Expressão do VEGF e dos receptores Flt-1 e Flk-1 no corpo cavernoso do rato. Acção do envelhecimento e da orquidectomia

Abstract

Aging and hypogonadic states are known risk factors for erectile dysfunction (ED). Both states contribute to vascular damage to the penile tissue. The incidence of cardiovascular disease correlates closely with the prevalence of ED, which is considered to be an early sign of impending cardiovascular problems. Vasculogenic ED, namely corporal venoocclusive dysfunction, which occurs in two-thirds of cases of ED, is caused by impairment of smooth muscle relaxation in the penile cavernosa associated with vascular insufficiency as well as structural alterations in the cavernous smooth muscle, nerves, and endothelium. To evaluate corpus cavernosum modifications associated with endothelial damage, expression of vascular endothelial growth factor (VEGF) and VEGF-specific membrane receptors (VEGFR- 1/Flt-1 and VEGFR-2/Flk-1) was studied through confocal immunofluorescence in the corpus cavernosum of control, aged (12 and 18 months) and orchidectomized (90 days of bilateral orchidectomy) Wistar rats. Immunohistochemical results demonstrated that both VEGF and VEGFR-1 were expressed in smooth muscle fibers, particularly in those surrounding the vascular endothelium, while endothelial expression was very low, especially in control and orchidectomized rats. VEGFR-2 expression was extended to the endothelium in all three groups: control group (2 months old), orchidectomized, and aged animals (12 and 18 months old). In aged rats, a shift resulting in VEGF and VEGFR-1 colocalization in the endothelial cell was observed. Our findings suggest an upregulation of VEGFR-1 in rat corpora cavernosa during aging, with a clear increase in expression by endothelial cells.