Perirenal fat associated with microalbuminuria in obese rats

Purpose To determine whether perirenal fat is associated with increased urinary albumin excretion and whether perirenal fat affects renal vascular endothelial function in obese rats. Methods Wistar rats were randomly divided into normal and obesity group, which were fed with normal and high-fat diet, respectively. Blood and urine samples were collected. Endothelial function of the aorta was determined by measuring endothelium-dependent vasodilatation. Renal tissues were collected for CD34 immunohistochemistry and free fatty acids (FFA) measurement. Levels of glomerular nitric oxide (NO) and reactive oxygen species (ROS) were measured. Results After 24 weeks, plasma FFA, high-sensitivity C-reactive protein, and malondialdehyde levels were elevated and were significantly higher in renal venous blood than in jugular venous blood in obese rats. Urinary albumin/creatinine ratio, glomerular CD34 expression, glomerular ROS level, and renal cortex FFA levels were higher in obese rats. Endothelial dysfunction was more severe in the infra-renal aorta than in the thoracic aorta in obese rats. Plasma adiponectin and glomerular NO levels were lower in obese rats. Conclusion Perirenal fat is associated with increased urinary albumin excretion in obese rats. The mechanism may be renal vascular endothelial dysfunction caused by increased oxidative stress and activation of inflammatory molecular pathways due to elevated FFA and low adiponectin levels.