Abstract

Diabetes mellitus is a chronic disease, which progresses with many complications such as the diabetic nephropathy (DN). P2X7 receptor is expressed in pathological conditions, in response to high concentrations of extracellular ATP, as seen in hyperglycemia. When constantly activated, P2X7 can induce inflammatory responses, leading to oxidative stress (OS) and triggering toxic biochemical processes. Coumarin derivatives, such as esculin, are mainly antioxidants but their pharmacodynamics are not yet fully understood. The aim of this study is to evaluate the effects of esculin on P2X7 expression in the kidneys of diabetic rats. In male Wistar rats 7 weeks old, diabetes was induced by a single dose of streptozotocin (60 mg/kg; i.v.); CTL group received only the vehicle. Diabetes was considered in animals with fasting glycaemia greater than 200 mg/dL, 48 hours after induction. Then, the animals received daily doses of esculin (50 mg/kg, p.o.) forming CTL+ESC and DM+ESC groups. 24-hours urine and a small aliquot of blood via retro-orbital plexus were collected for biochemical analysis. The animals were euthanized under anesthesia, at the end of the eighth week of protocol and the kidneys were collected for Western blotting analysis, using antibodies against P2X7. The results are described as mean ± SEM; significance for p<0.05. The protein content of P2X7 was significantly decreased in the renal cortex of diabetic animals that received esculin when compared to untreated diabetic animals (0.76±0.11 vs 1.33±0.21). These animals also presented lower proteinuria (38.72±4.82 vs 45.42±3.0) and urinary TBARS excretion (232.3±28.83 vs 282.0±7.2), both p<0.05 compared with untreated diabetic animals. Our data suggest that esculin treatment decreases the P2X7 receptor in diabetic animals, accompanied by reduced OS and proteinuria, an early marker of DN, pointing to a new treatment that can be applied to control the evolution of this disease.