MP43-16 TRANSPELVIC MAGNETIC STIMULATION (TPMS) AS A NOVEL THERAPY TO ENHANCE PENILE MICRO AND MACRO CIRCULATION

INTRODUCTION AND OBJECTIVES: It has been known that about 20~40% of patients receiving pelvic radiation treatment get erectile dysfunction.Therefore it is important for survivors and their physicians to know the strategy how to overcome ED against radiation therapy.We evaluated the effect of phosphodiesterase type 5 inhibitors (PDE5Is) on erectile function after pelvic radiation therapy in animal model.METHODS: 14 weeks old, 380g weighted, Wistar rats were used and 12.5 Gy pelvic irradiation was applied to penis, prostate and genital tissue in prone position.4 weeks after radiation, testis sizes were markedly reduced (0.8g vs 2.0g) in radiation group (R).Considering radiation induced hypogonadism, we added three more groups e 8 rats with testosterone enanthate IM (25mg/kg) (T) just after radiation (R+T), 8 rats with 4 weeks daily 20mg/kg udenafil (U) just after radiation (R+U), and 8 rats with R+T+U.Therefore, total 5 groups e Control (C), R, R+T, R+U, and R+T+U were tested for evaluating the effect of PDE5I (Udenafil) against radiation.RESULTS: Testosterone levels among C, R+T, and R+T+U were not different but the levels were markedly decreased in group R and R+U.Cortisol level was decreased after radiation but there was no difference among group R, R+T, R+U and R+T+U.Expression of mRNA of eNOS was decreased after radiation but it was partially restorated in R+U group (> R+T group); the level was markedly increased in R+T+U group.The mRNA expression level of gp91phox (NOX-2) was reduced in R+T, R+U (R+T was more reduced than R+U) and was lowest in R+T+U groups.Both testosterone and PDE5Is exert influences on up-regulating nitric oxide synthase and down-regulating superoxide production, however, testosterone rather than PDE5Is dominantly protect erectile tissue from superoxide production, and PDE5Is rather than testosterone may act dominantly in producing endothelial NO.CONCLUSIONS: PDE5Is still act via eNOS/nNOS pathway even after the radiation treatment.However, it should be always considered that pelvic irradiation could negatively affect gonadal homeostasis, and testosterone plays a role in reducing oxidative stress in corpus cavernosum, thus supplement of T in hypogonadism after irradiation would synnergically enhance the action of PDE5Is.