Altered Dynamics in the Renal Lymphatic Circulation of Type 1 and Type 2 Diabetic Mice

The dynamics of the renal lymphatic circulation in diabetic nephropathy is not fully elucidated. The present study evaluated the effect of diabetic nephropathy on the renal lymphatic circulation in streptozotocin (STZ)-induced type 1 diabetic mice (ICR-STZ) and in type 2 diabetic KK/Ta mice which were fed a high fat diet (KK/Ta-HF). The diabetic mouse kidneys developed edema because of the nephropathy. In control mice renal lymphatic vessels distributed in the cortex but rarely in the medulla while in ICR-STZ and KK/Ta-HF mice, there were many lymphatic vessels with small lumen in both cortex and medulla. Total numbers and areas of renal blood vessels in the diabetic mice were similar to those in the controls while the total numbers and areas of renal lymphatic vessels were larger in diabetic mice than in the controls. There were statistically significant differences in the numbers of lymphatic vessels with diameters of 50-100 µm between the ICR-STZ and the control ICR mice, and in the numbers of lymphatic capillaries with diameters smaller than 50 µm between the KK/Ta-HF and the control KK/Ta mice. The diabetic nephropathy may induce the lymphangiogenesis or result in at least the renal lymphatic vessel expansion.