The Role Of CHOP In The Endoplasmic Reticulum Stress Of Diabetic Rats’ Bladder

Objective:To evaluate the effect of CHOP on the endoplasmic reticulum stress of diabetic rats’ detrusor smooth muscle(DSM) and investigate the relationship between the endoplasmic reticulum stress and the development of diabetes cystopathy(DCP). To study the effects of CHOP in the occurrence and development of DCP and provide the basis for its treatment and etiology.Methods:45 healthy adult female Sprague-Dawley(SD) rats were randomly divided into five groups,a normal control group and four experimental groups. the experimental groups of type 1 diabetic rat models were induced by intraperitoneal injection of streptozotocin 50mg/kg.after 72 hours we take tail vein blood glucose concentration>300mg/dl as the successful standard of models. normal control group were injected with the same dose of saline. at different time points(4 weeks,8 weeks, 12 weeks, 16 weeks after induction of type 1 diabetic rat models),we resect the bladder tissue.The ultrastructure of endoplasmic reticulum(ER) was observed by transmission electron microscopy(TEM), and the terminal deoxynucleotidyl transferase-mediated DNA nick-end labeling(TUNEL) staining was used to identify the level of apoptosis of DSM cells. Moreover, the expression of the hallmarks of ERS-associated apoptosis,CCAAT/enhancer-binding protein homologous protein(CHOP), was detected by quantitative real-time polymerase chain reaction(RT-PCR) and Western blotting.Results:The endoplasmic reticulum of the normal control group arranges in neat rows at electron microscope.From 4 weeks to 16 weeks,the endoplasmic reticulum of experimental group gradually get disorder.The ultrastructural changes featuring the swollen and fused cisternaes(vacuolar structure)in ER zone and Ribosomes attached to the endoplasmic reticulum increases. Moreover,deformed and even collapsed nucleus were also observed in the detrusor smooth muscle.The apoptotic cells of DSM of normal control group are rare,and the nucleus were stained shallow. However,from 4 weeks to 16 weeks, the apoptotic DSM cells of the experimental group significantly increased, and the stained nuclear gradually get deepened. The percentage of apoptosis of all of the experimental group are higher than it of the normal control group. RT-PCR results showed that the levels of CHOP mRNA expression of 4 weeks, 8 weeks group, 12 week group and 16 week group gradually increased, and were higher than the normal control group.The results of western-blotting indicated that from 4 weeks to 16 weeks, the levels of CHOP protein expression of the experimental group were significantly higher than the control group, and showed an increasing trend.Conclusion:Endoplasmic reticulum stress(ERS) contributes to apoptosis of the DSM cell of the SD mouse, CHOP was positively correlated with the development of DCP.The role of CHOP in the occurrence and development of DCP and the ways in which CHOP affects the detrusor muscle cell function remain unclear.In the future, our studids will focus on time-dependent changes of bladder.