Intracavernosal Injection of Insulin Like Growth Factor-1 Improves Erectile Function in Aging Rat / 대한남성과학회지

ABSTRACT

PURPOSE: Insulin like growth factor-1 (IGF-1) is known to promote the proliferation and migration of penile cavernous smooth muscle cells in rat. The purpose of this study was to investigate whether IGF-1 could restore erectile function in the aging rat. MATERIALS AND METHODS: Male Sprague-Dawley rats were divided into two groups young (4~5 months; n=10) and old (24 months; n=30). The old group was further divided into vehicle only (phosphate buffered saline plus 0.1% bovine serum albumin; n=10) and IGF-1 treatment (100 microgram; n=20) groups. Half of the IGF-1 dose (50 microgram) was injected on the first day, and half was injected on the third day. After 2 and 4 weeks of treatment, erectile function was evaluated by hemodynamic study, and corpus cavernosal histology was examined by histomorphometric analysis. RESULTS: The ratio of peak intracavernosal pressure to systemic arterial blood pressure was significantly lower in the vehicle-only old rats (63.1 8.5%) compared to young rats (74.6 3.2%) (p=0.016). However, after 4 weeks of treatment, the ratio was significantly increased in the IGF-1 treatment group (77.2 7.0%) compared to the vehicle-only group (p<0.05). The percentage of smooth muscle was significantly lower in the vehicle-only old rats (12.8 2.2%) compared to young rats (17.8 3.7%) (p=0.047), whereas, it was significantly increased in the IGF-1 treatment group (19.4 3.3%) compared to the vehicle-only group (p=0.014). CONCLUSIONS: Intracavernosal injection of IGF-1 in the old rats resulted in increased intracavernosal pressure and higher percentage of cavernosal smooth muscle. These results suggest that intracavernosal injection of IGF-1 appears to restore smooth muscle integrity and improve erectile function in aged rats.