| Background and Objective: Diabetic nephropathy (DN) is one of the most common chronic complications of diabetes mellitus and accounts for increased mortality and morbidity in diabetics. The origin and pathogenesis of DN is extremely complex and has not been clarified completely yet. Hyperglycemia is a symbol of diabetes and also the chief cause of neph- ropathy complications. 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.This study was designed to explore the different effects of fluctuant high blood glucose and stable high blood glucose on apoptosis through the expression of RAGE in mesangial cells, find out the relationship between blood glucose flucose fluctuation and diabetes complications, and clarify the pathogenesis of diabetic nephropathy and find effective prevention and a new cure method.Methods:Rat'glomerular mesangial cells (GMC) were cultured in vitro and according to the differfence of the concentration of D-glucose and fluctuated glucose in culture medium, growth-arrested cells were devided into 6 groups: control group (N), constant high glucose group (H1 and H2), fluctuant blood glucose group (F), same total loading group (L), and mannitiol group (P), We changed the concentration of glucose in the me- dium of group F to establish the model of blood glucose fluctuantion. After added to different culture medium, cells were cultured 24h,48h,72h. The morphological changes were observed under an invertedmicroscope, the prollifeation of GMC was observed by MTT assay. The activities of SOD,the level of MDA in supernatant were measured by spectrophotometry and the expressions of RAGE mRNA were evaluated by RT-PCR.Results:1. In 48h, group L and group H1 promote cells proliferation. After 48h, compared with the control group, the cellular morphology of other group was changed as unclear, swelling, cytoplasmic vacuoles, decreased cellular number and arranged disorder. Cells in other groups occurred the trend of apoptosis, the differences were obvious (P<0.05). The damage of GMC in group F was much more serious (P<0.01), while high glucose level inhibited cellular proliferation in a dose dependent fashion.2. After 24h, the activities of SOD (U/ml) in group F (12.97±1.86) and group H2 (12.99±1.34) were significicantly decreased (P<0.05), compared with group N (15.80±0.88) and group P (15.47±0.72), whereas obvious difference was not found among group F and group H2 (P>0.05); After 48h,except group P, there are obvious differences between group N and other groups (P<0.05), the significant differences were also exist among group F and group H2. There was no difference among group N and group P (P>0.05).3. Compared with the control group, the level of MDA (μM) was greatly higher in the other groups (P<0.05), the significant differences were also exist among group F and group H2. No difference was found among group N and group P (P>0.05).4. All samples were detected RAGE mRNA. High glucose stimulate the expression of RAGE mRNA since 24h, which was in independent of the osmotic pressure. The expression in H group was in dose-dependent and time-dependent manner. RAGE mRNA levels of groups F and H were sigificantly higher than N group (P<0.01) in 48h while there were no difference between group N and group P.Conclusions:1. In vitro, high glucose promoted the proliferation of GMC in a centain range of time and dose, with prolonging reaction time, this effect disappeared. High glucose levels inhibited the GMC proliferation and Fluctuating extracellular high glucose had the more servious inhibition effect.2. High glucose could induce the oxydative stress injure for mesangial cells in dose-dependent and time-dependent manner, which mainly manifested as the low celluar survival rates, the reducted activities of SOD and the elevated levels of MDA.3. It was found that fluctuated glucose do more harm to cells compared with high stable glucose. It could cause the apoptosis of the cells and make the function of the cells disordered. The phenomenon were likely to be caused by oxidative stress, the confusion of glucose metabolism and increase of AGEs.The damage of blood glucose fluctuation on cells was much worse than that of constant high glucose. The blood glucose fluctuation might be one of the causes that induced diabetes complications. |
PDF Full Text Request