Effects of Denervation on Erectile Dysfunction: Reduced Erectile Activity Associated with Apoptosis of Smooth Muscle Cells in Rat Corpus Carvernosum

Kim, Soo Woong; Kim, Ki Dong; Paick, Jae Seung

Abstract

PURPOSE: Although many clinical observations support the idea that denervation may cause erectile dysfunction, there has been suggested as an underlying cause, resulting in decreased penile tissue and consequently impotence. This study was initiated to investigate whether apoptosis follows denervation of the rat penis.
MATERIALS AND METHODS
A total of 40 male Sprague-Dawley rats (10 weeks old) underwent abdominal exploration and unilateral or bilateral cavernous neurotomy. The penises were collected following sacrifice of animals at postoperation day 1, 2, 3, 6, or 10. Sham-operated animals served as controls. Tissues were embedded in paraffin and 3-?3 sections obtained. Deoxyribonucleic acid (DNA) fragmentation was analyzed by an in situ end-labeling method and by gel electrophoresis. Immunohistochemical study was carried out using monoclonal antibodies to p53.
RESULTS
DNA fragmentation was evident in the tissues. In situ labeling revealed that the number of apoptotic bodies increased in tandem with the length of denervation. This finding was confirmed by electrophoretic analysis of DNA. However, there was no difference between the unilaterally and bilaterally treated groups. Immunohistochemical localization showed that p53 expression was increased in tissue sections of denervated animals, whereas little or no expression was shown in normal controls.
CONCLUSIONS
Our results demonstrate that denervation causes apoptotic cell death in the rat penis. It is also suggested that unilateral nerve injury may be sufficient to affect normal erectile function. Further study will elucidate the molecular mechanisms of impotence caused by nerve-damaging operations such as prostatectomy.