title: Inhibition of Rho-kinase improves erectile function, increases nitric oxide signaling and decreases penile apoptosis in a rat model of cavernous nerve injury.
abstract: OBJECTIVE
  Bilateral cavernous nerve injury results in up-regulation of ROCK signaling in the penis. This is linked to erectile dysfunction in an animal model of post-prostatectomy erectile dysfunction. We evaluated whether daily treatment with the ROCK inhibitor Y-27632 (Tocris Bioscience, Ellisville, Missouri) would prevent erectile dysfunction in a rat model of bilateral cavernous nerve injury.
  
  
  METHODS
  Sprague-Dawley® rats underwent surgery to create sham (14) or bilateral (27) cavernous nerve injury. In the injury group 13 rats received treatment with Y-27632 (5 mg/kg twice daily) and 14 received vehicle. At 14 days after injury, rats underwent cavernous nerve stimulation to determine erectile function. Penes were assessed for neuronal and nitric oxide synthase membrane-endothelial nitric oxide synthase. ROCK2 was assessed by Western blot. Cyclic guanosine monophosphate was determined by enzyme-linked immunosorbent assay. Cavernous homogenates were tested for ROCK and protein kinase G enzymatic activity. Penile apoptosis was evaluated using the Apostain technique (Alexis, San Diego, California). Data were analyzed on ROCK using ANOVA and the t test.
  
  
  RESULTS
  While erectile function was decreased in rats with bilateral cavernous nerve injury, daily administration of Y-27632 improved erectile responses. Injury decreased neuronal and nitric oxide synthase membrane-endothelial nitric oxide synthase but ROCK2 was significantly increased. Y-27632 treatment restored neuronal nitric oxide synthase, nitric oxide synthase membrane-endothelial nitric oxide synthase and cyclic guanosine monophosphate levels, and protein kinase G activity. Treatment significantly decreased ROCK2 protein and ROCK activity. There were significantly fewer apoptotic cells after treatment than in injured controls.
  
  
  CONCLUSIONS
  These results provide evidence for up-regulation of the RhoA/ROCK signaling pathway with detrimental effects on erectile function after bilateral cavernous nerve injury. ROCK inhibition improved erectile dysfunction associated with bilateral cavernous nerve injury by preserving penile nitric oxide bioavailability and decreasing penile apoptosis.
authors.affiliation: James Buchanan Brady Urological Institute, Department of Urology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
authors.forename: Johanna L
authors.initials: JL
authors.lastname: Hannan
authors.forename: Maarten
authors.initials: M
authors.lastname: Albersen
authors.forename: Omer
authors.initials: O
authors.lastname: Kutlu
authors.forename: Christian
authors.initials: C
authors.lastname: Gratzke
authors.forename: Christian G
authors.initials: CG
authors.lastname: Stief
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Burnett
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Lysiak
authors.forename: Petter
authors.initials: P
authors.lastname: Hedlund
authors.forename: Trinity J
authors.initials: TJ
authors.lastname: Bivalacqua
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D007172:Erectile Dysfunction / Q000201:enzymology* / Q000209:etiology; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D010410:Penile Erection / Q000187:drug effects*; D010413:Penis / Q000201:enzymology / Q000293:injuries / Q000294:innervation*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation / Q000187:drug effects; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors*
chemical_list: D000577:Amides; D004791:Enzyme Inhibitors; D011725:Pyridines; C108830:Y 27632; D009569:Nitric Oxide; D054460:rho-Associated Kinases