Phosphodiesterase 5 inhibitors in the management of benign prostatic hyperplasia and erectile dysfunction: the best of both worlds:

Prunella vulgaris Extract Ameliorates Testosterone-Induced Benign Prostatic Hyperplasia by Regulating Androgen Levels, Cell Proliferation, and Apoptosis

BACKGROUND/OBJECTIVES

Benign prostatic hyperplasia (BPH) is a prevalent urological condition affecting elderly men. Prunella vulgaris L. (PV), a perennial herbaceous plant native to Europe and Asia, has anti-inflammatory, antioxidant, and antimicrobial effects. In this study, we determined the effect of PV extract on the development of BPH.

METHODS

Rats were treated via a daily hypodermic injection of testosterone propionate (TP; 3 mg/kg) for 4 weeks. Groups of BPH rats were treated with or without PV (60 or 80 mg/kg) by oral gavage.

RESULTS

In BPH model rats, PV considerably reduced their relative prostate weight and serum concentrations of dihydrotestosterone (DHT) and testosterone. The TP-induced increases in epithelial thickness in the prostate, proliferating cell nuclear antigen (PCNA) expression, and cyclin D1 expression were remarkably reduced, whereas terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells and cleaved caspase-3 levels were increased, in PV-treated rats compared to BPH rats. The mRNA expression levels of growth factors, such as transforming growth factor-β (TGF-β), fibroblast growth factor (FGF), and insulin-like growth factor (IGF-2), were significantly reduced in PV-treated rats. Mechanistically, the TP-induced activation of c-Jun N-terminal kinase (JNK) was reduced by PV administration.

CONCLUSIONS

These results designate that PV effectively ameliorates the development of testosterone-induced BPH through anti-androgenic, anti-proliferative, and pro-apoptotic activities, suggesting that it could be a potential therapeutic substance for BPH.

Advancements in Phosphodiesterase 5 Inhibitors: Unveiling Present and Future Perspectives

Phosphodiesterase 5 (PDE5) inhibitors presented themselves as important players in the nitric oxide/cGMP pathway, thus exerting a profound impact on various physiological and pathological processes. Beyond their well-known efficacy in treating male erectile dysfunction (ED) and pulmonary arterial hypertension (PAH), a plethora of studies have unveiled their significance in the treatment of a myriad of other diseases, including cognitive functions, heart failure, multiple drug resistance in cancer therapy, immune diseases, systemic sclerosis and others. This comprehensive review aims to provide an updated assessment of the crucial role played by PDE5 inhibitors (PDE5-Is) as disease-modifying agents taking their limiting side effects into consideration. From a medicinal chemistry and drug discovery perspective, the published PDE5-Is over the last 10 years and their binding characteristics are systemically discussed, and advancement in properties is exposed. A persistent challenge encountered with these agents lies in their limited isozyme selectivity; considering this obstacle, this review also highlights the breakthrough development of the recently reported PDE5 allosteric inhibitors, which exhibit an unparalleled level of selectivity that was rarely achievable by competitive inhibitors. The implications and potential impact of these novel allosteric inhibitors are meticulously explored. Additionally, the concept of multi-targeted ligands is critically evaluated in relation to PDE5-Is by inspecting the broader spectrum of their molecular interactions and effects. The objective of this review is to provide insight into the design of potent, selective PDE5-Is and an overview of their biological function, limitations, challenges, therapeutic potentials, undergoing clinical trials, future prospects and emerging uses, thus guiding upcoming endeavors in both academia and industry within this domain.

The regulation of transient receptor potential canonical 4 (TRPC4) channel by phosphodiesterase 5 inhibitor via the cyclic guanosine 3'5'-monophosphate

The transient receptor potential (TRP) protein superfamily consists of a diverse group of cation channels that bear structural similarities to the fruit fly Drosophila TRP. The TRP superfamily is distinct from other groups of ion channels in displaying a large diversity in ion selectivity, modes of activation, and physiological functions. Classical TRP (transient receptor potential canonical (TRPC)) channels are activated by stimulation of Gq-PLC-coupled receptors and modulated by phosphorylation. The cyclic guanosine monophosphate (cGMP)-PKG pathway is involved in the regulation of TRPC3 and TRPC6 channels. Phosphodiesterase (PDE) 5 inhibitor induced muscle relaxation in corporal smooth muscle cells and was used to treat erectile dysfunction by inhibiting cGMP degradation. Here, we report the functional relationship between TRPC4 and cGMP. In human embryonic kidney (HEK) 293 cells overexpressing TRPC4, cGMP selectively activated TRPC4 channels and increased cytosolic calcium level through TRPC4 channel. We investigated phosphorylation sites in TRPC4 channels and identified S688 as an important phosphorylation site for the cGMP-PKG pathway. Cyclic GMP also activated TRPC4-like current with doubly rectifying current-voltage relationship in prostate smooth muscle cell lines. Taken together, these results show that TRPC4 is phosphorylated by the cGMP-PKG pathway and might be an important target for modulating prostate function by PDE5 inhibitors.

D-004 ameliorates phenylephrine-induced urodynamic changes and increased prostate and bladder oxidative stress in rats

BACKGROUND

Lower urinary tract symptoms (LUTS) in patients with benign prostatic hyperplasia (BPH) mainly depend on alpha1-adrenoreceptors (α1-ADR) stimulation, but a link with oxidative stress (OS) is also involved. D-004, a lipid extract of Roystonea regia fruits, antagonizes ADR-induced responses and produces antioxidant effects. The objective of this study was to investigate whether D-004 produce antioxidant effects in rats with phenylephrine (PHE)-induced urodynamic changes.

METHODS

Rats were randomized into eight groups (ten rats/group): a negative vehicle control and seven groups injected with PHE: a positive control, three treated with D-004 (200, 400 and 800 mg/kg) and three others with tamsulosin (0.4 mg/kg), grape seed extract (GSE) (250 mg/kg) and vitamin E (VE) (250 mg/kg), respectively.

RESULTS

Effects on urinary total volume (UTV), volume voided per micturition (VM), malondialdehyde (MDA) and carbonyl groups (CG) concentrations in prostate and bladder homogenates were study outcomes. While VM and UTV lowered significantly in the positive control as compared to the negative control group, the opposite occurred with prostate and bladder MDA and CG values. D-004 (200-800 mg/kg) increased significantly both VM and UTV, lowered significantly MDA in prostate and bladder homogenates, and reduced GC levels only in the prostate. Tamsulosin increased significantly VM and UTV, but unchanged oxidative variables. GSE and VE unchanged the UTV, whereas VE, not GSE, modestly but significantly attenuated the PHE-induced decrease of VM.

CONCLUSIONS

Single oral administration of D-004 (200-800 mg/kg) was the only treatment that ameliorated the urodynamic changes and reduced increased oxidative variables in the prostate of rats with PHE-induced prostate hyperplasia.

Phosphodiesterase sequence variants may predispose to prostate cancer

We hypothesized that mutations that inactivate phosphodiesterase (PDE) activity and lead to increased cAMP and cyclic guanosine monophosphate levels may be associated with prostate cancer (PCa). We sequenced the entire PDE coding sequences in the DNA of 16 biopsy samples from PCa patients. Novel mutations were confirmed in the somatic or germline state by Sanger sequencing. Data were then compared to the 1000 Genome Project. PDE, CREB and pCREB protein expression was also studied in all samples, in both normal and abnormal tissue, by immunofluorescence. We identified three previously described PDE sequence variants that were significantly more frequent in PCa. Four novel sequence variations, one each in the PDE4B,PDE6C, PDE7B and PDE10A genes, respectively, were also found in the PCa samples. Interestingly, PDE10A and PDE4B novel variants that were present in 19 and 6% of the patients were found in the tumor tissue only. In patients carrying PDE defects, there was pCREB accumulation (P<0.001), and an increase of the pCREB:CREB ratio (patients 0.97±0.03; controls 0.52±0.03; P-value <0.001) by immunohistochemical analysis. We conclude that PDE sequence variants may play a role in the predisposition and/or progression to PCa at the germline and/or somatic state respectively.

Phosphodiesterase type 5 inhibitors for treating erectile dysfunction and lower urinary tract symptoms secondary to benign prostatic hyperplasia: A comprehensive review

Many men have coexistent erectile dysfunction (ED) and lower urinary tract symptoms secondary to benign prostatic hyperplasia (LUTS/BPH). Phosphodiesterase type 5 (PDE5) inhibitors are effective for treating both of these conditions independently. In this review we summarise the evidence supporting a link between ED and LUTS/BPH, and the results from key clinical studies related to the use of PDE5 inhibitors for treating both conditions. The results from these studies suggest that men who have both ED and LUTS/BPH, and are concerned about their sexual dysfunction, might benefit from single-agent, holistic treatment with a PDE5 inhibitor.

A multilingual evaluation of current health information on the Internet for the treatments of benign prostatic hyperplasia

Purpose

To compare the quality of current Internet information on benign prostatic hyperplasia (BPH) and its surgical and medical managements across four Western languages and a comparative analysis of website sponsors. BPH Internet information quality is particularly relevant in an era of expanding, minimally invasive and surgical therapies. However, no comprehensive analysis exists.

Methods

World Health Organization Health on the Net (HON) principles may be applied to websites using an automated toolbar function. Using a search engine (www.google.com), 9,000 websites were assessed using keywords related to BPH and its medical and surgical treatment in English, French, German, and Spanish. The first 150 websites in each language had HON principles measured whilst a further analysis of site sponsorship was undertaken.

Results

Very few BPH websites had greater than ten per cent HON accredited with significant differences (P<0.001) based on terms used for BPH, its medical and surgical management. Tertiles (thirds) of the first 150 websites returned differences in accredited websites (P<0.0001). English language had most accredited websites. Odds ratios for different terms returning accredited websites also were significantly different across terms (P<0.001). Websites were largely commercially sponsored.

Conclusions

A lack of validation of most BPH sites should be appreciated with discrepancies in quality and number of websites across diseases, languages and also between medical and alternate terms. Physicians should participate in and encourage the development of informative, ethical and reliable health websites on the Internet and direct patients to them.

Effect of chronic Sildenafil treatment on the prostate of C57Bl/6 mice

Sildenafil is a potent and selective inhibitor of phosphodiesterase-5 (PDE5) and is considered first-line therapy for erectile dysfunction. Nowadays, Sildenafil is used extensively throughout the world on patients with pulmonary hypertension. However, few studies have evaluated the possible side effects of chronic Sildenafil treatment on the male reproductive system, specifically in the prostate. In the present study, it was demonstrated via morphological and ultrastructural analysis that chronic treatment with Sildenafil induced an enhancement of the glandular activity of the prostate. In addition, mice treated with Sildenafil showed a significant increase in testosterone serum levels. However, no statistically significant differences were observed in nitric oxide serum levels, or in sGC, eNOS, PSA and TGF-β prostatic expression. In conclusion, the present study suggests that chronic use of Sildenafil does not cause evident prostatic damage, and therefore, can be used pharmacologically to treat a variety of disorders.

Phosphodiesterase-5 inhibitors for lower urinary tract symptoms secondary to benign prostatic hyperplasia: a systematic review and meta-analysis

OBJECTIVES

To evaluate the efficacy and safety of phosphodiesterase-5 (PDE-5) inhibitors for treating lower urinary tract symptoms secondary to benign prostatic hyperplasia.

METHODS

Randomized controlled trials were identified and extracted from MEDLINE, Embase, Cochrane Central, and relevant reference lists. The database search, quality assessment, and data extraction were independently performed by 2 reviewers. Heterogeneity was analyzed using the chi-square test and I(2) test. If lacking of heterogeneity, fixed-effects models were used for the meta-analysis, otherwise random-effects models were used.

RESULTS

A total of 5 studies (11 randomized controlled trials) were identified from the search strategy. Compared with placebo, short-term trials (≤12 weeks) indicated that PDE-5 inhibitors significantly improved the International Prostate Symptom Score (mean difference -2.60, 95% confidence interval [CI] -3.12 to -2.07; P < .00001), and statistical significance was observed in the International Prostate Symptom Score irritative and obstructive subscore, International Prostate Symptom Score quality of life and erectile function. However, no statistically significant difference was detected in maximal urinary flow rate (mean difference 0.21, 95% CI -0.21-0.64; P = .32) and postvoid residual urine volume (mean difference 0.09, 95% CI -4.71-4.89; P = .80). No statistically significant difference was found between the 2 groups in the incidence of serious adverse events (relative risk 0.52, 95% CI 0.25-1.07; P = .07), despite that adverse event with a greater incidence was detected in the PDE-5 group (relative risk 1.87, 95% CI 1.31-2.68; P = .0005).

CONCLUSIONS

As the first-line treatment of erectile dysfunction, the PDE-5 inhibitor is also effective and safe for lower urinary tract symptoms secondary to benign prostatic hyperplasia. It could be considered as the first-line treatment in the future for the treatment of patients with comorbid benign prostatic hyperplasia and erectile dysfunction.

Phosphodiesterase 5 inhibitors for lower urinary tract symptoms secondary to benign prostatic hyperplasia: a systematic review

OBJECTIVE

• To review the evidence in support of the effectiveness of phosphodiesterase 5 inhibitors in lower urinary tract symptoms (LUTS) caused by benign prostatic hyperplasia (BPH).

METHODS

• Relevant studies were identified by performing a literature search using MEDLINE® and The Cochrane Library®. The criteria used during the search included randomized, placebo-controlled trials of treatment for LUTS secondary to BPH using the International Prostate Symptom Score as an outcome measure.

RESULTS

• Four trials that included a total of 1928 patients met the inclusion criteria. All four studies showed a statistically significant difference in the International Prostate Symptom Score, quality of life and erectile function in favour of phosphodiesterase 5 inhibitors. • No study showed a statistically significant improvement of the maximum urinary flow. • Meta-analysis of the results was not possible because of heterogeneity across the studies.

CONCLUSIONS

• Phosphodiesterase 5 inhibitors used in the clinical setting can significantly improve LUTS secondary to BPH, erectile function and quality of life. Maximum urinary flow improvement is not statistically significant. • Future research should focus on pathophysiological principles and cost analysis.

The burden and extent of comorbid conditions in patients with erectile dysfunction

BACKGROUND

Erectile dysfunction (ED) is a common sexual problem in men. Under-reporting of ED is widespread, largely because of the embarrassing nature of the condition.

AIM

This paper reviews the comorbid conditions that are commonly found in patients with ED patients and discusses the implications.

DISCUSSION

Erectile dysfunction is often associated with other disorders such as diabetes, cardiovascular disease, hypertension, dyslipidaemia, obesity, depression, chronic obstructive pulmonary disease and lower urinary tract symptoms. Although the aetiology of ED is multifactorial, some of the associated comorbid conditions, including diabetes, cardiovascular disease and hypertension, can be a primary cause of ED. Similarly, ED could be a useful marker for comorbid conditions such as cardiovascular disease and diabetes. Effective treatments for ED are available, including the three phosphodiesterase type 5 inhibitors sildenafil citrate, tadalafil and vardenafil HCl.

CONCLUSIONS

Thorough medical screening of patients with ED is advisable, as this could lead to earlier diagnosis and treatment of comorbid conditions. Conversely, men with conditions such as cardiovascular disease, diabetes, obesity and depression may have undiagnosed ED and should be questioned appropriately to ascertain any erectile problems and initiate appropriate treatment.