An Increased Arginase Activity Is Associated with Corpus Cavernosum Impairment Induced by Hypercholesterolemia

IntroductionHypercholesterolemia is a prevalent risk factor for the development of erectile dysfunction (ED), mostly due to an increase in oxidative stress and impaired nitric oxide (NO) bioavailability within the penis. Arginase is an enzyme that shares the common substrate L-arginine with NO synthase. Augmented arginase activity reduces NO production and is associated with ED development. However, the contribution of arginase hyperactivity in hypercholesterolemia-induced ED is unknown. AimIn the present study, we investigated the activity and role of arginase in the corpus cavernosum of hypercholesterolemic mice. MethodsApolipoprotein E (ApoE) gene-deleted mice fed with a Western-type diet for 11 weeks were treated with the selective arginase inhibitor, N--Hydroxy-L-norarginine (NOHA), or vehicle (saline 0.9%) during the last 9 weeks. Arginase activity and expression were measured in penis protein extraction. Reactive oxygen species (ROS) content within the corpus cavernosum was measured by dihydroethidium staining. Functional in vitro studies were performed using cavernosal strips mounted in an isometric organ bath to evaluate NO production. Main Outcome MeasureArginase activity and its role in modulating NO and ROS production within the corpus cavernosum of hypercholesterolemic mice is the main outcome measure. ResultsTotal arginase activity and arginase type II protein expression were increased in hypercholesterolemic mice compared with wild-type mice. The long-term treatment with NOHA normalized this alteration. Moreover, pharmacological arginase inhibition by NOHA attenuated the augmented ROS production within the corpus cavernosum of ApoE(-/-) mice, which increased the NO-dependent response in cavernosal strips. ConclusionThese evidences indicate that arginase hyperactivity is associated with ED induced by hypercholesterolemia, suggesting that this enzyme is a potential target for treating ED. Fraga-Silva RA, Costa-Fraga FP, Faye Y, Sturny M, Santos RAS, da Silva RF, and Stergiopulos N. An increased arginase activity is associated with corpus cavernosum impairment induced by hypercholesterolemia. J Sex Med 2014;11:1173-1181.

An Oral Formulation of Angiotensin-(1-7) Reverses Corpus Cavernosum Damages Induced by Hypercholesterolemia

Danielle Gomes Passos Silva, Fabiana Pereira Da Costa Fraga, Nikolaos Stergiopulos

Introduction The renin angiotensin system plays a crucial role in erectile function. It has been shown that elevated angiotensin-II levels contribute to the development of erectile dysfunction (ED). Oppositely, angiotensin-(1-7) (Ang-[1-7]) mediates penile erection by activation of receptor Mas. Recently, we have developed a formulation based on Ang-(1-7) inclusion in cyclodextrin (CyD) [Ang-(1-7)-CyD], which allows for the oral administration of Ang-(1-7). Aim In the present study, we evaluated the effects of chronic treatment with Ang-(1-7)-CyD on penile fibrosis, oxidative stress, and endothelial function in hypercholesterolemic mice. Methods Apolipoprotein(Apo)E-/- mice fed a Western-type diet for 11 weeks received Ang-(1-7)-CyD or vehicle during the final 3 weeks. Collagen content and reactive oxygen species (ROS) production within the corpus cavernosum were evaluated by Sirius red and dihydroethidium staining, respectively. Protein expression of neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS), nicotinamide adenine dinucleotide phosphate (NADPH) subunits (p67-phox and p22-phox), and AT1 and Mas receptors in the penis was assessed by Western blotting. Nitric oxide (NO) production was measured by Griess assay in the mice serum. Cavernosal strips were mounted in an isometric organ bath to evaluate the endothelial function. Main Outcome MeasuresThe effect of Ang-(1-7)-CyD treatment on penile fibrosis, oxidative stress, and endothelial function in hypercholesterolemia-induced ED. Results Ang-(1-7)-CyD treatment reduced collagen content in the corpus cavernosum of ApoE(-/-) mice. This effect was associated with an attenuation of ROS production and a diminished expression of NADPH. Furthermore, Ang-(1-7)-CyD treatment augmented the expression of nNOS and eNOS in the penis and elevated vascular NO production. Importantly, these effects were accompanied by an improvement in cavernosal endothelial function. Conclusion Long-term treatment with Ang-(1-7)-CyD reduces penile fibrosis associated with attenuation of oxidative stress. Additionally, cavernosal endothelial function in hypercholesterolemic mice was markedly improved. These results suggest that Ang-(1-7)-CyD might have significant therapeutic benefits for the treatment of erectile dysfunction. Fraga-Silva RA, Costa-Fraga FP, Savergnini SQ, De Sousa FB, Montecucco F, da Silva D, Sinisterra RD, Mach F, Stergiopulos N, da Silva RF, and Santos RAS. An oral formulation of angiotensin-(1-7) reverses corpus cavernosum damages induced by hypercholesterolemia. J Sex Med 2013;10:2430-2442.

Wiley-Blackwell2013

Treatment with CB2 Agonist JWH-133 Reduces Histological Features Associated with Erectile Dysfunction in Hypercholesterolemic Mice

Younouss Faye, Rafaela Fernandes Da Silva, Nikolaos Stergiopulos

Hypercholesterolemia is one of the most important risk factors for erectile dysfunction, mostly due to the impairment of oxidative stress and endothelial function in the penis. The cannabinoid system might regulate peripheral mechanisms of sexual function; however, its role is still poorly understood. We investigated the effects of CB2 activation on oxidative stress and fibrosis within the corpus cavernosum of hypercholesterolemic mice. Apolipoprotein- E-knockout mice were fed with a western-type diet for 11 weeks and treated with JWH-133 ( selective CB2 agonist) or vehicle during the last 3 weeks. CB2 receptor expression, total collagen content, and reactive oxygen species ( ROS) production within the penis were assessed. In vitro corpus cavernosum strips preparation was performed to evaluate the nitric oxide ( NO) bioavailability. CB2 protein expression was shown incavernosal endothelial and smooth muscle cells of wild type and hypercholesterolemic mice. Treatment with JWH-133 reduced ROS production and NADPH-oxidase expression in hypercholesterolemic mice penis. Furthermore, JWH-133 increased endothelial NO synthase expression in the corpus cavernosum and augmented NO bioavailability. The decrease in oxidative stress levels was accompanied with a reduction in corpus cavernosum collagen content. In summary, CB2 activation decreased histological features, which were associated with erectile dysfunction in hypercholesterolemic mice.

Hindawi Publishing Corporation2013

Diminazene Protects Corpus Cavernosum Against Hypercholesterolemia-Induced Injury

Younouss Faye, Rafaela Fernandes Da Silva, Fabiana Pereira Da Costa Fraga, Nikolaos Stergiopulos, Mikaël Nils Sturny

IntroductionAngiotensin-converting enzyme 2 (ACE2) is a key enzyme of the renin angiotensin system, which breaks down angiotensin II and forms angiotensin-(1-7). In erectile tissues, it has been documented that angiotensin II contributes to the development of erectile dysfunction (ED), while treatment with angiotensin-(1-7) improves penile erection. However, the expression and function of ACE2 in erectile tissues have never been investigated. AimHere, we examined the expression of ACE2 in erectile tissues and its actions against hypercholesterolemia-induced corpus cavernosum (CC) injury. MethodsHypercholesterolemic apolipoprotein E knockout (ApoE(-/-)) mice, a well-known model of ED, were treated with diminazene aceturate (DIZE), an ACE2 activator compound, or vehicle for 3 weeks. Reactive oxygen species (ROS), collagen content, and protein expression of ACE2, neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase (eNOS), nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) subunits were evaluated in the penis of DIZE-treated and untreated ApoE(-/-) mice. Functional studies were performed in CC strips. Main Outcome MeasuresACE2 expression and its role in modulating nitric oxide (NO)/ROS production and fibrosis within the CC of hypercholesterolemic mice were the main outcome measures. ResultsACE2 was expressed in smooth muscle and endothelial cells of mouse CC. Interestingly, ACE2 was downregulated in penis of hypercholesterolemic mice with ED, suggesting a protective role of ACE2 on the CC homeostasis. In accordance with that, pharmacological ACE2 activation by DIZE treatment reduced ROS production and NADPH oxidase expression, and elevated nNOS and eNOS expression and NO bioavailability in the penis of ApoE(-/-) mice. Additionally, DIZE decreased collagen content within the CC. These beneficial actions of DIZE on the CC were not accompanied by improvements in atherosclerotic plaque size or serum lipid profile. ConclusionACE2 is expressed in erectile tissue and its reduction is associated with hypercholesterolemia-induced ED. Additionally, treatment with DIZE improved hypercholesterolemia-induced CC injury, suggesting ACE2 as a potential target for treating ED. Fraga-Silva RA, Costa-Fraga FP, Montecucco F, Sturny M, Faye Y, Mach F, Pelli G, Shenoy V, da Silva RF, Raizada MK, Santos RAS, and Stergiopulos N. Diminazene protects corpus cavernosum against hypercholesterolemia-induced injury. J Sex Med 2015;12:289-302.