The expression of POMC and AgRP in brain and kidney tissues at different stages of diabetic nephropathy rats

Abstract Objective To explore the changes of proopiomelanocortin (POMC) and Agouti-Related Peptide (AgRP) expression in brain and kidney tissues under insulin intervention at different stages of diabetic nephropathy (DN) rats. Methods The male Sprague-Dawley (SD) rats of DN were treated with high-fat diet for 8 weeks and induced by intraperitoneally injection of streptozotocin (30 mg/kg) for one time. Then DN rats were also injected insulin subcutaneously at 2–5 U/(kg·24 h) from initiation of the streptozotocin. Kidney tissue, blood sample, and 24 h-urine were collected to detect the ratio of kidney/body weight, blood glucose and 24-h urinary albumin excretion rate at different stages (4, 8, 12, and 16 weeks). Immunohistochemistry assay was used to measure the expression of POMC and AgRP at different stages of DN rats. Results The DN rats were established successfully. With the progression of DN, blood glucose, 24-h urinary albumin excretion rate and kidney body weight ratio increased significantly, while decreased when insulin was injected. Immunohistochemistry showed that the expression levels of POMC were decreased gradually in brain and kidney tissues. Conversely, the expression of AgRP in kidney was highest at week 8 and then decreased gradually. The effect of insulin on normalizing POMC and AgRP expression in brain and renal tissues was also observed in DKD rats. Conclusion With the progression of DN, the expression of POMC and AgRP in kidney tissues was observed at different stages of disease, and their expressions were significantly normalized by insulin. The mechanism of in situ expression of POMC and AGRP in kidney to the progression of DN needs further investigations.