Acetyl-L-carnitine improves erectile function in bilateral cavernous nerve injury rats via promoting cavernous nerve regeneration

Introduction

Acetyl-L-carnitine (ALCAR), an acetyl derivative of L-carnitine, has been proven to promote nerve repair and regeneration in a variety of neurodegenerative diseases. Neurogenic erectile dysfunction (NED) caused by CN injury is a common complication after radical prostatectomy, which lacks efficient curative treatments.

Objective

Although attempts have been made to apply ALCAR to treatment of peripheral neuropathy, the effects of ALCAR on NED remain unknown. Therefore, we intend to explore the potential role of ALCAR in the treatment of NED.

Methods

A rat model of bilateral cavernous nerve injury (BCNI) was established by crushing the CN 5 millimeters distal to the major pelvic ganglion (MPG). Twenty-four BCNI rats were randomly divided into BCNI group, BCNI+ALCAR-LD (50 mg/kg/day) group, and BCNI+ALCAR-HD (100 mg/kg/day) group, whereas the remaining eight age-matched rats were sham-operated as controls. Fourteen days after intraperitoneal injection of ALCAR, erectile function was evaluated by measuring intracavernosal pressure and mean arterial pressure. The penile tissues and CNs at the distal damage point were collected from each group of rats for subsequent histological and molecular biological analysis. Rat Schwann cell line S16 was used for CCK-8 and wound healing assay, and the expressions of SC markers Pmp22 and nerve growth factor (NGF) were verified by PCR.

Results

First, we found that the erectile function of rats in the BCNI model group was severely impaired, which was improved considerably in both BCNI+ALCAR-LD and BCNI+ALCAR-HD groups. Then, we observed that the penis was fibrotic after denervation in the BCNI group, which was manifested as decreased smooth muscle content and increased collagen content in the corpus cavernosum, and high expression of fibrosis indicators including TGF-beta, CTGF, and Smad 2/3. The above changes were alleviated after the administration of low and high-dose ALCAR. Meanwhile, our results also showed that after ALCAR treatment, the NO/cGMP pathway was promoted and the RhoA/ROCK pathway was inhibited in the corpus cavernosum of BCNI rats. Further, rats treated with ALCAR had high expression of ATF3 and S100 in the distal nerve tissues of the CN extrusion site, indicating the repairing effect of ALCAR on the CN. In vitro experiments showed that ALCAR promoted the proliferation and migration of SC, and increased the expression of Pmp22 and NGF.

Conclusions

ALCAR could boost CN repair and regeneration, thereby suppressing penile fibrosis and improving penile erection. ALCAR could inhibit penile fibrosis and improve penile erection by promoting proliferation and migration of SC and secretion of NGF to promote nerve repair and regeneration. Our study provides new insight into the therapeutic effect of ALCAR and preclinical evidence for a potential treatment strategy for NED.

Disclosure

Work supported by industry: no.