Edaravone ameliorates diabetes-induced dysfunction of NO-induced relaxation in corpus cavernosum smooth muscle in the rat.

Diabetes mellitus (DM) represents a major risk factor for erectile dysfunction (ED). Although the etiology of diabetes-induced ED is multifactorial and still unknown, reactive oxygen species are thought to be one of the key factors. The aim of this article is to investigate whether administration of edaravone, a free radical scavenger, could prevent type 1 diabetes-induced dysfunction of nitric oxide (NO)-induced relaxation in corpus cavernosum smooth muscle in the rat. Six-week-old male Wistar rats were randomly divided into three groups. One group was treated with citrate-phosphate buffer plus normal saline (group Cont), whereas in the other two groups, diabetes was induced by streptozotocin (50 mg/kg intraperitoneally [i.p.]). Subsequently, the diabetic rats were treated for 4 weeks either with edaravone (10 mg/kg/day, i.p.; group DM + E) or with normal saline (group DM). Serum glucose and malondialdehyde levels as well as penile cyclic guanosine monophosphate (cGMP) concentrations were determined, and penile function was estimated by organ bath studies with norepinephrine-mediated contractions and acetylcholine-mediated relaxations. The participation mRNA levels of muscarinic M(3) receptors, neuronal nitrous oxide synthase (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS), and participation protein levels of nNOS, eNOS, phosphorylated nNOS, and phosphorylated eNOS were investigated by quantitative real-time polymerase chain reaction (PCR) and immunoblot analysis, respectively. Treatment with edaravone prevented partially but significantly the decreased body and penile weight induced by diabetes. Treatment with edaravone significantly improved the increased diabetes-induced malondialdehyde levels, the decreased penile cGMP concentrations, the increased diabetes-induced norepinephrine-mediated contractions, and the decreased acetylcholine-mediated relaxation. Although there were no significant differences in expression levels of mRNAs in nNOS, diabetes-induced upregulation of muscarinic M(3) receptor and iNOS mRNAs as well as diabetes-induced downregulations of eNOS, phosphorylated nNOS, and phosphorylated eNOS were significantly prevented by edaravone. Edaravone decreases the oxidative insult in the penile corpus cavernosum by ameliorating the NO-NOS system and thus preventing partially the developing ED in DM in the rat.

Ohmasa F ，Saito M ，Tsounapi P ，Dimitriadis F ，Inoue S ，Shomori K ，Shimizu S ，Kinoshita Y ，Satoh K ... -  《-》

Hydroxyfasudil ameliorates penile dysfunction in the male spontaneously hypertensive rat.

Hypertension represents a major risk factor for erectile dysfunction. Although the etiology of hypertension-induced erectile dysfunction is multifactorial and still unknown, Rho-Rho kinase pathway is one of the key factors. To investigate whether administration of hydroxyfasudil, a Rho kinase inhibitor could prevent dysfunction of NO-induced relaxation in corpus cavernosum smooth muscle in the SHR (spontaneously hypertensive rat), twelve-week-old male SHRs were treated with hydroxyfasudil (3 or 10 mg/kg, i.p.) once a day for 6 weeks. Wistar rats and SHRs treatment with vehicle were used as age-matched controls. Penile cGMP concentrations and Rho kinase activities were determined, and penile function was estimated by organ bath studies with norepinephrine-induced contractions and acetylcholine-induced relaxations. The participation mRNA levels of eNOS and participation protein levels of eNOS and phosphorylated eNOS were investigated by quantitative real-time PCR methods and immunoblot analysis, respectively. The SHR showed significantly decreased cGMP concentrations, increased Rho kinase activities, norepinephrine-induced hyper-contractions, and acetylcholine-induced hypo-relaxations in the penile tissue. Treatment with hydroxyfasudil significantly improved the decreased penile cGMP concentrations, the increased Rho kinase activities, the increased norepinephrine-induced contractions, and the decreased acetylcholine-induced relaxation in a dose-dependent manner. Although there were no significant differences in expression protein levels of eNOS among any of the groups, down-regulation of eNOS mRNAs as well as phosphorylated eNOS were significantly ameliorated after treatment with hydroxyfasudil. Our data suggest that hydroxyfasudil ameliorates hypertension-associated dysfunction of NO-induced relaxation in corpus cavernosum smooth muscle possibly via inhibition of the Rho-Rho kinase pathway and activation of NO-eNOS pathway in the SHR.

Saito M ，Ohmasa F ，Dimitriadis F ，Tsounapi P ，Sejima T ，Shimizu S ，Kinoshita Y ，Satoh K ... -  《-》

Diabetes exacerbates the functional deficiency of NO/cGMP pathway associated with erectile dysfunction in human corpus cavernosum and penile arteries.

Angulo J ，González-Corrochano R ，Cuevas P ，Fernández A ，La Fuente JM ，Rolo F ，Allona A ，Sáenz de Tejada I ... -  《-》

Poly(ADP-ribose) polymerase inhibition improves erectile function by activation of nitric oxide/cyclic guanosine monophosphate pathway in diabetic rats.

Endothelial dysfunction-induced abnormalities of the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway in the corpus cavernosum are thought to be the main factors involved in the pathogenesis of diabetes-induced erectile dysfunction (ED). Recent studies have shown that the poly(adenosine diphosphate ribose) polymerase (PARP) pathway plays a critical role in diabetic endothelial dysfunction.   The aim of this study is to determine whether activation of the PARP pathway is involved in diabetic cavernosal endothelial dysfunction and abnormalities of the NO/cGMP pathway. Male Sprague-Dawley rats were randomly divided into three groups: age-matched controls, diabetic controls (DM), and the 3-aminobenzamide (3-AB, a PARP inhibitor)-treated diabetic group (DM+3-AB). Diabetes was induced by intraperitoneal injection of streptozotocin. Eight weeks after inducing diabetes, the DM+3-AB group was treated with 3-AB for 4 weeks. Erectile function was assessed at 12 weeks after inducing diabetes by stimulating the cavernous nerve. Expression of poly(ADP-ribose), protein kinase B (Akt), phospho-Akt, endothelial nitric oxide synthase (eNOS), phospho-eNOS, and neuronal nitric oxide synthase (nNOS) were evaluated by Western blot. Cavernous NO generation and cGMP levels were also determined. The DM group showed impaired erectile function and significantly increased PARP activity. Expression of total eNOS and nNOS, phospho-Akt, and eNOS decreased significantly in the DM group compared with those in the control group. In addition, cavernous NO generation and cGMP levels decreased significantly in the DM group compared with those in the control group. Treatment with 3-AB restored erectile function and significantly reversed all molecular alterations except decreased nNOS expression. Overactivation of the PARP pathway in the corpus cavernosum of diabetic rats was involved in cavernosal endothelial dysfunction and abnormalities of the NO/cGMP pathway resulting in ED. These findings may be applied to develop novel therapies for patients with diabetic ED.

Li WJ ，Peng Y ，Zhou J ，Li B ，Wang H ，Zhang J ，Wang Z ... -  《-》

Chronic treatment with taurine ameliorates diabetes-induced dysfunction of nitric oxide-mediated neurogenic and endothelium-dependent corpus cavernosum relaxation in rats.

This study was aimed to examine the effect of chronic taurine treatment on corpus cavernosum dysfunction in diabetic rats and to investigate possible underlying mechanisms. Thirty male rats were randomized to three groups of 10 each, including control, diabetic, and taurine-treated diabetic. Diabetes was induced in rats by streptozotocin (STZ, single intraperitoneal dose of 50 mg/kg body weight). Taurine was administered orally for 12 weeks (1% w/v in drinking water) from the day on which STZ was injected. At the end of the 12th week, strips of corpus cavernosum were suspended in an organ bath system for functional studies. Nitric oxide (NO)-mediated endothelium-dependent and neurogenic corpus cavernosum relaxation were evaluated by acetylcholine (ACh, 0.1-100 μm) and electrical field stimulation (EFS, 30 V, 5 ms, 2-32 Hz), respectively. The expressions of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS) (Ser-1177), neuronal nitric oxide synthase (nNOS), NADPH oxidase subunit gp91(phox) , Rho A, and Rho kinase in corpus cavernosum were semi-quantitatively assessed by immunohistochemistry. Induction of diabetes resulted in significant inhibition of NO-mediated endothelium-dependent and neurogenic corpus cavernosum relaxation. Furthermore, eNOS, p-eNOS, and nNOS expressions decreased significantly in diabetic rats compared to controls, while gp91(phox) , RhoA and Rho kinase expressions increased significantly. The diminished relaxation response to ACh and EFS as well as diabetes-related changes in expressions of these proteins in corpus cavernosum of diabetic rats was significantly improved by taurine. Taurine treatment improves NO-mediated relaxations of corpus cavernosum in diabetic rats probably by inhibiting NADPH oxidase/Rho kinase pathways.

Dalaklioglu S ，Kuscu N ，Celik-Ozenci C ，Bayram Z ，Nacitarhan C ，Ozdem SS ... -  《-》