Testosterone and erectile function: from basic research to a new clinical paradigm for managing men with androgen insufficiency and erectile dysfunction

Whole genome mRNA expression profiling revealed multiple deregulated pathways in stromal vascular fraction from erectile dysfunction patients

Background: Stem-cell-based therapies have recently been explored in the field of erectile dysfunction (ED). However, the cellular and molecular phenotype of adipose derived stem cells (ADSCs) stromal vascular fraction (SVF) from ED patients remains largely unknown. Herein we compared the global gene expression profile in the SVF from ED patients and healthy individuals and identified altered signaling pathways between the two groups.

Methods: Samples (2–5 g) of abdominal adipose tissue from ED patients (n = 6) and healthy individual controls (n = 3) undergoing elective cosmetic liposuction were collected. Immediately after removal, SVF was separated using Collagenase type I and type IV protocol. RNA was isolated and microarray experiments were conducted using the Agilent platform. Data were normalized and pathway analyses were performed using GeneSpring software.

Results: Our data revealed multiple differentially expressed genes between the ED and control group. Hierarchical clustering based on differentially expressed mRNAs revealed clear separation of the two groups. The distribution of the top enriched pathways for the up-regulated genes indicated enrichment in inflammatory response and T-cell receptor signaling, while pathway analysis performed on the down-regulated genes revealed enrichment in mitogen-activated protein kinase, TGF-β, senescence, FAK, adipogenesis, androgen receptor, and EGF–EGFR signaling pathways in SVF from ED patient.

Conclusion: Our data revealed the existence of multiple altered signaling pathways in the SVF from ED patients, which could potentially play a role in the etiology of this disease. Therefore, therapeutic strategies targeting these pathways might provide novel therapeutic opportunity for ED patients.

Impact of anabolic androgenic steroids on sexual function

Background

To describe the impact of supra-physiologic anabolic-androgenic steroid (AAS) use, including agent, dosage, and duration of therapy, on sexual function.

Methods

We reviewed data from an online survey of AAS users to evaluate their sexual function on and off AAS. The online survey consisted of questions addressing demographics, anabolic steroid use and patterns, ancillary medications, testosterone (T)-related symptoms while on and off of therapy, as well as sexual function which was assessed using the 5-item, International Index of Erectile Function (IIEF-5).

Results

A total of 321 men responded to the survey, of which 90 failed to meet inclusion criteria, for a final cohort of 231 AAS users. The majority of men were Caucasian (85%), employed (62%), and younger than 35 years (58%), while an equal mix were single (47%) or married (46%). The mean IIEF-5 was 22.5, with higher scores associated with increased T dosages (>600 mg/week), use of 17-alpha alkylated hormones and anti-estrogens, and absence of concurrent medical conditions. Lower mean IIEF scores were associated with current and pre-AAS low T symptoms, self-reported angry or violent tendencies, self-reported erectile dysfunction (ED), decreased libido, decreased energy, and depression. After controlling for age, low T symptoms and decreased energy remained significantly associated with lower IIEF scores. Among 127 men reporting de novo decreased libido when not taking AAS, several factors were significantly associated including frequency and duration of T and use of adjunctive therapies, while post-cycle therapies were protective. Men who reported any other de novo symptom (decreased energy, libido, muscle mass or depression) after discontinuing T were also more likely to report de novo ED, as well as those using >10 years or for >40 weeks per year.

Conclusions

The long-term impact of high dose AAS use on sexual function remains poorly defined. Although high T dosages appeared to be protective of erectile function during use, de novo symptoms such as decreased libido and ED occurred more frequently after discontinuing T, particularly among those using more frequently and for longer durations. Given the importance of these findings, long-term studies evaluating the impacts of discontinuing T on sexual dysfunction are indicated.

The Effect of Testosterone Replacement Therapy on Penile Hemodynamics in Hypogonadal Men With Erectile Dysfunction, Having Veno-Occlusive Dysfunction

Hypogonadism may cause veno-occlusive dysfunction (VOD) by structural and biochemical alterations in the cavernosal tissue. The aim of the study was to investigate the effect of testosterone replacement therapy (TRT) on penile hemodynamics in hypogonadal men with erectile dysfunction and VOD.

The study included 32 hypogonadal men with erectile dysfunction, having VOD. All patients underwent penile color Doppler ultrasonography (PCDU) at the beginning and 6 months after the initial evaluation. Erectile function was evaluated with the 5-item version of the International Index of Erectile Function (IIEF-5); hypogonadism was evaluated by testosterone measurement and the Aging Male Symptoms (AMS) scale. All patients received transdermal testosterone 50 mg/day for 6 months. Clinical and radiological findings were compared before and 6 months after the TRT.

The mean age was 58.81 ± 4.56 (52–69) years. Mean total testosterone levels were 181.06 ± 39.84 ng/dL and 509.00 ± 105.57 ng/dL before and after the therapy, respectively (p < .001). While all patients had physiological serum testosterone levels (>320 ng/dL) after the therapy, three cases (9.3%) had no clinical improvement of hypogonadism symptoms. Cavernosal artery peak systolic velocity (PSV) and resistive index (RI) significantly increased, and end diastolic velocity (EDV) significantly decreased after TRT. VOD no longer existed in 21 (65.6%) of the cases.

This study demonstrated that TRT may restore penile hemodynamics in hypogonadal men with VOD.

Testosterone Deficiency Causes Endothelial Dysfunction via Elevation of Asymmetric Dimethylarginine and Oxidative Stress in Castrated Rats

BACKGROUND

Testosterone is believed to mediate the penile erectile response by producing adequate nitric oxide; therefore, testosterone deficiency results in erectile dysfunction through decreased nitric oxide bioavailability. However, the mechanisms underlying endothelial dysfunction in testosterone deficiency remain unclear.

AIM

To investigate the mechanism of endothelial dysfunction in a rat model of testosterone deficiency.

METHODS

Rats were distributed into 3 groups: castrated (Cast), castrated and supplemented with testosterone (Cast + T), and sham (Sham). In the Cast + T group, castrated rats were treated daily with subcutaneous testosterone (3 mg/kg daily) for 4 weeks; Sham and Cast rats received only the vehicle.

OUTCOMES

Erectile function using intracavernosal pressure and mean arterial pressure measurements after electrical stimulation of the cavernous nerve, endothelial function using isometric tension, asymmetric dimethylarginine (ADMA) levels using ultra-performance liquid chromatography and tandem mass spectrometry, and inflammatory biomarker expression were performed 4 weeks after the operation.

RESULTS

In the Cast group, the ratio of intracavernosal pressure to mean arterial pressure significantly decreased, acetylcholine-induced relaxation was lower, and serum ADMA, oxidative stress, and inflammation biomarker levels were significantly increased (P < .01). Testosterone injection significantly improved each of these parameters (P < .01).

CLINICAL TRANSLATION

The present results provide scientific evidence of the effect of testosterone deficiency on erectile function and the effect of testosterone replacement therapy.

STRENGTHS AND LIMITATIONS

This study provides evidence of the influence of testosterone deficiency on endothelial function by investigating ADMA and oxidative stress. A major limitation of this study is the lack of a direct link of increased ADMA by oxidative stress to inflammation.

CONCLUSION

Testosterone deficiency increased not only ADMA levels but also oxidative stress and inflammation in castrated rats, which can cause damage to the corpus cavernosum, resulting in erectile dysfunction. Kataoka T, Hotta Y, Maeda Y, Kimura K. Testosterone Deficiency Causes Endothelial Dysfunction via Elevation of Asymmetric Dimethylarginine and Oxidative Stress in Castrated Rats. J Sex Med 2017;14:1540-1548.

Testosterone replacement in transgenic sickle cell mice controls priapic activity and upregulates PDE5 expression and eNOS activity in the penis

Sickle cell disease (SCD)-associated priapism is characterized by decreased nitric oxide (NO) signaling and downregulated phosphodiesterase (PDE)5 protein expression and activity in the penis. Priapism is also associated with testosterone deficiency, but molecular mechanisms underlying testosterone effects in the penis in SCD are not known. Given the critical role of androgens in erection physiology and NO synthase (NOS)/PDE5 expression, we hypothesized that testosterone replacement to eugonadal testosterone levels reduces priapism by reversing impaired endothelial (e)NOS activity and molecular abnormalities involving PDE5. Adult male transgenic Berkeley sickle cell (Sickle) and wild-type (WT) mice were implanted with testosterone pellets, which release 1.2 μg testosterone/day for 21 days, or vehicle. After 21 days, animals underwent erectile function assessment followed by collection of blood for serum testosterone measurements, penes for molecular analysis, and seminal vesicles as testosterone-responsive tissue. Serum testosterone levels were measured by radioimmunoassay; protein expressions of PDE5, α-smooth muscle actin, eNOS and nNOS, and phosphorylation of PDE5 at Ser-92, eNOS at Ser-1177, neuronal (n) NOS at Ser-1412, and Akt at Ser-473 were measured by Western blot in penile tissue. Testosterone treatment reversed downregulated serum testosterone levels and increased (p < 0.05) the weight of seminal vesicles in Sickle mice to levels comparable to that of WT mice, indicating restored testosterone levels in Sickle mice. Testosterone treatment reduced (p < 0.05) prolonged detumescence in Sickle mice and normalized downregulated P-PDE5 (Ser-92), PDE5, P-eNOS (Ser-1177), and P-Akt (Ser-473) protein expressions in the Sickle mouse penis. Testosterone treatment did not affect P-nNOS (Ser-1412), eNOS, nNOS, or α-smooth muscle actin protein expressions in the Sickle mouse penis. In conclusion, in the mouse model of human SCD, increasing testosterone to eugonadal levels reduced priapic activity and reversed impaired Akt/eNOS activity and PDE5 protein expression in the penis.

Benefits and Health Implications of Testosterone Therapy in Men With Testosterone Deficiency

INTRODUCTION

Testosterone (T) deficiency (TD; hypogonadism) has deleterious effects on men's health; negatively affects glycometabolic and cardiometabolic functions, body composition, and bone mineral density; contributes to anemia and sexual dysfunction; and lowers quality of life. T therapy (TTh) has been used for the past 8 decades to treat TD, with positive effects on signs and symptoms of TD.

AIM

To summarize the health benefits of TTh in men with TD.

METHODS

A comprehensive literature search was carried out using PubMed, articles relevant to TTh were accessed and evaluated, and a comprehensive summary was synthesized.

MAIN OUTCOME MEASURES

Improvements in signs and symptoms of TD reported in observational studies, registries, clinical trials, and meta-analyses were reviewed and summarized.

RESULTS

A large body of evidence provides significant valuable information pertaining to the therapeutic value of TTh in men with TD. TTh in men with TD provides real health benefits for bone mineral density, anemia, sexual function, glycometabolic and cardiometabolic function, and improvements in body composition, anthropometric parameters, and quality of life.

CONCLUSION

TTh in the physiologic range for men with TD is a safe and effective therapeutic modality and imparts great benefits on men's health and quality of life. Traish AM. Benefits and Health Implications of Testosterone Therapy in Men With Testosterone Deficiency. Sex Med Rev 2018;6:86-105.

Translational Perspective on the Role of Testosterone in Sexual Function and Dysfunction

INTRODUCTION

The biological importance of testosterone is generally accepted by the medical community; however, controversy focuses on its relevance to sexual function and the sexual response, and our understanding of the extent of its role in this area is evolving.

AIM

To provide scientific evidence examining the role of testosterone at the cellular and molecular levels as it pertains to normal erectile physiology and the development of erectile dysfunction and to assist in guiding successful therapeutic interventions for androgen-dependent sexual dysfunction.

METHODS

In this White Paper, the Basic Science Committee of the Sexual Medicine Society of North America assessed the current basic science literature examining the role of testosterone in sexual function and dysfunction.

RESULTS

Testosterone plays an important role in sexual function through multiple processes: physiologic (stimulates activity of nitric oxide synthase), developmental (establishes and maintains the structural and functional integrity of the penis), neural (development, maintenance, function, and plasticity of the cavernous nerve and pelvic ganglia), therapeutically for dysfunctional regulation (beneficial effect on aging, diabetes, and prostatectomy), and phosphodiesterase type 5 inhibition (testosterone supplement to counteract phosphodiesterase type 5 inhibitor resistance).

CONCLUSION

Despite controversies concerning testosterone with regard to sexual function, basic science studies provide incontrovertible evidence for a significant role of testosterone in sexual function and suggest that properly administered testosterone therapy is potentially advantageous for treating male sexual dysfunction.

Effects of taking tadalafil 5 mg once daily on erectile function and total testosterone levels in patients with metabolic syndrome

We aimed to evaluate the efficacy of tadalafil 5 mg once-daily treatment on testosterone levels in patients with erectile dysfunction (ED) accompanied by the metabolic syndrome. A total of 40 men with metabolic syndrome were evaluated for ED in this study. All the patients received 5 mg tadalafil once a day for 3 months. Erectile function was assessed using the five-item version of the International Index of Erectile Function (IIEF) questionnaire. Serum testosterone, follicle-stimulating hormone and luteinising hormone levels were also evaluated, and blood samples were taken between 08.00 and 10.00 in the fasting state. All participants have three or more criteria of metabolic syndrome. At the end of 3 months, mean testosterone values and IIEF scores showed an improvement from baseline values (from 3.6 ± 0.5 to 5.2 ± 0.3, from 11.3 ± 1.9 to 19 ± 0.8 respectively). After the treatment, serum LH levels were decreased (from 5.6 ± 0.6 to 4.6 ± 0.5). There was significantly difference in terms of baseline testosterone and luteinising hormone values and IIEF scores (p < .05). Based on our findings, we recommend tadalafil 5 mg once daily in those men with erectile dysfunction especially low testosterone levels accompanied by metabolic syndrome.

The inter-relational effect of metabolic syndrome and sexual dysfunction on hypogonadism in type II diabetic men

We sought to establish the interplay of metabolic syndrome (MetS) and/or sexual dysfunction (SD) on hypogonadism. Sexual functioning was assessed using Golombok Rust Inventory of Sexual Satisfaction in 274 consecutive diabetic men visiting the diabetic clinic of the Tema General Hospital between November 2010 and March 2011. MetS was assessed employing the criteria of World Health Organization, International Diabetic Federation and the National Cholesterol Education Program Adult Treatment Panel III while testosterone levels were estimated. The mean ages and duration of diabetes from this study were 59.9±11.3 and 6.8±5.9 years, respectively. The prevalence of hypogonadism was 7.3%, with the -SD/+MetS subjects showing the highest prevalence of hypogonadism, irrespective of the criteria used. Additionally, subjects with MetS and its components had a significantly lower level of testosterone compared with those without MetS and its components. Using standard nine-point scale, it was observed that subjects who avoided sexual act had significantly (P=0.0410) lower testosterone values (5.8±2.3 ng ml^-1) than subjects who did not avoid sexual act (6.4±2.6 ng ml^-1). MetS alone impacted more on hypogonadism than SD alone or both conditions altogether.

The relationship of salivary testosterone and male sexual dysfunction in opioid-associated androgen deficiency (OPIAD)

BACKGROUND

Opioids are an effective treatment for chronic non-malignant pain (CNP). Long-term use risks and side effects such as opioid-induced androgen deficiency (OPIAD) exist. This could be measured by saliva testosterone (Sal-T).

OBJECTIVES

To evaluate OPIAD in long-term opioid use in CNP patients.

METHODS

A cross-sectional study included CNP male outpatients under opioid treatment. Total-Testosterone (Total-T), Free-Testosterone (Free-T), Bio-Testosterone (Bio-T) and Sal-T were measured. Correlations were calculated by Spearman's rho (SPSS 20).

RESULTS

From 2012 to 2014, 134 from 249 (54%) consecutive male outpatients reported erectile dysfunction (ED), 37% of them related to opioids and 19% evidenced OPIAD. A total of 120 subjects (94 cases and 26 matched-controls) were included. A significantly lower luteinizing hormone, Total-T and Free-T were found, as well as, a significant correlation between Sal-T and Total-T (r = 0.234, p = 0.039), Bio-T (r = 0.241, p = 0.039), IIEF (r = 0.363, p = 0.003) and HAD-anxiety (r = -0.414, p = 0.012) in OPIAD patients. Sal-T levels were significantly lower in patients with severe-moderate ED versus mild ED (p = 0.045) and in patients with severe ED versus moderate-mild ED (p = 0.036).

CONCLUSIONS

These data demonstrate the high prevalence of ED in long-term use of opioids, part of this is associated to OPIAD, which can be tested by Sal-T as a non-invasive approach.

Testosterone replacement maintains smooth muscle content in the corpus cavernosum of orchiectomized rats

Objective

To evaluate the effects of testosterone (T) on the maintenance of corpus cavernosum (CC) structure and apoptosis.

Methods

Animals were divided into three groups: sham operation group (n = 8) underwent sham operation; Orchiectomized (Orchiec)+ oily vehicle group (n = 8) underwent bilateral orchiectomy and received a single dose of oily vehicle by intramuscular injection (i.m.) 30 days after orchiectomy; and Orchiec + T group (n = 8) underwent bilateral orchiectomy and received a single dose of T undecanoate 100 mg/kg i.m. 30 days after the surgery. Animals were euthanized 60 days after the beginning of the experiment with an anesthetic overdose of ketamine and xylazine. Blood samples and penile tissue were collected on euthanasia. Azan's trichrome staining was used to evaluate smooth muscle, Weigert's Fucsin-Resorcin staining was used to evaluate elastic fibers and Picrosirius red staining was used to evaluate collagen. Apoptosis was evaluated using TUNEL technique.

Results

T levels decreased in Orchiec + oily vehicle when compared to sham operation and Orchiec + T groups (p < 0.001). T deprivation reduced trabecular smooth muscle content and penile diameter and T replacement maintained both parameters (p = 0.005 and p = 0.001, respectively). No difference was observed in the content of sinusoidal space (p = 0.207), elastic fibers (p = 0.849), collagen (p = 0.216) and in apoptosis (p = 0.095).

Conclusion

Normal testosterone levels maintain CC smooth muscle content and do not influence elastic fibers, collagen content and apoptotic index. Further studies should be performed in order to investigate the mechanisms by which androgen mediates its effects on CC structure.

The role of estradiol in male reproductive function

Traditionally, testosterone and estrogen have been considered to be male and female sex hormones, respectively. However, estradiol, the predominant form of estrogen, also plays a critical role in male sexual function. Estradiol in men is essential for modulating libido, erectile function, and spermatogenesis. Estrogen receptors, as well as aromatase, the enzyme that converts testosterone to estrogen, are abundant in brain, penis, and testis, organs important for sexual function. In the brain, estradiol synthesis is increased in areas related to sexual arousal. In addition, in the penis, estrogen receptors are found throughout the corpus cavernosum with high concentration around neurovascular bundles. Low testosterone and elevated estrogen increase the incidence of erectile dysfunction independently of one another. In the testes, spermatogenesis is modulated at every level by estrogen, starting with the hypothalamus-pituitary-gonadal axis, followed by the Leydig, Sertoli, and germ cells, and finishing with the ductal epithelium, epididymis, and mature sperm. Regulation of testicular cells by estradiol shows both an inhibitory and a stimulatory influence, indicating an intricate symphony of dose-dependent and temporally sensitive modulation. Our goal in this review is to elucidate the overall contribution of estradiol to male sexual function by looking at the hormone's effects on erectile function, spermatogenesis, and libido.

Dutasteride-mediated morphological changes in the genitourinary tract associated with altered expression patterns of the androgen and estrogen receptors in male rats

We evaluated the effects of dutasteride on the genitourinary tract using fifteen 8-week-old male Sprague-Dawley rats. Animals were divided into three groups comprising five animals each and treated as follows. Group A was a control group, members of Group B received oral administration of dutasteride 0.1 mg/kg/day from the age of 8 to 16 weeks, and members of Group C were castrated at the age of 8 weeks. All rats were killed at the age of 16 weeks for the sample collection of blood, bladder, prostate, seminal vesicles, and penis. Then, we evaluated the pathological examination for evaluating the tissue fibrosis and hormonal receptor expression. The results showed that the mean size of the prostate and seminal vesicles was smaller in Group B and Group C than in Group A. Serum and tissue concentrations of both testosterone and dihydrotestosterone were remarkably reduced in serum and all tissues in Group C compared with Group A. On the other hand, in Group B, only dihydrotestosterone was reduced in serum and penis. Histopathological examination revealed that Group C showed statistically significant histological changes, such as an increase in fibrotic tissue in the bladder, prostate, and penis. Similarly, Group B showed fibrotic changes in the prostate and penis compared with the Group A. Immunofluorescent staining revealed that the androgen receptor was more strongly expressed than the estrogen receptor beta in Group A. On the other hand, in Group C, weak expression of the androgen receptor and strong expression of the estrogen receptor beta was noted. In Group B, these changes were noted in the prostate and penis. These findings suggest that dutasteride cause morphological changes not only in prostate but also in penis. These changes are associated with altered expression patterns of androgen receptor and estrogen receptor.

Challenges in Testosterone Measurement, Data Interpretation, and Methodological Appraisal of Interventional Trials

INTRODUCTION

Male hypogonadism is a common condition, with an increasing body of literature on diagnosis, implications, and management. Given the significant variability in testosterone (T) from a physiologic and assay perspective, a thorough understanding of factors affecting T values and study methodology is essential to interpret reported study outcomes appropriately. However, despite the large number of publications on T, there are no reference materials consolidating all relevant and potentially confounding factors necessary to interpret T studies appropriately.

AIMS

To create a resource document that reviews sources of T variability, free vs total T, assay techniques and questionnaires, and study methodology relevant to interpreting outcomes.

METHODS

A PubMed search was performed of all the T literature published on T variability, assay techniques, and T-specific questionnaires. Results were summarized in the context of their impact on interpreting T literature outcomes and methodology.

MAIN OUTCOME MEASURES

Effect of various factors on T variability and their relevance to study methodology and outcomes.

RESULTS

Several factors affect measured T levels, including aging, circadian rhythms, geography, genetics, lifestyle choices, comorbid conditions, and intraindividual daily variability. The utility of free T over total T is debatable and must be compared using appropriate threshold levels. Among various assay techniques, mass spectrometry and equilibrium dialysis are gold standards. Calculated empirical estimates of free T also are commonly used and accepted. Hypogonadism-specific questionnaires have limited utility in screening for hypogonadism, and their role as objective end points for quantifying symptoms remains unclear. Numerous aspects of study methodology can directly or indirectly affect reported outcomes, including design (randomized, prospective, retrospective), duration, populations studied (age, comorbid conditions), low T threshold, therapeutic agent used, objective measurements and end points selected, and statistical interpretation.

CONCLUSION

Critical appraisal of the T literature requires an understanding of numerous factors resulting in T variability, study design and methodology, and limitations of assay techniques and objective measurement scales.

Increased risk of osteoporosis in patients with erectile dysfunction: A nationwide population-based cohort study

In this study, we aimed to investigate the risk of osteoporosis in patients with erectile dysfunction (ED) by analyzing data from the Taiwan National Health Insurance Research Database (NHIRD). From the Taiwan NHIRD, we analyzed data on 4460 patients aged ≥40 years diagnosed with ED between 1996 and 2010. In total, 17,480 age-matched patients without ED in a 1:4 ratio were randomly selected as the non-ED group. The relationship between ED and the risk of osteoporosis was estimated using Cox proportional hazard regression models. During the follow-up period, 264 patients with ED (5.92%) and 651 patients without ED (3.65%) developed osteoporosis. The overall incidence of osteoporosis was 3.04-fold higher in the ED group than in the non-ED group (9.74 vs 2.47 per 1000 person-years) after controlling for covariates. Compared with patients without ED, patients with psychogenic and organic ED were 3.19- and 3.03-fold more likely to develop osteoporosis. Our results indicate that patients with a history of ED, particularly younger men, had a high risk of osteoporosis. Patients with ED should be examined for bone mineral density, and men with osteoporosis should be evaluated for ED.

Hyperhomocysteinaemia in rats is associated with erectile dysfunction by impairing endothelial nitric oxide synthase activity

To investigate the effect of hyperhomocysteinaemia (HHCy) on penile erectile function in a rat model, a methionine-rich diet was used in which erectile function, the reproductive system, and nitric oxide synthase were characterized. The intracavernous pressure, apomorphine experiments, measurement of oxidative stress, hematoxylin and eosin staining, immunohistochemistry analysis, reverse transcription-polymerase chain reactions and measurement of endothelial nitric oxide synthase activity were utilized. Our results showed that erections in the middle-dose, high-dose, and interference (INF) groups were significantly lower than the control (P < 0.05). INF group, being fed with vitamins B and folic acid, demonstrated markedly improved penile erections compared with the middle-dose group (P < 0.05). HHCy-induced eNOS and phospho-eNOS protein expression was reduced and the antioxidant effect was markedly impaired. The data of the present data provide evidence that HHCy is a vascular risk factor for erectile dysfunction by impairing cavernosa endothelial nitric oxide synthase activity. Intake of vitamins B can alleviate this abnormality.

Testosterone improves erectile function through inhibition of reactive oxygen species generation in castrated rats

Testosterone is overwhelmingly important in regulating erectile physiology. However, the associated molecular mechanisms are poorly understood. The purpose of this study was to explore the effects and mechanisms of testosterone in erectile dysfunction (ED) in castrated rats. Forty male Sprague-Dawley rats were randomized to four groups (control, sham-operated, castration and castration-with-testosterone-replacement). Reactive oxygen species (ROS) production was measured by dihydroethidium (DHE) staining. Erectile function was assessed by the recording of intracavernous pressure (ICP) and mean arterial blood pressure (MAP). Protein expression levels were examined by western blotting. We found that castration reduced erectile function and that testosterone restored it. Nitric oxide synthase (NOS) activity was decrease in the castrated rats, and testosterone administration attenuated this decrease (each p < 0.05). The testosterone, dihydrotestosterone, cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) concentrations were lower in the castrated rats, and testosterone restored these levels (each p < 0.05). Furthermore, the cyclooxygenase-2 (COX-2) and prostacyclin synthase (PTGIS) expression levels and phospho-endothelial nitric oxide synthase (p-eNOS, Ser1177)/endothelial nitric oxide synthase (eNOS) ratio were reduced in the castrated rats compared with the controls (each p < 0.05). In addition, the p40(phox) and p67(phox) expression levels were increased in the castrated rats, and testosterone reversed these changes (each p < 0.05). Overall, our results demonstrate that testosterone ameliorates ED after castration by reducing ROS production and increasing the activity of the eNOS/cGMP and COX-2/PTGIS/cAMP signaling pathways.

Different mechanisms for lead acetate, aluminum and cadmium sulfate in rat corpus cavernosum

INTRODUCTION

Some heavy metals show adverse vascular and neurological effects, however, their effect on erection is underestimated. This study aims to investigate the effect of Pb, Cd and Al on erectile function and their potential mechanism of action in rats.

METHODS

Measurement of intracavernosal pressure/mean arterial pressure (ICP/MAP) changes elicited by electrical stimulation of cavernous nerve in anesthetized rats treated with Pb-acetate, Al-sulfate, or Cd-sulfate acutely, and subacutely for 7 days. Serum creatinine, testosterone, TBARs, GSH levels and metal accumulation in corpus cavernosum were measured.

RESULTS

Pb, Al and Cd significantly reduced ICP/MAP in rats after acute (2,10-2,10 and 1,3 mg/kg respectively) and sub-acute (3, 3, and 1mg/kg/day respectively) treatments. They selectively accumulated in the corpus cavernosum reaching 25.107 ± 2.081 μg/g wet weight for Pb, 1.029 ± 0.193 for Cd, 31.343 ± 1.991 for Al, compared to 7.084 ± 1.517, 0.296 ± 0.067, and 8.86 ± 1.115 as controls respectively. Serum creatinine levels were not altered. Cd and Al significantly reduced testosterone level to 0.483 ± 0.059 and 0.419 ± 0.037 ng/ml respectively compared to 0.927 ± 0.105 ng/ml as control. Aluminum elevated TBARs significantly by 27.843%. The acute anti-erectile action of Pb was blocked by non-selective NOS and GC inhibitors and potassium channel blocker. Lead also masked the potentiatory effect of l-arginine and diazoxide on ICP/MAP. No interaction with muscarinic or nicotinic modulators was observed.

CONCLUSIONS

Pb, Cd and Al show anti-erectile effect independent on renal injury. They don not modulate cholinergic nor ganglionic transmission in corpus cavernosum. Pb may inhibit NO/cGMP/K+channel pathway. The effect of Cd and Al but not Pb seems to be hormonal dependent.

Basic Science Evidence for the Link Between Erectile Dysfunction and Cardiometabolic Dysfunction

INTRODUCTION

Although clinical evidence supports an association between cardiovascular/metabolic diseases (CVMD) and erectile dysfunction (ED), scientific evidence for this link is incompletely elucidated.

AIM

This study aims to provide scientific evidence for the link between CVMD and ED.

METHODS

In this White Paper, the Basic Science Committee of the Sexual Medicine Society of North America assessed the current literature on basic scientific support for a mechanistic link between ED and CVMD, and deficiencies in this regard with a critical assessment of current preclinical models of disease.

RESULTS

A link exists between ED and CVMD on several grounds: the endothelium (endothelium-derived nitric oxide and oxidative stress imbalance); smooth muscle (SM) (SM abundance and altered molecular regulation of SM contractility); autonomic innervation (autonomic neuropathy and decreased neuronal-derived nitric oxide); hormones (impaired testosterone release and actions); and metabolics (hyperlipidemia, advanced glycation end product formation).

CONCLUSION

Basic science evidence supports the link between ED and CVMD. The Committee also highlighted gaps in knowledge and provided recommendations for guiding further scientific study defining this risk relationship. This endeavor serves to develop novel strategic directions for therapeutic interventions.

A test of somatic mosaicism in the androgen receptor gene of Canada lynx (Lynx canadensis)

Background

The androgen receptor, an X-linked gene, has been widely studied in human populations because it contains highly polymorphic trinucleotide repeat motifs that have been associated with a number of adverse human health and behavioral effects. A previous study on the androgen receptor gene in carnivores reported somatic mosaicism in the tissues of a number of species including Eurasian lynx (Lynx lynx). We investigated this claim in a closely related species, Canada lynx (Lynx canadensis). The presence of somatic mosaicism in lynx tissues could have implications for the future study of exonic trinucleotide repeats in landscape genomic studies, in which the accurate reporting of genotypes would be highly problematic.

Methods

To determine whether mosaicism occurs in Canada lynx, two lynx individuals were sampled for a variety of tissue types (lynx 1) and tissue locations (lynx 1 and 2), and 1,672 individuals of known sex were genotyped to further rule out mosaicism.

Results

We found no evidence of mosaicism in tissues from the two necropsied individuals, or any of our genotyped samples.

Conclusions

Our results indicate that mosaicism does not manifest in Canada lynx. Therefore, the use of hide samples for further work involving trinucleotide repeat polymorphisms in Canada lynx is warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-015-0284-y) contains supplementary material, which is available to authorized users.

Side Effects of 5-Alpha Reductase Inhibitors: A Comprehensive Review

INTRODUCTION

5α-reductase inhibitors (5ARI) include finasteride and dutasteride, and are commonly prescribed in the treatment of benign prostatic hyperplasia and androgenic alopecia. 5ARIs are associated with several known adverse effects (AEs), with varying reported prevalence rates.

AIM

The aim was to review and summarize findings from published literature detailing AEs associated with 5ARI use. A secondary aim was to review potential mechanisms of action, which may account for these observed and reported AEs.

METHODS

A PubMed search was conducted on articles published from 1992 to 2012, which reported AEs with 5ARIs. Priority was given to randomized, placebo-controlled trials. Studies investigating potential mechanisms of action for 5ARIs were included for review.

MAIN OUTCOME MEASURES

AE data reported from available trials were summarized and reviewed.

RESULTS

Reported AEs with 5ARIs include sexual dysfunction, infertility, mood disorders, gynecomastia, high-grade prostate cancer, breast cancer, and cardiovascular morbidity/risk factors, although their true association, prevalence, causality, and clinical significance remain unclear. A pooled summary of all randomized, placebo-controlled trials evaluating 5ARIs (N = 62,827) revealed slightly increased rates over placebo for decreased libido (1.5%), erectile dysfunction (ED) (1.6%), ejaculatory dysfunction (EjD) (3.4%), and gynecomastia (1.3%). The limited data available on the impact of 5ARIs on mood disorders demonstrate statistically significant (although clinically minimal) differences in rates of depression and/or anxiety. Similarly, there are limited reports of reversible, diminished fertility among susceptible individuals. Post-marketing surveillance reports have questioned the actual prevalence of AEs associated with 5ARI use and suggest the possibility of persistent symptoms after drug discontinuation. Well-designed studies evaluating these reports are needed.

CONCLUSIONS

5ARIs are associated with slightly increased rates of decreased libido, ED, EjD, gynecomastia, depression, and/or anxiety. Further studies directed at identifying prevalence rates and persistence of symptoms beyond drug discontinuation are required to assess causality. Trost L, Saitz TR, and Hellstrom WJG. Side effects of 5-alpha reductase inhibitors: A comprehensive review. Sex Med Rev 2013;1:24-41.

Clomiphene Effects on Idiopathic Premature Ejaculation

Background:

Premature ejaculation (PE) is the inability to delay ejaculation, occurring sooner than they or their partner would like during sexual activities. PE is a challenging problem that can affect sexual enjoyment and may harm relationships of couples and affect their quality of life. In idiopathic PE, several helpful techniques and medicines are recommended, but none of them has yielded satisfactory results.

Objectives:

Our objective in this study was to evaluate the efficacy and safety of clomiphene as a selective estrogen receptor modulator on the treatment of idiopathic PE.

Patients and Methods:

In a randomized clinical trial, 178 married men with idiopathic PE defined according to the Diagnostic and Statistical Manual of Mental Disorders Third Revised Version (DSM-III-R) who referred to urology clinics over a 10-month period in 2012 were randomized into two groups, namely the study (clomiphene) and control (placebo) groups. They completed self-administered questionnaires that included intravaginal ejaculatory latency time (IELT), erectile dysfunction indexes, quality of life (QOL), sociodemographic characteristics, lifestyle, and medical illness. After 6 months of intervention, all data were compared with the baseline data and between the groups.

Results:

Within the 10-month study course, 126 patients (70.8%) completed this study. After intervention and comparison of the results between the two groups, IELT, sexual indexes, and QOL improved in the study group, but significant differences were observed only in the IELT and QOL findings.

Conclusions:

Clomiphene seems to be useful in the pharmacological treatment of PE compared to the placebo.

The interaction of serum testosterone levels and androgen receptor CAG repeat polymorphism on the risk of erectile dysfunction in aging Taiwanese men

Testosterone has been found to play important roles in men's sexual function. However, the effects of testosterone can be modulated by androgen receptor (AR) CAG repeat polymorphism. It could also contribute to the risk of erectile dysfunction (ED). The aim of this study is to evaluate the interaction of serum testosterone levels and AR CAG repeat polymorphism on the risk of ED in aging Taiwanese men. This cross-sectional data of Taiwanese men older than 40 years were collected from a free health screening held between August 2010 and August 2011 in Kaohsiung city, Taiwan. All participants completed a health questionnaires included five-item version of the International Index of Erectile Function (IIEF-5) and the International Prostate Symptoms Score, received a detailed physical examination and provided 20 cm3 whole blood samples for biochemical and genetic evaluation. The IIEF-5 was used to evaluate ED. Serum albumin, total testosterone (TT), and sex hormone-binding globulin levels were measured. Free testosterone level was calculated. AR gene CAG repeat polymorphism was determined by direct sequencing. Finally, 478 men with the mean age of 55.7 ± 4.8 years were included. When TT levels were above 330 ng/dL, the effect of testosterone level on erectile function seemed to reach a plateau and a significantly negative correlation between AR CAG repeat length and the score of IIEF-5 was found (r = -0.119, p = 0.034). After adjusting for other covariates, the longer AR CAG repeat length was still an independent risk factor for ED in subjects with TT above 330 ng/dL (p = 0.006), but not in TT of 330 ng/dL or below. In conclusion, both serum testosterone levels and AR CAG repeat polymorphism can influence erectile function concomitantly. In subjects with normal TT concentration, those with longer AR CAG repeat lengths have a higher risk of developing ED.

Role of androgens in modulating male and female sexual function

Advancement in basic and clinical research has provided considerable evidence suggesting a key role of androgens in the physiology and pathophysiology of sexual function. Evidence from clinical studies in men and women with androgen deficiency support a role of androgens in maintaining sexual function in men and women and are integral in maintaining sexual health. Preclinical studies utilizing male animal models demonstrated a role of androgens in maintenance of: (i) penile tissue structural integrity, (ii) penile trabecular smooth muscle growth and function, (iii) integrity of penile nerve fiber network, (iv) signaling pathways in the corpora cavernosa, (v) myogenic and adipogenic differentiation in the corpora cavernosa, (vi) physiological penile response to stimuli, and (vii) facilitating corporeal hemodynamics. These findings strongly suggest a role for androgen in the physiology of penile erection. In addition, clinical studies in hypogonadal men with erectile dysfunction treated with testosterone provided invaluable information on restoring erectile function and improving ejaculatory function. Similarly, clinical studies in surgically or naturally postmenopausal women with androgen deficiency suggested that androgens are important for maintaining sexual desire and testosterone treatment was shown to improve sexual desire, arousal and orgasm. Furthermore, studies in female animal models demonstrated that androgens maintain the integrity of vaginal nerve fiber network, muscularis volume, and enhance genital blood flow and mucification. Based on the biochemical, physiological and clinical findings from human and animal studies, we suggest that androgens are integral for maintaining sexual function and play a critical role in maintaining sexual health in men and women.

Effect of testosterone therapy on the urinary bladder in experimental hypogonadism of rats

Testosterone (T) deficiency is prevalent particularly in elderly men and lead to physical and sexual morbidities. Although low levels of T are associated with low urinary tract symptoms, the correlation between T deficiency and bladder dysfunction is not clearly identified. The aim of this study was to investigate the effect of high dose testosterone replacement therapy (TRT) on the histological structure of the UB in castrated rats. Twenty-five adult male rats were divided into three groups: control, castrated and castrated + TRT. T was administrated in high dose (100 mg/kg) two intramuscular injections/week for 60 days. UB sections were prepared and stained with H&E, Masson's trichrome and immunohistochemical detection of Cytokeratin 20 (Ck20). All data were morphometrically and statistically analyzed. In castrated group, significant atrophy of the urothelium (P < 0.001) accompanied with widening of the corium were observed. The smooth muscle appeared thin with marked increase in the collagen fibers. On treating the castrated group with TRT, atypical Ck20 expression as well as significant increase in urothelial thickness (P < 0.05) and smooth muscle/collagen ratio (P < 0.001) were detected. In castrated rat model, high dose TRT has a positive effect on the UB smooth muscle rather than the urothelium which acquired atypical patterns.

Hydrogen Sulfide and Urogenital Tract

In this chapter the role played by H2S in the physiopathology of urogenital tract revising animal and human data available in the current relevant literature is discussed. H2S pathway has been demonstrated to be involved in the mechanism underlying penile erection in human and experimental animal. Both cystathionine-β synthase (CBS) and cystathionine-γ lyase (CSE) are expressed in the human corpus cavernosum and exogenous H2S relaxes isolated human corpus cavernosum strips in an endothelium-independent manner. Hydrogen sulfide pathway also accounts for the direct vasodilatory effect operated by testosterone on isolated vessels. Convincing evidence suggests that H2S can influence the cGMP pathway by inhibiting the phosphodiesterase 5 (PDE-5) activity. All these findings taken together suggest an important role for the H2S pathway in human corpus cavernosum homeostasis. However, H2S effect is not confined to human corpus cavernosum but also plays an important role in human bladder. Human bladder expresses mainly CBS and generates in vitro detectable amount of H2S. In addition the bladder relaxant effect of the PDE-5 inhibitor sildenafil involves H2S as mediator. In conclusion the H2S pathway is not only involved in penile erection but also plays a role in bladder homeostasis. In addition the finding that it involved in the mechanism of action of PDE-5 inhibitors strongly suggests that modulation of this pathway can represent a therapeutic target for the treatment of erectile dysfunction and bladder diseases.

Testosterone deficiency and severity of erectile dysfunction are independently associated with reduced quality of life in men with type 2 diabetes

Erectile dysfunction (ED) and low testosterone levels are common in men with type 2 diabetes (T2D). We have investigated the impact of testosterone on quality of life (QoL) in diabetic men with ED. Men with ED were identified within a study cohort of 355 men with T2D. All subjects completed SF-36 health and Androgen Deficiency of the Aging Male questionnaires. Total tesosterone (TT), bioavailable testosterone (BT) and sex hormone-binding globulin levels of study participants were measured and free testosterone levels were calculated (cFT). A subgroup of 126 ED patients completed the International Index of Erectile Function-5 (IIEF-5) questionnaire. Linear regression analyses were corrected for age, body mass index (BMI), glycosylated haemoglobin (HbA1c), smoking, alcohol consumption and cardiovascular disease (CVD). Total SF-36 scores significantly and positively correlated with TT levels (r = 0.219, p = 0.001), BT levels (r = 0.199, p = 0.004) and cFT levels (r = 0.185, p = 0.007) among men with ED. These trends were strengthened after adjusting for age, BMI, HbA1c, smoking, alcohol consumption and CVD (TT r = 0.359, p = 0.015; BT r = 0.354, p = 0.024 and cFT r = 0.354, p = 0.024). IIEF-5 scores significantly correlated inversely with TT (r = 0.546, p = 0.001), BT (r = 0.506, p = 0.004) and cFT levels (r = 0.532, p = 0.001). A positive linear relationship was observed between IIEF-5 scores and total SF-36 score (r = 0.491, p = 0.003). Patients who reported having ED had an average SF-36 score of 9.1% less than those without ED (p < 0.001). Lower testosterone and greater severity of ED independently correlated with poorer physical function, social function, vitality and decline in general health domains of the SF-36. This is the first study to report that testosterone deficiency and severity of ED are both independently associated with reduced QoL in men with T2D. Furthermore, ED and low testosterone are markers of poor health which impact on an individual's self-perception of their health status.

Outcomes of testosterone therapy in men with testosterone deficiency (TD): part II

Testosterone (T) deficiency (TD) is a common clinical condition, which contributes to co-morbidities including loss of muscle mass, increased fat mass, increased inflammation, insulin resistance, risk of vascular disease, sexual dysfunction, fatigue, depressed mood and reduced quality of life. T therapy attenuates inflammation, increases insulin sensitivity, muscle mass and reduces fat mass and adiposity. T therapy improves lipid profiles and endothelial function and reduces systolic and diastolic blood pressure. In addition, T therapy may reduce risk of vascular disease and mortality. T therapy improves bone mineral density and increases energy and vitality and improves mood and sexual function and overall quality of life. T therapy appears to be safe if treatment and monitoring are appropriately executed. The evidence available to date does not support alleged concerns regarding risk of cardiovascular disease and prostate cancer. Indeed, T therapy remains controversial. The data in the contemporary literature suggest that T therapy reduces cardiovascular risk and fears promoted by some recent studies should be re-evaluated. The cardiovascular risk and mortality with T therapy must await large prospective controlled clinical trials, which depend on many complex factors. Such studies may be prohibitive in the current environment due to logistical challenges, such as recruiting large number of men to be treated for long-durations with appropriate follow-up, requiring astronomical cost.

Adverse health effects of testosterone deficiency (TD) in men

Testosterone and its metabolite, 5α-dihydrotestosterone are critical metabolic and vascular hormones, which regulate a host of biochemical pathways including carbohydrate, lipid and protein metabolism and modulate vascular function. Testosterone deficiency (TD) is a well-recognized medical condition with important health implications. TD is associated with a number of co-morbidities including increased body weight, adiposity and increased waist circumference, insulin resistance (IR) and type 2 diabetes mellitus (T2DM), hypertension, inflammation, atherosclerosis and cardiovascular disease, erectile dysfunction (ED) and increased incidence of mortality. In this review, we summarize the data in the literature on the prevalence of TD and its association with the various co-morbidities and suggest that T therapy is necessary to improve health outcomes in men with TD.

Comprehensive evaluation of androgen replacement therapy in aging Japanese men with late-onset hypogonadism

OBJECTIVE

This study assessed the efficacy and safety of testosterone replacement therapy (TRT) in aging Japanese men with late-onset hypogonadism (LOH).

METHODS

This study included 50 (median age: 57.7 years) Japanese men with LOH, who were consecutively enrolled and treated with TRT for at least six months at our institution. We evaluated the following measurements before and after six months of treatment with TRT as follows: blood tests, prostate volume, residual urine volume, self-ratings for International Index of Erectile Function 5 (IIEF-5), International Prostate Symptom Score (IPSS), Self-Rating Depression Scale (SDS), Aging Male Symptom (AMS) and the Medical Outcomes Study 8-item Short-Form health survey (SF-8).

RESULTS

Following six months of TRT, the levels of testosterone, red blood cells, hemoglobin and hematocrit were significantly increased from baseline, while total cholesterol level was significantly decreased from baseline. Furthermore, TRT led to a significant increase in IIEF-5 score and a significant decrease in IPSS score. Of 30 men who were diagnosed with depression at baseline, only 11 men (36.7%) were still suffering from depression after TRT, and SDS scores were significantly decreased from baseline at month six. Treatment with TRT led to a significant decrease in all scores of the AMS scale as well as a significant improvement in all scores of the SF-8 survey, with the exception of the bodily pain score.

CONCLUSION

These findings suggest that TRT is an effective and safe treatment for aging Japanese men with LOH. TRT improved depressive symptoms as well as health-related quality of life.

The effect of statins on erectile dysfunction: a meta-analysis of randomized trials

INTRODUCTION

Erectile dysfunction (ED) is common in older men, especially those with comorbidities such as diabetes and atherosclerotic disease, conditions where statins are frequently prescribed.

AIM

To examine the effect of statin therapy on ED using the five-item version of the International Inventory of Erectile Function (IIEF).

METHODS

We performed a random-effects meta-analysis of studies identified by a systematic search of MEDLINE, Web of Knowledge, the Cochrane Database, and ClinicalTrials.gov. Examination of the 186 retrieved citations resulted in the selection of 11 randomized trials for inclusion in the meta-analysis.

MAIN OUTCOME MEASURES

Change in the IIEF score.

RESULTS

IIEF increased by 3.4 points (95% CI 1.7-5.0, P = 0.0001) with statins compared to control. This effect remained statistically significant after multiple sensitivity analyses, including analysis for publication bias, a cumulative meta-analysis, and 11 repeated analyses with each study omitted sequentially. The increase in IIEF with statins was approximately one-third to one-half of that previously reported with phosphodiesterase-5 inhibitors and larger than the effect of lifestyle modification. Metaregression showed an increase in benefit with decreasing lipophilicity. The average age of participants and the degree of LDL cholesterol lowering did not alter the effect on IIEF.

CONCLUSION

Statins cause a clinically relevant improvement of erectile function as measured by the five-item version of the IIEF.

Protective effects of seahorse extracts in a rat castration and testosterone-induced benign prostatic hyperplasia model and mouse oligospermatism model

This study investigated the effects of seahorse (Hippocampus spp.) extracts in a rat model of benign prostatic hyperplasia (BPH) and mouse model of oligospermatism. Compared to the sham operated group, castration and testosterone induced BPH, indicated by increased penile erection latency; decreased penis nitric oxide synthase (NOS) activity; reduced serum acid phosphatase (ACP) activity; increased prostate index; and epithelial thickening, increased glandular perimeter, increased proliferating cell nuclear antigen (PCNA) index and upregulation of basic fibroblast growth factor (bFGF) in the prostate. Seahorse extracts significantly ameliorated the histopathological changes associated with BPH, reduced the latency of penile erection and increased penile NOS activity. Administration of seahorse extracts also reversed epididymal sperm viability and motility in mice treated with cyclophosphamide (CP). Seahorse extracts have potential as a candidate marine drug for treating BPH without inducing the side effects of erectile dysfunction (ED) or oligospermatism associated with the BPH drug finasteride.

[Plasma testosterone, obesity, metabolic syndrome and diabetes]

The frequency of diabetes and/or metabolic syndrome rises concurrently with that of body mass index (BMI). In adult men, plasma testosterone level changes evolve inversely to that of BMI. Plasma total testosterone, sex hormone-binding globulin (SHBG) and free testosterone are significantly lower in adult men with a clinical and biological pattern of metabolic syndrome (MetS) than in those without such a pattern. After adjustment for confounding factors, diabetes type 2 (DT2) remains associated with a significant decrease of plasma testosterone level. The androgenic blockade, used as a treatment for disseminated prostate cancer, induces a metabolic pattern similar to MetS. In men older than 65 years, a decrease of plasma testosterone level is associated with an increased risk of stroke or of death linked to a cardiovascular event. After exclusion of contraindications, the substitution with androgens of a demonstrated hypogonadism in a obese patient, notably when obesity is associated with a pattern of MetS and/or a DT2, could have some metabolic and cardiovascular advantages.

Combined testosterone and vardenafil treatment for restoring erectile function in hypogonadal patients who failed to respond to testosterone therapy alone

INTRODUCTION

The role of testosterone in erectile dysfunction (ED) is increasingly recognized. It is suggested that assessment of testosterone deficiency in men with ED and symptoms of hypogonadism, prior to first-line treatment, may be a useful tool for improving therapy.

AIM

In this prospective, observational, and longitudinal study, we investigated the effects of vardenafil treatment as adjunctive therapy to testosterone undecanoate in hypogonadal ED patients who failed to respond to testosterone treatment alone.

METHODS

One hundred twenty-nine testosterone deficient (serum total testosterone ≤ 3.4 ng/mL) patients aged 56 ± 3.9 years received intramuscular injections of long-acting parenteral testosterone undecanoate at 3-month intervals for 8 months mean follow-up.

MAIN OUTCOME MEASURES

Scores on the International Index of Erectile Function Questionnaire-five items (IIEF-5) and partner survey scores were compared at baseline and posttreatment with testosterone therapy alone or in combination with vardenafil. Patient baseline demographics and concomitant disease were correlated with patients' IIEF-5 scores.

RESULTS

Seventy one (58.2%) responded well to monotherapy within 3 months. Nonresponders had lower testosterone levels and higher rates of concomitant diseases and smoking. Thirty-four of the 51 nonresponders accepted the addition of 20 mg vardenafil on demand. Efficacy assessments were measured by the IIEF-erectile function domain (IIEF-EF, questions 1-5 plus 15, 30 points) and partner self-designed survey at baseline after 4-6 weeks and at study end point. Thirty out of 34 patients responded well to this combination. IIEF-EF Sexual Health Inventory for Men score improved from 12 to 24 (P < 0.0001), and partner survey showed significantly higher satisfaction (P < 0.001). These patients reported spontaneous or nocturnal and morning erections or tumescence. No changes in adverse effects were recorded.

CONCLUSIONS

These data suggest that combination therapy of testosterone and vardenafil is safe and effective in treating hypogonadal ED patients who failed to respond to testosterone monotherapy.

Androgens modulate endothelial function and endothelial progenitor cells in erectile physiology

The incidence of erectile dysfunction (ED) increases with age and cardiovascular disease risk factors, such as hypertension, hyperlipidemia, insulin resistance, obesity, and diabetes. These risk factors are thought to contribute to endothelial dysfunction and atherosclerosis, thus contributing to the pathophysiology of ED. The role of the endothelium in regulating erectile physiology is well established. However, the role of androgens in modulating endothelial function and endothelial repair mechanisms subsequent to vascular injury in erectile tissue remains a subject of intensive research. The clinical and preclinical evidence discussed in this review suggests that androgens regulate endothelial function and also play an important role in the development and maturation of endothelial progenitor cells (EPCs), which are thought to play a critical role in repair of endothelial injury in vascular beds. In this review, we discuss the data available on the effects of androgens on endothelial function and EPCs in the repair of vascular injury. Indeed, more research is needed to fully understand the molecular and cellular basis of androgen action in regulating the development, differentiation, maturation, migration, and homing of EPCs to the site of injury. A better understanding of these processes will be critical to the development of new therapeutic approaches to the treatment of vascular ED.