Liraglutide protects from renal damage via Akt-mTOR pathway in rats with diabetic kidney disease

OBJECTIVE: To explore the protective effect of liraglutide on renal damage in rats with diabetic kidney disease (DKD) through the protein kinase B-mammalian target of rapamycin (Akt-mTOR) pathway. MATERIALS AND METHODS: A total of 45 specific pathogen-free male Sprague-Dawley rats were divided into healthy group (no diabetes, n=15), diabetes group (diabetes, n=15), and liraglutide group (diabetes + liraglutide intervention, n=15). The differences in the biochemical indexes, lesion degree, glomerular Nephrin expression level, and mRNA and protein expressions of Akt-mTOR in renal tissues were detected in three groups via hematoxylin-eosin (HE) staining, immunohistochemistry, Western blotting, and quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR), respectively. RESULTS: The albumin-to-creatinine ratio (ACR) and levels of serum creatinine (Scr), urine microalbumin (UmAlb), fasting blood glucose (FBG), glycated hemoglobin (HbA1c), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and total cholesterol (TC) in renal tissues were the lowest in healthy group and the highest in diabetes group, while they significantly declined in liraglutide group compared with those in diabetes group. Also, there were statistically significant differences (p<0.05). The level of high-density lipoprotein cholesterol (HDL-C) in renal tissues was the highest in healthy group and the lowest in diabetes group, while it was significantly increased in liraglutide group compared with that in diabetes group. Also, there were statistically significant differences (p<0.05). In healthy group, the mesangial structure and renal tubules were normal, the tubular basement membrane was smooth and intact, and there were no interstitial widening and inflammatory cell infiltration. Compared with diabetes group, the mesangial cell proliferation and vacuolar degeneration were alleviated, while the tubular dilatation or atrophy, fibrous tissues, and inflammatory cells were reduced in liraglutide group. Moreover, the results of immunohistochemical staining revealed that the glomerular Nephrin protein was arranged uniformly and showed the blue-black particles in healthy group. The glomerular Nephrin protein expressed was significantly decreased and arranged disorderly in diabetes group compared with that in healthy group, while it was increased in liraglutide group compared with that in diabetes group (p< 0.05). The protein expression of Akt-mTOR in renal tissues was the lowest in healthy group and the highest in diabetes group, while it markedly declined in liraglutide group compared with that in diabetes group, displaying statistically significant differences (p<0.05). Similarly, the mRNA expression of Akt-mTOR in renal tissues was the lowest in healthy group and the highest in diabetes group, while it markedly declined in liraglutide group compared with that in diabetes group, displaying also statistically significant differences (p< 0.05). CONCLUSIONS: Liraglutide can significantly reduce the blood glucose and improve the renal function in rats by suppressing the protein expression of AKT-mTOR, thereby exerting a protective effect on renal damage in rats with DKD.