ORIGINAL RESEARCH—BASIC SCIENCE: Effect of Chronic Tadalafil Administration on Penile Hypoxia Induced by Cavernous Neurotomy in the Rat

The Effect of Combination Treatment with Low-Intensity Shockwave Therapy and Tadalafil on Mild and Mild-To-Moderate Erectile Dysfunction: A Double-Blind, Randomized, Placebo-Controlled Clinical Trial

BACKGROUND

Combination of different first-line treatments for erectile dysfunction (ED) has emerged as a promising therapeutic approach.

AIM

To conduct the first double-blind, randomized, placebo-controlled clinical trial to evaluate the efficacy and safety of combination therapy with low-intensity shockwave therapy (LiST) and tadalafil vs LiST and placebo in patients with mild or mild-to-moderate vasculogenic ED.

METHODS

Fifty sexually active patients fulfilling the eligibility criteria were randomly assigned to 6 sessions of LiST twice weekly for 3 weeks and tadalafil (n = 25) or placebo (n = 25) once daily for 4 weeks. Patients were evaluated at 1, 3, and 6 months after completion of the treatment protocol.

OUTCOMES

The primary outcome was the mean change from baseline in the International Index of Erectile Function-Erectile Function (IIEF-EF) domain between the 2 groups at 3 months after treatment. Erectile function was also assessed at 1 and 6 months. The number of patients attaining a minimal clinically important difference (MCID) in the IIEF-EF, as well as the safety of combination therapy were evaluated.

RESULTS

Adjusting for the baseline values, IIEF-EF improved by 0.8 points more (95% confidence interval [CI] = -0.2 to 1.9, P = .12) at 1 month, 1 point more (95% CI = 0.1-1.9, P = .02) at 3 months and 1.7 points more (95% CI = 0.8-2.7, P < .001) at 6 months in patients treated with combination therapy compared to monotherapy. The number of patients attaining a MCID in the IIEF-EF between the 2 groups improved significantly only at the 3-month evaluation. No adverse events were reported during the whole study period.

CLINICAL IMPLICATIONS

Combination of LiST twice weekly for 3 weeks and tadalafil 5 mg once daily for 4 weeks may further ameliorate mild or mild-to-moderate vasculogenic ED compared to LiST monotherapy.

STRENGTHS & LIMITATIONS

We conducted the first randomized trial exploring the role of LiST and tadalafil in the management of ED. Conversely, our study lacks external validity due to its single-center design.

CONCLUSION

The addition of daily low-dose tadalafil during application of LiST may further improve erectile function compared to application of LiST as a standalone treatment in patients with mild or mild-to-moderate vasculogenic ED. Still, further high-quality studies are warranted to corroborate our findings.

Penile rehabilitation with low-intensity extracorporeal shock wave therapy in patients after prostate cancer surgery. Early physiological changes and postoperative follow-up outcomes

INTRODUCTION

To investigate the efficacy, safety and postoperative outcomes of using tadalafil and low-intensity extracorporeal shock wave therapy (Li-ESWT) on penile rehabilitation and preventing urinary incontinence after radical prostatectomy.

METHODS

In total, we included 66 patients who used only tadalafil (n = 32) in group 1 and used tadalafil and treated by Li-ESWT (n = 34) in group 2. We noted International Index of Erectile Function (IIEF) 5, daily incontinence pad measurements at preoperative, postoperative 3rd, 6th and 12th months respectively. We also evaluated penis blood flow and neovascularisation by penile doppler ultrasonography at postoperative 3rd and 12th months for all patients. Statistical analyses were performed with SPSS version 18. A P-value < .05 was considered significant.

RESULTS

Preoperative demographic characteristics were similar in the two groups. There was a statistically significant improvement in IIEF-5, which started at the 6th month and continued increasingly at the 12th month in group 2 compared with group 1. Also, there was a significant decrease in incontinence rate in group 2 compared with group 1 in the sixth month.

CONCLUSIONS

Combined use of tadalafil and Li-ESWT is highly effective and safe for the treatment of erectile dysfunction and for the prevention of urinary incontinence after prostate cancer surgery.

Considerations for prescribing pharmacotherapy for the treatment of erectile dysfunction

Introduction: The effectiveness of phosphodiesterase type 5 inhibitors (PDE5i) in treating erectile dysfunction (ED) creates a new field of both medical practice and pharmaceutical manufacturing. Both paved the way for emerging minimally invasive therapies to restore male sexual function. However, what is the best drug to achieve the optimum outcome is still a challenging question to be answered.Areas covered: The general viewpoint of matching the pharmacotherapeutic characteristics with the patient's medical, social, and psychological variables, in order to balance between efficacy and safety. Several studies had investigated considerations for preference and long-term adherence for PDE5i. However, a thorough investigation of considerations for prescribing ED pharmacotherapy is still lacking in the literature. This is the aim of this manuscript.Expert opinion: Several issues should be considered in the planning of ED management such as the patient's and partner's expectations, etiologic considerations, performance status, safety, adverse effects, ease of administration, compliance, bad experiences with previous treatment, availability, cost, social factors, satisfaction, and finally, regimen considerations. Addressing the patient's and partner's individual needs help to tailoring treatment in order to minimize compromises and optimize gains.

Losartan improves erectile function through suppression of corporal apoptosis and oxidative stress in rats with cavernous nerve injury

This study aimed to investigate the functional and morphological changes in the corpus cavernosum after cavernous nerve (CN) injury or neurectomy and then reveal whether treatment with the angiotensin II Type 1 receptor antagonist losartan would improve erectile function as well as its potential mechanisms. A total of 48 10-week-old Sprague-Dawley male rats, weighing 300-350 g, were randomly divided into the following four groups (n = 12 per group): sham operation (Sham) group, bilateral cavernous nerve injury (BCNI) group, losartan-treated BCNI (BCNI + Losartan) group, and bilateral cavernous neurectomy (Neurectomy) group. Losartan was administered once daily by oral gavage at a dose of 30 mg kg^-1 day^-1 for 4 weeks starting on the day of surgery. The BCNI and the Neurectomy groups exhibited decreases in erectile response and increases in apoptosis and oxidative stress, compared with the Sham group. Treatment with losartan could have a modest effect on erectile function and significantly prevent corporal apoptosis and oxidative stress. The phospho-B-cell lymphoma 2 (Bcl-2)-associated death promoter (p-Bad)/Bad and phospho-the protein kinase B (p-AKT)/AKT ratios were substantially lower, while the Bcl-2-associated X protein (Bax)/Bcl-2 ratio, nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap-1), transforming growth factor-β 1 (TGF-β 1) and heme oxygenase-1 (HO-1) levels, and caspase-3 activity were higher in the BCNI and Neurectomy groups than in the Sham group. After 4 weeks of daily administration with losartan, these expression levels were remarkably attenuated compared with the BCNI group. Taken together, our results suggested that early administration of losartan after CN injury could slightly improve erectile function and significantly reduce corporal apoptosis and oxidative stress by inhibiting the Akt/Bad/Bax/caspase-3 and Nrf2/Keap-1 pathways.

Non-invasive Management Options for Erectile Dysfunction When a Phosphodiesterase Type 5 Inhibitor Fails

Phosphodiesterase type 5 inhibitors (PDE5Is) are the drug of choice for medical management of erectile dysfunction (ED). On-demand PDE5Is have an overall efficacy of 60-70% for ED; 30-35% of patients fail to respond to a PDE5I, and 30-50% of non-responders can be salvaged with detailed counseling on proper use and physician follow-up to ensure that the patient has been prescribed an appropriate and full PDE5I clinical trial. True non-responders may be offered intracavernosal injections of erectogenic drugs, intraurethral alprostadil, or surgical insertion of a penile prosthesis. Such options are not discreet and are associated with more adverse effects than PDE5Is. Thus patients may request additional non-invasive medical management options. This review describes published literature on patients who failed to respond to an on-demand PDE5I regimen and were treated with a non-invasive PDEI-based regimen, including switching from one PDE5I to another; increasing the dose of PDE5I above the labeled dosage range; using two PDE5Is concurrently; using a daily PDE5I regimen; or combining a PDE5I with a testosterone supplement, α-adrenergic antagonist, intraurethral or intracavernosal alprostadil, vacuum erection device, or low-intensity shock wave therapy. The limitations of published clinical trials do not allow for sufficient evidence to recommend one option over another. Therefore, in PDE5I-refractory patients, the choice of a specific next step should be individualized based on the preference of the patient and his sexual partner, the advantages and disadvantages of the various options, the concurrent medical illnesses and medications of the patient, and the patient's response to treatment.

Phosphodiesterase type 5 in men with vasculogenic and post-radical prostatectomy erectile dysfunction: is there a molecular difference?

OBJECTIVES

To clarify the molecular basis of penile erection at the human level and distinguish the mechanisms underlying vasculogenic and post-radical prostatectomy (RP) erectile dysfunction (ED) subtypes.

PATIENTS AND METHODS

Erectile tissue was obtained from men without history of ED who underwent penile surgery for Peyronie's disease (control group, n = 5) and from men with ED who underwent penile prosthesis implantation (n = 17). ED was categorized into vasculogenic (n = 8) and post-RP (n = 9) subtypes. Penile erectile tissue samples were collected for molecular analyses of protein expressions of neuronal and endothelial isoforms of nitric oxide synthase (nNOS and eNOS, respectively), phospho-nNOS (Ser-1412), phospho-eNOS (Ser-1177), phospho-protein kinase B (Ser-473), phosphodiesterase type 5 (PDE5), α-smooth muscle actin, phospho-myosin phosphatase target subunit 1, RhoA/Rho-associated protein kinase (ROCK)-α, ROCK-β, 4-hydroxy-2-nonenal, and nNOS and eNOS uncoupling by Western blot.

RESULTS

Vasculogenic ED was characterized by decreased eNOS protein expression and eNOS and nNOS phosphorylation on their activatory sites (Ser-1177 and Ser-1412, respectively), uncoupled eNOS, upregulated PDE5 protein expression, increased ROCK activity, and increased oxidative stress in erectile tissue. Post-RP ED was characterized by decreased nNOS protein expression, increased nNOS phosphorylation on its activatory site (Ser-1412), uncoupled nNOS, downregulated PDE5 protein expression, and increased oxidative stress in erectile tissue.

CONCLUSION

The mechanisms of vasculogenic and post-RP ED in the human penis involve derangements in constitutive nitric oxide synthase function, PDE5 protein expression and ROCK activity, and increased oxidative stress, which conceivably provide a molecular basis for chronically reduced nitric oxide bioavailability and increased smooth muscle contraction contributing to erectile impairment. Selective differences in PDE5 protein expression suggest distinct molecular mechanisms are in play for these ED subtypes.

Long-term inhibition of PDE5 ameliorates aging-induced changes in rat testis

NO-cGMP signaling pathway has been implicated in reduction of testicular steroidogenesis during aging. Here we analyzed the effect of PDE5 inhibition on old testicular phenotype formation. The old phenotype exhibited low testosterone and increased nitrite levels in circulation, increased cGMP accumulation in testicular interstitial fluid (TIF), progressive atrophy of testicular seminiferous tubules and enlargement of interstitial area followed by rise in blood vessel density and slight increase in the number of Leydig cells and macrophages. Leydig cells have reduced steroidogenic capacity, increased MAP kinases expression (MEK, ERK1/2, JNK) and antiapoptotic PRKG1 and AKT, suggesting increased proliferation/survival and accumulation of senescent Leydig cells in testis. In 12 month-old rats, a long-term treatment with sildenafil (PDE5 inhibitor) normalized testosterone/nitrite levels in circulation and cGMP accumulation in TIF; improved Leydig cell steroidogenic capacity; decreased MEK, ERK1/2 and PRKG1 expression; prevented an increase in the Leydig cells number and atrophy of seminiferous tubules leading to histological appearance of young rat testes. In 18 month-old rats, long-term PDE5 inhibition partially recovered testosterone and nitrite levels in serum; normalized PRKG1 expression without effect on MEK and ERK1/2; and slowed down Leydig cell and macrophage accumulation and regressive tubular changes. Culturing of primary Leydig cells from aged rats in presence of PDE5-inhibitor stimulated steroidogenic and MAPK gene expression. Taking together, results indicate that cGMP targeting alter both steroidogenesis and signaling pathways associated with cell proliferation/survival. The long-term PDE5 inhibition improves testicular steroidogenesis and slows-down regressive changes in testes during aging.

Dipyridamole reduces penile apoptosis in a rat model of post-prostatectomy erectile dysfunction

Purpose:

Despite the nerve-sparing technique, many patients suffer from erectile dysfunction after radical prostatectomy (RP) due to cavernous nerve injury. The aim of this study was to evaluate dipyridamole as a potential treatment agent of post-radical prostatectomy erectile dysfunction.

Material and methods:

A total of 18 male Sprague-Dawley rats were randomized into three experimental Groups (SHAM+DMSO, BCNI+DMSO and BCNI+DIP). An animal model of bilateral cavernous nerve crush injury (BCNI) was established to mimic the partial nerve damage during nerve-sparing RP. After creating of BCNI, dimethyl sulphoxide (DMSO) was administered transperitoneally as a vehicle to SHAM+DMSO and BCNI+DMSO Groups. BCNI+DIP Group received dipyiridamole (10mg/kg/day) as a solution in DMSO for 15 days. Afterwards, rats were evaluated for in vivo erectile response to cavernous nerve stimulation. Penile tissues were also analyzed biochemically for transforming growth factor-β1 (TGF-β1) level. Penile corporal apoptosis was determined by TUNEL method.

Results:

Erectile response was decreased in rats with BCNI and there was no significant improvement with dipyridamole treatment. TGF-β1 levels were increased in rats with BCNI and decreased with dipyridamole treatment. Dipyridamole led to reduced penile apoptosis in rats with BCNI and there was no significant difference when compared to sham operated rats.

Conclusions:

Although fifteen-day dipyridamole treatment has failed to improve erectile function in rats with BCNI, the decline in both TGF-β1 levels and apoptotic indices with treatment may be helpful in protecting penile morphology after cavernous nerve injury.

The expression and functional activities of smooth muscle myosin and non-muscle myosin isoforms in rat prostate

Benign prostatic hyperplasia (BPH) is mainly caused by increased prostatic smooth muscle (SM) tone and volume. SM myosin (SMM) and non-muscle myosin (NMM) play important roles in mediating SM tone and cell proliferation, but these molecules have been less studied in the prostate. Rat prostate and cultured primary human prostate SM and epithelial cells were utilized. In vitro organ bath studies were performed to explore contractility of rat prostate. SMM isoforms, including SM myosin heavy chain (MHC) isoforms (SM1/2 and SM-A/B) and myosin light chain 17 isoforms (LC_17a/b ), and isoform ratios were determined via competitive RT-PCR. SM MHC and NM MHC isoforms (NMMHC-A, NMMHC-B and NMMHC-C) were further analysed via Western blotting and immunofluorescence microscopy. Prostatic SM generated significant force induced by phenylephrine with an intermediate tonicity between phasic bladder and tonic aorta type contractility. Correlating with this kind of intermediate tonicity, rat prostate mainly expressed LC_17a and SM1 but with relatively equal expression of SM-A/SM-B at the mRNA level. Meanwhile, isoforms of NMMHC-A, B, C were also abundantly present in rat prostate with SMM present only in the stroma, while NMMHC-A, B, C were present both in the stroma and endothelial. Additionally, the SMM selective inhibitor blebbistatin could potently relax phenylephrine pre-contracted prostate SM. In conclusion, our novel data demonstrated the expression and functional activities of SMM and NMM isoforms in the rat prostate. It is suggested that the isoforms of SMM and NMM could play important roles in BPH development and bladder outlet obstruction.

Erectile function recovery in men treated with phosphodiesterase type 5 inhibitor administration after bilateral nerve-sparing radical prostatectomy: a systematic review of placebo-controlled randomized trials with trial sequential analysis

The impact of phosphodiesterase type 5 inhibitor (PDE5I) treatment modality (on-demand vs. daily), PDE5I half-life and time from surgery to PDE5I prescription on the achievement of drug-assisted erectile function (EF) recovery is uncertain. We systematically reviewed published randomized clinical trials (RCTs). We performed meta-analyses of data on 2317 men treated with PDE5Is after nerve-sparing radical prostatectomy (NSRP). A PubMed and SCOPUS search was performed for trials published from 1 January 1969 to 30 June 2016. PDE5Is are effective in achieving drug-assisted recovery of erectile function (EF). From a statistical standpoint, these studies were subjected to Trial Sequential Analysis to determine whether the pooled data were adequately powered to verify the study outcomes. On-demand treatment with PDE5Is was significantly better than daily treatment in recovering drug-assisted EF. This effect was maintained even when the drugs were stratified according with half-life. Although not based on head-to-head trials, Avanafil used on-demand was the most effective PDE5I in recovering drug-assisted EF. Whereas tadalafil was equally effective when used both on-demand and daily, vardenafil significantly improved drug-assisted EF recovery only when used on-demand. The start of PDE5I treatment six months or more after surgery compared to treatment started earlier did not negatively affect the rate of drug-assisted EF recovery or the possibility to have successful intercourse based on the Sexual Encounter Profile question-3 (SEP-3). Current trials do not support the hypothesis that PDE5I use recovers drug-unassisted EF, although chronic low-dose tadalafil administration may help to preserve erectile tissue integrity. Potential shortcomings in the trials design may partially explain these disappointing results and several questions concerning the recovery of drug-unassisted EF remain unanswered. Thus, there is a need for well-designed new RCTs requiring changes in the timing of PDE5I administration as well as in the dose and the treatment duration.

The Protective Effect of Salidroside on Hypoxia-Induced Corpus Cavernosum Smooth Muscle Cell Phenotypic Transformation

Salidroside, a major active ingredient isolated from Rhodiola rosea, has a long application in Chinese medical history. It has widely demonstrated effects on fatigue, psychological stress, and depression and exhibits potential antihypoxia activity. Emerging evidence shows that hypoxia is an important independent risk factor for erectile dysfunction (ED). The aim of this study was to clarify the effect of salidroside on hypoxia-induced phenotypic transformation of corpus cavernosum smooth muscle cells (CCSMCs). Our results showed that salidroside decreased the hypoxia-induced expression of collagen and content of vimentin, a corpus cavernosum smooth muscle synthetic protein, in vitro. Simultaneously, salidroside increased expression of the CCSMC contractile proteins, α-smooth muscle actin (α-SMA) and desmin. In vivo, similarly, the expressions of collagen and hypoxia-inducible factor-1α were increased in bilateral cavernous neurectomy (BCN) rats while they were decreased in the salidroside group. Among the phenotypic proteins, α-SMA and desmin increased and vimentin decreased after treating BCN rats with salidroside compared with the BCN alone group. Overall, our results demonstrate that salidroside has the ability to oppose hypoxia and can inhibit the CCSMC phenotypic transformation induced by hypoxia. Salidroside may provide a new treatment method for ED.

Current rehabilitation strategy: clinical evidence for erection recovery after radical prostatectomy

Erectile function (EF) recovery remains a prominent functional outcome underachievement of radical prostatectomy (RP), despite the success of anatomic “nerve-sparing” technique and its recent refinements in the modern surgical era. Delayed (for as much as a few years) or incomplete (partial and unusable) EF recovery commonly occurs in many men still today undergoing this surgery. “Penile rehabilitation”, alternatively termed “EF rehabilitation”, originated formally as a therapeutic practice approximately 15 years ago for addressing post-RP erectile dysfunction (ED) beyond conventional ED management. Although the premise of this therapy is conceptually sound and generally accepted, in reference to the implementation of strategies for promoting EF recovery to a naturally functional level in the absence of erectile aids (distinct from the premise of conventional ED management), the optimal manner and efficacy of currently suggested therapeutic strategies are far less established. Such strategies include regimens of standard ED-specific therapies (e.g., oral, intracavernosal, and intraurethral pharmacotherapies; vacuum erection device therapy) and courses of innovative interventions (e.g., statins, erythropoietin, angiotensin receptor blockers). An endeavor in evolution, erection rehabilitation may ideally comprise an integrative program of sexual health management incorporating counseling, coaching, guidance toward general health optimization and application of demonstrably effective “rehabilitative” interventions. Ongoing intensive discovery and rigorous investigation are required to establish efficacy of therapeutic prospects that fulfill the intent of post-RP erection rehabilitation.

Landmarks in erectile function recovery after radical prostatectomy

The description of the nerve-sparing technique of radical prostatectomy by Walsh was one of the major breakthroughs in the surgical treatment of prostate cancer in the 20(th) century. However, despite this advance and consequent technological refinements to nerve-sparing surgery, a large proportion of men still suffer from erectile dysfunction (ED) as a complication of prostatectomy. A plethora of therapeutic approaches have been proposed to optimize erectile function recovery in these patients. Several preclinical and translational studies have shown benefits of therapies including PDE5 inhibitor (PDE5I) treatment, immunomodulation, neurotrophic factor administration, and regenerative techniques, such as stem cell therapy, in animal models. However, most of these approaches have either failed to translate to clinical use or have yet to be studied in human subjects. Penile rehabilitation with PDE5Is is currently the most commonly used clinical strategy, in spite of the absence of solid clinical evidence to support its use.

Penile rehabilitation after radical prostatectomy: does it work?

CONTEXT

Erectile dysfunction (ED) represents one of the most common long-term side effects in patients with clinically localized prostate cancer (PCa) undergoing nerve-sparing radical prostatectomy (RP).

OBJECTIVE

To analyze the role of penile rehabilitation in the recovery of erectile function (EF) after nerve-sparing RP.

EVIDENCE SYNTHESIS

Penile rehabilitation is defined as the use of any intervention or combination with the goal not only to achieve erections sufficient for satisfactory sexual intercourses, but also to return EF to preoperative levels. The concept of rehabilitation is based on the implementation of protocols aimed at improving oxygenation, preserving endothelial structure, and preventing smooth muscle structural alterations. Nowadays, the most commonly adopted approaches for penile rehabilitation after nerve-sparing RP are represented by the administration of phosphodiesterase type-5 inhibitors (PDE5-Is), intracorporeal injection therapy, vacuum erection devices (VED), and the combination of these therapies. Several basic science studies support the rational for the adoption of penile rehabilitation protocols. Particularly, rehabilitation, set as early as possible, seems to be better than leaving the erectile tissues unassisted. On the other hand, results from solid prospective randomized trials finally assessing the long-term beneficial effects of PDE5-Is, intracavernosal injections, or VED on EF recovery after surgery are still lacking.

CONCLUSIONS

Although preclinical evidences support the rationale for penile rehabilitation after nerve-sparing RP, clinical studies reported conflicting results regarding its efficacy on long-term EF recovery. Nowadays, which is the optimal rehabilitation program still represents a matter of debate.

Current status of penile rehabilitation after radical prostatectomy

Although disease-free survival remains the primary goal of prostate cancer treatment, erectile dysfunction (ED) remains a common complication that affects the quality of life. Even though several preventive and therapeutic strategies are available for ED after radical prostatectomy (RP), no specific recommendations have been made on the optimal rehabilitation or treatment strategy. Several treatment options are available, including phosphodiesterase-5 inhibitors, vacuum erection devices, intracavernosal or intraurethral prostaglandin injections, and penile prostheses. Urologists must consider more effective ways to establish optimal treatments for ED after RP. ED is an important issue among patients with prostate cancer, and many patients hope for early ED recovery after surgery. This review highlights the currently available treatment options for ED after RP and discusses the limitations of each.

Topically applied NO-releasing nanoparticles can increase intracorporal pressure and elicit spontaneous erections in a rat model of radical prostatectomy

INTRODUCTION

Patients undergoing radical prostatectomy (RP) suffer from erectile dysfunction (ED) refractory to phosphodiesterase 5 inhibitors, which act downstream of cavernous nerve (CN)-mediated release of nitric oxide (NO). Direct delivery of NO to the penis could potentially circumvent this limitation.

AIM

This study aimed to determine if topically applied NO-releasing nanoparticles (NO-NPs) could elicit erections in a rat model of RP through increased blood flow.

METHODS

Twenty-six Sprague Dawley rats underwent bilateral transection of the CN. One week later, NO-NPs were applied topically to the penile shaft in dimethylsulfoxide (DMSO) gel (10 animals) or coconut oil (6 animals). Control animals were treated with empty NPs. Erectile function was determined through the intracorporal pressure/blood pressure ratio (ICP/BP). The effect of the NO-NPs on blood flow was determined using a hamster dorsal window chamber.

MAIN OUTCOME MEASURES

Animals were investigated for spontaneous erections, onset and duration of erectile response, and basal ICP/BP ratio. Microcirculatory blood flow was determined through measurements of arteriolar and venular diameter and red blood cell velocity.

RESULTS

Eight of 10 animals treated with NO-NPs suspended in DMSO gel had significant increases in basal ICP/BP, and 6 out of these 10 animals demonstrated spontaneous erections of approximately 1 minute in duration. Time to onset of spontaneous erections ranged from 5 to 37 minutes, and they occurred for at least 45 minutes. Similar results were observed with NO-NPs applied in coconut oil. No erectile response was observed in control animal models treated with empty NPs. The hamster dorsal window chamber experiment demonstrated that NO-NPs applied as a suspension in coconut oil caused a significant increase in the microcirculatory blood flow, sustained over 90 minutes.

CONCLUSIONS

Topically applied NO-NPs induced spontaneous erections and increased basal ICP in an animal model of RP. These effects are most likely due to increased microcirculatory blood flow. These characteristics suggest that NO-NPs would be useful in penile rehabilitation of patients following RP.

Phenotypic modulation of corpus cavernosum smooth muscle cells in a rat model of cavernous neurectomy

Background

Patients undergoing radical prostatectomy (RP) are at high risk for erectile dysfunction (ED) due to potential cavernous nerve (CN) damage during surgery. Penile hypoxia after RP is thought to significantly contribute to ED pathogenesis.

Aim

We previously showed that corpora cavernosum smooth muscle cells (CCSMCs) undergo phenotypic modulation under hypoxic conditions in vitro. Here, we studied such changes in an in vivo post-RP ED model by investigating CCSMCs in bilateral cavernous neurectomy (BCN) rats.

Methods

Sprague-Dawley rats underwent sham (n = 12) or BCN (n = 12) surgery. After 12 weeks, they were injected with apomorphine to determine erectile function. The penile tissues were harvested and assessed for fibrosis using Masson trichrome staining and for molecular markers of phenotypic modulation using immunohistochemistry and western blotting. CCSMC morphological structure was evaluated by hematoxylin-eosin (H&E) staining and transmission electron microscopy (TEM).

Results

Erectile function was significantly lower in BCN rats than in sham rats. BCN increased hypoxia-inducible factor-1α and collagen protein expression in corpora cavernous tissue. H&E staining and TEM showed that CCSMCs in BCN rats underwent hypertrophy and showed rough endoplasmic reticulum formation. The expression of CCSMC phenotypic markers, such as smooth muscle α-actin, smooth muscle myosin heavy chain, and desmin, was markedly lower, whereas vimentin protein expression was significantly higher in BCN rats than in control rats.

Conclusions

CCSMCs undergo phenotype modulation in rats with cavernous neurectomy. The results have unveiled physiological transformations that occur at the cellular and molecular levels and have helped characterize CN injury–induced ED.

Therapeutic potential of adipose-derived stem cells-based micro-tissues in a rat model of postprostatectomy erectile dysfunction

INTRODUCTION

Stem cells (SCs) show significant benefits in the treatment of postprostatectomy erectile dysfunction (ED). However, the low retention rate of the traditional single-cell strategy at the injection sites limits its therapeutic potential.

AIM

This study aims to investigate the feasibility and mechanism of adipose-derived stem cells (ADSCs)-based micro-tissues (MTs) in the treatment of ED in a rat model of bilateral cavernous nerves (CNs) injury.

METHODS

ADSCs labeled with 5-ethynyl-2-deoxyuridine (EdU) were used to generate MTs with hanging drop method. 10 Sprague-Dawley (SD) rats underwent sham surgery and intracavernous (IC) injection of phosphate buffer solution (PBS) (the sham group). Another 70 rats underwent bilateral CN crush and were then treated with PBS (n = 10, the crush group), dissociated ADSCs (n = 30, the ADSCs group), and MTs (n = 30, the MTs group), respectively. At day 1, 3, 7, 14 (n = 5), and 28 (n = 10) postsurgery, specimens were harvested for histology. At day 28, 10 rats in each group were examined for erectile function before tissue harvest.

MAIN OUTCOME MEASURES

Light microscopy of the dynamic aggregation of the MT, immunohistologic examination of the MTs, the retention and distribution of EdU + ADSCs in the corpus cavernosum (CC), and the penis histological analyses of collagen content, Western blot of functional proteins in MTs, intracavernous pressure recording on CN electrostimulation.

RESULTS

Three-day-old MTs became stable and expressed nerve growth factor, vascular endothelial growth factor, C-X-C chemokine receptor type 4, Wnt5a, and collagen IV. More EdU + ADSCs retained in the CC in the MTs group than that in the ADSCs group. IC injection of MTs resulted in significant restoration of the erectile function and histopathological changes compared with the ADSCs group.

CONCLUSION

IC-injected MTs resulted in a better restoration of erectile function than traditional single-cell strategy. The underlying mechanisms of recovery appear to involve enhanced cellular retention in the penis and upregulation of some paracrine factors.

Valproic acid prevents penile fibrosis and erectile dysfunction in cavernous nerve-injured rats

INTRODUCTION

Bilateral cavernous nerve injury (BCNI) causes profound penile changes such as apoptosis and fibrosis leading to erectile dysfunction (ED). Histone deacetylase (HDAC) has been implicated in chronic fibrotic diseases.

AIMS

This study will characterize the molecular changes in penile HDAC after BCNI and determine if HDAC inhibition can prevent BCNI-induced ED and penile fibrosis.

METHODS

Five groups of rats (8-10 weeks, n = 10/group) were utilized: (i) sham; (ii and iii) BCNI 14 and 30 days following injury; and (iv and v) BCNI treated with HDAC inhibitor valproic acid (VPA 250 mg/kg; 14 and 30 days). All groups underwent cavernous nerve stimulation (CNS) to determine intracavernosal pressure (ICP). Penile HDAC3, HDAC4, fibronectin, and transforming growth factor-β1 (TGF-β1) protein expression (Western blot) were assessed. Trichrome staining and the fractional area of fibrosis were determined in penes from each group. Cavernous smooth muscle content was assessed by immunofluorescence to alpha smooth muscle actin (α-SMA) antibodies.

MAIN OUTCOME MEASURES

We measured ICP; HDAC3, HDAC4, fibronectin, and TGF-β1 protein expression; penile fibrosis; penile α-SMA content.

RESULTS

There was a voltage-dependent decline (P < 0.05) in ICP to CNS 14 and 30 days after BCNI. Penile HDAC3, HDAC4, and fibronectin were significantly increased (P < 0.05) 14 days after BCNI. There was a slight increase in TGF-β1 protein expression after BCNI. Histological analysis showed increased (P < 0.05) corporal fibrosis after BCNI at both time points. VPA treatment decreased (P < 0.05) penile HDAC3, HDAC4, and fibronectin protein expression as well as corporal fibrosis. There was no change in penile α-SMA between all groups. Furthermore, VPA-treated BCNI rats had improved erectile responses to CNS (P < 0.05).

CONCLUSION

HDAC-induced pathological signaling in response to BCNI contributes to penile vascular dysfunction. Pharmacological inhibition of HDAC prevents penile fibrosis, normalizes fibronectin expression, and preserves erectile function. The HDAC pathway may represent a suitable target in preventing the progression of ED occurring post-radical prostatectomy.

The protective effect of single dose tadalafil in contrast-induced nephropathy: an experimental study

Objective:

Contrast-induced nephropathy (CIN) is one of the most common causes of acute renal failure in hospitalized patients. The direct toxic effect of contrast media; ischemic damage caused by reactive oxygen species; increased perivascular hydrostatic pressure; high viscosity and changes in the activity of vasoactive substances play important roles in the pathogenesis. Tadalafil inhibits the phosphodiesterase enzyme which destroys nitric oxide. Nitric oxide causes renal vasodilatation, increases renal medullar blood flow and mediates the removal of free oxygen radicals. Drugs that increase levels of nitric oxide are expected to reduce the development of contrast nephropathy due to contrast media. We aimed to test the hypothesis that tadalafil reduces the development of contrast nephropathy due to contrast toxicity.

Methods:

A total of 24 female Wistar albino rats, three groups of eight, were included in the study. After 48 hours of dehydration, contrast media (meglumine diatrozoate, 6 mL/kg) was administered to the first group, and contrast media with tadalafil (10 mg/kg) was administered to the second group. The third group served as the control group. Blood and tissue samples were taken 48 hours after this procedure.

Results:

Serum cystatin C, serum creatinine and blood urea nitrogen (BUN) values were significantly lower in the contrast with tadalafil group compared to the group given only contrast. Serum and tissue malondialdehyde (MDA) levels were significantly lower in the contrast with tadalafil group than in the contrast only group.

Conclusion:

These results demonstrate the protective effect of tadalafil in the prevention of CIN in rats.

Prophylactic sildenafil citrate improves select aspects of sexual function in men treated with radiotherapy for prostate cancer

PURPOSE

We studied adjuvant daily sildenafil citrate during and after radiotherapy for prostate cancer for erectile function preservation.

MATERIALS AND METHODS

We performed a randomized, prospective trial of 279 patients with localized prostate cancer treated with radiotherapy who received sildenafil citrate (50 mg daily) or placebo (2:1 randomization). Medication/placebo was initiated 3 days before treatment and continued daily for 6 months. Before therapy and 3, 6, 9, 12, 18 and 24 months after radiotherapy patients completed the IIEF questionnaire, including the erectile function domain, the I-PSS questionnaire and the RAND SF-36®. All IIEF domains were scored.

RESULTS

At 12 months erectile function scores were better for sildenafil citrate than placebo (p = 0.018), 73% of patients on sildenafil citrate vs 50% on placebo had mild/no erectile dysfunction (p = 0.024) and the sildenafil citrate arm had superior overall satisfaction (p = 0.027) and IIEF total scores (p = 0.043). At 24 months erectile function and IIEF scores were no longer significantly better for sildenafil citrate (p = 0.172 and 0.09, respectively) and yet overall satisfaction scores were higher (p = 0.033). Sexual desire scores in patients who received sildenafil citrate were higher at 24 months although they had completed drug therapy 18 months previously (p = 0.049). At 24 months 81.6% of patients on sildenafil citrate and 56.0% of those on placebo achieved functional erection with or without erectile dysfunction medication (p = 0.045).

CONCLUSIONS

Daily sildenafil citrate during and after radiotherapy for prostate cancer was associated with improved overall sexual function compared with placebo for various sexual function domains. To our knowledge this is the largest randomized, prospective, controlled trial to show the usefulness of a phosphodiesterase-5 inhibitor as a rehabilitation strategy in patients with prostate cancer who received radiation therapy.

Effects of tadalafil on ischemia/reperfusion injury in rat brain

Cerebral ischemia-reperfusion (I/R) injury is caused by lack of blood supply to the brain. The accumulation of toxic products such as reactive oxygen species (ROS) occurs on reperfusion, when the occlusion is removed. The resulting oxidative stress results in the initiation of pathways leading to necrotic and apoptotic cell death. Tadalafil (TAD) prevents the accumulation of ROS and increases antioxidant cellular protective mechanisms. The aim of this study was to investigate the effect of TAD treatment against short-term global brain I/R injury in rats. The study was carried out on 30 Wistar-albino rats, which were divided into three groups including a control group (n = 10), an I/R group (n = 10) and an I/R + TAD group (n = 10) (2 mg/kg/day for 4 days before ischemia). At the end of the experiment, tissue samples were collected for both biochemical and histopathological analyses. Malondialdehyde was significantly lower in the TAD-administered group (9.06 ± 0.15) than in the I/R group (p < 0.05). However, no significant difference was observed in nitric oxide levels in the TAD-administered group compared to the I/R group. The mean superoxide dismutase level was significantly higher in the I/R-TAD group than the I/R group. There was no statistically significant difference in glutathione peroxidase levels in I/R + TAD group compared to I/R group. Histopathologically, TAD-administered group provided significant morphological improvement compared to the I/R group. We concluded that TAD prevented I/R-induced neurotoxicity as shown by obtained biochemical and histopathological findings.

The opposing roles of nitric oxide and cGMP in the age-associated decline in rat testicular steroidogenesis

The molecular mechanism of the aging-associated dysfunction of Leydig cells (LCs) is complex and poorly understood. In this study, we analyzed the contribution of nitric oxide (NO) and cGMP signaling to the age-dependent decline in LC function. Significant (>50%) decreases in serum, intratesticular, and LC androgens in aging rats (15-24 months) were accompanied by a proportional increase in NO production, an up-regulation of cGMP levels, and the expression of soluble guanylyl cyclase-1B and protein kinase G1 in LCs. In contrast, LC cAMP levels decreased with age, most likely reflecting the up-regulation of cAMP-specific phosphodiesterase expression. Moreover, the expression of genes encoding enzymes responsible for cholesterol transport and its conversion to T were reduced. Exposing LCs from aged animals to NO further increased cGMP levels and decreased cAMP and androgen production, whereas the addition of cell-permeable 8-bromoguanosine-cGMP alone had the opposite effect. In vivo inhibition of cGMP-specific phosphodiesterase-5 for 3 and 6 months in aged rats led to a partial restoration of androgens, NO, and cyclic nucleotide levels, as well as the expression of steroidogenic and NO/cGMP signaling genes. These results indicate that a progressive increase in NO production contributes to the age-dependent decrease in steroidogenesis in a cGMP-independent manner, whereas the sustained elevation in cGMP levels significantly slows the decline in LC function.

Effectiveness of intracavernous delivery of adenovirus encoding Smad7 gene on erectile function in a mouse model of cavernous nerve injury

INTRODUCTION

Men with erectile dysfunction (ED) respond poorly to oral phosphodiesterase-5 inhibitors following radical prostatectomy. Recent studies have reported that up-regulation of transforming growth factor-β1 (TGF-β1) and activation of the Smad signaling pathway play important roles in cavernous fibrosis and in the deterioration of erectile function in a mouse model of cavernous nerve injury (CNI) and in patients with spinal cord injury. The mothers against decapentaplegic homolog 7 (Smad7) is known to inhibit the phosphorylation of Smad2 and Smad3.

AIM

To investigate the effectiveness of adenoviruses encoding Smad7 gene (Ad-Smad7) on erectile function in a mouse model of CNI.

METHODS

Twelve-week-old C57BL/6J mice were used and distributed into 7 groups: sham operation group, untreated CNI group, and CNI groups receiving a single intracavernous injection of adenovirus encoding LacZ (1 × 10(8) virus particles [vp]/20 μL) or adenovirus encoding Smad7 (Ad-Smad7; 1 × 10(7), 1 × 10(8), 2 × 10(8), or 1 × 10(9) vp/20 μL).

MAIN OUTCOME MEASURES

Two weeks after bilateral cavernous nerve crushing and treatment, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was harvested for histologic examinations and Western blot analysis.

RESULTS

The highest erectile response was noted in CNI mice treated with Ad-Smad7 at a dose of 1 × 10(8)  vp, which reached up to 82-85% of sham control values. Local delivery of Ad-Smad7 significantly decreased endothelial cell apoptosis and the production of extracellular matrix proteins, including plasminogen activator inhibitor-1, fibronectin, collagen I, and collagen IV, and induced endothelial nitric oxide synthase phosphorylation in the corpus cavernosum tissue of CNI mice.

CONCLUSION

The adenovirus-mediated gene transfer of Smad7 successfully restored erectile function by enhancing endothelial cell function and through antifibrotic effects. These findings suggest that inhibition of the TGF-β signaling pathway by use of Smad7 may represent a promising therapeutic strategy for ED induced by radical prostatectomy.

Penile rehabilitation after radical prostatectomy: what the evidence really says

The pathophysiology of erectile dysfunction after radical prostatectomy (RP) is believed to include neuropraxia, which leads to temporarily reduced oxygenation and subsequent structural changes in penile tissue. This results in veno-occlusive dysfunction, therefore, penile rehabilitation programmes focus on tissue oxygenation. Animal studies support the use of phosphodiesterase type 5 inhibitors (PDE5Is) after cavernous nerve damage but results from human studies are contradictory. The largest study to date found no long-term effect of either daily or on-demand PDE5I administration after RP compared with placebo. The effects of prostaglandin and vacuum erection devices are questionable and high-quality studies are lacking. Better documentation for current penile rehabilitation and/or better rehabilitation protocols are needed. One must be careful not to repeat the statement that penile rehabilitation improves erectile function after RP so many times that it becomes a truth even without the proper scientific backing.

Sildenafil citrate-restored eNOS and PDE5 regulation in sickle cell mouse penis prevents priapism via control of oxidative/nitrosative stress

Sildenafil citrate revolutionized the practice of sexual medicine upon its federal regulatory agency approval approximately 15 years ago as the prototypical phosphodiesterase type 5 inhibitor indicated for the treatment of male erectile dysfunction. We now provide scientific support for its alternative use in the management of priapism, a clinical disorder of prolonged and uncontrolled penile erection. Sildenafil administered continuously to sickle cell mice, which show a priapism phenotype, reverses oxidative/nitrosative stress effects in the penis, mainly via reversion of uncoupled endothelial nitric oxide synthase to the functional coupled state of the enzyme, which in turn corrects aberrant signaling and function of the nitric oxide/cyclic GMP/protein kinase G/phosphodiesterase type 5 cascade. Priapism tendencies in these mice are reverted partially toward normal neurostimulated erection frequencies and durations after sildenafil treatment in association with normalized cyclic GMP concentration, protein kinase G activity and phosphodiesterase type 5 activity in the penis. Thus, sildenafil exerts pleiotropic effects in the penis that extend to diverse erection disorders.

Sildenafil citrate improves erectile function after castration in a rat model

TAKE HOME MESSAGE

The administration of phosphodiesterase 5 inhibitor commencing at the time of castration might preserve erectile function.

OBJECTIVE

To determine if sildenafil citrate treatment could improve erectile function after castration. To determine if sildenafil citrate treatment reduces collagenisation and apoptosis in erectile tissue after castration.

MATERIALS AND METHODS

In all, 60 Sprague-Dawley rats were studied; the rats were divided into the following groups: sham - no orchidectomy (S), control - orchidectomy only (O) and treatment - orchidectomy plus sildenafil treatment (V), with 10 rats per group. Erectile haemodynamics assessment was done at 7 days (S7, O7, V7) and at 28 days (S28, O28, V28) yielding a total of six groupings. Functional assessment measured the mean maximum intracavernosal pressure-mean arterial pressure (ICP/MAP) ratio. TUNEL assay was used to define apoptotic indices (AIs) and Masson's trichrome staining was used to evaluate smooth muscle-collagen (SM-C) ratios.

RESULTS

The S28 group had the highest and the O7 group the lowest ICP/MAP ratio, at a mean (sd) of 70 (6)% and 36 (6)%, respectively. Both treatment groups, V7 [42 (12)%] and V28 [49 (13)%] showed statistically significant improvements over their corresponding control groups: O7 [36 (6)%] and O28 [37 (9)%] (P < 0.05). However, ICP/MAP values for V7 and V28 remained significantly below the S28 group (P < 0.001). There were no significant differences in ICP/MAP values between the 28-day and 7-day ICP/MAP ratios within each group (S, O, V). There were no significant differences in SM-C ratio between the O and V groups (O7 vs V7, P = 0.45; O28 vs V28, P = 0.16). There were no significant differences in AIs between the O and V groups (O7 vs V7, P = 0.54; O28 vs V28, P = 0.8).

CONCLUSIONS

Daily treatment with sildenafil improved erectile function in rats after castration. ICP/MAP ratios increased significantly in the treatment groups compared with the control groups with the greatest erectile function occurring 28 days from administration. In this series of experiments the improved erectile function recovery with sildenafil after surgical castration cannot be explained by smooth muscle protection and decreased collagenisation. The improved erectile function with sildenafil after surgical castration cannot be explained by reduced apoptosis in erectile tissue.

PDE5-Is for the Treatment of Concomitant ED and LUTS/BPH

Epidemiologic data in adult men exhibit a strong relationship between erectile dysfunction (ED) and lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH), indicating that men affected by ED should also be investigated for LUTS/BPH and those presenting with storage or voiding LUTS should be investigated for co-morbid ED. Common pathophysiolgical mechanisms underlying both LUTS/BPH and ED, including alteration of NO/cGMP or RhoA/Rho-kinase signaling and/or vascular or neurogenic dysfunction, are potential targets for proposed phosphodiesterase type 5 inhibitors (PDE5-Is). Several randomized controlled trials and only a few reviews including all commercially available PDE5-Is demonstrated the safety and efficacy of these drugs in the improvement of erectile function and urinary symptoms, in patients affected either by ED, LUTS, or both conditions.

Current penile-rehabilitation strategies: Clinical evidence

We review the current strategies used for penile rehabilitation (PR) after a radical prostatectomy, where PR is defined as the attempt to restore spontaneous erectile function so that the patient can generate erections with no need for erectile aids. We searched PubMed for relevant reports, using the keywords ‘radical prostatectomy’, ‘penile rehabilitation’, ‘phosphodiesterase inhibitors’, ‘vacuum erection device’, ‘injection therapy’, ‘urethral suppository’, and ‘erectile dysfunction’. In all, 155 articles were identified and reviewed, and had a level of evidence ranging from 1b-4. The use of PR strategies should be based on the patient’s goals after a thorough explanation of realistic expectations, and the risks and consequences of the various treatment options. While a multitude of studies suggest a benefit with PR strategies, there are no established, proven regimens. Further research is needed to establish the optimal approaches to PR.

Nerve injury-induced protein 1 (Ninjurin-1) is a novel therapeutic target for cavernous nerve injury-induced erectile dysfunction in mice

INTRODUCTION

Radical prostatectomy for prostate cancer can not only induce cavernous nerve injury (CNI) but also result in structural changes in the cavernous tissues. Nerve injury-induced protein 1, Ninjurin-1 (Ninj1), is known to be involved in neuroinflammatory processes and to be related to vascular regression during the embryonic period.

AIM

The study aims to determine whether and how Ninj1 neutralizing antibody (Ninj1-Ab) restores erectile function in mice with CNI.

METHODS

Twelve-week-old C57BL/6J mice were used and distributed into four groups: sham operation group and CNI groups receiving a single intracavernous injection of immunoglobulin G (IgG) control antibody, low-dose Ninj1-Ab (1.0 μg/20 μL), or high-dose Ninj1-Ab (2.5 μg/20 μL).

MAIN OUTCOME MEASURES

One week after bilateral cavernous nerve crush, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was harvested for histologic examinations and Western blot analysis.

RESULTS

The cavernous expression of Ninj1 protein was upregulated up to 7 days after CNI and returned to baseline levels thereafter. Local delivery of Ninj1-Ab significantly increased penile neuronal nitric oxide synthase and neurofilament contents, induced cavernous endothelial proliferation and phosphorylation of Akt and endothelial nitric oxide synthase, and decreased endothelial cell apoptosis in the CNI mice by upregulating angiopoietin-1 and downregulating angiopoietin-2. High-dose Ninj1-Ab induced profound restoration of erectile function in the CNI mice (91% of sham control values), whereas low-dose Ninj1-Ab elicited partial improvement.

CONCLUSION

The dual neurotrophic and angiogenic effects of Ninj1 blockade may provide a good opportunity for treating erectile dysfunction resulting from radical prostatectomy.

Testosterone and farnesoid X receptor agonist INT-747 counteract high fat diet-induced bladder alterations in a rabbit model of metabolic syndrome

In the male, metabolic syndrome (MetS) is associated to an increased risk of benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS). A recently established rabbit model of high fat diet (HFD)-induced MetS showed hypogonadism and the presence of prostate gland alterations, including inflammation, hypoxia and fibrosis. The present study investigated whether HFD-induced MetS might also alter bladder structure and function. Testosterone and the farnesoid X receptor (FXR) agonist INT-747, were evaluated for possible effects on HFD bladder. MetS rabbits develop bladder alterations, including fibrosis (reduced muscle/fiber ratio), hypoxia [2-fold increase as compared to regular diet (RD) group], low-grade inflammation (increased leukocyte infiltration and inflammatory markers) and RhoA/ROCK hyperactivity. Bladder strips from HFD rabbits, pre-contracted with carbachol, showed an overactive response to the selective ROCK inhibitor Y-27632. All these HFD-induced bladder alterations were partially blunted by testosterone and almost completely reverted by INT-747. Both treatments prevented some MetS features (glucose intolerance and visceral fat increase), thus suggesting that their effects on bladder could be ascribed to an improvement of the metabolic and/or hypogonadal state. However, a pathogenetic role for hypogonadism has been ruled out as GnRH analog-induced hypogonadal rabbits, fed a regular diet, did not show any detectable bladder alterations. In addition, INT-747 did not revert the MetS-induced hypogonadal state. FXR mRNA was highly expressed in rabbit bladder and positively associated with visceral fat increase. A direct effect of INT-747 on bladder smooth muscle was further suggested by inhibition of RhoA/ROCK-mediated activity by in vitro experiments on isolated cells. In conclusion, HFD-related MetS features are associated to bladder derangements, which are ameliorated by testosterone or INT-747 administration. INT-747 showed the most marked effects in counteracting MetS-related RhoA/ROCK overactivity, thus opening novel therapeutic opportunities for this drug.

Inhibition of Rho-kinase improves erectile function, increases nitric oxide signaling and decreases penile apoptosis in a rat model of cavernous nerve injury

PURPOSE

Bilateral cavernous nerve injury results in up-regulation of ROCK signaling in the penis. This is linked to erectile dysfunction in an animal model of post-prostatectomy erectile dysfunction. We evaluated whether daily treatment with the ROCK inhibitor Y-27632 (Tocris Bioscience, Ellisville, Missouri) would prevent erectile dysfunction in a rat model of bilateral cavernous nerve injury.

MATERIALS AND METHODS

Sprague-Dawley® rats underwent surgery to create sham (14) or bilateral (27) cavernous nerve injury. In the injury group 13 rats received treatment with Y-27632 (5 mg/kg twice daily) and 14 received vehicle. At 14 days after injury, rats underwent cavernous nerve stimulation to determine erectile function. Penes were assessed for neuronal and nitric oxide synthase membrane-endothelial nitric oxide synthase. ROCK2 was assessed by Western blot. Cyclic guanosine monophosphate was determined by enzyme-linked immunosorbent assay. Cavernous homogenates were tested for ROCK and protein kinase G enzymatic activity. Penile apoptosis was evaluated using the Apostain technique (Alexis, San Diego, California). Data were analyzed on ROCK using ANOVA and the t test.

RESULTS

While erectile function was decreased in rats with bilateral cavernous nerve injury, daily administration of Y-27632 improved erectile responses. Injury decreased neuronal and nitric oxide synthase membrane-endothelial nitric oxide synthase but ROCK2 was significantly increased. Y-27632 treatment restored neuronal nitric oxide synthase, nitric oxide synthase membrane-endothelial nitric oxide synthase and cyclic guanosine monophosphate levels, and protein kinase G activity. Treatment significantly decreased ROCK2 protein and ROCK activity. There were significantly fewer apoptotic cells after treatment than in injured controls.

CONCLUSIONS

These results provide evidence for up-regulation of the RhoA/ROCK signaling pathway with detrimental effects on erectile function after bilateral cavernous nerve injury. ROCK inhibition improved erectile dysfunction associated with bilateral cavernous nerve injury by preserving penile nitric oxide bioavailability and decreasing penile apoptosis.

Effect of testosterone and frequent low-dose sildenafil/tadalafil on cavernous tissue oxidative stress of aged diabetic rats

This study aimed to assess the effect of testosterone (T) administration and chronic low-dose sildenafil/tadalafil on cavernous tissue oxidative stress (OS) of aged diabetic rats. In all, 140 Sprague-Dawley aged rats were subdivided into the following: controls; streptozotocin (STZ)-induced diabetic rats; diabetic rats injected with T every 4 weeks; diabetic rats on sildenafil orally daily; diabetic rats on T and daily sildenafil; diabetic rats on tadalafil orally every other day; diabetic rats on T and tadalafil; diabetic rats on alternate sildenafil/tadalafil; and diabetic rats on alternate sildenafil/tadalafil with T. After 12 weeks, the rats were euthanised where in dissected cavernous tissues malondialdehyde (MAD), glutathione peroxidase (GPx) and cGMP (cyclic guanosine monophosphate) were estimated. Compared with controls, aged diabetic rats demonstrated significant increase in cavernous tissue MDA and significant decrease in GPx and cGMP where diabetic rats injected with T had marked improvement of these parameters. Diabetic rats on sildenafil, tadalafil or alternate sildenafil/tadalafil demonstrated significant increased cavernous tissue GPx, cGMP and decreased cavernous MDA that was further improved when supplemented with T. It is concluded that frequent low-dose use of sildenafil and/or tadalafil supplemented with T has a marked impact on ameliorating cavernous OS in aged diabetic rats.

Transient rise of serum testosterone level after single sildenafil treatment of adult male rats

INTRODUCTION

Phosphodiesterase type 5 (PDE5) inhibitors have been established in therapy for a variety of physiological disorders including erectile dysfunction. Despite its popularity and wide usage in erectile dysfunction treatment, the short-term effect of PDE5 inhibition on Leydig cell functionality and testosterone dynamics is missing.

AIM

This study was designed to assess the acute in vivo effects of sildenafil citrate (Viagra) treatment on testosterone production.

METHODS

Male adult rats were given sildenafil (1.25 mg/kg BW) per os, and testosterone production were analyzed 30, 60, 120, and 180 minutes after treatment. Additionally, in vitro effect of sildenafil extract on Leydig cell steroidogenesis was estimated.

MAIN OUTCOME MEASURES

The formation of testicular interstitial fluid (TIF), and testosterone, cyclic guanosine monophosphate (cGMP), cyclic adenosine monophosphate (cAMP) content was followed. Occurrence and phosphorylation of mature steroidogenic acute regulatory protein (StAR) and interaction with protein kinase G 1 (PRKG1) were assessed by immunoprecipitation and Western blot.

RESULTS

Serum testosterone was increased 60 and 120 minutes after sildenafil treatment. In 60 minutes, TIF volume was doubled and stayed increased till the end of the experimental period. cGMP and testosterone content in TIF were increased 30 minutes after treatment, and cAMP decreased in 60 minutes. Further, sildenafil-induced stimulation of testosterone production was abolished by ex vivo addition of PRKG1 inhibitor but not by protein kinase A inhibitor. Sildenafil treatment increased the level of phosphorylated and total StAR protein. Moreover, co-immunoprecipitation of StAR and PRKG1 was increased following sildenafil treatment suggesting the active role of this kinase in initiation of testosterone synthesis. Additionally, sildenafil extract applied in vitro on primary Leydig cell culture increased cGMP accumulation and testosterone production in time- and dose-dependent manner without effect on cAMP level.

CONCLUSION

Acute sildenafil treatment enlarged TIF volume but also stimulated testosterone production which may be significant considering the positive testosterone effect in regulation of sexual activity.

Testosterone protects from metabolic syndrome-associated prostate inflammation: an experimental study in rabbit

Metabolic syndrome (MetS) and benign prostatic hyperplasia (BPH)/lower urinary tract symptoms (LUTS) are often associated. One of their common denominators is hypogonadism. However, testosterone supplementation is limited by concerns for potential prostatic side effects. The objective was to determine whether MetS-associated prostate alterations are prevented by testosterone supplementation. We used a previously described animal model of MetS, obtained by feeding male rabbits a high-fat diet (HFD) for 12 weeks. Subsets of HFD rabbits were treated with testosterone or with the farnesoid X receptor agonist INT-747. Rabbits fed a standard diet were used as controls. HFD-animals develop hypogonadism and all the MetS features: hyperglycemia, glucose intolerance, dyslipidemia, hypertension, and visceral obesity. In addition, HFD-animals show a prostate inflammation. Immunohistochemical analysis demonstrated that HFD-induced prostate fibrosis, hypoxia, and inflammation. The mRNA expression of several proinflammatory (IL8, IL6, IL1β, and TNFα), T lymphocyte (CD4, CD8, Tbet, Gata3, and ROR γt), macrophage (TLR2, TLR4, and STAMP2), neutrophil (lactoferrin), inflammation (COX2 and RAGE), and fibrosis/myofibroblast activation (TGFβ, SM22α, αSMA, RhoA, and ROCK1/ROCK2) markers was significantly increased in HFD prostate. Testosterone, as well as INT-747, treatment prevented some MetS features, although only testosterone normalized all the HFD-induced prostate alterations. Interestingly, the ratio between testosterone and estradiol plasma level retains a significant, negative, association with all the fibrosis and the majority of inflammatory markers analyzed. These data highlight that testosterone protects rabbit prostate from MetS-induced prostatic hypoxia, fibrosis, and inflammation, which can play a role toward the development/progression of BPH/LUTS.

Tadalafil in the treatment of erectile dysfunction

The treatment for erectile dysfunction (ED) was revolutionized with the development of phosphodiesterase type 5 (PDE5) inhibitors. Tadalafil (Cialis((R)); Eli Lilly and Company, Indianapolis, IN, USA) is the newest and most versatile PDE5 inhibitor in the clinical armamentarium for the treatment of ED. Its most unique characteristic is its long half-life of 17.5 hours, which lends itself to a longer therapeutic window with on-demand dosing and effective steady-state plasma concentrations with once-daily dosing. Clinical trials have proven its safety and efficacy with both dosing strategies for all severities and etiologies of ED, including difficult-to-treat ED. This thorough review will discuss ED, the physiology of penile erection and the role of PDE5, and all aspects of tadalafil, from its development, through its pharmacology, to its latest clinical studies and indications.