasing the index of liver. It could minimize the damage of liver and pancreas, consequently improve the secretion of insulin and the synthesis of liver glycogen;3. The expression of MnSOD in pancreas was up-regulated by EP, thus the activity of TSOD was induced and the iNOS activity was suppressed. The hypoglycemic effect of EP was worked by above mentioned process which related with the suppression of oxidative stress;4. The expression of Bcl-2 was up-regulated and the expression of Bax was down-regulated by EP. Consequently,βcell was persevered and the apoptosis was inhibited.