Insulin-like growth factor-1 receptor inhibitor alleviates diabetic kidney disease mouse tubulopathy

Abstract

Objective To investigate the effects of insulin-like growth factor 1 receptor (IGF-1R) inhibitor on tubulopathy in diabetic kidney disease (DKD) mice. Methods C57BL/6J male mice were randomly divided into normal control group (n=10) and DKD model group (n=30), by giving a single intraperitoneal injection of STZ 150 mg/kg to establish a DKD model. After established successfully, the mice in DKD model group were randomly divided into DKD group (n=10), benazepril group (n=10) and IGF-1R inhibitor group (n=10). IGF-1R inhibitor group was given intraperitoneal injection of IGF-1R inhibitor (30 mg·kg-1·d-1) and benazepril group was given intraperitoneal injection of benazepril (30 mg·kg-1·d-1). Normal control group and DKD group were given an equal amount of normal saline. After 8 weeks of feeding, mice were euthanatized. Body weight and kidney weight were recorded. Blood, urine and kidney samples were collected. Biochemical tests such as blood glucose and urine albumin were measured by automatic biochemical instruments and albumin excretion rate was calculated. Pathological changes of mice were observed by hematoxylin-eosin staining (HE) and periodic acid-schiff staining (PAS). Phosph (p) IGF-1R expression level was determined by immunohistochemistry and Western blotting. Results Compared with the normal control group, blood glucose, kidney weight/body weight and urinary albumin excretion rate were significantly higher in DKD group (all P<0.01). In DKD mice, glomerular expansion, tubular stenosis, tubular swelling and tubular atrophy were significantly detected. Meanwhile, the number of proximal tubular epithelial (PTE) cells was decreased, and the renal tubular injury scores, the average glomerular volume, and pIGF-1R protein expression were increased (all P<0.05). Compared with the DKD group, albumin excretion rate was significantly reduced (P<0.01), the above pathological changes were alleviated and the effect of IGF-1R inhibitor was more significant. Compared with the DKD group, the pIGF-1R protein expression was reduced in IGF-1R inhibitor group (P<0.05). Compared with the benazepril group, the pIGF-1R protein expression was reduced in IGF-1R inhibitor group (P<0.05). Conclusion IGF-1R inhibitor has better effect than benazepril on alleviating the tubulopathy of DKD mice. Key words: Diabetic nephropathies; Receptor, IGF type 1; Kidney tubules