An oral formulation of angiotensin-(1-7) reverses corpus cavernosum damages induced by hypercholesterolemia

Oxidative Stress and Erectile Dysfunction: Pathophysiology, Impacts, and Potential Treatments

Erectile dysfunction (ED) is a prevalent condition affecting men's sexual health, with oxidative stress (OS) having recently been identified as a significant contributing causative factor. This narrative review aims to elucidate the role of OS in the pathophysiology of ED, focusing on impact, mechanisms, and potential therapeutic interventions. Key findings indicate that OS disrupts endothelial function and nitric oxide (NO) signaling, crucial for erectile function. Various sources of reactive oxygen species (ROS) and their detrimental effects on penile tissue are discussed, including aging, diabetes mellitus, hypertension, hyperlipidemia, smoking, obesity, alcohol consumption, psychological stress, hyperhomocysteinemia, chronic kidney disease, and sickle cell disease. Major sources of ROS, such as NADPH oxidase, xanthine oxidase, uncoupled endothelial NO synthase (eNOS), and mitochondrial electron transport, are identified. NO is scavenged by these ROS, leading to endothelial dysfunction characterized by reduced NO availability, impaired vasodilation, increased vascular tone, and inflammation. This ultimately results in ED due to decreased blood flow to penile tissue and the inability to achieve or maintain an erection. Furthermore, ROS impact the transmission of nitrergic neurotransmitters by causing the death of nitrergic neurons and reducing the signaling of neuronal NO synthase (nNOS), exacerbating ED. Therapeutic approaches targeting OS, including antioxidants and lifestyle modifications, show promise in ameliorating ED symptoms. The review underscores the need for further research to develop effective treatments, emphasizing the interplay between OS and vascular health in ED. Integrating pharmacological and non-pharmacological strategies could enhance clinical outcomes for ED patients, advocating for OS management in ED treatment protocols to improve patient quality of life.

Mechanism of Social Stress-Related Erectile Dysfunction in Mice: Impaired Parasympathetic Neurotransmission and Ketamine

This study aimed to investigate the mechanism underlying social stress (SS)-induced erectile dysfunction (ED) and evaluate the effects of a single subanesthetic dose of ketamine on SS-related ED. Male FVB mice were exposed to retired male C57BL/6 mice for 60 min daily over a 4-week period. In the third week, these FVB mice received intraperitoneal injections of either saline (SSS group) or ketamine (SSK group). Erectile function was assessed by measuring the intracavernosal pressure (ICP) during electrical stimulation of the major pelvic ganglia. Corpus cavernosum (CC) strips were utilized for wire myography to assess their reactivity. Both SSS and SSK mice exhibited significantly lower ICP in response to electrical stimulation than control mice. SS mice showed increased contractility of the CC induced by phenylephrine. Acetylcholine-induced relaxation was significantly reduced in SSS and SSK mice. Sodium nitroprusside-induced relaxation was higher in SSS mice compared to control and SSK mice. Nicotine-induced neurogenic and nitric oxide-dependent relaxation was significantly impaired in both SSS and SSK mice. An immunohistochemical analysis revealed co-localization of tyrosine hydroxylase and neuronal nitric oxide synthase-immunoreactive fibers in the CC. These findings highlight the complex nature of SS-related ED and suggest the limited efficacy of ketamine as a therapeutic intervention.

Angiotensin-(1-7) improves diabetes mellitus-induced erectile dysfunction in rats by regulating nitric oxide synthase levels

This study explores the role of inducible nitric oxide synthase (iNOS) in the pathogenesis of diabetes mellitus-induced erectile dysfunction (DMED) and the effect of angiotensin 1-7 (Ang- [1-7]) on NOS levels. A type 2 diabetes mellitus (DM) rat model was established. Erectile function was assessed by measuring intracavernous pressure and mean arterial pressure after electrical stimulation. The expression of iNOS, endothelial NOS (eNOS), eNOS phosphorylated at Ser 1177 (p-eNOS [Ser 1177]), and AKT/p-AKT in corpus cavernosum smooth muscle cells (CCSMCs) was measured by Western blotting and immunofluorescence. The plasma levels of NO, SOD, malondialdehyde, and peroxynitrite were calculated. Intracellular calcium content was determined by flow cytometry. DMED rats exhibited decreased erectile function and severe oxidative stress. Ang-(1-7) treatment improved erectile response and suppressed oxidative stress by upregulating p-eNOS/eNOS and downregulating iNOS levels. Silencing iNOS in CCSMCs decreased oxidative stress and intracellular calcium levels induced by high glucose. In turn, iNOS overexpression increased oxidative stress and intracellular calcium level. Treatment with the MAS receptor antagonist A779 and the Akt antagonist LY294002 reversed the effects of Ang-(1-7) on iNOS. Ang-(1-7) improved DMED through the MAS/AKT signaling pathway.

Low-Intensity Electrostimulation Enhances Neuroregeneration and Improves Erectile Function in a Rat Model of Cavernous Nerve Injury

BACKGROUND

Neurogenic erectile dysfunction (ED) following radical prostatectomy (RP) is a frequent complication often leading to erectile tissue remodeling and permanent ED. Low-intensity electrostimulation (LIES) has been shown to enhance peripheral nerve regeneration, however, its application on cavernous nerves (CN) has never been investigated.

AIMS

To investigate whether LIES enhances CN regeneration, improves erectile function (EF) recovery, and prevents corpora cavernosal remodeling after CN injury, which is a principal factor for ED following RP.

METHODS

Adult male Sprague-Dawley rats were divided into Sham, Bilateral Cavernous Nerve Injury (BCNI), and BCNI + LIES (1V, 0.1ms, 12Hz, 1h/day). After 7days, EF was assessed (ICP measurement). Penes and CN were collected for molecular analyses of TGF-β1, Il-6, CRP, eNOS, ERK and AKT protein levels in corpus cavernosum (CC), and immunohistological analysis of DHE, total collagen and α-SMA in CC and S-100, Tub-III, DAPI, TUNEL, and nNOS in CN.

OUTCOMES

Effects of LIES on EF, erectile tissue remodeling and CN structure.

RESULTS

EF was decreased (P < .05) 7 days after BCNI and increased (P < .05) by LIES. Intracavernosal reactive oxygen species (DHE) was increased (P < .05) after BCNI and normalized by LIES. Protein expressions of TGF-β1, IL-6, and CRP were increased in the penis (P < .05) after BCNI and normalized by LIES. The α-SMA and/or total collagen ratio was decreased (P < .05) after BCNI in the penis and normalized by LIES. Protein expression ratio of p-ERK/ERK and p-AKT/AKT did not change after BCNI but increased (P < .05) in LIES group. Myelination and number of nNOS positive cells in the CN were decreased (P < .05) after BCNI and normalized by LIES. The number of apoptotic nerve cells within the dorsal penile nerve was increased (P < .05) after BCNI and decreased (P < .05) by LIES compared to the BCNI group. There were no differences in eNOS expression in the penis between study groups.

CLINICAL TRANSLATION

LIES may offer a potential new tool for penile rehabilitation and ED management following RP, potentially enhancing EF recovery and minimizing the side effects of this surgery.

STRENGTHS & LIMITATIONS

This study provides evidence of the protective effect of LIES on EF and tissue remodeling following CN injury; nevertheless, this study has been conducted on animals and the translation to humans remains to be demonstrated. Further research to identify the underlying mechanisms of action is required.

CONCLUSION

This study demonstrates that LIES of the CN after CN injury protects CN structure, enhances EF recovery, and prevents corpora cavernosal remodeling. Sturny M, Karakus S, Fraga-Silva R, et al. Low-Intensity Electrostimulation Enhances Neuroregeneration and Improves Erectile Function in a Rat Model of Cavernous Nerve Injury. J Sex Med 2022;19:686-696.

Alternative RAS in Various Hypoxic Conditions: From Myocardial Infarction to COVID-19

Alternative branches of the classical renin–angiotensin–aldosterone system (RAS) represent an important cascade in which angiotensin 2 (AngII) undergoes cleavage via the action of the angiotensin-converting enzyme 2 (ACE2) with subsequent production of Ang(1-7) and other related metabolites eliciting its effects via Mas receptor activation. Generally, this branch of the RAS system is described as its non-canonical alternative arm with counterbalancing actions to the classical RAS, conveying vasodilation, anti-inflammatory, anti-remodeling and anti-proliferative effects. The implication of this branch was proposed for many different diseases, ranging from acute cardiovascular conditions, through chronic respiratory diseases to cancer, nonetheless, hypoxia is one of the most prominent common factors discussed in conjugation with the changes in the activity of alternative RAS branches. The aim of this review is to bring complex insights into the mechanisms behind the various forms of hypoxic insults on the activity of alternative RAS branches based on the different duration of stimuli and causes (acute vs. intermittent vs. chronic), localization and tissue (heart vs. vessels vs. lungs) and clinical relevance of studied phenomenon (experimental vs. clinical condition). Moreover, we provide novel insights into the future strategies utilizing the alternative RAS as a diagnostic tool as well as a promising pharmacological target in serious hypoxia-associated cardiovascular and cardiopulmonary diseases.

Apelin-13 Protects Corpus Cavernosum Against Fibrosis Induced by High-Fat Diet in an MMP-Dependent Mechanism

BACKGROUND

An increased fibrosis of the corpora cavernosa is a prevalent process that underlies most cases of erectile dysfunction. Apelin, an endogenous circulating peptide, has been documented as an important effector on cardiovascular homeostasis, controlling vascular function and reducing fibrosis in multiple pathological conditions. Recently, initial studies have shown that Apelin, acting through the APJ receptor, also modulates penile erection, however, the role of this system on penile structure and intracorporal collagen remodeling has not been investigated yet.

AIMS

Here we sought to investigate the effect of chronic Apelin treatment on the corpus cavernosum structure of hyperchOlesterolemic mice.

METHODS

Apolipoprotein gene-deleted (ApoE^-/-) mice were fed with a Western diet for 11 weeks and received Apelin-13 (2 mg/kg/day) or vehicle during the last 3 weeks. Penile samples were obtained for histological and biochemical analyses to assess the intracorporal collagen content and key proteins expression. Furthermore, the effect of Apelin-13 was evaluated in cultured NIH3T3 mouse fibroblasts stimulated with TGF-β.

OUTCOME

Local expression of Apelin-13 in mouse corpus cavernosum and its protective effect against fibrosis.

RESULTS

Apelin and APJ receptor were expressed (gene and protein) within the corpus cavernosum of ApoE^-/- mice, indicating a local modulation of the Apelin system. Interestingly, 3 weeks of Apelin-13 treatment strongly reduced intracavernosal collagen content. In addition, Apelin-13 enhanced total matrix metalloproteinase (MMP) activity in the mice penis, which was associated with an increased protein expression of MMP-1, MMP-3, MMP-8, and MMP-9, while tissue inhibitor of metalloproteinase were unaltered. These beneficial actions were not associated with changes in nNOS or eNOS protein expression, intracavernosal reactive oxygen species content, or atherosclerotic plaque deposition. Additionally, in cultured fibroblast, Apelin-13 inhibited TGF-β-induced fibroblast to myofibroblast differentiation and collagen production, possibly through the activation of ERK1/2 kinase.

CLINICAL TRANSLATION

These results point out Apelin/APJ system as a potential target to treat intracavernosal fibrosis-related disorders.

STRENGTH & LIMITATIONS

These results provide the first evidence of the Apelin system's positive role on erectile tissue structure/remodeling. Nevertheless, additional functional study addressing erectile response would bring extended validation regarding the relevance of such effect.

CONCLUSION

These results suggest a local modulation of the Apelin system within the corpus cavernosum. Remarkably, Apelin-13 reduced intracavernosal fibrosis in hypercholesterolemic mice by: (i) enhancing MMPs expression and activity; and (ii) inhibiting fibroblast differentiation into myofibroblast. Altogether, these results suggest an essential protective role of Apelin, indicating Apelin/APJ system as a promising candidate for the development of fibrosis-associated erectile dysfunction treatments. Sturny M, Anguenot L Costa-Fraga FP, et al. Apelin-13 Protects Corpus Cavernosum Against Fibrosis Induced by High-Fat Diet in an MMP-Dependent Mechanism. J Sex Med 2021;18:875-888.

Angiotensin-converting enzyme 2 (ACE2), angiotensin-(1-7) and Mas receptor in gonadal and reproductive functions

Angiotensin (Ang)-(1-7) is an active peptide formed from Ang I or Ang-(1-9) by multiple proteolytic steps involving angiotensin-converting enzyme (ACE) 1 and other peptidases, or by a single cleavage of Ang II catalyzed chiefly by ACE2. The effects of Ang-(1-7) are mediated by the G protein-coupled receptor Mas (or Mas1), encoded by the protooncogene MAS. The reproductive system expresses ACE2 quite abundantly and therefore is able to generate Ang-(1-7) using precursor peptides produced locally or taken from circulation. In several mammalian species, Ang-(1-7) stimulates ovarian follicle growth, oocyte maturation and ovulation. The peptide is found in human endometrium, mostly during the secretory phase of menstrual cycle when the uterus is receptive to embryo implantation. Rat models and human observational studies suggest that Ang-(1-7) is part of the maternal adaptive response to pregnancy and its deficiency is associated with poor circulation in the placental bed. Knockout mice revealed a relevant participation of Mas-mediated stimulus to the maintenance of normal spermatogenesis, even though the animal can still reproduce without it. In addition, the vasorelaxant effect of Ang-(1-7) participates in the physiological mechanism of corpus cavernosum blood influx and penile erection. We conclude that preclinical evidence encourages the pursuit of treatments for female and male reproductive dysfunctions based on Mas agonists, starting with its natural ligand Ang-(1-7).

The ACE2/Angiotensin-(1-7)/MAS Axis of the Renin-Angiotensin System: Focus on Angiotensin-(1-7)

The renin-angiotensin system (RAS) is a key player in the control of the cardiovascular system and hydroelectrolyte balance, with an influence on organs and functions throughout the body. The classical view of this system saw it as a sequence of many enzymatic steps that culminate in the production of a single biologically active metabolite, the octapeptide angiotensin (ANG) II, by the angiotensin converting enzyme (ACE). The past two decades have revealed new functions for some of the intermediate products, beyond their roles as substrates along the classical route. They may be processed in alternative ways by enzymes such as the ACE homolog ACE2. One effect is to establish a second axis through ACE2/ANG-(1-7)/MAS, whose end point is the metabolite ANG-(1-7). ACE2 and other enzymes can form ANG-(1-7) directly or indirectly from either the decapeptide ANG I or from ANG II. In many cases, this second axis appears to counteract or modulate the effects of the classical axis. ANG-(1-7) itself acts on the receptor MAS to influence a range of mechanisms in the heart, kidney, brain, and other tissues. This review highlights the current knowledge about the roles of ANG-(1-7) in physiology and disease, with particular emphasis on the brain.

Anti-atherosclerotic effect of the angiotensin 1-7 mimetic AVE0991 is mediated by inhibition of perivascular and plaque inflammation in early atherosclerosis

BACKGROUND AND PURPOSE

Inflammation plays a key role in atherosclerosis. The protective role of angiotensin 1-7 (Ang-(1-7)) in vascular pathologies suggested the therapeutic use of low MW, non-peptide Ang-(1-7) mimetics, such as AVE0991. The mechanisms underlying the vaso-protective effects of AVE0991, a Mas receptor agonist, remain to be explored.

EXPERIMENTAL APPROACH

We investigated the effects of AVE0991 on the spontaneous atherosclerosis in apolipoprotein E (ApoE)-/- mice, in the context of vascular inflammation and plaque stability.

KEY RESULTS

AVE0991 has significant anti-atherosclerotic properties in ApoE-/- mice and increases plaque stability, by reducing plaque macrophage content, without effects on collagen. Using the descending aorta of chow-fed ApoE-/- mice, before significant atherosclerotic plaque develops, we gained insight to early events in atherosclerosis. Interestingly, perivascular adipose tissue (PVAT) and adventitial infiltration with macrophages and T-cells precedes atherosclerotic plaque or the impairment of endothelium-dependent NO bioavailability (a measure of endothelial function). AVE0991 inhibited perivascular inflammation, by reducing chemokine expression in PVAT and through direct actions on monocytes/macrophages inhibiting their activation, characterized by production of IL-1β, TNF-α, CCL2 and CXCL10, and differentiation to M1 phenotype. Pretreatment with AVE0991 inhibited migration of THP-1 monocytes towards supernatants of activated adipocytes (SW872). Mas receptors were expressed in PVAT and in THP-1 cells in vitro, and the anti-inflammatory effects of AVE0991 were partly Mas dependent.

CONCLUSIONS AND IMPLICATIONS

The selective Mas receptor agonist AVE0991 exhibited anti-atherosclerotic and anti-inflammatory actions, affecting monocyte/macrophage differentiation and recruitment to the perivascular space during early stages of atherosclerosis in ApoE-/- mice.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Therapeutic uses for Angiotensin-(1-7)

INTRODUCTION

Angiotensin-(1-7) is a key component of the Renin-Angiotensin System, which can counter-regulate several deleterious effects caused by angiotensin II. Due to the potential for therapeutic use, several of its actions are specifically described in patents.

AREAS COVERED

In this review, the authors describe a plethora of therapeutic uses for Angiotensin-(1-7), claimed and supported by experimental evidence in patent documents and applications.

EXPERT OPINION

The clinical potential of Angiotensin-(1-7) as a therapeutic agent to treat several pathologies is evidenced by the variety of patents and clinical trials involving this peptide. Cancer treatment is one of the most advanced therapeutic areas, but clinical studies are also available in several other areas, such as cardiovascular, hematological, transplantation, surgical and medical procedures.

Analysis of erectile responses to bradykinin in the anesthetized rat

The kallikrein-kinin system is expressed in the corpus cavernosa, and bradykinin (BK) relaxes isolated corpora cavernosal strips. However, erectile responses to BK in the rat have not been investigated in vivo. In the present study, responses to intracorporal (ic) injections of BK were investigated in the anesthetized rat. BK, in doses of 1-100 μg/kg ic, produced dose-related increases in intracavernosal pressure (ICP) and dose-related deceases in mean arterial pressure (MAP). When decreases in MAP were prevented by intravenous injections of angiotensin II (Ang II), increases in ICP, in response to BK, were enhanced. Increases in ICP, ICP/MAP ratio, and area under the curve and decreases in MAP in response to BK were inhibited by the kinin B2 receptor antagonist HOE-140 and enhanced by the angiotensin-converting enzyme (ACE) inhibitor captopril and by Ang-(1-7). Increases in ICP, in response to BK, were not attenuated by the nitric oxide (NO) synthase inhibitor (N(ω)-nitro-L-arginine methyl ester) or the soluble guanylate cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) but were attenuated by the cyclooxygenase inhibitor, sodium meclofenamate. Decreases in MAP were not attenuated by either inhibitor. These data suggest that erectile responses are mediated by kinin B2 receptors and modulated by decreases in MAP. These data indicate that ACE is important in the inactivation of BK and that erectile and hypotensive responses are independent of NO in the penis or the systemic vascular bed. Erectile responses to cavernosal nerve stimulation are not altered by BK or HOE-140, suggesting that BK and B2 receptors do not modulate nerve-mediated erectile responses under physiologic conditions. These data suggest that erectile responses to BK are mediated, in part, by the release of cyclooxygenase products.

Senescent Cells Impair Erectile Function through Induction of Endothelial Dysfunction and Nerve Injury in Mice

Erectile dysfunction (ED) is a major health problem, particularly in the elderly population, which is rapidly increasing. It is necessary to elucidate the mechanism by which ED occurs in the elderly. Cellular senescence is commonly detected in old tissues, and it is well known that senescent cells not only withdraw from the cell cycle but also remain viable and actively produce a variety of cytokines. We examined the effect of senescent cells on erectile function after injection of senescent cells into the penises of mice. Human umbilical vein endothelial cells were infected with an adenovirus expressing a constitutively active mutant of Ras to induce senescence, and were injected into the penises of nude mice. These senescent cells expressed proinflammatory cytokines such as interleukin-1β (IL-1β). Injection of senescent cells impaired erectile function, as assessed by the measurement of intracavernous pressure. Although the structure of the cavernous body did not remarkably change, expression of the catalytically active form of endothelial nitric oxide synthase and that of total neural nitric oxide synthase significantly decreased after injection. The penises injected with the senescent cells expressed human IL-1β and subsequently endogenous proinflammatory cytokines such as mouse IL-1β and tumor necrosis factor-α. These results suggested that senescent cells impaired erectile function through induction of endothelial dysfunction and nerve injury. These effects may be mediated by proinflammatory cytokines produced by senescent cells.

Gas what: NO is not the only answer to sexual function

The ability to get and keep an erection is important to men for several reasons and the inability is known as erectile dysfunction (ED). ED has started to be accepted as an early indicator of systemic endothelial dysfunction and subsequently of cardiovascular diseases. The role of NO in endothelial relaxation and erectile function is well accepted. The discovery of NO as a small signalling gasotransmitter led to the investigation of the role of other endogenously derived gases, carbon monoxide (CO) and hydrogen sulphide (H2 S) in physiological and pathophysiological conditions. The role of NO and CO in sexual function and dysfunction has been investigated more extensively and, recently, the involvement of H2 S in erectile function has also been confirmed. In this review, we focus on the role of these three sister gasotransmitters in the physiology, pharmacology and pathophysiology of sexual function in man, specifically erectile function. We have also reviewed the role of soluble guanylyl cyclase/cGMP pathway as a common target of these gasotransmitters. Several studies have proposed alternative therapies targeting different mechanisms in addition to PDE-5 inhibition for ED treatment, since some patients do not respond to these drugs. This review highlights complementary and possible coordinated roles for these mediators and treatments targeting these gasotransmitters in erectile function/ED.

Angiotensin-(1-7) reverses angiogenic dysfunction in corpus cavernosum by acting on the microvasculature and bone marrow-derived cells in diabetes

INTRODUCTION

Angiotensin (Ang)-(1-7) is a recently identified vasoprotective heptapeptide, and it appears to activate the reparative functions of bone marrow-derived stem/progenitor cells (BMPCs).

AIM

This study evaluated the effect of Ang-(1-7) in the angiogenic function of cavernosum in type 1 diabetes (T1D) and delineated the role of BMPCs in this protective function.

METHODS

T1D was induced by streptozotocin in mice, and mice with 20-24 weeks of diabetes were used for the study. Ang-(1-7) was administered subcutaneously by using osmotic pumps. Cavernosa, and BMPCs from peripheral blood and bone marrow were evaluated in different assay systems.

MAIN OUTCOME MEASURES

Angiogenic function was determined by endothelial tube formation in matrigel assay. Circulating BMPCs were enumerated by flow cytometry and proliferation was determined by BrdU incorporation. Cell-free supernatant of BMPCs were collected and tested for paracrine angiogenic effect. Expression of angiogenic factors in BMPCs and cavernosa were determined by real-time polymerase chain reaction.

RESULTS

Ang-(1-7) (100 nM) stimulated angiogenesis in mouse cavernosum that was partially inhibited by Mas1 receptor antagonist, A779 (10 μM) (P < 0.05). In cavernosa of T1D, the angiogenic responses to Ang-(1-7) (P < 0.005) and VEGF (100 nM) (P < 0.03) were diminished. Ang-(1-7) treatment for 4 weeks reversed T1D-induced decrease in the VEGF-mediated angiogenesis. Ang-(1-7) treatment increased the circulating number of BMPCs and proliferation that were decreased in T1D (P < 0.02). Paracrine angiogenic function of BMPCs was reduced in diabetic BMPCs, which was reversed by Ang-(1-7). In diabetic BMPCs, SDF and angiopoietin-1 were upregulated by Ang-(1-7), and in cavernosum, VEGFR1, Tie-2, and SDF were upregulated and angiopoietin-2 was down-regulated.

CONCLUSIONS

Ang-(1-7) stimulates angiogenic function of cavernosum in diabetes via its stimulating effects on both cavernosal microvasculature and BMPCs.

Effects of testosterone supplementation on prevention of age-related penile remodeling

Erectile dysfunction develops among 46.2% of men between 40 and 70 years. Studies demonstrated substitution on detrusor muscle by collagen due testosterone deprivation. It is clear the correlation among aging and oxidative stress, accelerating apoptosis process in many tissues. This study aims to demonstrate the collagen substitution over the muscle fibers on muscle structure of rat's penis and the effects of testosterone supplementation. Sixteen senescent Wistar rats were divided into two groups: treatment (receiving standard supplementation testosterone dose) and control (receiving equivalent saline solution). Testosterone was dosed on D0 and D56 of study. All penises were prepared with picrosirius colored histology; stereology was applied to determine the volumetric density of collagen fibers (Vv). Analysis of variance demonstrated testosterone group's replacement therapy to be effective, while the androgenic decline continued by the time of experiment in control group (p < 0.05). Testosterone group had Vv of 20.6%, lower than control group (47.8%); t-test (p < 0.001). Pearson's correlation demonstrated an inverse correlation between the Vv and testosterone's levels (p < 0.001). This is a pioneer study on demonstration of structural alterations over the cavernous corpora muscle caused by deprivation of testosterone on elderly rat. These finding implicate that the testosterone levels can influence, not only the libido, but also the erectile function.

Chronic treatment with Ang-(1-7) reverses abnormal reactivity in the corpus cavernosum and normalizes diabetes-induced changes in the protein levels of ACE, ACE2, ROCK1, ROCK2 and omega-hydroxylase in a rat model of type 1 diabetes

Angiotensin-(1-7) [Ang-(1-7)] may have beneficial effects in diabetes mellitus-induced erectile dysfunction (DMIED) but its molecular actions in the diabetic corpus cavernosum (CC) are not known. We characterized the effects of diabetes and/or chronic in vivo administration of Ang-(1-7) on vascular reactivity in the rat corpus cavernosum (CC) and on protein expression levels of potential downstream effectors of the renin-angiotensin-aldosterone system (RAAS) such as angiotensin-converting enzyme (ACE), ACE2, Rho kinases 1 and 2 (ROCK1 and ROCK2), and omega-hydroxylase, the cytochrome-P450 enzyme that metabolizes arachidonic acid to form the vasoconstrictor, 20-hydroxyeicosatetraenoic acid. Streptozotocin-treated rats were chronicically administered Ang-(1-7) with or without A779, a Mas receptor antagonist, during weeks 4 to 6 of diabetes. Ang-(1-7) reversed diabetes-induced abnormal reactivity to vasoactive agents (endothelin-1, phenylepherine, and carbachol) in the CC without correcting hyperglycemia. Six weeks of diabetes led to elevated ACE, ROCK1, ROCK 2, and omega-hydroxylase and a concomitant decrease in ACE2 protein expression levels that were normalized by Ang-(1-7) treatment but not upon coadministration of A779. These data are supportive of the notion that the beneficial effects of Ang-(1-7) in DMIED involve counterregulation of diabetes-induced changes in ACE, ACE2, Rho kinases, and omega-hydroxylase proteins in the diabetic CC via a Mas receptor-dependent mechanism.

Treatment of erectile dysfunction: new targets and strategies from recent research

In recent years, research on penile erection has increasingly been centered on the molecular mechanisms involved. Major progress has been made in the field and at present a whole number of neurotransmitters, chemical effectors, growth factors, second-messenger molecules, ions, intercellular proteins, and hormones have been characterized as components of the complex process of erection. This knowledge has led to the discovery of several new therapeutic targets and multiple medical approaches for the treatment of erectile dysfunction (ED). This review focuses on the progress made in this field within the last few years.

Treatment with CB2 agonist JWH-133 reduces histological features associated with erectile dysfunction in hypercholesterolemic mice

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 in cavernosal 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.