Assessment of SGLT2 inhibitors on kidney morphology and albumin excretion in rats with experimental diabetes mellitus type 1

Abstract

Background. Recently, as the therapy of diabetes mellitus, have been approved several members of a new class of drugs – SGLT2 inhibitors. SGLT2 inhibitors reduce glycemia and normalize renal perfusion. However renoprotective effect is still the subject of research.The aim of this study was to evaluate the effect of SGLT2 inhibitors on renal tissue of rats with experimental type 1 diabetes (DM).Materials and methods. This study was conducted on 22 white male rats at the age of 10 months with streptozotocin - induced diabetes. For the selection of the rats in the experiment were evaluated glycemia. The criteria for diabetes was blood glucose levels > 7 mmol / L and / or a positive glucose tolerance test. Rats were divided into 3 groups: 1 group (healthy control) - a group of 10 animals without DM, 2 group - (diabetic control) 6 animals with DM receiving insulin NPH; 3 -6 animals with DM receiving insulin NPH and dapagliflozin 0.1 mg / kg for 4 weeks. At the end of the study, animals were kept in metabolic cages and 24 hour urine was collected for estimation of albuminuria. Next animals were removed from the experiment, and kidney tissue was sampled for morphological evaluation. Sections were stained with haematoxylin and eosin (H&E), and PAS reaction stains for histopathological examination. Statistical significance of differences was assessed and linkages by standard methods of nonparametric statistics.Results. Sections of kidney from control group had classical structure of renal tissue. In contrast, histological sections from rats treated with insulin had showed cortical glomerulosclerosis, proliferation of mesangial cells and narrowed Bowman's spaces. In most of the proximal convoluted tubules was observed excessive hypertrophy, vacuolization and pyknotic nuclei. The kidneys of rats treated with dapagliflozin and insulin had a lower severity of degenerative processes compared with a group of rats treated with insulin. Many glomeruli had increased cellularity with normal Bowman’s spaces, while in the proximal convoluted tubules was observed weakly pronounced vacuolization and pyknotic nuclei and some less hypertrophy of tubular epithelium. Kidney sections of insulin-treated rats were showed signs of diffuse expansion of mesangial area with proliferation of mesangial cells and its PAS-positive matrix. While signs of mesangial expansion were absent in the dapagliflozin group. Analysis of the degree of glomerulosclerosis data was showed significant differences between the group of rats treated with dapagliflozin and insulin and the group of rats treated with insulin - 0.5 (0.4 - 0.6) and 1.1 (1.0 - 1.2), respectively ( p = 0.005). Furthermore, it revealed significant difference in percentage of mesangial area between group of rats treated with dapagliflozin and insulin and the group of rats treated with insulin - 28% (23 - 32) and 37% (33 - 41), respectively (p = 0.0082). Insulin-treated rats were showed significantly higher level of albuminuria compared with dapagliflozin-treated rats - 91.8 mg / 24h. (74.1 - 108.5) and 50.9 mg / 24 hr (41.3 - 60.2), respectively, (p = 0.012).Conclusions. Administration of dapagliflozin slows the progression of glomerulosclerosis and reduces the degree of its severity and the level of albuminuria, which may suggest a renoprotective properties.