Role Of Fluctuated Glucose On Liver And Kidney Of Mice And Cultured Bovine Arterial Endothelial Cell And Its Possible Mechanism

With the extensive research on chronic diabetes complications, the role of fluctuant blood glucose on these diseases has been attached great importance. Clinical studies show that the development of chronic diabetes complications is not only related to high blood glucose but to fluctuant blood glucose as well. Our previous research indicated that fluctuant blood glucose can cause the oxidative damage of liver and kidney of mice and the mesangial cells and bovine arterial endothelial cells in culture. In this study, we investigated the damage of fluctuated glucose on liver and kidney of mice and cultured bovine arterial endothelial cell in different ways in order to find out the relationship between blood glucose fluctuation and diabetes complications. The research can be divided into three parts.1. To establish the mice model with fluctuant blood glucose: To establish the mice model with fluctuant blood glucose and to compare the influences between non-fluctuant blood glucose groups and fluctuant blood glucose groups. The experimental mice were divided into 4 groups: control group (N), fluctuant blood glucose group (F), diabetic group (DM) and diabetic fluctuant blood glucose group (DM+F). We established the mice model with fluctuant blood glucose by injecting 0.4mL glucose solution (250g/L) at different time points per day. At the same time, group N and group DM were injected 0.4mL physiological salt solution (PSS). After 4 weeks, we detected FPG, FINS, FA and glucose tolerance. Meanwhile, IR, IAI, HBCI and FBCI were calculated.The experimental result showed that the levels of blood glucose of group F and group DM+F occurred significant fluctuation in one day (P<0.001) . Compared with the control group, IR occurred at accelerated rates in the group DM and group DM+F while IAI decreased extremely. Levels of FA and impained glucose tolerance occurred extremely significant differences between non-fluctuant blood glucose groups and fluctuant blood glucose groups (P<0.001) .We can conclude that to inject glucose solution can establish the sensitive, accurate and reliable mice model with fluctuant blood glucose. It can help us to investigate the damage of blood glucose fluctuation to viscera and to find out the relationship with diabetes complications. 2. Animal level: To investigate the damage of fluctuant blood glucose on liver and kidney of mice and to find out the relationship with diabetes complications. We established the mice model with fluctuant blood glucose and 4 weeks later, we detected some indicators about polyols metabolic pathways (the extent of sorbierite, SDH and AR), oxidative damage (the extent of SOD, GSH and MDA)and advanced glycation end products pathways (the extent of AGEs and the expression of RAGE). At the same time, we detected the blood vascular permeability.The extent of oxidative damage and the content of sorbierite and AGEs from mice in fluctuant group were obviously increased than that in control group. In fluctuant group, the level of RAGE mRNA in liver and kidney tissues were upregulated (P<0.01 and P<0.001) and the vasopermeability in liver, pancreas, kidney, heart and brain of mice was more serious. We can conclude that the blood glucose fluctuation will aggravate the condition of diabetes in mice and damage the viscera (esp. liver and kidney) more seriously. It might be one of the causes that induced diabetes complications.3. Cell level: To investigate the damage of blood glucose fluctuation on bovine arterial endothelial cell and to find out its relationship with diabetes complications. After the cell culture, the experimental were divided into 3 groups: control group (N), constant high glucose group (H) and fluctuant blood glucose group (F). We changed the concentration of glucose in the medium of group F to establish the model of blood glucose fluctuation. After 48h, we detected the survival rate and the celluar membranes fluidity of endothelial cell and measured the content of DNA by FCM. Meanwhile, we detected some indicators about polyols metabolic pathways (the extent of sorbierite, SDH and AR), oxidative damage (the extent of SOD, GSH and MDA) and advanced glycation end products pathways (the extent of AGEs and the expression of RAGE). At the same time, the expressions of eNOS and ET-1 and the secretion of NO were measured.Cells in group H and group F occurred the trend of apoptosis. The extent of oxidative damage and the content of sorbierite, AGEs and AR in group H and group F were obviously increased (P<0.01 and P<0.001) than that in control group, but the survival rate and the celluar membranes fluidity of endothelial cell obviously decreased (P<0.05 and P<0.001) . The damage of endothelial cell in group F was much more serious. In group H and group F, the levels of RAGE mRNA. eNOS mRNA and ET-1 mRNA were upregulated greatly (P<0.01 and P<0.001) . The evidences mentioned above indicate that the damage of blood glucose fluctuation on cells is much worse than that of constant high glucose. The blood glucose fluctuation might be one of the causes that induced diabetes complications.All in all, we can conclude as follows:1. To inject glucose solution can establish the sensitive, accurate and reliable mice model with fluctuant blood glucose. It can help us to investigate the damage of blood glucose fluctuation to viscera and to find out the relationship with diabetes complications.2. The blood glucose fluctuation will aggravate the condition of diabetes in mice and damage the viscera (esp. liver and kidney) more seriously. It might be one of the causes that induced diabetes complications.3. The damage of blood glucose fluctuation on cells is much worse than that of constant high glucose. It can cause the apoptosis of the cells and make the function of the cells disordered. The blood glucose fluctuation might be one of the causes that induced diabetes complications.4. Several factors such as polyols metabolic pathways, oxidative damage, advanced glycation end products pathways and cytokines secretion lead to the diabetes complications. The blood glucose fluctuation might be the initial factor of all.