Immunofluorescent Characterization of VEGF, VEGFR1 and VEGFR2 Expression in the Corpus Cavernosum of the Diabetic Rat after Prolonged Ingestion of Epigallocatechin Gallate

Abstract

Diabetes type 1 is a very common chronic disease that frequently initiates in youth. Patients suffering from this disease have an increased risk of developing complications such as cardiovascular disease or erectile dysfunction. This is partially due to oxidative stress in affected cells, induced by the increasing production of reactive oxygen species (ROS) that, in addition to oxidative macromolecular damage, inactivate nitric oxide (NO). This condition strongly affects blood vessels of corpus cavernosum (CC), decreasing erectile capability of penis. Thus, we hypothesise that treatment with antioxidants present in the green tea in the initial phase of diabetes type 1 may protect CC from structural and molecular changes induced by oxidative damage. In support of this hypothesis a previous study of our group demonstrated that green tea long-term ingestion led to decrease in lipid perivascular deposition and vascular endothelial growth factor (VEGF) and its receptor VEGFR 2 expression in CC of aged rats. VEGF is the main angiogenic factor in tissues that induces proliferation and survival of endothelial cells after binding to VEGFR2. In fact, VEGF/VEGFR2 system is involved in both physiological and pathological angiogenic processes, and most of the molecular changes observed in aged CC derive from oxidative stress coupled to impairment of angiogenic mechanisms. VEGF also engage VEGFR1, nevertheless the exact role of VEGFR1 activation in cavernous tissue is not yet clarified.