Reactive oxygen species and erectile dysfunction: possible role of NADPH oxidase

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.

Role of hydrogen sulfide in the male reproductive system

As an important gas signaling molecule, hydrogen sulfide (H2S) affects multiple organ systems, including the nervous, cardiovascular, digestive, and genitourinary, reproductive systems. In particular, H2S not only regulates female reproductive function but also holds great promise in the treatment of male reproductive diseases and disorders, such as erectile dysfunction, prostate cancer, varicocele, and infertility. In this review, we summarize the relationship between H2S and male reproductive organs, including the penis, testis, prostate, vas deferens, and epididymis. As lower urinary tract symptoms have a significant impact on penile erection disorders, we also address the potential ameliorative effects of H2S in erectile dysfunction resulting from bladder disease. Additionally, we discuss the regulatory role of H2S in cavernous smooth muscle relaxation, which involves the NO/cGMP pathway, the RhoA/Rho-kinase pathway, and K+ channel activation. Recently, various compounds that can alleviate erectile dysfunction have been reported to be at least partly dependent on H2S. Therefore, understanding the role of H2S in the male reproductive system may help develop novel strategies for the clinical treatment of male reproductive system diseases.

Higher oxidative balance score was associated with decreased risk of erectile dysfunction: a population-based study

BACKGROUND

Erectile dysfunction (ED) is a prevalent condition that is thought to be significantly impacted by oxidative stress. The oxidative balance score (OBS) has been built to characterize the state of antioxidant/pro-oxidant balance. There is less known regarding the relationship of OBS with ED.

METHODS

This study conducted cross-sectional analyses on 1860 males who participated in the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2004. OBS was constructed by the 16 dietary components and 4 lifestyle factors. Self-reported ED was defined as men who indicated that they "never" or "sometimes" could achieve or keeping an erection adequate for satisfactory intercourse. Multivariate logistic regression models were applied to examine the association between OBS and the risk of ED.

RESULTS

Among 1860 participants, the median OBS was 20 (IQR 15-26), and OBS was lower in males with ED vs. those without ED (P = 0.001). The results of our analyses indicated a negative correlation between OBS and ED among male subjects. Specifically, each one-unit increase in the continuous OBS was relate to 3% reduction in the odds of ED after full adjustment. Moreover, when extreme OBS quartiles were compared, the adjusted odds ratio (95% confidence interval) for the 4th OBS category was 0.53 (0.32 to 0.88) after full adjustment (P for trend < 0.05). There was also statistical significance in the relationships between dietary/lifestyle OBS with ED, and the association between lifestyle OBS and ED may be even tighter. For each unit increase in lifestyle OBS, the odds of ED decreased by 11% after full adjustment.

CONCLUSION

Higher OBS was associated with reduced risk of ED in U.S. males. These findings suggested that adopting an antioxidant-rich diet and engaging in antioxidant-promoting lifestyle behaviors may contribute to a lower incidence of ED. These results provided recommendations for a comprehensive dietary and lifestyle antioxidants for ED patients.

The relationship between oxidative balance score and erectile dysfunction in the U.S. male adult population

Oxidative stress strongly influences the pathophysiology of erectile dysfunction (ED). In this study, we used the oxidative balance score (OBS), a composite index, to measure the effects of oxidative stress triggered by diet and lifestyle factors. Here, we conducted a cross-sectional study to determine the statistical relationship between OBS and ED among adult males in the U.S. The data from 3318 participants in the National Health and Nutrition Examination Survey (NHANES) 2001-2004 were analyzed. Weighted logistic regression was used to correct for confounding factors and acquire nationwide representative estimates. Generalized additive modeling was used to explore the nonlinear relationship. We also supplemented subgroup and sensitivity analysis to examine the robustness of the main results. Multivariate logistic regression indicated a consistent negative linear association between OBS and ED across all participants [OR (95% CI) = 0.96 (0.94, 0.98)]. After categorizing OBS into tertiles, participants in the highest tertile had 43% lower odds of having ED than those in the lowest tertile [OR (95% CI) = 0.57 (0.37, 0.87)]. The generalized additive model also visualized the linear trend of this association. Furthermore, this linear relationship remained relatively consistent, regardless of whether subgroup or sensitivity analyses were performed. Our findings suggest that adopting a lifestyle and diet pattern that promotes favorable OBS may effectively protect against the development of ED, regardless of the underlying causes.

Therapeutic Potential of Hydrogen Sulfide in Reproductive System Disorders

Hydrogen sulfide (H2S), previously regarded as a toxic exhaust and atmospheric pollutant, has emerged as the third gaseous signaling molecule following nitric oxide (NO) and carbon monoxide (CO). Recent research has revealed significant biological effects of H2S in a variety of systems, such as the nervous, cardiovascular, and digestive systems. Additionally, H2S has been found to impact reproductive system function and may have therapeutic implications for reproductive disorders. This paper explores the relationship between H2S and male reproductive disorders, specifically erectile dysfunction, prostate cancer, male infertility, and testicular damage. Additionally, it examines the impact of H2S regulation on the pathophysiology of the female reproductive system, including improvements in preterm birth, endometriosis, pre-eclampsia, fetal growth restriction, unexplained recurrent spontaneous abortion, placental oxidative damage, embryo implantation, recovery of myometrium post-delivery, and ovulation. The study delves into the regulatory functions of H2S within the reproductive systems of both genders, including its impact on the NO/cGMP pathway, the activation of K+ channels, and the relaxation mechanism of the spongy smooth muscle through the ROCK pathway, aiming to broaden the scope of potential therapeutic strategies for treating reproductive system disorders in clinical settings.

Investigating the prevalence of erectile dysfunction among men exposed to organophosphate insecticides

INTRODUCTION

Erectile dysfunction (ED) poses a significant disease morbidity and contributor to male infertility, where an estimated 20-40% of men are affected annually. While several risk factors have been identified in the etiology of ED (e.g., aging, heart disease, diabetes, and obesity), the complete pathogenesis remains to be elucidated. Over the last few decades, the contribution of environmental exposures to the pathogenesis of ED has gained some attention, though population studies are limited and results are mixed. Among environmental contaminants, organophosphate (OP) insecticides represent one of the largest chemical classes, and chlorpyrifos is the most commonly used OP in the U.S. OP exposure has been implicated in driving biological processes, including inflammation, reactive oxygen species production, and endocrine and metabolism disruption, which have been demonstrated to adversely affect the hypothalamus and testes and may contribute to ED. Currently, studies evaluating the association between OPs and ED within the U.S. general population are sparse.

METHODS

Data were leveraged from the National Health and Nutrition Examination Survey (NHANES), which is an annually conducted, population-based cross-sectional study. Urinary levels of 3,5,6-trichloro-2-pyridinol (TCPy), a specific metabolite of the most pervasive OP insecticide chlorpyrifos, were quantified as measures of OP exposure. ED was defined by responses to questionnaire data, where individuals who replied "sometimes able" or "never able" to achieve an erection were classified as ED. Chi-square, analysis of variance (ANOVA), and multivariable, weighted linear and logistic regression analyses were used to compare sociodemographic variables between quartiles of TCPy exposure, identify risk factors for TCPy exposure and ED, and to analyze the relationship between TCPy and ED.

RESULTS

A total of 671 adult men were included in final analyses, representing 28,949,379 adults after survey weighting. Approximately 37% of our cohort had ED. Smoking, diabetes, aging, Mexican-American self-identification, and physical inactivity were associated with higher ED prevalence. Analysis of TCPy modeled as a continuous variable revealed nonsignificant associations with ED (OR = 1.02 95% CI [0.95, 1.09]). Stratification of total TCPy into quartiles revealed increased odds of ED among adults in the second and fourth quartiles, using the first quartile as the reference (OR = 2.04 95% CI [1.11, 3.72], OR = 1.51 95% CI [0.58, 3.93], OR = 2.62 95% CI [1.18, 5.79], for quartiles 2, 3, and 4, respectively).

CONCLUSIONS

The results of our study suggest a potential role for chlorpyrifos and other OPs the pathogenesis of ED. Future studies are warranted to validate these findings, determine clinical significance, and to investigate potential mechanisms underlying these associations.

Neurovascular dysfunction associated with erectile dysfunction persists after long-term recovery from simulations of weightlessness and deep space irradiation

There has been growing interest within the space industry for long-duration manned expeditions to the Moon and Mars. During deep space missions, astronauts are exposed to high levels of galactic cosmic radiation (GCR) and microgravity which are associated with increased risk of oxidative stress and endothelial dysfunction. Oxidative stress and endothelial dysfunction are causative factors in the pathogenesis of erectile dysfunction, although the effects of spaceflight on erectile function have been unexplored. Therefore, the purpose of this study was to investigate the effects of simulated spaceflight and long-term recovery on tissues critical for erectile function, the distal internal pudendal artery (dIPA), and the corpus cavernosum (CC). Eighty-six adult male Fisher-344 rats were randomized into six groups and exposed to 4-weeks of hindlimb unloading (HLU) or weight-bearing control, and sham (0Gy), 0.75 Gy, or 1.5 Gy of simulated GCR at the ground-based GCR simulator at the NASA Space Radiation Laboratory. Following a 12-13-month recovery, ex vivo physiological analysis of the dIPA and CC tissue segments revealed differential impacts of HLU and GCR on endothelium-dependent and -independent relaxation that was tissue type specific. GCR impaired non-adrenergic non-cholinergic (NANC) nerve-mediated relaxation in the dIPA and CC, while follow-up experiments of the CC showed restoration of NANC-mediated relaxation of GCR tissues following acute incubation with the antioxidants mito-TEMPO and TEMPOL, as well as inhibitors of xanthine oxidase and arginase. These findings indicate that simulated spaceflight exerts a long-term impairment of neurovascular erectile function, which exposes a new health risk to consider with deep space exploration.

Heart Failure and Erectile Dysfunction: a Review of the Current Evidence and Clinical Implications

PURPOSE OF REVIEW

Heart failure (HF) and erectile dysfunction (ED) are two common conditions that affect millions of men worldwide and impair their quality of life. ED is a frequent complication of HF, as well as a possible predictor of cardiovascular events and mortality. ED deserves more attention from clinicians and researchers.

RECENT FINDINGS

The pathophysiology of ED in HF involves multiple factors, such as endothelial dysfunction, reduced cardiac output, neurohormonal activation, autonomic imbalance, oxidative stress, inflammation, and drug side effects. The diagnosis of ED in HF patients should be based on validated questionnaires or objective tests, as part of the routine cardiovascular risk assessment. The therapeutic management of ED in HF patients should be individualized and multidisciplinary, considering the patient's preferences, expectations, comorbidities, and potential drug interactions. The first-line pharmacological treatment for ED in HF patients with mild to moderate symptoms (NYHA class I-II) is phosphodiesterase type 5 inhibitors (PDE5Is), which improve both sexual function and cardiopulmonary parameters. PDE5Is are contraindicated in patients who use nitrates or nitric oxide donors for angina relief, and these patients should be advised to avoid sexual activity or to use alternative treatments for ED. Non-pharmacological treatments for ED, such as psychotherapy or couples therapy, should also be considered if there are significant psychosocial factors affecting the patient's sexual function or relationship. This review aims to summarize the most recent evidence regarding the prevalence of ED, the pathophysiology of this condition with an exhaustive analysis of factors involved in ED development in HF patients, a thorough discussion on diagnosis and management of ED in HF patients, providing practical recommendations for clinicians.

Argonaute 2 Restores Erectile Function by Enhancing Angiogenesis and Reducing Reactive Oxygen Species Production in Streptozotocin (STZ)-Induced Type-1 Diabetic Mice

Severe vascular and nerve damage from diabetes is a leading cause of erectile dysfunction (ED) and poor response to oral phosphodiesterase 5 inhibitors. Argonaute 2 (Ago2), a catalytic engine in mammalian RNA interference, is involved in neurovascular regeneration under inflammatory conditions. In the present study, we report that Ago2 administration can effectively improve penile erection by enhancing cavernous endothelial cell angiogenesis and survival under diabetic conditions. We found that although Ago2 is highly expressed around blood vessels and nerves, it is significantly reduced in the penis tissue of diabetic mice. Exogenous administration of the Ago2 protein restored erectile function in diabetic mice by reducing reactive oxygen species production-signaling pathways (inducing eNOS Ser¹¹⁷⁷/NF-κB Ser⁵³⁶ signaling) and improving cavernous endothelial angiogenesis, migration, and cell survival. Our study provides new evidence that Ago2 mediation may be a promising therapeutic strategy and a new approach for diabetic ED treatment.

Risk of Erectile Dysfunction in Male Patients with Gout Treated with Febuxostat or Allopurinol: A Propensity Score-Matched Cohort Study

OBJECTIVE

To evaluate and compare the risk of erectile dysfunction (ED) associated with the use of allopurinol and febuxostat in adult male gout patients.

METHODS

We conducted a cohort study using TriNetX (Cambridge, MA, USA), a global federated health research network that provides real-time electronic medical record datasets. We analyzed and compared the associated risk of ED in gout patients who started taking allopurinol or febuxostat within 12 months. Propensity score matching was performed to adjust for demographic variables, comorbidities, and medication use. Kaplan-Meier analysis was used to estimate the probability of the outcome of interest. The hazard ratio (HR) and associated confidence intervals were calculated along with the proportionality test using R's Survival Package v3.2-3.

RESULTS

We identified 679,862 patients with gout among 107,517,445 patients in the database. Of these patients, 24,000 were treated with febuxostat and 299,726 with allopurinol. After propensity matching, 9075 patients receiving febuxostat without allopurinol (febuxostat group) and 9075 corresponding patients receiving allopurinol without febuxostat (allopurinol group) were analyzed for comparison. Among all male patients over 19 years of age, febuxostat was associated with a significantly higher risk of ED versus allopurinol (HR 1.354; 95% confidence interval (CI) 1.003-1.829; log rank test, p = 0.047). After subgroup analysis, in gout patients aged 19-64 years, a significantly higher incidence of ED was observed in the febuxostat group than in the allopurinol group (HR 2.002, 95% CI 1.282-3.126). The risk of ED did not differ significantly between the allopurinol and febuxostat groups in gout patients older than 65 years.

CONCLUSIONS

Febuxostat may be associated with a higher risk of ED than allopurinol in adult male patients with gout. Future large-scale prospective studies are warranted to confirm our results.

Plantain peels restore sexual performance, hormonal imbalance, and modulate nitric oxide production and key enzymes of penile function in paroxetine-sexually impaired male rats

This study focused on the effect of unripe (UPP) and ripe (RPP) plantain peels' extracts (200 and 400 mg/kg) on sexual behavior, hormonal profiles [testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH)], and enzymes [acetylcholinesterase (AChE), phosphodiesterase-5' (PDE-5), arginase, angiotensin-I converting enzyme (ACE), ecto-5'neucleotidase, and adenosine deaminase (ADA)] in paroxetine (PAR)-induced penile dysfunction rats. From the result, arginase, PDE-5', ACE, ecto-5'-nucleotidase ADA, and AChE activities, sexual activities, hormonal profile, and NO level were reduced, while thiobarbituric acid reactive species (TBARS) level increased (p < .05) relative to normal control rats. However, treatment with UPP and URP reduced the activities of these enzymes, decreased TBARS levels, and increased hormones, and penile NO levels in PAR-induced rats. Thus, the use of UPP and RPP could be channeled towards the improvement of sexual performance in erectile dysfunction (ED) disorder. PRACTICAL APPLICATIONS: Plantain fruits are a tropical staple food crop commonly consumed at various stages of ripeness and cooking methods. However, its peels are regarded as a waste product with reported cases of environmental menace. Interestingly, plantain peel is being used as a major raw material for industrial applications in the agro-based industries and in folklore for the treatment of many human ailments due to its rich phytochemicals such as polyphenols, carotenoids, alkaloids, etc., which have been reported. A prelude study has also indicated its usefulness in ED management, but further pharmacological investigations are needed to proffer information on its effect in ED management and its anti-androgenic activity in male Wistar rats. The information from this study could be of pharmaceutical importance in designing natural remedies capable of improving penile rigidity, hormone profiles, and alteration of enzymes linked with ED.

Tadalafil against hyperoxia-induced oxidative stress; an experimental study

This study aimed to investigate the protective effect of tadalafil on reactive oxygen species induced by a hyperoxia model in rats, both in terms of enzymes such as superoxide dismutase (SOD) and nitric oxide (NO), and its pathological effects on the corpus cavernosum. Overall, 24 rats were divided into three groups. The control group (eight rats) was not exposed to any intervention. The second group (eight rats), was exposed to hyperoxia in a hyperoxia cabinet for 8 h a day for 10 days. The third group (eight rats) was exposed to hyperoxia the same as in the second group, tadalafil at a dose of 10 mg/kg was given orally as a dissolved form in water in the amount of 10-12 ml/100 g/day to the rats placed in separate cages having removed from the hyperoxia cabin. SOD levels differ enough to create a difference, but there was no significant difference in terms of NO levels. The SOD level was highest in hyperoxia conditions and lowest in the group given tadalafil. While corpus cavernosum hyperemia was found to be higher statistically in the experimental groups than in the control group, we found that the severity of hyperemia was less in the group given tadalafil. The corpus cavernosum was found to be statistically more dilated in the experimental groups than in the control group. We determined that hyperoxia status increased the level of SOD and this level decreased with tadalafil administration, which would make a statistical difference.

Pathological Roles of Reactive Oxygen Species in Male Reproduction

Reactive oxygen species (ROS) are free radicals that have at least one unpaired electron and play specific roles in the human body. An imbalance of ROS and antioxidant levels gives rise to a condition called oxidative stress. High levels of ROS in the male reproductive tract can interfere with its normal functioning and can even pose as toxic to the sperm, inhibiting sperm functioning (including motility) and metabolism. Oxidative stress resulting from ROS and lipid peroxidation is one of the major causes of male infertility including infertility in varicocele patients. These may cause DNA and peroxidative damage and apoptosis. Production of ROS in excess also leads to erectile dysfunction (ED). In recent years, studies have also linked oxidative stress with the development, progress, and therapy response of prostate cancer patients. The present study summarizes the pathological roles of ROS in male reproductive problems such as infertility, ED, and prostate cancer and also provide an insight into the probable mechanism through which ROS exert their pathological impact.

Effect of Antioxidants Supplementation on Erectile Dysfunction: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

INTRODUCTION

In Erectile dysfunction (ED) patients, phosphodiesterase type 5 (PDE5) inhibitors are considered as the first-line therapy. However, 30-50% of ED patients fail to follow this therapeutic option because of adverse events, lack of efficacy, or drug costs. Antioxidant supplementation is widely applied in clinical practice and viewed as a potential therapeutic option for ED. Therefore, it is attractive to assess the effect of antioxidants supplementation on ED patients.

OBJECTIVES

To evaluate the effects of antioxidants supplementation on ED.

METHODS

Published randomized controlled trials of antioxidants in ED were searched in the PubMed, Embase, and Cochrane Library databases from inception to October 3, 2021. Meta-analyses were carried out using a random-effects model. The results were presented as standard mean differences (SMDs) with their 95% confidence intervals (CIs).

RESULTS

Eighteen studies with 1,331 ED patients were included in the study. Compared with placebo, antioxidants alone treatment showed a statistical increase in International Index of Erectile Function (IIEF) score (SMD = 1.93; 95% CI: 0.15, 3.72; P = .034). Compared with placebo, antioxidants compound treatment elicited a significant increase in IIEF score (SMD = 2.74; 95% CI: 1.67, 3.81; P < .001) as well as sexual satisfaction score (SMD = 1.61; 95% CI: 0.63, 2.59; P = .001). Compared with the PDE5 inhibitors alone, combination of PDE5 inhibitors and antioxidants showed a significant increase in IIEF score (SMD = 1.1; 95% CI: 0.51, 1.68; P < .001) and sexual satisfaction score (SMD = 1.28; 95% CI: 0.06, 2.51; P = .04).

CONCLUSION

This study found that the effect of antioxidant alone treatment on ED may be limited. However, antioxidant compound treatment, as well as combination of PDE5 inhibitors and antioxidants, were associated with improved ED, and can be considered as an accessary therapeutic option for ED. Su L, Yang Z, Qu H, et al. Effect of Antioxidants Supplementation on Erectile Dysfunction: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Sex Med Rev 2021;XX:XXX-XXX.

Environmental Factors-Induced Oxidative Stress: Hormonal and Molecular Pathway Disruptions in Hypogonadism and Erectile Dysfunction

Hypogonadism is an endocrine disorder characterized by inadequate serum testosterone production by the Leydig cells of the testis. It is triggered by alterations in the hypothalamic–pituitary–gonadal axis. Erectile dysfunction (ED) is another common disorder in men that involves an alteration in erectile response–organic, relational, or psychological. The incidence of hypogonadism and ED is common in men aged over 40 years. Hypogonadism (including late-onset hypogonadism) and ED may be linked to several environmental factors-induced oxidative stresses. The factors mainly include exposure to pesticides, radiation, air pollution, heavy metals and other endocrine-disrupting chemicals. These environmental risk factors may induce oxidative stress and lead to hormonal dysfunctions. To better understand the subject, the study used many keywords, including “hypogonadism”, “late-onset hypogonadism”, “testosterone”, “erectile dysfunction”, “reactive oxygen species”, “oxidative stress”, and “environmental pollution” in major online databases, such as SCOPUS and PUBMED to extract relevant scientific information. Based on these parameters, this review summarizes a comprehensive insight into the important environmental issues that may have a direct or indirect association with hypogonadism and ED in men. The study concludes that environmental factors-induced oxidative stress may cause infertility in men. The hypothesis and outcomes were reviewed critically, and the mechanistic approaches are applied through oxidant-sensitive pathways. This study also provides reccomendations on future therapeutic interventions and protective measures against such adverse environmental factors-induced hypogonadism and ED.

Vasculogenic Erectile Dysfunction: The Impact of Diet and Lifestyle

Vasculogenic erectile dysfunction has been aptly called the "canary in the coal mine" for cardiovascular disease because it almost always precedes other manifestations of atherosclerotic cardiovascular disease, including myocardial infarction and stroke. It is common, associated with the presence of modifiable cardiovascular risk factors, and impacted by diet and lifestyle choices. This concise review provides an update on the use of dietary and other lifestyle interventions to improve vasculogenic erectile dysfunction and atherosclerotic cardiovascular disease.

Beyond Arthritis: Understanding the Influence of Gout on Erectile Function: A Systematic Review

OBJECTIVE

To review the evidence suggesting a significant association between gout and erectile dysfunction (ED) and evaluate possible underlying pathways that may explain this relationship.

METHODS

English medical literature was searched from January 1, 2010, to January 1, 2020, for randomized or quasi-randomized controlled trials, cross-sectional studies, case-cohort studies, or meta-analysis evaluating the relationship between gout and ED.

RESULTS

All nine gout studies included in the study found a significant association between gout and ED. ED pathophysiology in gout involves hyperuricemia, increased reactive oxygen species, decreased nitric oxide synthesis, and low-grade inflammation.

CONCLUSION

The findings of this review suggest that the effect of urate-lowering therapy on the incidence of ED in gout patients should be studied. Additionally, we propose that all gout patients should be assessed for ED.

Oxidative stress in the pathophysiology of male infertility

The effects of reactive oxygen species on male fertility are governed by the oxidative paradox, defined by a delicate balance between oxidative stress and antioxidant capacity. When regulated appropriately, reactive oxygen species ensure effective function; however, when uninhibited, they represent key players in male factor infertility. Mechanisms responsible for this include oxidative destruction of sperm lipid membranes, damage to gamete DNA both by gene mutation and by direct breakdown of the DNA backbone, mitochondrial dysfunction and apoptotic cell death. Utilizing various male pathologies as case studies, we see ways in which oxidative stress has the potential to impact fertility in a negative way. Varicocele, erectile dysfunction, testicular cancer and even idiopathic male infertility highlight common mechanistic pathways, as well as subtle variations in the ways reactive oxygen species can operate. Oxidative biomarkers have emerged to better study male infertility, predict reproductive success and modify assisted reproductive technologies to minimize oxidative stress.

Melatonin Treatment Ameliorates Hyperhomocysteinemia-Induced Impairment of Erectile Function in a Rat Model

BACKGROUND

Hyperhomocysteinemia (HHcy) has been reported to be strongly correlated with the occurrence of erectile dysfunction (ED), but the mechanisms are not fully understood. Moreover, whether melatonin could be a potential treatment of HHcy-induced ED needs to be elucidated.

AIM

The aim of this study was to investigate the effects of melatonin on HHcy-induced ED and the potential mechanisms via modulating oxidative stress and apoptosis.

METHODS

The Sprague-Dawley (SD) rat model of HHcy was induced by 7% methionine (Met)-rich diets. 36 male SD rats were randomly distributed into 3 groups (n = 12 per group): control group, 7% Met group, and 7% Met + melatonin (Mel; 10 mg/kg, intraperitoneal injection) treatment group. After 4 weeks, the erectile function of all rats was evaluated by electrical stimulation of the cavernous nerve. Histologic and molecular alterations of the corpus cavernosum were also analyzed by immunofluorescence, immunohistochemistry, enzyme-linked immunosorbent assay, Western blotting, and polymerase chain reaction.

OUTCOMES

HHcy-induced ED rat models were successfully established, and Mel could preserve erectile function mainly through inhibiting oxidative stress via the Erk1/2/Nrf2/HO-1 signaling pathway and suppression of apoptosis.

RESULTS

Erectile function was significantly reduced in the rats with HHcy compared with that in the control group and was ameliorated in the HHcy rats treated with Mel. Compared with the control group, the rats in the HHcy group showed the following: (1) higher levels of total plasma homocysteine; (2) fewer neuronal nitric oxide synthase-positive cells in the corpus cavernous; (3) higher levels of reactive oxygen species and malondialdehyde, higher expression levels of nicotinamide adenine dinucleotide phosphate oxidase, and lower activities of superoxide dismutase, indicating an overactivated oxidative stress; (4) lower expression levels of Erk1/2/Nrf2/HO-1 signaling pathway components; and (5) higher levels of apoptosis, as determined by the expression levels of Bax, Bcl-2, and caspase 3. Mel treatment improved the erectile response, as well as histologic and molecular alterations.

CLINICAL TRANSLATION

Our study on a rodent model of HHcy provided evidence that Mel could be a potential therapeutic method for HHcy-related ED.

CONCLUSIONS

Mel treatment improves erectile function in rats with HHcy probably by potential antioxidative stress activity. This finding provides evidence for a potential new therapy for HHcy-induced ED. Tang Z, Song J, Yu, Z, et al. Melatonin Treatment Ameliorates Hyperhomocysteinemia-Induced Impairment of Erectile Function in a Rat Model. J Sex Med 2019;16:1506-1517.

MyD88 overexpression deteriorates Ang-II-induced ED via upregulating MPO and COX2 and downregulating eNOS in the corpus cavernosum of rats

INTRODUCTION

Erectile dysfunction (ED) is a common sexual problem for men and the exploration of its treatment is still in mire demand. We aim to investigate the role of the Toll-like receptor 4 (TLR4)/myeloid differentiation primary response gene 88 (MyD88) signaling pathway in the pathogenesis of angiotensin II (Ang-II) induced ED.

METHODS

Male Sprague-Dawlay rats were treated with Ang-II and intracavernous pressure (ICP) was measured to confirm the occurrence of ED. The corpus cavernosum penises of rats were transfected with plasmids to overexpressed MyD88. Inflammatory and vascular parameters including myeloperoxidase (MPO), cyclooxygenase2 (COX2), endothelial nitric oxide synthase (eNOS), malondialdehyde (MDA), superoxide dismutase (SOD), reactive oxygen species (ROS), and cytokines in treated and untreated ED rats were measured. Flow cytometry was used to determine the apoptosis of endothelial cells of corpus cavernosum penises of rats.

RESULTS

Ang-II-induced ED rats were found to contain upregulated TLR4, MyD88, MPO, and COX2, and downregulated eNOS. MyD88 overexpression deteriorates cavernous structural damage, reduces ICP and ICP/MAP values and reverses the therapeutic effect of anti-TLR4 antibodies in rats with Ang-II-induced ED. Moreover, overexpression of MyD88 further upregulated MPO and COX2, downregulated eNOS, promoted oxidative stress, inflammation, and cell apoptosis rate via positively regulating the TLR4/MyD88 signaling pathway, while anti-TLR4 antibodies downregulated MPO and COX2, upregulated eNOS, suppressed oxidative stress, inflammation, and cell apoptosis rate via inactivating the TLR4/MyD88 signaling pathway in the rat corpus cavernosum penises. Furthermore, MyD88 overexpression promotes oxidative stress and inflammation and reverses the effect of anti-TLR4 antibodies in the penis of ED rats.

CONCLUSION

MyD88 overexpression deteriorates Ang-II-induced ED via upregulating MPO and COX2 and downregulating eNOS in the corpus cavernosum rats.

Semen reactive oxygen species levels are correlated with erectile function among chronic prostatitis/chronic pelvic pain syndrome patients

Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS) is often associated with erectile dysfunction (ED). However, the underlying pathophysiological mechanisms of ED occurrence are still unclear in patients with CP/CPPS. The aim of the study was to investigate superoxide anion (O₂^•-) and total reactive oxygen species (ROS) production in semen of men with category IIIA CP/CPPS and their association with ED. This prospective study included 33 men with category IIIA CP/CPPS. Control group consisted of 13 healthy men. Total ROS and O₂^•- production were assayed by luminol and lucigenin-dependent chemiluminescence (CL) methods, respectively. ED was evaluated using the IIEF-5 questionnaire. Patients with CP/CPPS had significantly higher seminal total ROS and O₂^•- levels than healthy control subjects (2.9 ± 0.5 relative light unit (RLU) vs. 2.4 ± 0.2 RLU, p < 0.001; luminol-dependent CL and 2.5 ± 0.4 RLU vs. 2.3 ± 0.2 RLU, p = 0.02; lucigenin-dependent CL, respectively). Seminal O₂^•- and ROS levels were negatively correlated with IIEF-5 scores (r = -0.556, r = -0.536; p < 0.001, respectively). These results may suggest O₂^•-/ROS overproduction could be one of the important mechanisms in the etiology of ED development in CP/CPPS patients.

Superparamagnetic iron oxide nanoparticle targeting of adipose tissue-derived stem cells in diabetes-associated erectile dysfunction

Erectile dysfunction (ED) is a major complication of diabetes, and many diabetic men with ED are refractory to common ED therapies. Adipose tissue-derived stem cells (ADSCs) have been shown to improve erectile function in diabetic animal models. However, inadequate cell homing to damaged sites has limited their efficacy. Therefore, we explored the effect of ADSCs labeled with superparamagnetic iron oxide nanoparticles (SPIONs) on improving the erectile function of streptozotocin-induced diabetic rats with an external magnetic field. We found that SPIONs effectively incorporated into ADSCs and did not exert any negative effects on stem cell properties. Magnetic targeting of ADSCs contributed to long-term cell retention in the corpus cavernosum and improved the erectile function of diabetic rats compared with ADSC injection alone. In addition, the paracrine effect of ADSCs appeared to play the major role in functional and structural recovery. Accordingly, magnetic field-guided ADSC therapy is an effective approach for diabetes-associated ED therapy.

Mechanisms of vascular dysfunction in acute phase of Trypanosoma cruzi infection in mice

Vascular disorders have a direct link to mortality in the acute phase of Trypanosoma cruzi infection. However, the underlying mechanisms of vascular dysfunction in this phase are largely unknown. We hypothesize that T. cruzi invades endothelial cells causing dysfunction in contractility and relaxation of the mouse aorta. Immunodetection of T. cruzi antigen TcRBP28 was observed in endothelial cells. There was a decreased endothelial nitric oxide synthase (eNOS)-derived NO-dependent vascular relaxation, and increased vascular contractility accompanied by augmented superoxide anions production. Endothelial removal, inhibition of cyclooxygenase 2 (COX-2), blockade of thromboxane A2 (TXA2) TP receptors, and scavenger of superoxide normalized the contractile response. COX-2, thromboxane synthase, inducible nitric oxide synthase (iNOS), p65 NFκB subunit and p22(phox) of NAD(P)H oxidase (NOX) subunit expressions were increased in vessels of chagasic animals. Serum TNF-α was augmented. Basal NO production, and nitrotyrosine residue expression were increased. It is concluded that T. cruzi invades mice aorta endothelial cells and increases TXA2/TP receptor/NOX-derived superoxide formation. Alongside, T. cruzi promotes systemic TNF-α increase, which stimulates iNOS expression in vessels and nitrosative stress. In light of the heart failure that develops in the chronic phase of the disease, to understand the mechanism involved in the increased contractility of the aorta is crucial.

Molecular mechanisms associated with diabetic endothelial-erectile dysfunction

Erectile dysfunction (ED) is a common complication of diabetes, affecting up to 75% of all diabetic men. Although the aetiology of diabetic ED is multifactorial, endothelial dysfunction is recognized as a mainstay in the pathophysiology of the disease. Endothelial dysfunction is induced by the detrimental actions of high glucose levels and increased oxidative stress on endothelial cells that make up the vascular lining. Besides directly injuring the endothelium, diabetes might also hamper vascular repair mechanisms of angiogenesis and vasculogenesis. These states exacerbate and maintain endothelial dysfunction, impairing vasorelaxation events and cavernosal blood perfusion, which are crucial for normal erectile function.

Low serum insulin-like growth factor-1 in patients with erectile dysfunction

OBJECTIVE

Endothelial dysfunction and microvascular damage play a crurical role in the pathogenesis of erectile dysfunction (ED). Insulin-like growth factor-1 (IGF-1) is one of the growth factors that have a wide range of biologic effects. IGF-1 is an important mediator of cell growth, differentiation and transformation in various tissues. The purpose of the current study was to determine the association between IGF-1 levels and ED.

MATERIALS AND METHODS

All men were evaluated for ED and divided into two groups: 80 patients suffering from ED for > 1 year and 80 subjects without ED were enrolled as a control group in this study. Diagnosis of ED was based on the International Index of Erectile Function Score-5. IGF-1 levels were measured in serum by an automated chemiluminescence immunoassay. The relationship between IGF-1 levels and ED scores in patients was statistically evaluated.

RESULTS

The mean age of patients in ED group was 60.4 ± 11.3 years and 55.4 ± 9.6 in control group. The plasma IGF-1 levels were significantly lower in ED than in control group (96.5 ± 38.3 and 132.5 ± 53.3 ng/ mL, respectively, P < 0.001). The IGF-1 levels were positively correlated with ED score (r = 0.623, P < 0.01).

CONCLUSION

In this study serum IGF-1 levels were found to be associated with endothelial dysfunction that predicts ED. Serum IGF-1 level appears to be a specific predictor of ED, and it might be used in early prediction of ED in male population.

Association between plasma fluorescent oxidation products and erectile dysfunction: A prospective study

BACKGROUND

Existing epidemiological studies of the association between oxidative stress and erectile dysfunction (ED) are sparse and inconclusive, which is likely due to cross-sectional design and small sample size. Therefore, we investigated the association between biomarkers of oxidative stress and ED in prospective setting among a relatively large sample size of men.

METHODS

We conducted the prospective study among 917 men ages between 47 and 80 years at the time of blood draw, which is a part of nested prospective case-control study of prostate cancer in the Health Professionals Follow-up Study. Plasma fluorescent oxidation products (FlOPs), a global biomarker for oxidative stress, were measured at three excitation/emission wavelengths (360/420 nm named as FlOP_360; 320/420 nm named as FlOP_320 and 400/475 nm named as FlOP_400).

RESULTS

Approximately 35% of men developed ED during follow-up. We did not find an independent association between FlOP_360, FlOP_320, FlOP_400 and risk of ED in the multivariable adjusted model (Tertile 3 vs. tertile 1: odds ratio [OR] = 0.90, 95% confidence interval [CI] = 0.61-1.34, P(trend) = 0.54 for FlOP_360; OR = 0.73, 95% CI = 0.49-1.07, P(trend) = 0.27 for FlOP_320; and OR = 0.98, 95% CI = 0.66-1.45, P(trend) = 0.72 for FlOP_400). Further analysis of the association between FlOPs and ED in the fasting samples or controls only (free of prostate cancer incidence) did not change the results appreciably.

CONCLUSIONS

Plasma FlOPs were not associated with the risk of ED, suggesting oxidative stress may not be an independent risk factor for ED.

Oxidative stress associated with middle aging leads to sympathetic hyperactivity and downregulation of soluble guanylyl cyclase in corpus cavernosum

Impairment of nitric oxide (NO)-mediated cavernosal relaxations in middle age contributes to erectile dysfunction. However, little information is available about the alterations of sympathetic neurotransmission and contraction in erectile tissue at middle age. This study aimed to evaluate the alterations of the contractile machinery associated with tyrosine hydroxylase (TH) in rat corpus cavernosum (RCC) at middle age, focusing on the role of superoxide anion. Male Wistar young (3.5-mo) and middle-aged (10-mo) rats were used. Electrical-field stimulation (EFS)- and phenylephrine-induced contractions were obtained in RCC strips. Levels of reactive-oxygen species (ROS) and TH mRNA expression, as well as protein expressions for α1/β1-subunits of soluble guanylyl cyclase (sGC), in RCC were evaluated. The neurogenic contractile responses elicited by EFS (4–32 Hz) were greater in RCC from the middle-aged group that was accompanied by elevated TH mRNA expression ( P < 0.01). Phenylephrine-induced contractions were also greater in the middle-aged group. A 62% increase in ROS generation in RCC from middle-aged rats was observed. The mRNA expression for the α1A-adrenoceptor remained unchanged among groups. Protein levels of α1/β1-sGC subunits were decreased in RCC from the middle-aged compared with young group. The NADPH oxidase inhibitor apocynin (85 mg·rat−1·day−1, 4 wk) fully restored the enhanced ROS production, TH mRNA expressions, and α1/β1-subunit sGC expression, indicating that excess of superoxide anion plays a major role in the sympathetic hyperactivity and hypercontractility in erectile tissue at middle age. Reduction of oxidative stress by dietary antioxidants may be an interesting approach to treat erectile dysfunction in aging population.

Prolonged therapy with the soluble guanylyl cyclase activator BAY 60-2770 restores the erectile function in obese mice

INTRODUCTION

Cardiovascular and endocrine-metabolic diseases associated with increased oxidative stress such as obesity lead to erectile dysfunction (ED). Activators of soluble guanylyl cyclase (sGC) such as BAY 60-2770 reactivate the heme-oxidized sGC in vascular diseases.

AIM

This study aimed to evaluate the effects of 2-week oral intake with BAY 60-2270 on a murine model of obesity-associated ED.

METHODS

C57BL/6 male mice were fed for 12 weeks with standard chow or high-fat diet. Lean and obese mice were treated with BAY 60-2770 (1 mg/kg/day, 2 weeks).

MAIN OUTCOME MEASURES

Measurements of intracavernosal pressure (ICP), along with acetylcholine (10(-9) to 10(-5)  M) and electrical field stimulation (EFS; 4-10 Hz)-induced corpus cavernosum relaxations in vitro, were obtained. Levels of cyclic guanosine monophosphate (cGMP), reactive oxygen species (ROS), and sGC protein expressions in cavernosal tissues were measured.

RESULTS

Cavernous nerve stimulation caused frequency-dependent ICP increases, which were significantly lower in obese compared with lean mice (P < 0.05). Two-week therapy with BAY 60-2770 fully reversed the decreased ICP in obese group. Acetylcholine-induced cavernosal relaxations were 45% lower (P < 0.001) in obese mice, which were fully restored by BAY 60-2770 treatment. Likewise, the EFS-induced relaxations in obese mice were restored by BAY 60-2770. Basal cGMP content in erectile tissue was 68% lower (P < 0.05) in obese mice, an effect normalized by BAY 60-2770. Levels of ROS were 52% higher (P < 0.05) whereas protein expression of α1 sGC subunit was reduced in cavernosal tissue of obese mice, both of which were normalized by BAY 60-2770. In lean group, BAY 60-2770 did not significantly affect any functional, biochemical, or molecular parameter analyzed.

CONCLUSIONS

Two-week therapy with BAY 60-2770 restores the erectile function in obese mice that is associated with reduced ROS levels, up-regulation of α1 sGC subunit, and increased cGMP levels in the erectile tissue.

Lipoprotein-associated phospholipase A2 levels are associated with erectile dysfunction in patients without known coronary artery disease

Endothelial dysfunction and microvascular damage play a crucial role in the pathogenesis of erectile dysfunction (ED). Lp-PLA2 is a calcium-independent member of the phospholipase A2 family and hydrolyses oxidised phospholipids on low-density lipoprotein (LDL) particles that plays a pivotal role in ox-LDL-induced endothelial dysfunction. The purpose of the current study was to determine the association between Lp-PLA2 levels and ED in patients without known coronary artery disease (CAD). All patients were evaluated for ED and divided into two groups: 88 patients suffering from ED for >1 year were enrolled as an experimental group and 88 patients without ED were enrolled as a control group in this study. Diagnosis of ED was based on the International Index of Erectile Function Score-5. Levels of Lp-PLA2 were measured in serum by colorimetric assay. The relationship between Lp-PLA2 levels and ED in patients was evaluated statistically. The mean age of patients with ED group was 59.4 ± 11.32 and 55.8 ± 9.67 in the control group. Plasma Lp-PLA2 levels were significantly higher in ED than in the control group (220.3 ± 66.90 and 174.8 ± 58.83 pg ml(-1) , respectively, P < 0.001). The Lp-PLA2 levels were negatively correlated with score of ED (r = -0.482, P < 0.05). In logistic regression analysis, enhanced plasma Lp-PLA2 levels result in approximately 1.2-fold increase in ED [1.22 (1.25-2.76)]. In this study, serum Lp-PLA2 levels were found to be associated with endothelial dysfunction predictive of ED. Serum Lp-PLA2 level appears to be a specific predictor of ED, and it may be used in early prediction of ED in the male population.

Resveratrol, an activator of SIRT1, restores erectile function in streptozotocin-induced diabetic rats

The high incidence of erectile dysfunction (ED) in diabetes highlights a need for effective treatment strategies. Resveratrol, an activator of silent information regulator 2-related enzymes 1 (sirtuin1, SIRT1), has received attention for its valuable effects in cancer, neurodegenerative diseases, longevity and cardiovascular disease. To explore the effects of resveratrol in diabetes-induced ED, resveratrol was administered to rats with streptozocin (65 mg kg(-1))-induced diabetes. Erectile function, cavernous structure, tissue protein expression of silent information regulator 2-related enzymes 1 (sirtuin1, SIRT1), p53 and forkhead transcription factor O 3a (FOXO3a), superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels in the corpora cavernosa were studied. We found that SIRT1 was expressed in cavernosal tissue, and it was downregulated in the corpora of diabetic rats. The administration of resveratrol upregulated the expression of SIRT1 and restored erectile function. In contrast, resveratrol downregulated the expression of p53 and FOXO3a, which regulate apoptosis and oxidative stress. Furthermore, the resveratrol-treated group showed an improvement in smooth muscle content, SOD activity and MDA levels when compared with the diabetic group. Therefore, the ability of resveratrol to improve diabetes-induced ED is likely related to its activation of SIRT1 expression, thus causing the suppression of apoptosis and resistance towards oxidative stress.

S-allyl cysteine restores erectile function through inhibition of reactive oxygen species generation in diabetic rats

Excessive production of reactive oxygen species (ROS) by an overactive nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system in penile tissue is an important mechanism of erectile dysfunction (ED). S-allyl cysteine (SAC), a bioactive component derived from garlic, was recently reported to exert versatile antioxidant properties. We hypothesized that SAC would be able to resolve diabetes-related ED by reducing ROS generation, and designed this study to investigate this possibility as well as to determine the related underlying mechanisms. A streptozotocin-induced diabetes rat model was established and used for comparative analysis of 4-week treatment regimens with insulin or SAC. The ratio of maximal intracavernous pressure (ICP) to mean arterial blood pressure (MAP) was measured to determine erectile function. Differential levels of ROS, NADPH oxidase subunits, nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signalling pathway, and apoptosis were evaluated in cavernous tissues. Max ICP/MAP was found to be markedly decreased in untreated diabetic rats; SAC, but not insulin, treatment restored the ratio to baseline (in non-diabetic untreated controls). The corpus cavernosum of untreated diabetic rats showed increased p47(phox) and p67(phox) expression, ROS production and penile apoptotic index, and decreased phospho-endothelial nitric oxide synthase (phospho-eNOS, Ser1177) expression, cGMP concentration, B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein (Bax) ratio and smooth muscle cell number. SAC treatment normalized all the diabetes-induced effects, whereas insulin treatment partially normalized the alterations, but produced no effects on P47(phox) expression, penile ROS level, apoptotic index, Bcl-2/Bax ratio and smooth muscle cell number. Collectively, these data indicate that SAC treatment can restore erectile function in diabetic rats by preventing ROS formation through modulation of NADPH oxidase subunit expression. Furthermore, the poor efficacy of conventional insulin treatment for diabetic ED may be associated with an elevated level of ROS in penile tissue.

Superoxide anion production by NADPH oxidase plays a major role in erectile dysfunction in middle-aged rats: prevention by antioxidant therapy

INTRODUCTION.: Prevalence of erectile dysfunction (ED) increases progressively with aging, but the ED pathophysiology at its early stages is still poorly investigated. AIM.: This study aimed to evaluate the functional and molecular alterations of erectile function at middle age, focusing on the contribution of oxidative stress in erectile tissue for the ED. METHODS.: Young (3.5-month) and middle-aged (10-month) male Wistar rats were used. Rat corpus cavernosum (RCC) was dissected free and mounted in 10-mL organ baths containing Krebs solution. Intracavernosal pressure (ICP) in anesthetized rats was evaluated. MAIN OUTCOME MEASURES.: Concentration-response curves to endothelium-dependent and endothelium-independent agents, as well as to electrical field stimulation (EFS), were obtained in RCC strips. Measurement of cyclic guanosine monophosphate (cGMP) and expressions of neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS), gp91(phox) and superoxide dismutase-1 (SOD-1) expressions in RCC were evaluated. RESULTS.: ICP was significantly reduced in middle-aged compared with young rats. RCC relaxations to acetylcholine (10(-8) to 10(-2)  M), sodium nitroprusside (10(-8) to 10(-2)  M), sildenafil (10(-9) to 10(-5)  M), BAY 41-2272 (10(-9) to 10(-5)  M), and EFS (4-32 Hz) were decreased in middle-aged group, which were nearly normalized by apocynin (NADPH oxidase inhibitor; 10(-4)  M) or SOD (75 U/mL). Prolonged treatment with apocynin (85 mg/rat/day, 4 weeks) also restored the impaired relaxations in middle-aged rats. Relaxations to 8-bromoguanosine 3',5'-cyclic monophosphate sodium salt (8-Br-cGMP; 10(-8) to 3 × 10(-4)  M) remained unchanged between groups. Basal and stimulated cGMP production were lower in middle-aged group, an effect fully restored by apocynin and SOD. Protein expression of nNOS and phosphorylated eNOS (p-eNOS) (Ser-1177) reduced, whereas gp(91phox) mRNA expression increased in RCC from middle-aged rats. CONCLUSIONS.: ED in middle-aged rats is associated with decreased NO bioavailability in erectile tissue due to upregulation of NADPH oxidase subunit gp91(phox) and downregulation of nNOS/p-eNOS. Antioxidant therapies may be a good pharmacological approach to prevent ED at its early stages.

Effect of felodipine with irbesartan or metoprolol on sexual function and oxidative stress in women with essential hypertension

OBJECTIVE

To evaluate the impact of felodipine with irbesartan on sexual function compared with felodipine with metoprolol in hypertensive women.

METHODS

This was a prospective, randomized, parallel, active-controlled, open-label study (ClinicalTrials.org: NCT01238705) in 160 women (18-60 years) with mild or moderate hypertension, randomized to a once-daily treatment with felodipine combined with irbesartan or metoprolol for 48 weeks. Patients' sexual function was evaluated using a female sexual function index (FSFI) questionnaire at baseline and after 24 and 48 weeks of therapy. Levels of serum estradiol, testosterone, 8-hydroxy-2'-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA) were measured.

RESULTS

The two combination regimens were similarly effective in lowering blood pressure. After 48 weeks, in felodipine-irbesartan group, total scores of FSFI improved (P < 0.001). Items showing improvement in scores corresponded to desire, arousal and orgasm (P < 0.001; P = 0.002; P = 0.049, respectively). Levels of estradiol increased under treatment with felodipine-irbesartan (P = 0.003) and decreased under felodipine-metoprolol treatment (P < 0.001). The concentration of testosterone declined after felodipine-irbesartan therapy (P < 0.001) and increased under felodipine-metoprolol treatment (P < 0.001). In the felodipine-irbesartan group, decreases of 8-OHdG, 4-HNE (P < 0.001) and MDA (P < 0.001) were observed. The felodipine-irbesartan combination resulted in less oxidative stress. The differences in changes in 8-OHdG, 4-HNE and MDA between the two groups were significant (P < 0.05).

CONCLUSION

These results suggested that the felodipine-irbesartan combination regimen improved sexual function in hypertensive women, whereas felodipine-metoprolol regiment did not. The reason for the different influence of these two combination therapy on female sexual function might be their different impacts on oxidative stress and hormone levels.

Amelioration of diabetes-induced cavernosal fibrosis by antioxidant and anti-transforming growth factor-β1 therapies in inducible nitric oxide synthase-deficient mice

OBJECTIVE

•  To investigate whether sustained long-term separate treatments of diabetic inducible nitric oxide synthase knockout (iNOSKo) mice with allopurinol, an antioxidant inhibiting xanthine oxidoreductase, decorin, a transforming growth factor-β1 (TGFβ1) -binding antagonist, and molsidomine, a long-life nitric oxide donor, prevent the processes of diabetes-induced cavernosal fibrosis.

MATERIALS AND METHODS

•  Eight week old male iNOS knock out (iNOSKo) mice were made diabetic by injecting 150 mg/kg B.W Streptozotocin (1P) with were either left untreated or treated with the oral antioxidant allopurinol (40 mg/kg/day), or decoin (50 mg, 1P, twice), as an anti-TGFβ1 agent (n = 8/group). •  Glycemia and oxidative stress markers were determined in blood and urine. •  Paraffin-embedded tissue sections from the penile shaft were subjected to Masson trichrome staining for the smooth muscle (smc)/collagen ratio, and imunostaining for smc content, profibrotic factors, oxidative stress, cell replication and cell death markers followed by quantitative image analysis.

RESULTS

•  Eight-week treatment with either allopurinol or decorin counteracted the decrease in smooth muscle cells and the increase in apoptosis and local oxidative stress within the corpora tissue. •  Decorin but not allopurinol increased the smooth muscle cell/collagen ratio, whereas allopurinol but not decorin inhibited systemic oxidative stress. •  Molsidomine was effective in reducing both local and systemic oxidative stress, but did not prevent corporal fibrosis.

CONCLUSION

•  Both allopurinol and decorin appear as promising approaches either as a single or a combined pharmacological modality for protecting the diabetic corpora from undergoing apoptosis and fibrosis although their functional effects still need to be defined.

Mammalian Cyclic Nucleotide Phosphodiesterases: Molecular Mechanisms and Physiological Functions

The superfamily of cyclic nucleotide (cN) phosphodiesterases (PDEs) is comprised of 11 families of enzymes. PDEs break down cAMP and/or cGMP and are major determinants of cellular cN levels and, consequently, the actions of cN-signaling pathways. PDEs exhibit a range of catalytic efficiencies for breakdown of cAMP and/or cGMP and are regulated by myriad processes including phosphorylation, cN binding to allosteric GAF domains, changes in expression levels, interaction with regulatory or anchoring proteins, and reversible translocation among subcellular compartments. Selective PDE inhibitors are currently in clinical use for treatment of erectile dysfunction, pulmonary hypertension, intermittent claudication, and chronic pulmonary obstructive disease; many new inhibitors are being developed for treatment of these and other maladies. Recently reported x-ray crystallographic structures have defined features that provide for specificity for cAMP or cGMP in PDE catalytic sites or their GAF domains, as well as mechanisms involved in catalysis, oligomerization, autoinhibition, and interactions with inhibitors. In addition, major advances have been made in understanding the physiological impact and the biochemical basis for selective localization and/or recruitment of specific PDE isoenzymes to particular subcellular compartments. The many recent advances in understanding PDE structures, functions, and physiological actions are discussed in this review.

8-isoprostane F2α up-regulates the expression of type 5 phosphodiesterase in cavernosal vascular smooth muscle cells: inhibition with sildenafil, iloprost, nitric oxide and picotamide

OBJECTIVES

To explore the possible role of of 8-isoprostane F(2α) (8-IPF(2α) ) in the aetiology of erectile dysfunction (ED), as the over-production of superoxide (O(2)(-)) derived from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase results in the formation of 8-IPF(2α) in vascular tissue, which has similar properties to thromboxane A(2) (TXA(2) ). TXA(2) is vasoconstrictor and up-regulates the expression of NADPH oxidase and phosphodiesterase type 5 (PDE5).

MATERIALS AND METHODS

Cavernosal vascular smooth muscle cells (CVSMCs) were incubated with 8-IPF(2α) or the TXA(2) analogue, U46619, ±sildenafil, iloprost (a stable prostacyclin [PGI(2) ] analogue) or the nitric oxide (NO) donor NONOate for 16 h. The formation of O(2)(-) was then measured, PDE5 expression assessed using Western blotting and PGI(2) and 8-IPF(2α) formation measured using enzyme-linked immunoassays.

RESULTS

8-IPF(2α) promoted the formation of O(2)(-) , an effect inhibited by apocynin (an NADPH oxidase inhibitor) and up-regulated the expression of PDE5. Under identical incubation conditions, 8-IPF(2α) induced an increase in the formation of 8-IPF(2α) but reduced the formation of PGI(2) . All, these effects were reversed by sildenafil, iloprost, NONOate and picotamide.

CONCLUSIONS

These data show that O(2) (-) derived from NADPH oxidase influences the relative balance of PGI(2) and 8-IPF(2α) in CVSMCs, which in turn alters the degree of PDE5 expression. This is a novel pathogenic mechanism underlying ED and a novel mechanism of action of sildenafil.

Effect of hydrogen sulphide-donating sildenafil (ACS6) on erectile function and oxidative stress in rabbit isolated corpus cavernosum and in hypertensive rats

OBJECTIVE To study the effect of the H(2)S-donating derivative of sildenafil (ACS6) compared to sildenafil citrate and sodium hydrosulphide (NaHS) on relaxation, superoxide formation and NADPH oxidase and type 5 phosphodiesterase (PDE5) expression in isolated rabbit cavernosal tissue and smooth muscle cells (CSMCs), and in vivo on indices of oxidative stress induced with buthionine sulphoximine (BSO). MATERIALS AND METHODS Relaxation was studied in an organ bath in response to carbachol and after incubation with interleukin-1beta for 12 h. CSMCs were incubated with tumour-necrosis factor-alpha or the thromboxane A(2) (TXA(2)) analogue, U46619, with or with no sildenafil citrate, ACS6 or NaHS for 16 h. Superoxide formation and the expression of p47(phox) (an active subunit of the NADPH oxidase complex) and PDE5 protein was then assessed using Western blotting. Rats were also treated with BSO (with or with no sildenafil citrate or ACS6) for 7 days; cavernosal cGMP, cAMP, glutathionine and plasma TXA(2) and 8-isoprostane F(2alpha) was measured by enzyme-linked immunosorbent assay. RESULTS ACS6 and sildenafil citrate relaxed cavernosal smooth muscle equipotently; NaHS alone had little effect at up to 100 microm. The formation of superoxide and expression of p47(phox) and PDE5 was reduced by ACS6, sildenafil citrate and NaHS (order of potency: ACS6 > sildenafil citrate > NaHS). The effects of ACS6 were blocked by inhibitors of protein kinase A (PKA) and PKG. In rats treated with BSO, both ASC6 and sildenafil citrate reduced the increased plasma levels of TXA(2) and 8-isoprostane F(2alpha) but increased cGMP, cAMP and glutathionine levels in corpus cavernosum. CONCLUSIONS By virtue of a dual action on PKA and PKG activation, ACS6 not only promotes erection, acutely, but might also have a long-term beneficial effect through inhibition of oxidative stress and downregulation of PDE5.