Expression level of neutrophil gelatinase-associated lipocalin and protective effect of probucol in rats with diabetic contrast-associated nephropathy

Abstract

Objective To investigate the expression level of neutrophil gelatinase-associated lipocalin (NGAL) in rats with diabetic contrast-associated nephropathy (CAN) , and to determine analyze the renal protective effect of probucol (PB) . Methods Forty-five healthy male SD rats were randomly divided into the control group (n=15) and diabetic CAN group (n=30) by weight. Diabetic CAN group was given disposable single-dose peritoneal injection of 60 mg/kg Streptozotocin (STZ) and tail vein injection of 10 mg/kg Iopromide. After successful modeling, the rats were randomly divided into CAN group (n=15) and PB group (n=15) . PB group was intragastrically administered with 110 mg·kg-1·d-1 PB, and the control group and CAN group were given intragastric administration with equal volume of normal saline. Five rats in each group were sacrificed at 4, 8 and 12 weeks, respectively. The levels of 24 h urinary protein, triglyceride (TG) , cholesterol (TC) , blood urea nitrogen (BUN) and serum creatinine (SCr) were measured. Hematoxylin-eosin (HE) staining was used to determine the pathological changes of kidneys under an optical microscope. The expression level of NGAL was examined by immunohistochemistry and Western blotting. Results (1) Compared with the control group, the levels of 24 h urinary protein, TG, TC, BUN and SCr in CAN group and PB group began to increase at the end of 4 weeks, gradually increased at the end of 8 and 12 weeks significantly. The levels in PB group were significantly lower than those in CAN group at different time points, with statistically significant differences (all P<0.05) . (2) At the end of 4 weeks, there were no obvious pathological changes of kidneys in CAN group and PB group. At the end of 8 weeks, the renal glomerular volume increased, the mesangial area widened, and the focal mesangial matrix increased with segmental sclerosis in CAN group. At the end of 12 week after progression, the above pathological changes were more obvious. The pathological changes in PB group were significantly alleviated compared with those in CAN group at the same time point, which were more severe than those in the control group. (3) The findings of immunohistochemistry showed that the expression level of NGAL in CAN group and PB group was low at the end of 4 weeks, and gradually increased at the end of 8 and 12 weeks. The expression level of NGAL in PB group was significantly lower than that in CAN group at time points, with statistically significant difference (all P<0.05) . (4) The findings of Western blotting showed that the protein expression level of NGAL in the renal tissues in the CAN group and PB group began to increase at the end of 4 weeks, and gradually increased at the end of 8 and 12 weeks. The expression level of NGAL in PB group was significantly lower than that in CAN group, with statistically significant difference (all P<0.05) . Conclusion The expression level of NGAL in kidneys of diabetic CAN rats significantly increases. PB treatment or down-regulation of NGAL expression level may reduce the lipid peroxidation injury and damage of vascular endothelial function, thereby protecting kidneys. Key words: Diabetic contrast-associated nephropathy; Neutrophil gelatinase-associated lipocalin; Probucol; Rats