Synergetic effect of testosterone and phophodiesterase-5 inhibitors in hypogonadal men with erectile dysfunction: A systematic review

Effect of hypoandrogenism on expression of transient receptor potential vanilloid channels in rat penile corpus cavernosum and erectile function

BACKGROUND

Hypoandrogenism is a cause of erectile dysfunction (ED). Vascular smooth muscle cell contraction and relaxation are regulated by TRPV1-4 channels. However, the influence of hypoandrogenism on TRPV1-4 and its relationship with erectile function remain unclear.

AIM

To reveal whether hypoandrogenism affects erectile function by influencing TRPV1-4 expression in the corpus cavernosum of rats.

METHODS

Male Sprague-Dawley rats (N = 36) aged 8 weeks were assigned to 6 groups at random (n = 6): sham operation, castrated, castrated + testosterone replacement, sham operation + transfection, castrated + transfection, and castrated + empty transfection. Four weeks after castration, 20 μL of lentiviral vector (1 × 108 TU/mL) carrying the TRPV4 gene was injected into the penile cavernous tissue of the transfection groups. One week after transfection, the maximum intracavernous pressure (ICPmax)/mean arterial pressure (MAP) and the content of TRPV1-4, phosphorylated eNOS (p-eNOS)/eNOS, and nitric oxide (NO) in penile cavernous tissue of each group were measured.

OUTCOMES

Under low androgen conditions, TRPV4 expression in endothelial cells in the rat penile cavernosum was sharply reduced, resulting in a decrease in p-eNOS/eNOS and NO content, which could inhibit erectile function.

RESULTS

In rat penile cavernous tissue, TRPV1-4 was expressed in the cell membranes of endothelial cells and smooth muscle cells. The ICPmax/MAP and the content of TRPV4, p-eNOS/eNOS, and NO end product nitrite level in rat penile cavernous tissue was markedly reduced in the castrated group as compared with the sham group (P < .05). The ICPmax/MAP and the content of TRPV4, p-eNOS/eNOS, and NO end product nitrite level in rat penile cavernous tissue were markedly improved in the castrated + transfection group vs the castrated group (P < .01).

CLINICAL IMPLICATIONS

Upregulation of TRPV4 expression in penile cavernosum tissue might be a viable therapeutic for ED caused by hypoandrogenism.

STRENGTHS AND LIMITATIONS

The specific mechanism of TRPV4 in ED needs to be further verified by androgen receptor or TRPV4 gene knockout experiments.

CONCLUSION

Hypoandrogenism may cause ED by reducing the expression of TRPV4 in rat penile cavernous tissue. Upregulation of TRPV4 expression in penile cavernous tissue can increase the ratio of p-eNOS/eNOS and NO levels and ameliorate the erectile function of castrated rats.

Effect of SA3X (Spilanthes acmella) Supplementation on Serum Testosterone Levels in Males with Erectile Dysfunction - A Parallel Double-Blind Randomized Controlled Trial

Objectives:To determine whether SA3X (Spilanthes acmella) supplementation improves serum testosterone levels, in comparison with placebo, in participants with erectile dysfunction (ED) and low testosterone levels. Material and methods:This double-blind placebo-controlled parallel-group was conducted in Hyderabad, India, among male participants who were randomized to SA3X therapy or placebo (1:1) for three months. The change of serum testosterone levels from baseline to months 1, 2, 3 and 6 (three months after completion of the intervention) were assessed using a mixed model repeated measures analysis. Additional secondary outcomes were the change in the Male Sexual Health Questionnaire (MSHQ), International Index of Erectile Function (IIEF) and the duration of penile erection. Stratifying the effect of SA3X on testosterone levels was done to account for potential confounders and effect modifiers. Safety was evaluated. Results:The intention-to-treat population included 215 patients (105 - SA3X therapy; 110 - placebo). SA3X intervention increased the testosterone levels significantly (21.85 vs. 1.89 ng/dL; P<0.001) at the end of month 3. The elevated testosterone levels were maintained at month 6 (18.69 vs. 1.79; P<0.001) even after discontinuation of the intervention. The MSHQ scores, IIEF scores, and duration of penile erection also increased significantly in the SA3X group. Sensitivity analysis showed that the effect of SA3X on testosterone significantly differed by BMI, presence of comorbid conditions and intake of phosphodiesterase-5 inhibitors. Dysgeusia (7.61%) was the significant drug-related adverse effect. Conclusion:Supplementation with SA3X for people with ED and low testosterone is a safe option as it significantly increases testosterone levels along with erectile function.

Canadian Urological Association guideline: Erectile dysfunction

Erectile dysfunction (ED) impacts the wellness and quality of life of millions of Canadians. An evaluation focused on the identification of reversible and irreversible underlying factors is recommended for patients presenting with ED. Through a shared decision-making model framework, the goal of ED treatment is to improve functional outcomes and enhance sexual satisfaction while minimizing adverse effects associated with treatment. Given that ED is assessed and treated by multiple different types of health practitioners, the purpose of this guideline is to provide the best available evidence to facilitate care delivery through a Canadian lens. After a narrative review of ED assessment and treatment for general readership, five key clinical questions relating to priority areas of ED are assessed using the GRADE and evidence-to-decision-making frameworks.

Natural Molecules as Talented Inhibitors of Nucleotide Pyrophosphatases/Phosphodiesterases (PDEs)

BACKGROUND

Phosphodiesterases (PDEs) are a wide group of enzymes with multiple therapeutic actions, including vasorelaxation, cardiotonic, antidepressant, anti-inflammatory, antithrombotic, anti-spasmolytic, memory-enhancing, and anti-asthmatic. PDEs with eleven subtypes from PDE-1 to PDE-11 typically catalyze the cleavage of the phosphodiester bond and, hence, degrades either cyclic adenosine monophosphate (cAMP) or cyclic guanosine monophosphate (cGMP).

OBJECTIVE

Several selective or non-selective inhibitors of the PDE subtypes are used clinically, i.e. sildenafil, rolipram, cysteine, etc. Recently, interest in plant-based pharmacologically bioactive compounds having potent PDEs inhibitory potential has increased. Purposely, extensive research has been carried out on natural products to explore new inhibitors of various PDEs. Therefore, this review summarizes the published data on natural PDEs inhibitors and their potential therapeutic applications.

METHODS

For this purpose, natural compounds with PDE inhibitory potential have been surveyed through several databases, including PubMed, Web of Sciences (WoS), Scopus, and Google Scholar.

RESULTS

According to a detailed literature survey, the most promising class of herbal compounds with PDE-inhibiting property has been found to belong to phenolics, including flavonoids (luteolin, kaempferol, icariin, etc.). Many other encouraging inhibitors from plants have also been identified, such as coumarins (23, 24) (licoarylcoumarin and glycocoumarin,), saponins ( agapanthussaponins), lignans (31, 33) [(±)-schizandrin and kobusin], terpenes (28, 29, 31) (perianradulcin A, quinovic acid, and ursolic acid), anthraquinones (18, 19) (emodin and chrysophanol), and alkaloids (Sanjoinine-D) (36).

CONCLUSION

In this review, studies have revealed the PDE-inhibitory potential of natural plant extracts and their bioactive constituents in treating various diseases; however, further clinical studies comprising synergistic use of different therapies (synthetic & natural) to acquire multi-targeted results might also be a promising option.

Erectile dysfunction in common neurological conditions: A narrative review

Neurogenic erectile dysfunction (NED) can be defined as the inability to achieve or maintain an erection due to central or peripheral neurologic disease. Neurologic diseases can also affect the physical ability and psychological status of the patient. All these factors may lead to a primary or secondary NED. Medication history plays an important role since there are many drugs commonly used in neurologic patients that can lead to ED. The assessment of NED in these patients is generally evolving with the application of evoked potentials technology in the test of somatic and autonomic nerves, and functional magnetic resonance imaging. With the electrophysiological examinations, neurogenic causes can be determined. These tools allow to categorize neurologic lesion and assess the patient prognosis. The first-line treatment for NED is phosphodiesterase inhibitors. Second-line treatments include intracavernous and intraurethral vasoactive injections. Third-line treatments are penile prostheses. The efficacy and safety of each treatment modality depend on the specific neurologic condition. This review discusses the physiology, pathophysiology, diagnosis, and treatment of ED in multiple peripheral and central neurologic conditions, as well as for future research.

Effect of low androgen status on the expression of adenosine A2A and A2B receptors in rat penile corpus cavernosum

To investigate whether low androgen status affects erectile function by regulating the expression of adenosine A_2A and A_2B receptors in rat penile corpus cavernosum. Thirty-six 8-week-old male Sprague-Dawley rats were randomly divided into six groups: sham-operated group (4w-sham, 8w-sham), castration group (4w-cast, 8w-cast) and androgen replacement group (4w-cast+T, 8w-cast+T). The rats in the androgen replacement groups were subcutaneously injected with testosterone propionate (3 mg/kg) every other day after castration. The maximum intracavernous pressure/mean arterial pressure (ICPmax/MAP), the expression of A_2A , A_2B , AKT and eNOS and the concentrations of cAMP and cGMP in the corpus cavernosum were detected at the 4th and 8th weeks after the operation. The serum testosterone level and the ratio of ICPmax/MAP decreased significantly in the castration group as compared to other groups (p < 0.01). There was no significant difference in the expression of A_2A receptor among groups, while the expression of A_2B , AKT and eNOS and the concentrations of cAMP and cGMP in the castration group were significantly lower than in other groups (p < 0.01). Low androgen status inhibits the AKT/eNOS/cGMP signalling pathways and the production of cAMP in the corpus cavernosum of castrated rats by down-regulating the expression of A_2B receptor, and results in decreased of ICPmax/MAP.

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.

A Combination of Testosterone and White Blood Cell Count as a Predictive Factor of Overall Survival in Localized Prostate Cancer

BACKGROUND

It has been shown that neutrophil count or an elevated neutrophil-to-lymphocyte ratio (NLR) as well as testosterone levels are separately associated with increased mortality in patients with localized prostate cancer.

OBJECTIVE

We tested a combination of testosterone levels and white blood cell (WBC) counts to predict overall survival (OS) in a prospective cohort of patients treated with radiotherapy for localized prostate cancer.

PATIENTS AND METHODS

The 381 patients included in this study were prospectively enrolled in phase 2 or 3 studies. Multivariate Cox proportional hazards models were used to analyze the influence of WBC count and testosterone level on biochemical recurrence and OS. Cutoff levels of ≤10.4 nmol/L (300 ng/dL) for testosterone and a median value of 6.2 (×10⁹/L) for WBC count were used.

RESULTS

The median follow-up for biochemical recurrence and OS were 72 and 78 months, respectively. A WBC count of ≥6.2 alone was not associated with OS (hazard ratio [HR] 0.66; 95% confidence interval [CI] 0.30-1.46). When combined with a testosterone level of >10.3 nmol/L, a WBC count of ≥6.2 was associated with increased mortality (HR 2.96; 95% CI 1.45-6.06) when compared with a WBC count of <6.2 (p-interaction = 0.01). The HR for biochemical recurrence for patients with a testosterone level >10.3 nmol/L combined with a lymphocyte level above or equal to the median was nearly identical to the HR of a testosterone level >10.3 nmol/L with a WBC above or equal to the median. There was no association between testosterone level and the NLR.

CONCLUSIONS

A high WBC and lymphocyte count combined with normal testosterone levels increases the overall mortality of patients treated with radiotherapy for localized prostate cancer within the first 6-7 years post-treatment. Validation in larger cohorts is necessary.

Current use of phosphodiesterase inhibitors in urology

The causes of male erectile dysfunction (ED) are quite variable and are now commonly divided into etiologies such as ischemia, smooth muscle damage, or altered blood flow. Although varying rates of ED have been reported in literature, the number of men with ED is projected to increase worldwide by 2025 to approximately 322 million. Since the introduction of phosphodiesterase 5 (PDE5) inhibitors, there has been a paradigm shift in the treatment of ED because PDE5 inhibitors address a broad spectrum of etiologies for ED. Today, the American Urological Association recommends the use of three PDE5 inhibitors (sildenafil, tadalafil, and vardenafil) as a first-line therapy for the treatment of ED. This review evaluates the pharmacological mechanism of PDE5 inhibitors along with the impact and use of sildenafil, vardenafil, tadalafil, and avanafil. By increasing intracellular cGMP levels, PDE5 inhibitors have been shown to be effective in the treatment of ED. Through their effects on other cellular signaling pathways, PDE5 inhibitors have the potential for treating other urologic conditions as well. The use of PDE5 inhibitors can also be combined to produce a synergistic effect in conditions such as male hypogonadism and benign prostatic hyperplasia in addition to ED.

Testosterone replacement therapy: who to evaluate, what to use, how to follow, and who is at risk?

BACKGROUND

Hypogonadism, defined as a low serum testosterone in the presence of signs and symptoms, is common, particularly in aging men. Testosterone supplementation therapy (TST) is the standard treatment for male hypogonadism. It has been demonstrated to have a significant impact on the signs and symptoms of hypogonadism, but there are concerns about the increase in TST and its potential adverse effects, particularly cardiovascular effects.

OBJECTIVE

This review presents health care providers with current information regarding the prevalence and impact of hypogonadism, as well as the diagnosis, evaluation, and treatment of hypogonadism. The beneficial and potential adverse effects are reviewed with a discussion on the current cardiovascular controversy.

METHODS

We reviewed current and "landmark" articles in the English-language literature pertaining to hypogonadism, its prevalence, etiologies, presentation, evaluation, and treatment.

RESULTS

Authorities in the field have offered guidelines and recommendations regarding the diagnosis, evaluation, and management of hypogonadism. Although there is a consensus as to the definition of hypogonadism as the presence of a low serum testosterone with signs and symptoms of hypogonadism, there is variability in the definition of "low testosterone." Various testosterone formulations exist, differing in route and frequency of administration as well as in side-effect profiles. Testosterone supplementation therapy should be continued in individuals demonstrating an improvement in signs and symptoms, which may take 3 months to a year for maximum response. Individuals treated with TST require monitoring for adverse effects. Further studies are needed to determine the impact of TST on cardiovascular health.

CONCLUSION

Hypogonadism is common, particularly in aging men. Symptomatic individuals who have no contraindications to TST should be offered treatment. A careful assessment of treatment response after adequate titration and duration of therapy as well as monitoring for adverse effects is essential in treating patients for hypogonadism. Although hypogonadism is associated with increased all-cause and cardiovascular-related mortality, controversy exists regarding the impact of TST on cardiovascular risk, highlighting the need for further studies.