Résumé
Objective To investigate autophagy and proteasome system alteration in vivo and in vitro of diabetic nephropathy (DN) model rats.Methods Rat glomerular mesangial cells were primaryly cultured,and cell proliferation was tested by MTT assay.The mesangial cells were cultured under different concentrations of glucose (5.4 mmol/L for normal control and 30 mmol/L for high glucose) for 0,8,16,72 hours.The expression of autophagy (LC3) and proteasome (PSMAs) proteins was examined by Western blotting analysis.Spontaneous type 2 diabetes model OLETF and its normal control LETO rats were observed for 36 weeks.The levels of blood glucose and 24 hours urinary protein were evaluated in every 4 weeks.All the rats were sacrificed at the 36th week,and renal pathological changes were semi-quantitively analyzed.The expression of PSMAs and LC3 proteins was also examined in kidney cortex by Western blotting.Results Under high glucose concentrations,the abundance of PSMAs and LC3 proteins significantly reducedin the mesangial cells at 8 hours.There was no significant difference at other time points.The levels of blood glucose and 24 h urinary protein in OLETT rats exhibited progressive increase compared to those in LETO rats (all P＜0.01).And glomerular sclerosis index and tubulointerstitial injury index were significantly higher than those in LETO rats (all P＜0.01).The abundance of PSMAs proteins was significantly reduced in renal cortex of OLETF rats compared with LETO rats,while the abundance of LC3 proteins had no significant difference between two groups.Conclusion Proteolytic system dysfunction may play a role in pathogenesis of DN.