Ex vivo Akt inhibition reverses castration induced internal pudendal artery and penile endothelial dysfunction.

AIMS

Androgen deprivation therapy is a common prostate cancer treatment which causes men to have castrate levels of testosterone. Unfortunately, most testosterone deficient patients will suffer severe erectile dysfunction (ED) and have no effective ED treatment options. Testosterone deficiency causes endothelial dysfunction and impairs penile vasodilation necessary to maintain an erection. Recent evidence demonstrates testosterone activates androgen receptors (AR) and generates nitric oxide (NO) through the Akt-endothelial NO synthase (eNOS) pathway; however, it remains unknown how castration impacts this signaling pathway.

MATERIALS AND METHODS

In this study, we used a surgically castrated rat model to determine how castration impacts ex vivo internal pudendal artery (IPA) and penile relaxation through the Akt-eNOS pathway.

KEY FINDINGS

Unlike systemic vasculature, castration causes significant IPA and penis endothelial dysfunction associated with a 50% AR reduction. Though testosterone and acetylcholine (ACh) both phosphorylate Akt and eNOS, castration did not affect testosterone-mediated IPA and penile Akt or eNOS phosphorylation. Surprisingly, castration increases ACh-mediated Akt and eNOS phosphorylation but reduces the eNOS dimer to monomer ratio. Akt inhibition using 10DEBC preserves IPA eNOS dimers. Functionally, 10DEBC reverses castration induced ex vivo IPA and penile endothelial dysfunction.

SIGNIFICANCE

These data demonstrate how castration uncouples eNOS and provide a novel strategy for improving endothelial-dependent relaxation necessary for an erection. Further studies are needed to determine if Akt inhibition may treat or even prevent ED in testosterone deficient prostate cancer survivors.