RhoA/Rho-Kinase Suppresses Endothelial Nitric Oxide Synthase in the Penis: A Mechanism for Diabetes-Associated Erectile Dysfunction

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 101; no. 24; pp. 9121 - 9126
• Main Authors: Bivalacqua, Trinity J., Champion, Hunter C., Usta, Mustafa F., Cellek, Selim, Chitaley, Kanchan, Webb, R. Clinton, Lewis, Ronald L., Mills, Thomas M., Wayne J. G. Hellstrom, Kadowitz, Philip J., Ignarro, Louis J.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 15.06.2004; National Acad Sciences
• Subjects: Adeno-associated virus; Adenoviridae - genetics; Amides - pharmacology; Animals; Biological Sciences; Blood Glucose - metabolism; Body Weight; Cyclic GMP - biosynthesis; Diabetes; Diabetes complications; Diabetes Mellitus, Experimental - blood; Diabetes Mellitus, Experimental - complications; Diabetes Mellitus, Experimental - enzymology; Endothelium; Enzyme Inhibitors - metabolism; Enzymes; Erectile dysfunction; Erectile Dysfunction - enzymology; Erectile Dysfunction - etiology; Gene Expression; Impotence; Intracellular Signaling Peptides and Proteins; Male; Muscle Relaxants, Central - pharmacology; Myosin-Light-Chain Phosphatase - biosynthesis; Nervous system; Nitric oxide; Nitric Oxide Synthase - antagonists & inhibitors; Nitric Oxide Synthase - biosynthesis; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type III; Oxides; Penis - drug effects; Penis - enzymology; Pharmacology; Phosphorylation; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Protein-Serine-Threonine Kinases - biosynthesis; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - physiology; Pyridines - pharmacology; Rats; Rats, Sprague-Dawley; rho-Associated Kinases; Smooth muscle; Transfection; Type 1 diabetes mellitus; Vehicles
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0400520101

Significant impairment in endothelial-derived nitric oxide is present in the diabetic corpus cavernosum. RhoA/Rho-kinase may suppress endothelial nitric oxide synthase (eNOS). Here, we tested the hypothesis that RhoA/Rho-kinase contributes to diabetes-related erectile dysfunction and down-regulation of eNOS in the streptozotocin (STZ-diabetic rat penis. Colocalization of Rho-kinase and eNOS protein was present in the endothelium of the corpus cavernosum. RhoA/Rho-kinase protein abundance and MYPT-1 phosphorylation at Thr-696 were elevated in the STZ-diabetic rat penis. In addition, eNOS protein expression, cavernosal constitutive NOS activity, and cGMP levels were reduced in the STZ-diabetic penis. To assess the functional role of RhoA/Rho-kinase in the penis, we evaluated the effects of an adeno-associated virus encoding the dominant-negative RhoA mutant (AAVTCMV19NRhoA) on RhoA/Rho-kinase and eNOS and erectile function in vivo in the STZ-diabetic rat. STZ-diabetic rats transfected with AAVCMVT19NRhoA had a reduction in RhoA/Rho-kinase and MYPT-1 phosphorylation at a time when cavernosal eNOS protein, constitutive NOS activity, and cGMP levels were restored to levels found in the control rats. There was a significant decrease in erectile response to cavernosal nerve stimulation in the STZ-diabetic rat. AAVT19NRhoA gene transfer improved erectile responses in the STZ-diabetic rat to values similar to control. These data demonstrate a previously undescribed mechanism for the down-regulation of penile eNOS in diabetes mediated by activation of the RhoA/Rho-kinase pathway. Importantly, these data imply that inhibition of RhoA/Rho-kinase improves eNOS protein content and activity thus restoring erectile function in diabetes.