Aging and orchidectomy modulate expression of VEGF receptors (Flt-1 and Flk-1) on corpus cavernosum of the rat.

Abstract

Aging and hypogonadic states are known risk factors for erectile dysfunction (ED), contributing together to vascular damage of penile tissue. In the present study, VEGF-specific membrane receptor (VEGFR-1/Flt-1 and VEGFR-2/Flk-1) expression was studied by confocal immunofluorescence in the corpus cavernosum of control rats, rats aged 12 and 18 months, and orchidectomized Wistar rats (90 days of bilateral orchidectomy). Immunocytochemical results demonstrated VEGFR-2 expression restricted to the endothelium in both control and orchidectomized rats. Aged animals (12 and 18 months) presented enlarged vessels with intense VEGFR-2 endothelial staining. On the other hand, VEGFR-1 was demonstrated in smooth muscle fibers, particularly in those that surround vessel endothelium, the endothelial expression being very low in control and orchidectomized rats. However, in the aged rats, a shift resulting in a VEGFR-1 and VEGFR-2 co-localization in the endothelial cell was observed. The findings suggest an upregulation of VEGFR-1 in the corpora cavernosa during aging in the rat, which is evident from an increased expression by endothelial cells.