EFFECT OF BILATERAL CAVERNOUS NERVE INJURY ON NITRIC OXIDE AND RHO-KINASE SIGNALING IN A RAT MODEL OF POST- RADICAL PROSTATECTOMY ERECTILE DYSFUNCTION

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THE JOURNAL OF UROLOGY®

METHODS: Forty rats were randomly assigned into four groups. Group 1 (n=10), no surgery, no treatment. Group 2 (n=10), sham surgery, no BCNC. Group 3 (n=10), BCNC, without any therapy LVRÀXUDQH LQKDODWLRQ GDLO\ 0RQGD\ WKURXJK )ULGD\ EXW ZLWKRXW 9(' application). Group 4 (n=10), BCNC, with VED therapy (Monday through )ULGD\GDLO\XQGHULVRÀXUDQHLQKDODWLRQ 3HQLOHOHQJWKZDVPHDVXUHG RQZHHNO\EDVLV3HQLOHEORRGÀRZZDVPHDVXUHGE\3HUL6FDQ3,0 Laser Doppler Imager. On day 60, intracavernosal pressure (ICP) and mean arterial pressure (MAP) were measured under cavernous nerve stimulation (CNS) under anesthesia. The penis was processed for :HVWHUQEORWDQDO\VLVRI3,.WRWDOSKRVSKR$NWH1267*)ȕ1+,)Į DQGĮVPRRWKPXVFOHDFWLQ$60$ DQGKLVWRRULPPXQRKLVWRFKHPLVWU\ with quantitative image analysis for: ASMA, smooth muscle/collagen, collagen III/I, proliferating cell nuclear antigen (cell proliferation marker) and TUNEL (apoptotic index). Total collagen content is determined by hydroxyproline assay. 5(68/76:HKDYHGHYHORSHGWKHQHZUDWVSHFL¿F9(' DQGVXFFHVVIXOO\DSSOLHGWRUDWSHQLVHV7KHQHZUDWVSHFL¿F9(' WKHUDS\ VLJQL¿FDQWO\ LQFUHDVHG SHQLOH EORRG ÀRZ  3UHOLPLQDU\ GDWD VKRZHG WKH QHZ UDWVSHFL¿F 9(' WKHUDS\ LV HIIHFWLYH IRU SUHYHQWLQJ penile shortening after BCNC. &21&/86,2165DWVSHFL¿F9('LVVXFFHVVIXOO\HVWDEOLVKHG in our lab. Our preliminary data showed the VED treated BCNC rats had EHWWHUSHQLOHEORRGÀRZDQGSHQLOHOHQJWKPDLQWHQDQFHFRPSDUHGZLWK control. The following study will provide the molecular mechanism of this therapy and possibly support the clinic use of VED as the effective PR method. Source of Funding: None

660 EFFECT OF BILATERAL CAVERNOUS NERVE INJURY ON NITRIC OXIDE AND RHO-KINASE SIGNALING IN A RAT MODEL OF POST- RADICAL PROSTATECTOMY ERECTILE DYSFUNCTION Travis D Strong, Milena Gebska, Hunter C Champion, Arthur L Burnett, Trinity J Bivalacqua*. Baltimore, MD. INTRODUCTION AND OBJECTIVE: One of the major complications after radical prostatectomy is the development of erectile dysfunction (ED). It is unclear what affect cavernous nerve injury has critical molecular mechanisms in the penis. The purpose of the present study was to: 1) determine the effect of bilateral cavernous nerve injury (BCNI) on erectile function in vivo,DQG FKDUDFWHUL]HWKHPROHFXODU changes after BCNI that occur in the major vasodilator (nitric oxide synthase (NOS), protein kinase G (PKG), phosphodiesterase type 5 (PDE5) and vasoconstrictor (RhoA/Rho-kinase) pathways that regulate penile vascular function. 0(7+2'6 7ZR JURXSV RI UDWV ZHUH XWLOL]HG   VKDP operated, and 2) BCNI (crush of cavernous nerve bilaterally). All groups underwent cavernous nerve electrical stimulation (CNS) 14 days after sham operation or BCNI. Western blot analysis for total endothelial NOS, neuronal NOS, PKG, PDE5, Rho-kinase (ROCK) 1 and 2, and 3KRV7KU0<37S0<37DPDUNHURI5KRNLQDVHDFWLYLW\ ZHUH performed at this time point. Rho-kinase and PKG activity assays were also performed. RESULTS: There was a voltage-dependent decline (P<0.05) in intracavernous pressure to CNS 14 days after BCNI validating the animal model. Penile endothelial (membrane fraction) and neuronal 126LVRIRUPV3.*DQG3'(ZHUHDOOVLJQL¿FDQWO\UHGXFHG3  14 days after BCNI. PKG activity was also decreased at this time point. 7KHUHZDVDVLJQL¿FDQWLQFUHDVH3 LQ52&.DQGS0<37LQ penes 14 days after BCNI. The ROCK-1 isoform was unchanged after BCNI. Additionally, total Rho-kinase activity was increased (P<0.05) in penes 14 days after BCNI. CONCLUSIONS: These data suggest that reductions in NOS/ PKG/PDE5 after BCNI contribute to post-radical prostatectomy ED and SURYLGHQHZLQVLJKWLQWRRQHSRWHQWLDOPHFKDQLVPRIGHFUHDVHGHI¿FDF\ of PDE5 inhibitors in this patient population. Additionally, we show that increased ROCK-2 expression and phosphorylation of MYPT-1 (Rhokinase activity) may be contributing to impaired erectile function via increased penile vascular tone. These data document the importance of neural preservation in the maintenance of normal penile vascular

Vol. 179, No. 4, Supplement, Monday, May 19, 2008

homeostasis and provide new insight into the pathophysiology of postradical prostatectomy ED. Source of Funding: AUA Foundation Astellas USA Foundation MD/PhD Fellowship.

661 AGE-RELATED DECREASE FOR IN VIVO BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) EXPRESSION IN RESPONSE TO CAVERNOUS NERVE AXOTOMY: A NEUROMODULATORY TARGET FOR ENHANCING NERVE RECOVERY Anthony J Bella*, Guiting Lin, Kavirach Tantiwongse, Lia Banie, William O Brant, Tom F Lue. Ottawa, ON, Canada, San Francisco, CA, and Denver, CO. INTRODUCTION AND OBJECTIVE: Advanced age is a powerful predictor of compromised erectile function following radical prostatectomy. Timing and expression of neuromodulatory growth IDFWRUVDIWHUFDYHUQRXVQHUYHLQMXU\LVLQFRPSOHWHO\XQGHUVWRRGDVLPLODU knowledge gap exists for effects of aging on this response. We report LQYLYR¿QGLQJVIRUWKHHQGRJHQRXVEUDLQGHULYHGQHXURWURSKLFIDFWRU (BDNF) response in young and aged rats. METHODS: 36 male Fisher 344 rats (3 and 24 months, n=18 per group) underwent bilateral cavernous nerve transection. The major pelvic ganglion and penis with attached cavernous nerve segment were removed at 0, 12 and 24 hours, 5 and 12 days after axotomy. Immunohistochemical, protein, and messenger RNA (mRNA) analysis was performed, quantifying BDNF expression and establishing timing of the endogenous response. RESULTS: BDNF response in young and aged rats is timedependent, with maximal levels attained within 24 hours and returning to baseline within 5 days. mRNA and protein expression of BDNF was upregulated in the penis after injury in both groups, although maximal H[SUHVVLRQ GLIIHUHG ZLWK VLJQL¿FDQWO\ GHFUHDVHG H[SUHVVLRQ LQ DJHG animals (p<0.05). The JAK/STAT pathway (BDNF target) was activated in the MPG after transection, although to a lesser extent in the aged group (p<0.05). CONCLUSIONS: Endogenous expression of BDNF is known to exert neuroregenerative effects following cavernous nerve injury. Decreased levels of BDNF observed in aged animals may contribute to poorer peripheral nerve regeneration or neuroprotection after injury. $VQHXURWURSKLQH[SUHVVLRQRFFXUVZLWKLQDZHOOGH¿QHGWLPHSHULRG SRWHQWLDOQHXURPRGXODWRU\WUHDWPHQWVDUHGHSHQGHQWXSRQGH¿QLQJDQG enhancing the inherent neurobiological response to injury. Source of Funding: NIH 2R01-DK-45370 (TFL) and American Urological Association Foundation Robert J Krane Scholar (AJB).

662 ATP RELEASE FROM CAVERNOSAL TISSUE IS GREATER IN PATIENTS FOLLOWING PROSTATECTOMY AS COMPARED TO PATIENTS WITH ORGANIC ED Mohit Khera*, Osama Mohamed, Desiderio Avila, Wesley Ekeruo, David A Gangitano, Larry I Lipshultz, George T Somogyi. Houston, TX. INTRODUCTION AND OBJECTIVE: ATP has been shown to act as a potent, and nitric oxide independent, relaxant agent of human cavernosal tissue. It is unclear if electrical stimulation of cavernosal tissue has any effect on ATP release. It is also unknown whether ED in men following a radical prostatectomy (RP) is due to nerve injury or due to poorly functioning penile tissue. The purpose of our study was to evaluate the release of ATP from human cavernosal tissue after electrical and chemical stimulation from patients following RP and compared to patients with organic ED (OED). METHODS: Cavernosal tissue was obtained from patients undergoing placement of a penile prosthesis. The cavernosal tissue was vertically mounted in an organ bath and perfused with Krebbs solution. 7KH HIÀXHQFH ZDV FROOHFWHG HYHU\  VHFRQGV$IWHU  PLQXWHV WKH WLVVXHZDVVWLPXODWHGZLWK+=IRUPLQXWH$WPLQXWHVWKHWLVVXH was then stimulated with phenylephrine (10uM). At 9 minutes, the tissue ZDVVWLPXODWHGZLWK+=IRUPLQXWHLQWKHSUHVHQFHRISKHQ\OHSKULQH 7KHHIÀXHQFHZDVDQDO\]HGIRUWRWDOSXULQHFRQWHQWXVLQJ+3/&