Restoration of erectile function by suppression of corporal apoptosis, fibrosis and corporal veno-occlusive dysfunction with rho-kinase inhibitors in a rat model of cavernous nerve injury

Purpose: We determined whether Rho-kinase inhibition would improve corporal veno-occlusive dysfunction by suppressing apoptosis and fibrosis via normalization of the Rho-kinase driven pathways related to the 2 structural alterations in a rat model of cavernous nerve crush injury.

Materials and methods: A total of 30 male 10-week-old male Sprague Dawley® rats were equally divided into 3 groups, including sham surgery, cavernous nerve crush injury and cavernous nerve crush injury treated with fasudil. The treated group received fasudil (30 mg/kg) daily for 4 weeks starting day 1 postoperatively. Electrostimulation and dynamic infusion cavernosometry were performed 4 weeks postoperatively. Penile tissue was processed for imm unohistochemistry, double immunofluorescent and Masson trichrome staining, TUNEL, caspase-3 activity assay and Western blot.

Results: The cavernous nerve crush injury group showed significantly lower intracavernous pressure/mean arterial pressure, and higher maintenance and drop rates than the sham surgery group. Rho-kinase inhibition in the injury plus fasudil group restored erectile responses and dynamic infusion cavernosometry parameters. Increased apoptosis, decreased immunohistochemical staining of α-SMA and increased caspase-3 activity were noted in the injury group. In that group densitometry revealed increased ROCK1 expression, increased MYPT1 phosphorylation, decreased Akt phosphorylation, decreased Bad phosphorylation and a decreased Bcl2-to-Bax ratio. A significantly decreased smooth muscle-to-collagen ratio and increased fibroblast pCofilin were also observed in the injury group, as was increased phosphorylation of cofilin, a downstream effector of LIMK2. Rho-kinase inhibition in the injury plus fasudil group alleviated the histological and molecular dysregulation.

Conclusions: Our data suggest that early inhibition of Rho-kinase after cavernous nerve crush injury may prevent corporal apoptosis and fibrosis by suppressing the Akt/Bad/Bax/caspase-3 and LIMK2/cofilin pathways, preventing corporal veno-occlusive dysfunction and erectile dysfunction.