Abstract

Diabetes mellitus is the largest epidemic disease of the 21st century and the International Diabetes Federation estimated that around 415 million people were diagnosed as diabetic by the year 2015; the projections for 2035 estimate that there will be 592 million in the World. Hyperglycemia, characteristic of this disease activates several pathways that in association with mitochondrial dysfunction culminate in the exacerbated production of reactive oxygen species. A previous study in our laboratory showed that oxidative stress was associated with an increases synthesis and activation of the P2X7 receptor (P2X7R), at the 8th week of diabetes, but the exact moment when its production become significant remains unknown. Purpose of this study is to evaluate the first moment in which P2X7R becomes highly expressed in the earliest phase of diabetes. Male Wistar rats at 7 weeks of age were all nephrectomized unilaterally. In half of the animals the diabetes was induced with streptozotocin (60mg/kg, i.v.) (DM), the others received its vehicle (CTL). After 24h of induction diabetes was confirmed as glycemia > 200mg/dL. The animals were euthanized on the first and subsequent weeks of diabetes up to eighth week and the kidney was collected and stored in a freezer at -80°C. The renal cortex was homogenized for Western blotting and quantified by polymerase chain reaction (qPCR). The results were analyzed with ANOVA of repeated measures with significance determined for p <0.05. RESULTS: Our qPCR data showed that only after the third week there was a decrease in P2X7 mRNA levels; however, in the sixth week of diabetes a significant increase in the mRNA synthesis was observed in DM group when compared to CTL; in the seventh and eighth weeks it presented a progressive decrease of these levels. The protein profile (Western blot) was similar to the qPCR data; in the first five weeks of DM, the P2X7 protein production was lower, but at the sixth week there was a significant increase in protein content for this receptor. Conclusion: Our preliminary data suggest that in the sixth week of diabetes the first and significant increase of the P2X7 gene expression and protein occurred. This is perhaps the main initial mark of the damage which can be caused by this receptor, as part of diabetes pathology.