Management of sildenafil treatment failures

Knockdown of programmed cell death factor 4 restores erectile function by attenuating apoptosis in rats with bilateral cavernous nerve crush injury

BACKGROUND

Apoptosis is an important pathologic mechanism of erectile dysfunction after radical prostatectomy. Studies have shown that programmed cell death factor 4 is connected to the modulation of apoptosis in many cells. However, the programmed cell death factor 4 function in the cavernous nerve injury erectile dysfunction is unclear.

OBJECTIVE

This investigation aimed to explore the programmed cell death factor 4 function in erectile dysfunction in rats with bilateral cavernous nerve crush.

MATERIALS AND METHODS

The experiment used 30 male Sprague Dawley rats (18 months old) that were screened for normal erectile function by the apomorphine test. Ten rats were randomized into Sham and bilateral cavernous nerve crush groups to detect changes in programmed cell death factor 4 expression. The remaining 20 rats were distributed at random to four groups: the Sham group treated by sham surgery, the phosphate-buffered saline group, the lentivirus containing negative control short hairpin RNA group, and the lentivirus containing short hairpin RNA targeting programmed cell death factor 4 group underwent bilateral cavernous nerve crush and were afterward administered intracavernous injections of phosphate-buffered saline, lentivirus containing negative control short hairpin RNA, or lentivirus containing short hairpin RNA targeting programmed cell death factor 4. Electrical stimulation of the cavernous nerve was conducted 2 weeks later for penile erectile function assessment. The cavernous tissue was collected for histological analysis and western blotting.

RESULTS

The apoptosis level in rat corpus cavernosum was elevated, and programmed cell death factor 4 expression was increased after bilateral cavernous nerve crush. Knockdown of programmed cell death factor 4 significantly improved erectile function in bilateral cavernous nerve crush rats. Furthermore, lentivirus containing short hairpin RNA targeting programmed cell death factor 4 treatment raised smooth muscle content and attenuated cavernous fibrosis and apoptotic levels. Additionally, programmed cell death factor 4 was found to mediate the PI3K/AKT pathway.

DISCUSSION AND CONCLUSION

Elevated programmed cell death factor 4 expression may be an important pathogenetic mechanism for erectile dysfunction after bilateral cavernous nerve crush, and the knockdown of programmed cell death factor 4 enhanced erectile function in 18-month-old rats after cavernous nerve damage. The potential mechanism may be the stimulation of the PI3K/AKT pathway to attenuate the cavernous apoptosis level.

Mode of cell death in the penile cavernous tissue of type 1 diabetes mellitus rats

BACKGROUND

Diabetes mellitus commonly causes endothelial cell and smooth muscle cell death in penile cavernous tissue.

AIM

The study sought to study the mode of cell death in the penile cavernous tissue in type 1 diabetic rats.

METHODS

A total of 36 Sprague Dawley rats 10 weeks of age were randomly divided into 2 groups: a normoglycemic group and type 1 diabetic group (intraperitoneal injection of Streptozotocin (STZ), 60 mg/kg). We randomly selected 6 rats from each group for tests at the end of 11, 14, and 18 weeks of age, respectively. All rats were able to eat and drink freely. The ratio of maximum intracavernous pressure to mean arterial pressure, concentration of serum testosterone, level of nitric oxide in the penile cavernosum, and expression of active caspase-1 (pyroptosis) and active caspase-3 (apoptosis) were determined.

OUTCOMES

At the end of weeks 4 and 8 of type 1 diabetes, the proportions of endothelial cells and smooth muscle cells undergoing apoptosis and pyroptosis in penile cavernous tissue are different.

RESULTS

The ratio of maximum intracavernous pressure to mean arterial pressure and nitric oxide levels were significantly lower in the 4- and 8-week diabetic groups than in the normoglycemic group (P < .01). Penile endothelial cell pyroptosis (5.67 ± 0.81%), smooth muscle cell apoptosis (23.72 ± 0.48%), total cell pyroptosis (9.67 ± 0.73%), and total apoptosis (10.52 ± 1.45%) were significantly greater in the 4-week diabetic group than in the normoglycemic group (P < .01). The proportion of endothelial cell pyroptosis (24.4 ± 3.69%), endothelial cell apoptosis (22.13 ± 2.43%), total cell pyroptosis (14.75 ± 0.93%), and total apoptosis (14.82 ± 1.08%) in the penile tissues of the 8-week diabetic group were significantly greater than those in the normoglycemic group (P < .01).The 8-week survival proportions of diabetic endothelial cells (38.86 ± 8.85%) and smooth muscle cells (44.46 ± 2.94%) was significantly lower than the 4-week survival proportions of endothelial cells (93.17 ± 8.07%) and smooth muscle cells (75.12 ± 4.76%) (P < .05).

CLINICAL TRANSLATION

Inhibition of cell death by different methods at different stages may be the key to the treatment of type 1 diabetes-induced erectile dysfunction.

STRENGTHS AND LIMITATIONS

The effect of type 1 diabetes on other types of cell death in penile cavernous tissue needs further study.

CONCLUSION

The mode of death of endothelial cells in the cavernous tissue of the penis in the early stage in diabetic rats is dominated by pyroptosis, and the death of smooth muscle cells is dominated by apoptosis. Endothelial cell and smooth muscle cell death are not consistent at different stages of diabetes progression.

A low androgenic state inhibits erectile function by suppressing endothelial glycosides in the penile cavernous tissue of rats

Background

The endothelial glycocalyx is an important barrier that protects the structure and function of endothelial cells. Androgen deficiency is a common factor that causes structural and functional impairment of endothelial cells.

Aim

To investigate changes in the endothelial glycocalyx in the penile corpus cavernosum of the rat with low androgen status and its relationship with erection function.

Methods

Eighteen 10-week-old Sprague-Dawley male rats were randomly divided into 3 groups (n = 6 each): sham operation, castration, and castration + testosterone replacement. The maximum intracavernosal pressure/mean arterial pressure of the penis was measured after modeling for 4 weeks. The expression levels of endothelial nitric oxide synthase (eNOS), phospho-eNOS, syndecan 1, heparanase, and nitric oxide in penile cavernous tissue and the serum levels of heparan sulfate, hyaluronic acid, tumor necrosis factor α, and interleukin 6 were determined. Transmission electron microscopy was used to observe the ultrastructure of the endothelial glycocalyx in penile tissue.

Outcomes

The thickness of the endothelial glycocalyx in the penile corpus cavernosum of castrated rats was significantly lower than that of the control group.

Results

In the castrated rats, the endothelial glycocalyx thickness, syndecan 1 level, ratio of phospho-eNOS to eNOS, nitric oxide level, and maximum intracavernosal pressure/mean arterial pressure (3 V, 5 V) were significantly lower than those in the sham group (P < .05). The expression of heparanase and the serum levels of tumor necrosis factor α and interleukin 6 were significantly higher in the castrated group than in the sham group (P < .05).

Clinical Translation

Upregulating the expression of the endothelial glycocalyx in the penile corpus cavernosum may be a new method for treating erectile dysfunction caused by low androgen levels.

Strengths and Limitations

This study confirms that low androgen status promotes the breakdown of the endothelial glycocalyx. However, further research is needed to determine whether androgens are related to the synthesis of the endothelial glycocalyx.

Conclusion

Low androgen status may suppress the level of nitric oxide in the cavernous tissue of the penis via impairment of the endothelial glycocalyx, resulting in inhibited erection function in rats.

Efficacy of Chinese Herbal Medicine Formula in the Treatment of Mild to Moderate Erectile Dysfunction: Study Protocol for a Multi-Center, Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

Introduction

Erectile dysfunction (ED) is a prevalent condition in urology, primarily managed with PDE5 inhibitors (PDE5Is). However, approximately 20% of patients do not experience improvement in overall sexual satisfaction (OS) after taking PDE5Is. Among these, traditional Chinese medicine (TCM) has emerged as a complementary approach, with formulas like Hongjing I granules (HJIG) showing promise in preliminary studies. This study aims to rigorously evaluate the effectiveness and safety of HJIG in mild to moderate ED cases, assessing improvement in both sexual function and TCM pattern alignment.

Methods

This study is a randomized, double-blind, placebo-controlled multicentre trial. Recruitment will be conducted from patients who have a strong willingness to try using only traditional Chinese medicine treatment (This is very common in traditional Chinese medicine hospitals.). A total of 100 patients diagnosed with mild to moderate ED caused by qi deficiency and blood stasis will be recruited and randomly assigned to receive one of two treatments: HJIG (N = 50) or placebo (N = 50). Patients will receive 8 weeks of treatment and a 16-week follow-up starting from the fourth week of treatment. Outcome measures, including the International Index of Erectile Function-Erectile Function domain (IIEF-EF) score, Sexual Encounter Profile (SEP), and Traditional Chinese Medicine symptom score, will be evaluated.

Discussion

The expected outcome of this trial is that the use of the herbal formula HIJG alone can improve overall sexual satisfaction (OS) in patients with mild to moderate ED, while also improving their traditional Chinese medicine symptom scores. This will provide evidence-based support for the use of Chinese medicine in the treatment of ED in China.

Trial Registration

Chinese Clinical Trial Registry, ChiCTR2000041127, Registered on 19 December 2020, https://www.chictr.org.cn/showproj.html?proj=46469.

Trial Status

Recruitment began in March 2021, therefore 80 patients have been recruited. It is expected to finish recruiting in December 2023.

LIPUS-SCs-Exo promotes peripheral nerve regeneration in cavernous nerve crush injury-induced ED rats via PI3K/Akt/FoxO signaling pathway

OBJECTIVE

Clinical treatment of erectile dysfunction (ED) caused by cavernous nerve (CN) injury during pelvic surgery is difficult. Low-intensity pulsed ultrasound (LIPUS) can be a potential strategy for neurogenic ED (NED). However, whether Schwann cells (SCs) can respond to LIPUS stimulation signals is unclear. This study aims to elucidate the signal transmission between SCs paracrine exosome (Exo) and neurons stimulated by LIPUS, as well as to analyze the role and potential mechanisms of exosomes in CN repair after injury.

METHODS

The major pelvic ganglion (MPG) neurons and MPG/CN explants were stimulated with LIPUS of different energy intensities to explore the appropriate LIPUS energy intensity. The exosomes were isolated and purified from LIPUS-stimulated SCs (LIPUS-SCs-Exo) and non-stimulated SCs (SCs-Exo). The effects of LIPUS-SCs-Exo on neurite outgrowth, erectile function, and cavernous penis histology were identified in bilateral cavernous nerve crush injury (BCNI)-induced ED rats.

RESULTS

LIPUS-SCs-Exo group can enhance the axon elongation of MPG/CN and MPG neurons compared to SCs-Exo group in vitro. Then, the LIPUS-SCs-Exo group showed a stronger ability to promote the injured CN regeneration and SCs proliferation compared to the SCs-Exo group in vivo. Furthermore, the LIPUS-SCs-Exo group increased the Max intracavernous pressure (ICP)/mean arterial pressure (MAP), lumen to parenchyma and smooth muscle to collagen ratios compared to the SCs-Exo group in vivo. Additionally, high-throughput sequencing combined with bioinformatics analysis revealed the differential expression of 1689 miRNAs between the SCs-Exo group and the LIPUS-SCs-Exo group. After LIPUS-SCs-Exo treatment, the phosphorylated levels of Phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt) and forkhead box O (FoxO) in MPG neurons increased significantly compared to negative control (NC) and SCs-Exo groups.

CONCLUSION

Our study revealed that LIPUS stimulation could regulate the gene of MPG neurons by changing miRNAs derived from SCs-Exo, then activating the PI3K-Akt-FoxO signal pathway to enhance nerve regeneration and restore erectile function. This study had important theoretical and practical significance for improving the NED treatment.

Effect of low androgen levels on transient receptor potential channels expression in rat penile corpus cavernosum tissue and its relationship with erectile function

The exact mechanism by which testosterone deficiency causes ED has not yet been elucidated. TRPC is involved in the process of smooth muscle cell contraction and relaxation. The effect of androgens on TRPCs and their relationship with erectile function are currently unclear. Thirty male SD rats were randomly divided into six groups: control group, castration group, castration + testosterone (T) group (cast + T), control + transfection group (control + trans), control + empty transfection group and castration + transfection group (cast + trans). The transfection group rats were given with lentivirus (1 × 10⁸ TU/mL, 15 μl) carrying the siRNA targeting TRPC4 gene in the rat penile cavernous tissue at 4 weeks after castration. The tests were performed at 5 weeks after castration. Comparing the cast group with the control, the ICPmax/MAP, p-eNOS/eNOS and NO levels in the rat penile tissue were significantly lower (p < 0.01) and the level of TRPC3, TRPC4 and TRPC6 in the rat penile tissue was significantly increased (p < 0.01). When the cast + trans group was compared to the cast group, ICPmax/MAP was markedly higher (p < 0.05), and the level of the TRPC4 was remarkably lower (p < 0.05). Low androgen levels might inhibit an erectile function through up-regulation of the expression of TRPC3, TRPC4 and TRPC6 in rat penile cavernous tissue. Inhibition the level of TRPC4 in rat penile tissue may improve the erectile function in low androgen levels.

Low androgen status inhibits erectile function by up-regulating the expression of proteins of mitochondria-associated membranes in rat corpus cavernosum

OBJECTIVE

To investigate the effect of low androgen status on mitochondria-associated membranes (MAMs) and its relationship with erectile function.

METHODS

A total of 36 eight-week-old male Sprague-Dawley rats were randomly divided into 6 groups: the control (sham-operated) group, the castration group, the castration + testosterone (cast + T) group, the control + siRNA group, the cast + siRNA group, and the cast + empty vector group. Testosterone propionate (3 mg/kg) was subcutaneously injected into the rats in the cast + T group every other day starting from the second day after the surgery. Four weeks later, lentiviral vectors carrying phosphofurin acidic cluster sorting protein 2 (PACS-2) gene-specific siRNA (1 × 10⁸ TU/ mL, 10 μL) were injected into the rats in the siRNA groups. At the 6th week of castration, the ratio of the maximum intracavernous pressure/the mean arterial pressure (ICPmax/MAP), the levels of nitric oxide (NO), endothelial nitric oxide synthase (eNOS), phospho-eNOS (p-eNOS), fatty acid-CoA ligase 4 (FACL-4), PACS-2, and inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) in the penile corpus cavernosum were determined.

RESULTS

The FACL-4, PACS-2 and IP3R1 were primarily localized in the cytoplasm of endothelial cells and part of smooth muscle cells in the corpus cavernosum. The level of NO, the ratio of ICPmax/MAP, and p-eNOS/eNOS were decreased significantly in the castration group compared with the control group (P<0.01). The expressions of FACL-4, PACS-2, and IP3R1 were increased significantly in the castration group compared with the control group (P<0.01). The level of NO, the ratios of ICPmax/MAP, and the ratio of p-eNOS/eNOS were increased significantly in the cast + siRNA group compared with the castration group (P<0.01). The expressions of FACL-4 and PACS-2 were decreased significantly in the cast + siRNA group compared with the castration group (P<0.01).

CONCLUSION

Low androgen status up-regulated the expressions of patients in MAMs (FACL-4, PACS-2 and IP3R1) in the corpus cavernosum and inhibited the eNOS/NO/cGMP signaling pathway, resulting in impaired erectile function in rats. Erectile function may be improved by inhibiting the high expression of PACS-2 in the corpus cavernosum under low androgen state. This article is protected by copyright. All rights reserved.

Pre- and Post-Injection Needle Pain in Patients Undergoing First Intracavernosal Injection

BACKGROUND

Intracavernosal injections (ICI) are a well-established treatment option for men with erectile dysfunction (ED); however, the anticipation of pain with injection remains a significant barrier to the use of ICI.

AIM

To evaluate the patient-anticipated degree of pain versus the experienced degree of pain pre- and post-ICI in men undergoing their first injection with an erectile agent.

METHODS

We studied 51 patients who underwent their first ICI in our men's health clinic. Anticipated needle-associated pain was judged with a pre-injection score, and pain experienced during the injection was judged with a post-injection score. All patients graded their pre- and post-ICI pain using a standard 10-point scale (0-10).

OUTCOMES

Pre- and post-ICI pain was defined with the visual analogue scale (0-10) in men undergoing their first penile injection.

RESULTS

Medians and interquartile ranges (IQRs) of the patients' age [65 years (54.5-68.0)], pre-injection pain [5 (4-7)], and post-injection pain [1 (1-2)] were recorded. Most men in the study had erectile dysfunction (68.6%) and/or Peyronie's Disease (64.7%). The average pre-injection prediction pain score was 5.45 ± 2.15; the average post-injection perceived pain score was 1.20 ± 0.73. Thus, there was an average discrepancy of over 4 points in predicted pain vs perceived pain. A paired t-test was performed which showed a statistically significant difference between pre- and post-injection scores (P < .05). A Wilcoxson Signed Rank Test showed statistical significance in the difference between pre- and post-injection pain scores (P < .05).

CLINICAL IMPLICATIONS

ICI is a safe, effective treatment for patients with ED and is associated with significantly less pain than is anticipated by patients.

STRENGTHS & LIMITATIONS

This is the first report to describe the discrepancy between pre-ICI anticipated pain and post-ICI experienced pain. Limitations include an overall small sample size.

CONCLUSION

Patients experience significantly less pain with ICI than they anticipate having. This represents an important factor to consider when counseling patients about available ED treatments. Baird B, Wajswol E, Ericson C et al. Pre- and Post-Injection Needle Pain in Patients Undergoing First Intracavernosal Injection. J Sex Med 2022;19:590-593.

Analysis of the Impact of Clinical Factors on Low-Intensity Extracorporeal Shockwave Therapy for Erectile Dysfunction

INTRODUCTION

Predictive factors for the treatment success of low-intensity extracorporeal shockwave therapy (Li-ESWT) for erectile dysfunction (ED) are still under debate.

METHODS

Li-ESWT was performed in 50 patients suffering from ED by applying 3,000 shock waves once a week over a period of 6 weeks. Treatment success was defined as an increase in the International Index of Erectile Function 5 (IIEF-5) score by ≥5 points or an Erectile Hardness Score (EHS) of ≥3 points. IIEF-5 and EHS were measured at baseline and at 3 and 6 months of follow-up.

RESULTS

Treatment success according to either the IIEF-5 score or EHS at any time of follow-up was achieved in 28 patients (56%). Twenty-five patients (50%) experienced an improvement during the first 3 months, which lasted for 6 months in 8 cases (16%). Three patients reported improved erectile function only after 6 months. When stratifying the cohort with regard to potential influencing factors, a significantly improved IIEF-5 score could be achieved in men with cardiovascular risk factors (p = 0.026) and in men with antihypertensive medication (p = 0.009). Men without cardiovascular risk factors showed no therapeutic benefit from Li-ESWT.

DISCUSSION/CONCLUSION

Li-ESWT is a valid but often short-lived treatment option for ED, especially in men with cardiovascular risk factors or controlled hypertension. Future studies should assess the feasibility and safety of repeated applications of Li-ESWT.

Restoration of erectile function by a combination of antiapoptosis by JNK inhibitor and preservation of smooth muscle or endothelium by hepatocyte growth factor in a rat model of cavernous nerve injury

BACKGROUND

Because of structural alterations in the corpus cavernosum after radical prostatectomy (RP), post-RP erectile dysfunction remains a very difficult condition to treat. We aimed to determine if the combined administration of a Jun-amino terminal kinase (JNK) inhibitor and hepatocyte growth factor (HGF) in the immediate post-injury period would restore erectile function by antiapoptotic and pro-regenerative effects through the rectification of molecular pathways related to the structural integrity of the penis in a rat model of bilateral cavernosal nerve crush injury (CNCI).

METHODS

A total of 70 rats were divided into five groups: Sham surgery (S), CNCI (I), and once-daily intraperitoneal administration of 10.0 mg/kg JNK inhibitor + twice-weekly intracavernosal administration of low-dose (2.1 μg), medium-dose (4.2 μg), or high-dose (8.4 μg) HGF (I + J + LH or I + J + MH or I + J + HH, respectively) in the immediate post-injury period. Erectile responses to electrostimulation (1.0, 3.0, and 5.0 V), histological staining, caspase-3 activity, and Western blotting were evaluated 9 days after surgery.

RESULTS

Group I showed lower intracavernosal pressure (ICP)/mean arterial pressure (MAP) after stimulation at each voltage, lower area under the curve (AUC)/MAP after stimulation at each voltage, less smooth muscle (SM) content, a lower SM/collagen ratio, higher caspase-3 activity, increased cJun phosphorylation, decreased protein expression of PECAM-1, decreased cMet phosphorylation, and decreased endothelial nitric oxide synthase (eNOS) phosphorylation compared to Group S. The SM content, SM/collagen ratio, protein expression of ICP/MAP, or AUC/MAP after stimulation at each voltage in Group I + J + LH were partially restored, despite the normalization of cJun phosphorylation and caspase-3 activity. The ICP/MAP, AUC/MAP, caspase-3 activity, SM content, protein expression of PECAM-1, cJun phosphorylation, cMet phosphorylation, and eNOS phosphorylation in both Groups I + J + MH and I + J + HH were restored to the levels observed in Group S, while the SM/collagen ratio was significantly improved but not completely normalized.

CONCLUSIONS

Our data indicated that the combined administration of a JNK inhibitor and medium or high-dose HGF to nerve-injured rats in the immediate post-injury period after CNCI may restore erectile function to a level comparable to the normal level by suppressing cavernosal apoptosis and preserving the integrity of SM or endothelium via rectification of the cJun and cMet/eNOS pathways.

Low androgen status inhibits erectile function by increasing pyroptosis in rat corpus cavernosum

BACKGROUND

The mechanism of erectile dysfunction (ED) caused by low androgen status is not fully understood.

OBJECTIVES

To investigate whether low androgen status inhibits erectile function of rats by inducing pyroptosis in the corpus cavernosum (CC).

MATERIALS AND METHODS

Thirty-six eight-weeks-old healthy male Sprague-Dawley rats were equally divided into six groups: sham-operated group (4w sham, 8w sham), castration group (4w cast, 8w cast), and castration + testosterone (T) group (4w cast + T, 8w cast + T). The rats in castration + T groups were injected with testosterone propionate subcutaneously every other day. After 4 and 8 weeks, the ratio of maximum intracavernous pressure (ICPmax)/mean arterial pressure (MAP), the level of serum T, the concentration of nitric oxide (NO) and interleukin-1β (IL-1β), the expression of NOD-like receptor pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), Caspase-1 p20, gasdermin D-N (GSDMD-N), transforming growth factor β1 (TGF-β1), collagen-I, and collagen-III, the ratio of smooth muscle/collagen (SM/C), and the proportion of pyroptotic cells in the CC were analyzed.

RESULTS

The ratio of ICPmax/MAP (3/5 V) and SM/C, the level of NO and serum T was significantly decreased in castration groups when compared to other groups (p < 0.01). NLRP3, ASC, Caspase-1, and GSDMD were mainly expressed in the cytoplasm of smooth muscle cells (SMCs) and endothelial cells (ECs) in the CC. The expression of NLRP3, ASC, Caspase-1p20, GSDMD-N, IL-1β, TGF-β1, collagen-I, and collagen-III was significantly increased in castration groups when compared with other groups (p < 0.01). The proportion of pyroptotic cells in the CC was increased significantly in castration groups when compared with other groups (p < 0.05).

DISCUSSION AND CONCLUSION

Low androgen status inhibits erectile function of rats by promoting CC fibrosis and reducing NO synthesis through pyroptosis of SMCs and ECs in the CC.

Rectification of cavernosal fibrosis and veno-occlusive dysfunction by administration of suberoylanilide hydroxamic acid in a rat model of cavernosal nerve injury: Comparison with a PDE5 inhibitor

BACKGROUND

Cavernosal fibrosis, which is induced by cavernosal nerve (CN) injury and progresses with time, is the main cause of cavernosal veno-occlusive dysfunction (CVOD) after radical prostatectomy.

OBJECTIVES

To determine whether daily oral administration of suberoylanilide hydroxamic acid (SAHA; vorinostat) for 5-weeks from the immediate post-injury period after CN injury would rectify CVOD by suppressing cavernosal fibrosis and normalizing HDAC pathway in a rat model of CN crush injury (CNCI) and to compare the results with those obtained using chronic administration of PDE5-inhibitors (a positive control).

METHODS

Fifty-six 12-week-old rats were randomized into the four groups: sham surgery (S), CNCI (I), and CNCI treated with daily administration of 25.0 mg/kg SAHA (V) or 20.0 mg/kg udenafil (P). Group-V and Group-P received the respective treatment for 5-weeks from the following day after CNCI. At 5 weeks after surgery, dynamic infusion cavernosometry (DIC), histological staining, and Western blot analysis were performed.

RESULTS

Group-I had a significantly decreased papaverine response, higher maintenance rate or drop rate, lower smooth muscle (SM)/collagen ratio, decreased SM content, and increased protein expression of HDAC2, HDAC3, TGF-β1, and collagen-1, compared with Group-S. The three DIC parameters in Group-V and Group-P significantly improved compared to those in Group-I. Except for the maintenance rate, the improvement in papaverine response and drop rate in Group-V was not significantly different from that in Group-P. Group-V and Group-P showed the rectification of SM/collagen ratio and protein expression of TGF-β1 or collagen-1. SM content was improved in Group-P, but not in Group-V. Group-V showed the normalization of protein expression of both HDAC2 and HDAC3, whereas protein expression of only HDAC2 was partially restored in Group-P.

DISCUSSION

Treatment strategies targeting the HDAC pathway might be helpful to alleviate CVOD induced by CN injury.

CONCLUSIONS

According to our data, chronic administration of SAHA improves post-injury CVOD by suppressing cavernosal fibrosis via rectifying the HDAC/TGF-β1 pathway in nerve-injured rats, comparable to that with PDE5 inhibitors.

Restoration of Cavernous Veno-Occlusive Function through Chronic Administration of a Jun-Amino Terminal Kinase Inhibitor and a LIM-Kinase 2 Inhibitor by Suppressing Cavernous Apoptosis and Fibrosis in a Rat Model of Cavernous Nerve Injury: A Comparison with a Phosphodiesterase Type 5 Inhibitor

Purpose

To determine if chronic administration of Jun-amino terminal kinase (JNK)-inhibitors and LIM-kinase 2 (LIMK2)-inhibitors from the immediate post-injury period in a rat model of cavernous-nerve-crush-injury could normalize cavernous-veno-occlusive-function, and to compare it with phosphodiesterase type 5 (PDE5)-inhibitors.

Materials and Methods

A total of 75 12-week-old male Sprague–Dawley-rats were randomized into five groups: sham-surgery (S), cavernous-nerve-crush-injury (I), cavernous-nerve-crush-injury treated with 10.0 mg/kg LIMK2-inhibitor (L) or 10.0 mg/kg JNK-inhibitor and 10.0 mg/kg LIMK2-inhibitor (J+L) or 20.0 mg/kg udenafil (P) for five-weeks. Five-weeks after surgery, dynamic-infusion-cavernosometry, histological-studies, caspase-3-activity-assay, and Western-blot were investigated.

Results

Group-I had lower papaverine-response, higher maintenance-rate and higher drop-rate, compared to Group-S. Group-L, Group-J+L and Group-P showed improvement in the three dynamic-infusion-cavernosometry parameters. The papaverine-response and drop-rate in Group-J+L and Group-P recovered to sham-control level, but those in Group-L did not. Regarding apoptosis, Group-I had decreased content of α-smooth-muscle-actin, increased caspase-3 activity and increased cJun-phosphorylation. The cJun-phosphorylation improved only in Group-J+L. The α-smooth-muscle-actin content and caspase-3-activity in Group-J+L and Group-P improved, but those in Group-L were not. Regarding fibrosis, Group-I had decreased smooth muscle (SM)/collagen-ratio, increased protein-expression of fibronectin, and increased Cofilin-phosphorylation. Cofilin-phosphorylation was normalized in Group-L and Group-J+L, but not in Group-P. SM/collagen-ratio and protein-expression of fibronectin in Group-L, Group-J+L and Group-P improved.

Conclusions

Our data indicate that chronic inhibition of JNK and LIMK2 can restore cavernous-veno-occlusive-function by suppressing cavernous-apoptosis and cavernous-fibrosis, comparable to the results by PDE5-inhibitors. Chronic inhibition of JNK and LIMK2 might be a potential mechanism-specific targeted therapy for cavernous-veno-occlusive-dysfunction induced by cavernous nerve-injury.

Extracorporeal Shock Waves Therapy Delivered by Aries Improves Erectile Dysfunction in Spontaneously Hypertensive Rats Through Penile Tissue Remodeling and Neovascularization

Background

Low-intensity extracorporeal shock wave therapy (Li-ESWT) has been reported to improve erectile function in patients with moderate-to-severe erectile dysfunction (ED) or even convert phosphodiesterase type 5 inhibitors nonresponders to responders. ED is highly prevalent in hypertensive patients. The effect of Li-ESWT on an animal model of hypertension-associated ED has not been reported.

Aim

To investigate the effect of Li-ESWT on hypertension-associated ED and provide plausible mechanisms of action of Li-ESWT on local mechanisms of penile erection.

Methods

Spontaneously hypertensive rats (SHRs) in the active group (n = 13) received Li-ESWT at energy flux density 0.06 mJ/mm² (Aries; Dornier MedTech, Wessling, Germany) twice weekly for 6 weeks. The emitter was set to zero for SHRs in the sham group (n = 12). Erectile function was assessed 4 weeks post-treatment by monitoring intracavernosal pressure (ICP) in response to electrical stimulation of cavernous nerve before and after single dose of 0.3 mg/kg intravenous sildenafil. Cavernosal tissue was then evaluated for collagen/smooth muscle content, neuronal nitric oxide synthase (nNOS), and vascular endothelial factor (CD31) expression.

Outcomes

Erectile function was assessed with ICP, erectile tissue remodeling was studied by smooth muscle/collagen ratio, nNOS and CD31 were semiquantitatively evaluated on cavernosal sections.

Results

The improvement of ICP parameters was greater in Li-ESWT–treated rats compared with controls with and without sildenafil. Sildenafil led to 20% increase in area under the intracavernosal pressure curve measured during the entire response/mean arterial pressure at 10 Hz in ESWT_SHR + sildenafil compared with ESWT_SHR. The smooth muscle/collagen ratio increased 2.5-fold in Li-ESWT compared with sham. Expression of CD31 tended to be increased whereas nNOS was unchanged.

Conclusions

Li-ESWT by Aries may represent an effective noninvasive therapeutic alternative and a relevant add-on therapy to phosphodiesterase type 5 inhibitors for ED in hypertensive patients, and it is suggested that it acts via remodeling of the penile tissue and promoting cavernosal vascularization.

Assaly R, Giuliano F, Clement P, et al. Extracorporeal Shock Waves Therapy Delivered by Aries Improves Erectile Dysfunction in Spontaneously Hypertensive Rats Through Penile Tissue Remodeling and Neovascularization. Sex Med 2019;7:441–450

Combination of LIM-kinase 2 and Jun Amino-terminal Kinase Inhibitors Improves Erectile Function in a Rat Model of Cavernous Nerve Injury

OBJECTIVE

To determine if combined administration of LIMK2 and JNK inhibitors in a rat model of erectile dysfunction induced by cavernosal nerve (CN) injury could restore erectile function by suppressing both cavernosal apoptosis and fibrosis via rectification of molecular pathways related to the structural alterations.

METHODS

Sixty 12-week-old male Sprague-Dawley rats were categorized into 4 groups: (1) Sham-surgery (Sham) group, (2) CN-crush-injury (CNCI), (3) CNCI group (CNCI+L+1.0J) treated with a combination of 10.0 mg/kg LIMK2-inhibitors and low-dose (1.0 mg/kg) JNK-inhibitors, and (4) CNCI group (CNCI+L+10.0J) treated with a combination of 10.0 mg/kg LIMK2-inhibitors and a high dose (10.0 mg/kg) of JNK-inhibitors. Ten days after surgery, erectile response, histological-studies, and Western-blot was investigated.

RESULTS

The CNCI group showed a reduced maximal ICP/MAP or AUC/MAP, decreased immunohistochemical-staining of α-SMA, decreased SM/collagen ratio, increased phospho-cJun-positive apoptotic cells, increased phospho-LIMK2-positive fibroblasts, increased cJun-phosphorylation, increased LIMK2/Cofilin-phosphorylation, decreased Bcl-2/Bax ratio, and increased protein-expression of fibronectin, compared to the Sham group. Both the CNCI+L+1.0J and CNCI+L+10.0J groups showed improvements in erectile-responses, content of cavernosal α-SMA, number of phospho-cJun-positive apoptotic cells, Bcl-2/Bax ratio and cJun phosphorylation. Their improvements in the CNCI+L+10.0J group showed a tendency to be greater than those in the CNCI+L+1.0J group. Also, in the 2 treatment groups, rectification of SM/collagen ratio, number of phospho-LIMK2-positive fibroblasts, LIMK2/Cofilin-phosphorylation, and protein-expression of fibronectin was observed.

CONCLUSION

This study suggests that combined inhibition of JNK and LIMK2 may improve erectile function by suppressing cavernosal apoptosis and fibrosis via restoration of cJun/Bcl-2/Bax and LIMK2/Cofilin pathways at 10 days after CN injury.

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.

Small and Intermediate Calcium-Activated Potassium Channel Openers Improve Rat Endothelial and Erectile Function

Modulation of endothelial calcium-activated potassium (KCa) channels has been proposed as an approach to restore endothelial function. The present study investigated whether novel openers of KCa channels with small (KCa2.x) and intermediate (KCa3.1) conductance, NS309 and NS4591, improve endothelium-dependent relaxation and erectile function. Rat corpus cavernosum (CC) strips were mounted for isometric tension recording and processed for immunoblotting. Mean arterial pressure (MAP), intracavernosal pressure (ICP), and electrocardiographic (ECG) measurements were conducted in anesthetized rats. Immunoblotting revealed the presence of KCa2.3 and large KCa conductance (KCa1.1) channels in the corpus cavernosum. NS309 and NS4591 increased current in CC endothelial cells in whole cell patch clamp experiments. Relaxation induced by NS309 (<1 μM) was inhibited by endothelial cell removal and high extracellular potassium. An inhibitor of nitric oxide (NO) synthase, and blockers of KCa2.x and KCa1.1 channels, apamin and iberiotoxin also inhibited NS309 relaxation. Incubation with NS309 (0.5 μM) markedly enhanced acetylcholine relaxation. Basal erectile function (ICP/MAP) increased during administration of NS309. Increases in ICP/MAP after cavernous nerve stimulation with NS309 were unchanged, whereas NS4591 significantly improved erectile function. Administration of NS309 and NS4591 caused small changes in the electrocardiogram, but neither arrhythmic events nor prolongation of the QTc interval were observed. The present study suggests that openers of KCa2.x and KCa3.1 channels improve endothelial and erectile function. The effects of NS309 and NS4591 on heart rate and ECG are small, but will require additional safety studies before evaluating whether activation of KCa2.3 channels has a potential for treatment of erectile dysfunction.

Low Intensity Extracorporeal Shock Wave Therapy Improves Erectile Function in a Model of Type II Diabetes Independently of NO/cGMP Pathway

PURPOSE

Erectile dysfunction is highly prevalent in type II diabetes mellitus. Low intensity extracorporeal shock wave therapy improves erectile function in patients with erectile dysfunction of vasculogenic origin, including diabetes. However, its mode of action remains unknown. We investigated the effects of low intensity extracorporeal shock wave therapy compared to or combined with sildenafil on erectile dysfunction in a type II diabetes mellitus model. Our purpose was to test our hypothesis of a mode of action targeting the cavernous nitric oxide/cyclic guanosine monophosphate pathway.

MATERIALS AND METHODS

GK rats, a validated model of type II diabetes mellitus, and age matched Wistar rats were treated with low intensity extracorporeal shock wave therapy twice weekly for 3 weeks. Treatment was repeated after a 3-week no-treatment interval. The penis was stretched and dipped in a specifically designed water-filled cage. Shock waves were delivered by a calibrated probe yielding a controlled energy flux density (0.09 mJ/mm(2)). The probe was attached to an electrohydraulic unit with a focused shock wave source, allowing for accurate extrapolation to humans. Following a 4-week washout period erectile function was assessed as well as endothelium dependent and independent, and nitrergic relaxations of the corpus cavernosum of GK rats.

RESULTS

Low intensity extracorporeal shock wave therapy significantly improved erectile function in GK rats to the same extent as sildenafil. Treatment effects were potentiated when combined with sildenafil. Shock wave effects were not associated with improved cavernous endothelium dependent or independent, or nitrergic reactivity.

CONCLUSIONS

Low intensity extracorporeal shock wave therapy improved erectile function in GK rats. Unexpectedly, this was not mediated by a nitric oxide/cyclic guanosine monophosphate dependent mechanism. Sildenafil increased shock wave efficacy. This preclinical paradigm to deliver low intensity extracorporeal shock wave therapy to the rat penis should help further exploration of the mode of action of this therapy on erectile tissue.

Expectations do not Influence the Response to Phosphosdiesterase Type 5 Inhibitor Therapy for Erectile Dysfunction

It has been reported that patients frequently discontinue treatment for erectile dysfunction (ED) with phosphodiesterase type 5 inhibitors (PDE5Is) despite apparently good therapeutic results. Because expectations have been shown to affect patients’ appraisals of many drugs, the purpose of this study was to determine whether expectations affected the therapeutic response to PDE5Is in men with apparent psychogenic ED. An unvalidated questionnaire was used to collect data on expectations in 80 men commencing PDE5I therapy, and after three and six months of treatment. At the same time, subjects completed the International Index of Erectile Function (IIEF), the Sexual Excitation/Inhibition Scale (SIS/SES) and Beck’s Depression Inventory (BDI). No evidence of an effect on expectations on changes in IIEF or BDI scores could be identified. Although changes in IIEF, and BDI scores from recruitment to three months were indicative of improved sexual function and less depression, scores for most items on the expectations scale decreased, suggesting that expectations were not being met. The items for which scores decreased were the expectation to be prescribed a drug, that the drug would restore the sexual function to normal, would work within 30 minutes of administration, improve patients confidence to engage in sexual activity, and that the medication was the best treatment for ED across the three data collection points. The findings of this study indicate that improvements in erectile function did not translate into changes in medication expectations that suggested user satisfaction.

Pharmacogenetics of erectile dysfunction: navigating into uncharted waters

Sildenafil and other PDE-5 inhibitors have revolutionized erectile dysfunction (ED) treatment. However, a significant number of patients do not respond or present adverse reactions to these drugs. While genetic polymorphisms may underlie this phenomenon, very little research has been undertaken in this research field. Most of the current knowledge is based on sildenafil, thus almost completely ignoring other important pharmacological therapies. Currently, the most promising genes with pharmacogenetic implications in ED are related to the nitric oxide and cGMP pathway, although other genes are likely to affect the responsiveness to treatment of ED. Nevertheless, the small number of studies available opens the possibility of further exploring other genes and phenotypes related to ED. This article provides a comprehensive overview of the genes being tested for their pharmacogenetic relevance in the therapy of ED.

DPP-4 inhibition improves a sexual condition?

Erectile dysfunction (ED) is a condition of persistent inability to achieve or maintain an erection sufficient for satisfactory sexual intercourse. The etiology of ED is predominantly vascular, explained by nitric oxide metabolism disturbances being in the background. Nitric oxide enhancing drugs like phosphodiesterase 5 inhibitors, which delay the breakdown of nitric oxide, are widely used, but still without complete success. Restauration of endogenous nitric oxide production focused on improving endothelial dysfunction could be a more effective way of treatment, addressing also other vessels in the body and preventing more serious cardiovascular disease. Endothelial progenitor cells are bone marrow-derived cells found also in human circulation, and may under circumstances be embedded into the vascular intima leading to improvements in nitric oxide production and thus in endothelial function in many organs, including the penis. In this article we hypothesize the potential role of DPP-4 inhibitors, a novel class of antidiabetic drugs in increasing the number of circulating endothelial progenitor cells. Speculated mechanisms include several substrates for DPP-4 inhibitors: GLP-1, SDF-1α, substance P, and PACAP. As DPP-4 inhibitors show favorable safety profiles and do not cause hypoglycemia, they seem to be an attractive treatment option, at least in diabetic patients, and could become a part of vascular regenerative pharmacotherapy, ameliorating also symptoms related to erectile dysfunction. Since erectile dysfunction may precede other cardiovascular vascular events, because the penile arteries are smaller in size and therefore more susceptible to decreased nitric oxide production, treating this condition with an agent affecting positively also other blood vessels could help in preventing other cardiovascular events, including myocardial infarction and stroke. However, caution is required, because DPP-4 inhibitors are a heterogenous class of drugs, with variations regarding strength and duration of action, as well as selectivity and cardiovascular safety profile, which may affect properties other than those important in glucocontrol.

The role of statins in erectile dysfunction: a systematic review and meta-analysis

To evaluate the effect of statins for erectile dysfunction (ED), a systematic review of the literature was conducted in the Cochrane Library, Embase and PubMed from the inception of each database to June 2013. Only randomized controlled trials (RCTs) comparing treatment for ED with statins were identified. Placebo RCTs with the International Index of Erectile Function (IIEF) as the outcome measure were eligible for meta-analysis. A total of seven RCTs including two statins with a total of 586 patients strictly met our criteria for systematic review and five of them qualified for the meta-analysis. A meta-analysis using a random effects model showed that statins were associated with a significant increase in IIEF-5 scores (mean difference (MD): 3.27; 95% confidential interval (CI):1.51 to 5.02; P < 0.01) and an overall improvement of lipid profiles including total cholesterol (MD: −1.08; 95% CI: −1.68 to −0.48; P < 0.01), low-density lipoprotein (LDL) cholesterol (MD: −1.43; 95% CI: −2.07 to −0.79; P < 0.01), high-density lipoprotein (HDL) cholesterol (MD: 0.24; 95% CI: 0.13 to 0.35; P < 0.01) and triglycerides (TGs) (MD: −0.55; 95% CI: −0.61 to −0.48; P < 0.01). In summary, our study revealed positive consequences of these lipid-lowering drugs on erectile function, especially for nonresponders to phosphodiesterase type 5 inhibitors (PDE5Is). However, it has been reported that statin therapy may reduce levels of testosterone and aggravate symptoms of ED. Therefore, larger, well-designed RCTs are needed to investigate the double-edged role of statins in the treatment of ED.

Bladder and erectile dysfunctions in the Type 2 diabetic Goto-Kakizaki rat

Despite the fact that urogenito-sexual complications significantly impact the quality of life of diabetic patients, a robust in vivo experimental model is lacking. Bladder and erectile function in the Type 2 diabetic Goto-Kakizaki (GK) rat and responses to standard-of-care treatments for each disorder have been assessed. GK rats (n = 25, 18-wk-old, GK/Par colony) and age-matched Wistar rats (n = 23), characterized for their metabolic parameters, were used. Bladder function was assessed by cystometry in conscious rats treated by intravenous solifenacin (1 mg/kg). Subsequently, erectile function was assessed under anesthesia following electrical stimulation of the cavernous nerve in presence of intravenous sildenafil (0.3 mg/kg). GK rats displayed detrusor overactivity with a significant increase in frequency/amplitude of nonvoiding contractions during the filling phase, together with an increase in bladder capacity, intercontraction interval, voided volume, and maximal pressure of voiding contraction. Solifenacin significantly decreased parameters characterizing voiding contractions without modifying voiding efficiency. Erectile function in GK rats was markedly impaired and remained so after sildenafil treatment despite a significant improvement. GK rats display both bladder and erectile dysfunctions and respond at least partially to standard-of-care treatments for each disorder, thus representing a suitable model to investigate the pathophysiology and assess the efficacy of new therapeutic agents for Type 2 diabetes-associated bladder and erectile complications.

Chronic treatment with taurine ameliorates diabetes-induced dysfunction of nitric oxide-mediated neurogenic and endothelium-dependent corpus cavernosum relaxation in rats

This study was aimed to examine the effect of chronic taurine treatment on corpus cavernosum dysfunction in diabetic rats and to investigate possible underlying mechanisms. Thirty male rats were randomized to three groups of 10 each, including control, diabetic, and taurine-treated diabetic. Diabetes was induced in rats by streptozotocin (STZ, single intraperitoneal dose of 50 mg/kg body weight). Taurine was administered orally for 12 weeks (1% w/v in drinking water) from the day on which STZ was injected. At the end of the 12th week, strips of corpus cavernosum were suspended in an organ bath system for functional studies. Nitric oxide (NO)-mediated endothelium-dependent and neurogenic corpus cavernosum relaxation were evaluated by acetylcholine (ACh, 0.1-100 μm) and electrical field stimulation (EFS, 30 V, 5 ms, 2-32 Hz), respectively. The expressions of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS) (Ser-1177), neuronal nitric oxide synthase (nNOS), NADPH oxidase subunit gp91(phox) , Rho A, and Rho kinase in corpus cavernosum were semi-quantitatively assessed by immunohistochemistry. Induction of diabetes resulted in significant inhibition of NO-mediated endothelium-dependent and neurogenic corpus cavernosum relaxation. Furthermore, eNOS, p-eNOS, and nNOS expressions decreased significantly in diabetic rats compared to controls, while gp91(phox) , RhoA and Rho kinase expressions increased significantly. The diminished relaxation response to ACh and EFS as well as diabetes-related changes in expressions of these proteins in corpus cavernosum of diabetic rats was significantly improved by taurine. Taurine treatment improves NO-mediated relaxations of corpus cavernosum in diabetic rats probably by inhibiting NADPH oxidase/Rho kinase pathways.

Atorvastatin improves erectile dysfunction in patients initially irresponsive to Sildenafil by the activation of endothelial nitric oxide synthase

This study aimed at comparing the effects of atorvastatin and vitamin E on erectile dysfunction in patients initially irresponsive to sildenafil, with investigation into the underlying possible mechanisms. Sixty patients were randomly divided into three groups: the atorvastatin group received 80 mg daily, the vitamin E group received 400 IU daily and the control group received placebo capsules. Patients were examined both before and after 6 weeks of treatment for biochemical tests; Superoxide dismutase (SOD), glutathione peroxidase (GPO), C-reactive protein (CRP), interleukin-6 (IL-6), nitric oxide (NO) and endothelial nitric oxide synthase (eNOS) and for erectile function tests; International index of erectile function (IIEF-5) scores and Rigiscan. Both atorvastatin and vitamin E showed a statistically significant GPO increase (P<0.05) and a statistically significant IL-6 decrease (P<0.05). Only atorvastatin showed a statistically significant increase in NO (15.19%, P<0.05), eNOS (20.58%, P<0.01), IIEF-5 score (53.1%, P<0.001) and Rigiscan rigidity parameters (P<0.01), in addition to a statistically significant decrease in CRP (57.9%, P<0.01). However, SOD showed a statistically significant increase only after vitamin E intake (23.1%, P<0.05). Both atorvatstain and vitamin E had antioxidant and anti-inflammatory activities. Although activating eNOS by atorvastatin was the real difference, and expected to be the main mechanism for NO increase and for improving erectile dysfunction. Atorvastatin, but not vitamin E, is a promising drug for sildenafil nonresponders.

Erectile dysfunction

Erectile dysfunction is a common clinical entity that affects mainly men older than 40 years. In addition to the classical causes of erectile dysfunction, such as diabetes mellitus and hypertension, several common lifestyle factors, such as obesity, limited or an absence of physical exercise, and lower urinary tract symptoms, have been linked to the development of erectile dysfunction. Substantial steps have been taken in the study of the association between erectile dysfunction and cardiovascular disease. Erectile dysfunction is a strong predictor for coronary artery disease, and cardiovascular assessment of a non-cardiac patient presenting with erectile dysfunction is now recommended. Substantial advances have occurred in the understanding of the pathophysiology of erectile dysfunction that ultimately led to the development of successful oral therapies, namely the phosphodiesterase type 5 inhibitors. However, oral phosphodiesterase type 5 inhibitors have limitations, and present research is thus investigating cutting-edge therapeutic strategies including gene and cell-based technologies with the aim of discovering a cure for erectile dysfunction.

Increased phosphodiesterase type 5 levels in a mouse model of type 2 diabetes mellitus

INTRODUCTION

Diabetes mellitus (DM) is a major risk factor for developing erectile dysfunction (ED) and men with DM are often less responsive to phosphodiesterase type 5 (PDE5) inhibitors than ED due to other causes.

AIMS

The aim of this study was to explore potential mechanisms whereby PDE5 inhibitors may have reduced efficacy in type 2 DM.

METHODS

At 4 weeks of age, mice were either fed a high-fat diet (HFD) for 22-36 weeks or fed regular chow (control). An additional group of mice in the same genetic background had a genetic form of type 1 DM.

MAIN OUTCOME MEASURES

Glucose tolerance testing, intracorporal pressures (ICPs), oxidative stress (OS), apoptotic cell death (active caspase-3 and apostain), PDE5, p53, and cyclic guanosine monophosphate (cGMP) levels, and histological examination of inflow arteries were performed in mice fed a HFD and control mice. A group of mice with type 1 DM were studied for PDE5 expression levels.

RESULTS

All mice fed a HFD had impaired glucose tolerance compared with the age-matched mice fed on standard chow diet (control). HFD fed mice had reduced maximum ICPs following in vivo cavernous nerve electrical stimulation and increased apoptotic cell death, OS, and p53 levels in the corporal tissue. Interestingly, PDE5 levels were increased and cGMP levels were decreased. In contrast, mice with type 1 DM did not have increases in PDE5.

CONCLUSIONS

Taken together, our results suggest that type 2 DM-induced ED is associated with findings that could lead to reduced cGMP and may account for reduced efficacy of PDE5 inhibitors.

Combination of BAY 60-4552 and vardenafil exerts proerectile facilitator effects in rats with cavernous nerve injury: a proof of concept study for the treatment of phosphodiesterase type 5 inhibitor failure

BACKGROUND

Radical prostatectomy (RP) is frequently responsible for erectile dysfunction (ED). Post-RP patients often show a failure to respond to phosphodiesterase type 5 (PDE5) inhibitors.

OBJECTIVE

The acute effect of BAY 60-4552, the soluble guanylate cyclase (sGC) stimulator, and vardenafil were evaluated alone or in combination on erectile responses to electrical stimulation of the cavernous nerve (ES CN) in rats with cavernous nerve (CN) crush injury-induced ED.

DESIGN, SETTING, AND PARTICIPANTS

Male adult Sprague-Dawley rats underwent laparotomy (sham, n=10) or bilateral CN crush injury (n=56). After 3 wk of recovery, erectile function was evaluated under urethane anaesthesia following ES CN at different frequencies.

MEASUREMENTS

The acute effects of intravenous (IV) injection of vehicle, vardenafil 0.03 mg/kg, BAY 60-4552 0.03 mg/kg or 0.3 mg/kg, or a BAY 60-4552 0.03 mg/kg plus vardenafil 0.03 mg/kg combination were evaluated in CN-crushed rats.

RESULTS AND LIMITATIONS

Bilateral CN crush injury followed by a 3-wk recovery period decreased erectile responses to ES CN by about 50%. In CN-crushed rats, IV vardenafil 0.03 mg/kg and BAY 60-4552 (0.03 or 0.3 mg/kg) increased erectile responses to ES CN to the same extent: Δ intracavernosal pressure/mean arterial pressure (ICP/MAP) at 10 Hz ES CN was 21±1% after vehicle, 25±3% (p<0.001) after vardenafil, and 26±5% and 27±5% after BAY 60-4552 0.03 mg/kg (p<0.01) and 0.3 mg/kg (p<0.001), respectively. The combination of vardenafil with BAY 60-4552 in CN-crushed rats totally restored erectile responses to ES CN equivalent to sham rats (ΔICP/MAP at 10 Hz ES CN: 34±4% after BAY 60-4552/vardenafil combination vs 39±4% in sham rats; not significant).

CONCLUSIONS

The present study supports the concept that the combined administration of a sGC stimulator, BAY 60-4552, and vardenafil provides synergistic beneficial effects and might therefore salvage patients who experience treatment failures with PDE5 inhibitors after RP.

Do lifestyle changes work for improving erectile dysfunction?

The main cause of erectile dysfunction (ED) is organic in nature, with vascular etiologies being the most common risk factors. Although there have been sufficient data on the relationship between ED and several well-recognized risk factors, including aging, coronary artery disease, atherosclerosis, diabetes mellitus, dyslipidemia, high blood pressure, and pelvic surgeries, little attention has been paid by the urologists to the role of lifestyle factors in ED. However, accumulating data from basic science and clinical studies have determined a link between the occurrence of ED and a number of lifestyle factors, such as smoking, obesity, alcohol consumption, and lack of physical activity. The application of findings from animal and human studies to the clinical practice regarding the modification of lifestyle factors could help improving ED as well as reducing the risks of developing cardiovascular diseases. This communication addresses the impact of lifestyle factors on erectile function and the potential benefits of modifying these factors to improve ED in respect to the current evidence.

Combination of alfuzosin and tadalafil exerts in vitro an additive relaxant effect on human corpus cavernosum

INTRODUCTION

Phosphodiesterase type 5 (PDE5) inhibitors, such as tadalafil, are a first-line treatment for erectile dysfunction (ED). Nevertheless, some patients do not respond to this treatment. Clinical data suggest that the addition of alpha1-adrenoceptor blocker, such as alfuzosin, commonly prescribed for lower urinary tract symptoms suggestive of benign prostatic hyperplasia, may be of benefit. Aim. Evaluation of the effect of alfuzosin, tadalafil or the combination of both on human corpus cavernosum.

METHODS

Human cavernosal tissues were obtained from 10 patients undergoing penile surgery. Strips contractility was studied in organ baths. Concentration-response curves to tadalafil were generated on norepinephrine (NE, 1-10 microM)-precontracted strips in the presence of alfuzosin or vehicle. Frequency-response curves (FRC) to electrical field stimulation (EFS, 0-64 Hz, 3 ms, 10 seconds, 300 mA) were generated in the presence of vehicle, alfuzosin, tadalafil, or both drugs combined. EFS (20 Hz, 1 ms, 10 seconds, 300 mM)-induced nitrergic relaxation on NE-precontracted strips was studied in the presence of vehicle, alfuzosin, tadalafil, or both drugs combined.

MAIN OUTCOME MEASURES

Functional measurement of cavernosal smooth muscle relaxation in the presence of tadalafil and alfuzosin.

RESULTS

The relaxation induced by tadalafil (10(-10) to 10(-5) M) on precontracted strips was enhanced by alfuzosin at both 10(-8) and 10(-7) M. The combination of alfuzosin (3.10(-8) M) and tadalafil (10(-7) M) was more efficient to inhibit FRC-induced contractions than each compound alone. The combination of tadalafil (10(-6) M) and alfuzosin (10(-8) M) increased the relaxation induced by EFS and its effect was greater than tadalafil alone. In addition, the combination of tadalafil (10(-6) M) and alfuzosin (10(-7) M) prolonged EFS-induced relaxation to a greater extent than each compound alone.

CONCLUSIONS

In vitro, the combination of alfuzosin and tadalafil is more efficient than each compound alone to relax adrenergic tone or to enhance nitrergic relaxation of the human corpus cavernosum. Such a combination deserves further investigation in placebo-controlled studies to evaluate its benefit in ED patients who are not sufficiently improved by PDE5 inhibitors.