POSSIBLE MOLECULAR MECHANISMS OF CRYOABLATION-INDUCED IMPOTENCE IN A RAT MODEL

Objectives. Cryoablation of the prostate has been reported to induce i mpotence as a consequence of cavernosal nerve injury. This study is de signed to investigate the early and late effects of cavernosal nerve c ryoablation on growth factor expression and erectile function in a rat model. Methods. Forty male rats were divided into two groups (n = 20 each). The first group underwent unilateral cavernosal nerve freezing (experimental group). Before their euthanization at 1 and 3 months (10 rats each), erectile function was assessed by electrostimulation of t he cavernous nerves. The second group served as the control and was ki lled at the same time points. Western blot and reverse transcriptase-p olymerase chain reaction (RT-PCR) techniques were used to identify pro tein and gene expression of nerve growth factor (NGF), transforming gr owth factor-alpha (TGF-alpha), epidermal growth factor (EGF), and insu lin-like growth factor-1 (IGF-1) in the rat penis and pelvic ganglia. Results, Electrostimulation of the frozen nerve after 3 months reveale d a significantly higher maximal intracavernosal pressure and a shorte r latency period than in the 1-month group. At 3 months, immunoblot sh owed upregulation of NGF, TGF-alpha, and the precursor form of IGF-1 p rotein expression in the penile tissue; RT-PCR showed downregulation o f NGF gene expression in the pelvic ganglia of the frozen side. Conclu sions. The results show that erectile function decreased at 1 month an d then partially recovered 3 months after cavernosal nerve freezing. T his alteration in erectile function was associated with differential g ene and protein expression of the growth factors (NGF, TGF-alpha, EGF, and IGF-1). Further studies are required to elucidate the potential r ole of these growth factors in the prevention and treatment of cryoabl ation-induced impotence. (C) 1998, Elsevier Science Inc. All rights re served.