Evaluation of renal disease progression in obese and vitamin D-deficient rats after renal ischemia/reperfusion insult and the alternative effects of dapaglifozin on renal impairment in a 5/6 nephrectomy model associated with Obesity

Abstract

Obesity is a chronic disease commonly characterized by the accumulation of body fat and considered a worldwide epidemic conditioned by lifestyle habits. Renal changes associated with obesity are related to hemodynamic changes, mainly glomerular hyperperfusion, increased filtration fraction and proteinuria. In addition, structural changes such as increased renal weight, glomerulomegaly, thickening of the glomerular basement membrane, mesangial matrix expansion and podocyte dysfunction are observed in the course of the main renal pathologies associated with obesity. Lately, there has been a great interest in studying the influence of risk factors such as hypovitaminosis D and obesity on the progression of kidney disease. Furthermore, the alternative use of SGLT-2 inhibitors has been offering new perspectives and strategies for the treatment of kidney disease, regardless of their glucosuric effects. The present study aims to evaluate the progression of renal disease in obese and vitamin D deficient rats submitted to renal ischemia/reperfusion (IRR) insult. In addition, we will investigate the effects of the selective SGLT-2 inhibitor dapaglifozin as an alternative treatment on renal impairment in an obesity-associated 5/6 nephrectomy (Nx) model. Wistar rats (180-200 g) will be used for protocols 1 and 2. Protocol 1: the animals will be submitted to IRR surgery on day 45 and followed until the day 90. The animals will be allocated to four groups according to the diet received: standard (I/R), vitamin D depleted (I/R+DVD), high fat (I/R+H) or high fat vitamin D depleted (I/R+HDVD). Protocol 2: the animals will be submitted to Nx surgery on day 40 day and followed up until the day 100. Dapagliflozin (2 mg/kg/day) will be administered in the water from the 41st day. The animals will be divided into four groups according to the diet/treatment received: standard (N+SD); hyperlipidic (N+H); standard+dapaglifozin (N+SD+G); and hyperlipidic+dapaglifozin (N+H+G). At the end of both protocols we will perform morphometric measurements, assessment of inulin clearance, renal hemodynamic studies and biochemistry in plasma (electrolytes, cytokines, hormones) and urine (electrolytes) samples. We will use kidney tissue (frozen or fixed) for protein, gene and immunohistochemical expression studies to quantify cytokines, markers of inflammation and phenotypic change, extracellular matrix proteins and histomorphometric evaluation. Our results will allow us to evaluate the synergistic effects of obesity and vitamin D deficiency on the progression of kidney disease after IRR insult and also whether the alternative use of dapagliflozin will exert renoprotective effects in an obesity model associated with Nx. (AU)