The ontogenetic expression pattern of type 5 phosphodiesterase correlates with androgen receptor expression in rat corpora cavernosa

Measurement of PDE5 concentration in human serum: proof-of-concept and validation of methodology in control and prostate cancer patients

PURPOSE

We aimed to investigate if the type 5 phosphodiesterase (PDE5), an enzyme with cardinal biological functions in sexual and cardiovascular health, can be detected and quantited in human serum.

METHODS

Blood samples were collected from control male and female subjects. PDE5 levels were measured by a specific ELISA kit. ROC curves weighted for age and serum levels of PSA (male subjects), or age (female subjects) were used to identify the predictive ability in the detection of PCa. Sensitivity, specificity, PPV and NPV values were determined for cut-off value determined during ROC curve analysis.

RESULTS

41 control male subjects, 18 control female subjects, and 55 consecutive subjects, of which 25 were affected by benign prostatic hypertrophy (BPH) and 30 with histologically confirmed prostate cancer (PCa), were studied. PDE5 serum levels were detectable in all subjects (range: 5 to 65 ng/ml). Analysis by MANCOVA identified a significant difference in serum PDE5 between control subjects or hyperplasia patients and PCa patients. Marginal means of serum PDE5 concentrations showed a significant difference (p < 0.001). The ROC curve demonstrated that PDE5 serum levels can predict men with or without PCa, with 0.806 AUC value (p < 0.0001). Using a 12.705 ng/ml PDE5 serum cut-off yielded sensitivity, specificity, PPV, and NPV of 83.3%, 77.27%, 62.5%, and 91.1% in detecting men with histologically proven PCa, respectively.

CONCLUSIONS

We demonstrated, for the first time, that PDE5 levels can be detected in human sera and that PCa patients have significantly higher PDE5 concentration compared to BPH patients or male and female controls. While serum PDE5 level measurement may open new research avenues, the clinical relevance of PDE5 levels in PCa patients deserves further investigation.

The role of acupuncture in treating premature ejaculation and its probable neurobiological mechanism

BACKGROUND

Premature ejaculation (PE) is one of the most common diseases in andrology and leads to serious male sexual dysfunction. Although several targeted oral drug therapies are used to treat PE, they often face challenges related to imprecise targeting and adverse effects. Acupuncture has shown potential in prolonging ejaculation time and improving couples' sexual quality of life. This review aims to summarize the benefits of acupuncture in treating PE and explore its probable neurobiological mechanisms.

RESULTS

The review included eight clinical trials involving 679 patients, of which 294 were treated with acupuncture. Furthermore, this review analyzed acupuncture points, needle retention time, treatment duration, and their probable neurobiological mechanisms. The proposed mechanisms include stimulating the frontal functional lobe, inhibiting spinal cord neural pathways, regulating serotonin levels, enhancing 5-hydroxytryptamine receptor IB excitability, reducing penile sensitivity, and modulating hormone levels.

CONCLUSIONS

Acupuncture is a viable alternative or complementary therapy for PE, and neurobiological mechanisms appear to play a key role, but further experimental validation is needed.

Effects of testosterone treatment on clitoral haemodynamics in women with sexual dysfunction

PURPOSE

To explore the effects of 6-month systemic testosterone (T) administration on clitoral color Doppler ultrasound (CDU) parameters in women with female sexual dysfunction (FSD).

METHODS

81 women with FSD were retrospectively recruited. Data on CDU parameters at baseline and after 6 months with four different treatments were available and thus further longitudinally analyzed: local non-hormonal moisturizers (NH group), n = 37; transdermal 2% T gel 300 mcg/day (T group), n = 23; local estrogens (E group), n = 12; combined therapy (T + E group), n = 9. Patients underwent physical, laboratory, and genital CDU examinations at both visits and completed different validated questionnaires, including the Female Sexual Function Index (FSFI).

RESULTS

At 6-month visit, T therapy significantly increased clitoral artery peak systolic velocity (PSV) when compared to both NH (p < 0.0001) and E (p < 0.0001) groups. A similar increase was found in the T + E group (p = 0.039 vs. E). In addition, T treatment was associated with significantly higher FSFI desire, pain, arousal, lubrication, orgasm, and total scores at 6-month visit vs. baseline. Similar findings were observed in the T + E group. No significant differences in the variations of total and high-density lipoprotein-cholesterol, triglycerides, fasting glycemia, insulin and glycated hemoglobin levels were found among the four groups. No adverse events were observed.

CONCLUSION

In women complaining for FSD, systemic T administration, either alone or combined with local estrogens, was associated with a positive effect on clitoral blood flow and a clinical improvement in sexual function, showing a good safety profile.

TRIAL REGISTRATION NUMBER

NCT04336891; date of registration: April 7, 2020.

Type 5 phosphodiesterase (PDE5) and the vascular tree: From embryogenesis to aging and disease

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Vascular development depends on the timely differentiation of endothelial and smooth muscle cells.

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Vascular aging and vascular disease are influenced by endothelial and vascular smooth muscle cell compartments.

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A survey of the literature on the role of PDE5 in vascular development, aging and disease is reported.

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The role of PDE5 on vascular development, aging and disease needs to be further investigated by its genetic ablation.

Vascular tree development depends on the timely differentiation of endothelial and vascular smooth muscle cells. These latter are key players in the formation of the vascular scaffold that offers resistance to the blood flow. This review aims at providing an overview on the role of PDE5, the cGMP-specific phosphodiesterase that historically attracted much attention for its involvement in male impotence, in the regulation of vascular smooth muscle cell function. The overall goal is to underscore the importance of PDE5 expression and activity in this cell type in the context of the organs where its function has been extensively studied.

Needs and Expectations of Patients with Erectile Dysfunction: An Update on Pharmacological Innovations in Phosphodiesterase Type 5 Inhibition with Focus on Sildenafil

INTRODUCTION

Phosphodiesterase type 5 inhibitors (PDE5-Is) have an excellent efficacy and tolerability profile and remain the first-line choice for the treatment of erectile dysfunction (ED). However, ED is still an underdiagnosed and undertreated condition, and many men prematurely discontinue therapy with conventional dosage formulations despite successful intercourse.

AIM

To review the unmet needs and expectations of patients with ED and describe the latest pharmaceutical innovations in the field of PDE5-I formulations designed to address these needs, with particular reference to a new orodispersible film (ODF) formulation of the PDE5-I, sildenafil.

METHODS

Online literature search in PubMed and the Cochrane Library.

MAIN OUTCOME MEASURE

To identify English-language publications relevant to the aims of the present review.

RESULTS

Improved recognition and management of ED would enable the early diagnosis of underlying and comorbid conditions that contribute to ED, leading to improved patient health and health-related quality of life. To ensure successful outcomes and patient and partner satisfaction, the complex and personal issues that influence the patient's needs and expectations regarding treatment for ED must be considered along with their personal experiences and preferences. Innovative drug delivery systems, including orally disintegrating formulations, have been developed as alternatives to conventional dosage forms with the aim of improving patient convenience and acceptability and enhancing compliance. These alternative formulations include the sildenafil ODF, which is designed to improve acceptance and compliance over conventional solid dosage forms and extend the treatment options for men with ED by offering a convenient and discrete dosage form of a drug with proven efficacy.

CONCLUSION

The sildenafil ODF is an example of an innovative dosage formulation for ED that can be used interchangeably with the conventional film-coated formulation to better address the needs and expectations of men with ED. Jannini EA, Droupy S. Needs and Expectations of Patients with Erectile Dysfunction: An Update on Pharmacological Innovations in Phosphodiesterase Type 5 Inhibition with Focus on Sildenafil. Sex Med 2019;7:1-10.

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

INTRODUCTION

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Platelet-derived growth factor regulation of type-5 phosphodiesterase in human and rat penile smooth muscle cells

INTRODUCTION

Relaxation of cavernous smooth muscle cells (SMCs) is a key component in the control of the erectile mechanism. SMCs can switch their phenotype from a contractile differentiated state to a proliferative and dedifferentiated state in response to a change of local environmental stimuli. Proliferation and contraction are both regulated by the intracellular second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are degraded by phosphodiesterases (PDEs). The most abundant PDE present in corpora cavernosa is the electrolytic cGMP-specific phosphodiesterase type 5 (PDE5).

AIM

We investigated the cellular localization of PDE5 in in vitro cultured corpora cavernosa cells and the effect of mitogenic stimulation on PDE5 expression.

METHODS

Biochemical ad molecular techniques on cultured SMCs from human and rat penis.

MAIN OUTCOME MEASURES

We studied the ability of the quiescent SMC phenotype vs. the proliferating phenotype in modulation of PDE5 expression.

RESULTS

We demonstrated that PDE5 is localized in the cytoplasm, in the perinuclear area, and in discrete cytoplasmic foci. As previously demonstrated in human myometrial cells, the cytoplasmic foci may correspond to centrosomes. In corpora cavernosa, PDE5 protein levels are strongly regulated by the mitotic activity of the SMCs, as they were increased in quiescent cultures. In contrast, treatment with platelet-derived grow factor (PDGF), one of the most powerful mitogenic factors for SMCs, reduces the expression of PDE5 after 24 hours of treatment.

CONCLUSION

We found that PDGF treatment downregulates PDE5 expression in proliferating SMCs, suggesting that PDE5 may represent one of the markers of the contractile phenotype of the SMCs of corpora cavernosa.

The hormonal control of ejaculation

Hormones regulate all aspects of male reproduction, from sperm production to sexual drive. Although emerging evidence from animal models and small clinical studies in humans clearly point to a role for several hormones in controlling the ejaculatory process, the exact endocrine mechanisms are unclear. Evidence shows that oxytocin is actively involved in regulating orgasm and ejaculation via peripheral, central and spinal mechanisms. Associations between delayed and premature ejaculation with hypothyroidism and hyperthyroidism, respectively, have also been extensively documented. Some models suggest that glucocorticoids are involved in the regulation of the ejaculatory reflex, but corresponding data from human studies are scant. Oestrogens regulate epididymal motility, whereas testosterone can affect the central and peripheral aspects of the ejaculatory process. Overall, the data of the endocrine system in regulating the ejaculatory reflex suggest that widely available endocrine therapies might be effective in treating sexual disorders in these men. Indeed, substantial evidence has documented that treatments of thyroid diseases are able to improve some ejaculatory difficulties.

Ontogenetic profile of the expression of thyroid hormone receptors in rat and human corpora cavernosa of the penis

Introduction

In the last few years, various studies have underlined a correlation between thyroid function and male sexual function, hypothesizing a direct action of thyroid hormones on the penis.

Aim

To study the spatiotemporal distribution of mRNA for the thyroid hormone nuclear receptors (TR) α1, α2 and β in the penis and smooth muscle cells (SMCs) of the corpora cavernosa of rats and humans during development.

Methods

We used several molecular biology techniques to study the TR expression in whole tissues or primary cultures from human and rodent penile tissues of different ages.

Main Outcome Measure

We measured our data by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) amplification, Northern blot and immunohistochemistry.

Results

We found that TRα1 and TRα2 are both expressed in the penis and in SMCs during ontogenesis without development-dependent changes. However, in the rodent model, TRβ shows an increase from 3 to 6 days post natum (dpn) to 20 dpn, remaining high in adulthood. The same expression profile was observed in humans. While the expression of TRβ is strictly regulated by development, TRα1 is the principal isoform present in corpora cavernosa, suggesting its importance in SMC function. These results have been confirmed by immunohistochemistry localization in SMCs and endothelial cells of the corpora cavernosa.

Conclusions

The presence of TRs in the penis provides the biological basis for the direct action of thyroid hormones on this organ. Given this evidence, physicians would be advised to investigate sexual function in men with thyroid disorders. Carosa E, Di Sante S, Rossi S, Castri A, D'Adamo F, Gravina GL, Ronchi P, Kostrouch Z, Dolci S, Lenzi A, and Jannini EA. Ontogenetic profile of the expression of thyroid hormone receptors in rat and human corpora cavernosa of the penis. J Sex Med 2010;7:1381–1390.