Mechanisms of penile erection and basis for pharmacological treatment of erectile dysfunction

Association between atorvastatin and erectile dysfunction: a comprehensive analysis incorporating real-world pharmacovigilance and Mendelian randomization

Background

Atorvastatin is a commonly prescribed medication for the prevention of cardiovascular diseases. Recent observational studies have suggested a potential association between atorvastatin use and the occurrence of Erectile Dysfunction (ED). In this study, we aimed to explore the relationship between atorvastatin and ED using real-world data from the FAERS database and employed Mendelian randomization to assess causality.

Methods

To evaluate the disproportionality of atorvastatin in relation to ED, we conducted several pharmacovigilance analyses, including odds ratio (ROR), proportional reporting ratio (PRR), Bayesian Confidence propagation neural network (BCPNN), and gamma-Poisson contractile apparatus (GPS). Additionally, we employed Mendelian randomization to investigate the causal relationship between atorvastatin and ED.

Results

Pharmacovigilance disproportionality analysis revealed a significant association between atorvastatin and ED, as indicated by the following results: ROR [3.707078559, 95% CI (3.33250349, 4.123756054)], PRR [3.702969038, χ2 (669.2853829)], IC [1.870490139, IC025 (1.702813857)], and EBGM [3.656567867, EBGM05 (3.28709656)]. Furthermore, the two-sample Mendelian randomization analysis provided evidence supporting a causal relationship between atorvastatin use and ED, with an inverse variance weighted estimate of β = 3.17 (OR = 23.91, p = 0.02 < 0.05).

Conclusion

Based on comprehensive analyses incorporating pharmacovigilance and Mendelian randomization, our findings suggest that atorvastatin use is associated with an increased risk of ED and indicate a causal relationship. These results emphasize the importance of considering potential adverse effects, such as ED, when prescribing atorvastatin for cardiovascular disease prevention. Further research and clinical monitoring are warranted to better understand the underlying mechanisms and develop appropriate strategies to mitigate this side effect.

Association between severe headache or migraine and erectile dysfunction in American adults: a cross-sectional of data study from the NHANES

Currently, few studies have explored the relationship between severe headache or migraine and erectile dysfunction (ED). The aim of our study was to assess the association between severe headache or migraine and ED in adult men in the US from the National Health and Nutrition Examination Survey (NHANES). We used data from two separate NHANES datasets for the analysis: 2001-2002 and 2003-2004. We used multiple logistic regression, subgroup analysis, and sensitivity analyses to assess the relationship between severe headache or migraine and ED. From 2001 to 2004, 3117 adult male participants (582 ED patients, 2535 non-ED patients) were identified. Categorical and continuous variables are described using counts and frequencies and means and standard errors, respectively. For continuous variables, the two groups were compared using survey-weighted linear regression, while for categorical variables, survey-weighted chi-square tests were performed. Multiple logistic regression analysis showed that in the fully adjusted Model 3, severe headache or migraine was statistically significantly associated with ED (OR 1.51; 95% CI 1.14-1.99; P = 0.0036). In the fully adjusted Model 3, the results of the subgroup analysis showed that an age of 40-60 years (OR = 1.55, 95% CI: 1.05, 2.31, P = 0.029), a body mass index (BMI) < 25 kg/m2 (OR = 1.68, 95% CI: 1.02, 2.75, P = 0.0406) or ≥30 kg/m2 (OR = 1.65, 95% CI: 1.07, 2.54, P = 0.022), hypertension (OR = 1.78, 95% CI: 1.22, 2.60, P = 0.0029), diabetes mellitus (OR = 1.71, 95% CI: 1.26, 2.31, P < 0.001), CVD (OR = 1.54, 95% CI: 1.12, 2.10, P = 0.011) and hyperlipidemia (OR = 1.83, 95% CI: 1.07, 3.13, P = 0.028) were associated with ED with severe headache or migraine. This study demonstrated a statistically significant association between severe headache or migraine and ED among adult men in the US. However, the results of the study should be interpreted with caution due to the failure to assess the effects of depression and anxiety on the outcomes.

A novel reuptake inhibitor, IP2015, induces erection by increasing central dopamine and peripheral nitric oxide release

BACKGROUND AND PURPOSE

An estimated 40% of patients with erectile dysfunction have a poor prognosis for improvement with currently available treatments. The present study investigated whether a newly developed monoamine transport inhibitor, IP2015, improves erectile function.

EXPERIMENTAL APPROACH

We investigated the effects of IP2015 on monoamine uptake and binding, erectile function in rats and diabetic mice and the effect on corpus cavernosum contractility.

KEY RESULTS

IP2015 inhibited the uptake of 5-HT, noradrenaline and dopamine by human monoamine transporters expressed in cells and in rat brain synaptosomes. Intracavernosal pressure measurement in anaesthetized rats revealed that IP2015 dose-dependently increased the number and the duration of spontaneous erections. Whereas pretreatment with the dopamine D2-like receptor antagonists, clozapine and (-)-sulpiride, or cutting the cavernosal nerve inhibited IP2015-induced erectile responses, the phosphodiesterase type 5 inhibitor sildenafil further enhanced the IP2015-mediated increase in intracavernosal pressure. IP2015 also increased the number of erections in type 2 diabetic db/db mice. Direct intracavernosal injection of IP2015 increased penile pressure, and in corpus cavernosum strips, IP2015 induced concentration-dependent relaxations. These relaxations were enhanced by sildenafil and blunted by endothelial cell removal, a nitric oxide synthase inhibitor, NG-nitro-l-arginine and a D1-like receptor antagonist, SCH23390. Quantitative polymerase chain reaction (qPCR) showed the expression of the dopamine transporter in the rat corpus cavernosum.

CONCLUSION AND IMPLICATIONS

Our findings suggest that IP2015 stimulates erectile function by a central mechanism involving dopamine reuptake inhibition and direct NO-mediated relaxation of the erectile tissue. This novel multi-modal mechanism of action could offer a new treatment approach to erectile dysfunction.

Ursodeoxycholic acid ameliorates erectile dysfunction and corporal fibrosis in diabetic rats by inhibiting the TGF-β1/Smad2 pathway

Corporal tissue fibrosis is critical in diabetes-associated erectile dysfunction. Transforming growth factor-β1/Small mothers against decapentaplegic-2 (TGF-β1/Smad2) contributes to the induction of fibrosis in corporal tissue. Smad7 is accepted as a general negative regulator of Smad signaling, although its role in corporal fibrosis is unknown. Ursodeoxycholic acid (UDCA) is a hydrophilic bile acid used for biliary and liver related disorders and has antifibrotic effects in the liver. This study investigated the effects of UDCA on diabetic erectile dysfunction. Forty-eight male Spraque Dawley rats were divided into six groups: nondiabetic (n = 6), nondiabetic+20 mg/kg UDCA (n = 6), nondiabetic+80 mg/kg UDCA (n = 6), diabetic (n = 10), diabetic+20 mg/kg UDCA (n = 10), diabetic+80 mg/kg UDCA (n = 10). Diabetes was induced by intraperitoneal injection of 60 mg/kg Streptozocin. UDCA (20 and 80 mg/kg/day) or saline was subsequently administered via oral gavage for 56 days. Erectile function was evaluated as measurement of maximum intracavernosal pressure (m-ICP)/mean arterial pressure (MAP) and total ICP/MAP. Corporal tissues were evaluated by Western blotting and Masson's trichrome staining. Electrical stimulation-induced m-ICP/MAP responses were higher in UDCA-treated diabetic rats compared to untreated diabetic rats, respectively (20 mg/kg; 4 V: 0.77 ± 0.11 vs 0.45 ± 0.09, p = 0.0001 and 80 mg/kg; 4 V: 0.78 ± 0.11 vs 0.45 ± 0.09, p = 0.0001) UDCA prevented the increase in phospho-Smad2 and fibronectin protein expressions in diabetic corporal tissue both at 20 mg/kg (p = 0.0002, p = 0.002 respectively) and 80 mg/kg doses (p < 0.0001 for both). Smad7 protein expressions were significantly increased in the UDCA-treated diabetic groups compared to the untreated diabetic group (20 mg/kg: p = 0.0079; 80 mg/kg: p = 0.004). Furthermore, UDCA significantly prevented diabetes-induced increase in collagen (20 mg/kg: p = 0.0172; 80 mg/kg: p = 0.0003) and smooth muscle loss (20 mg/kg: p = 0.044; 80 mg/kg: p = 0.039). In conclusion, UDCA has a potential protective effect on erectile function in diabetic rats by altering fibrotic pathways via inhibition of TGF-β1/Smad2 and activation of Smad7.

Exploring rat corpus cavernosum alterations induced by finasteride treatment and withdrawal

Despite its efficacy for treating androgenetic alopecia, finasteride, an inhibitor of 5α-reductase (i.e., the enzyme converting testosterone, T, into dihydrotestosterone, DHT), is associated with several side effects including sexual dysfunction (e.g., erectile dysfunction). These side effects may persist after drug suspension, inducing the so-called post-finasteride syndrome (PFS). The effects of subchronic treatment with finasteride (i.e., 20 days) and its withdrawal (i.e., 1 month) in rat corpus cavernosum have been explored here. Data obtained show that the treatment was able to decrease the levels of the enzyme 5α-reductase type II in the rat corpus cavernosum with increased T and decreased DHT levels. This local change in T metabolism was linked to mechanisms associated with erectile dysfunction. Indeed, by targeted metabolomics, we reported a decrease in the nitric oxide synthase (NOS) activity, measured by the citrulline/arginine ratio and confirmed by the decrease in NO2 levels, and a decrease in ornithine transcarbamylase (OTC) activity, measured by citrulline/ornithine ratio. Interestingly, the T levels are negatively correlated with NOS activity, while those of DHT are positively correlated with OTC activity. Finasteride treatment also induced alterations in the levels of other molecules involved in the control of penile erection, such as norepinephrine and its metabolite, epinephrine. Indeed, plasma levels of norepinephrine and epinephrine were significantly increased and decreased, respectively, suggesting an impairment of these mediators. Interestingly, these modifications were restored by suspension of the drug. Altogether, the results reported here indicate that finasteride treatment, but not its withdrawal, affects T metabolism in the rat corpus cavernosum, and this alteration was linked to mechanisms associated with erectile dysfunction. Data here reported could also suggest that the PFS sexual side effects are more related to dysfunction in a sexual central control rather than peripheral compromised condition.

Fibroblasts enable penile erection

Perivascular fibroblasts may underlie erectile dysfunction.

Soluble guanylate cyclase stimulators and activators: new horizons in the treatment of priapism associated with sickle cell disease

Priapism, defined as a prolonged and often painful penile erection occurring without sexual stimulation or desire, is a common complication in sickle cell disease (SCD), affecting up to 48% of male patients. This condition presents significant clinical challenges and can lead to erectile dysfunction if not properly managed. Current pharmacological treatments for SCD-related priapism are primarily reactive rather than preventative, highlighting a gap in effective medical intervention strategies. A critical factor in developing priapism is the reduced basal bioavailability of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) in erectile tissues. New prevention strategies should ideally target the underlying pathophysiology of the disease. Compounds that stimulate and activate soluble guanylate cyclase (sGC) emerge as potential therapeutic candidates since these compounds have the property of inducing cGMP production by sGC. This review explores the potential of sGC stimulators and activators in treating priapism associated with SCD. We discuss the advantages of these agents in the face of the challenging pathophysiology of SCD. Additionally, the review underscores the impact of intravascular hemolysis and oxidative stress on priapism pathophysiology in SCD, areas in which sGC stimulators and activators may also have beneficial therapeutic effects.

Genetic prediction of modifiable lifestyle factors for erectile dysfunction

Background

The causal relationship between certain lifestyle factors and erectile dysfunction (ED) is still uncertain.

Aim

The study sought to investigate the causal effect of 9 life factors on ED through 2-sample single-variable Mendelian randomization (SVMR) and multivariable Mendelian randomization (MVMR).

Methods

Genetic instruments to proxy 9 risk factors were identified by genome-wide association studies. The genome-wide association studies estimated the connection of these genetic variants with ED risk (n = 223 805). We conducted SVMR, inverse variance-weighting, Cochran's Q, weighted median, MR-Egger, MR-PRESSO (Mendelian Randomization Pleiotropy RESidual Sum and Outlier), and MVMR analyses to explore the total and direct relationship between life factors and ED.

Outcomes

The primary outcome was defined as self or physician-reported ED, or using oral ED medication, or a history of surgery related to ED.

Results

In SVMR analyses, suggestive associations with increased the risk of ED were noted for ever smoked (odds ratio [OR], 5.894; 95% confidence interval [CI], 0.469 to 3.079; P = .008), alcohol consumption (OR, 1.495; 95% CI, 0.044 to 0.760; P = .028) and body mass index (BMI) (OR, 1.177; 95% CI, 0.057 to 0.268; P = .003). Earlier age at first intercourse was significantly related to reduced ED risk (OR, 0.659; 95% CI, -0.592 to -0.244; P = 2.5 × 10-6). No strong evidence was found for the effect of coffee intake, time spent driving, physical activity, and leisure sedentary behaviors on the incidence of ED (All P > .05). The result of MVMR analysis for BMI (OR, 1.13; 95% CI, 1.01 to 1.25; P = .045) and earlier age at first intercourse (OR, 0.77; 95% CI, 0.56 to 0.99; P = .018) provided suggestive evidence for the direct impact on ED, while no causal factor was detected for alcoholic drinks per week and ever smoked.

Clinical implications

This study provides evidence for the impact of certain modifiable lifestyle factors on the development of ED.

Strengths and limitations

We performed both SVMR and MVMR to strengthen the causal relationship between exposures and outcomes. However, the population in this study was limited to European ancestry.

Conclusion

Ever smoked, alcoholic drinks per week, BMI, and age first had sexual intercourse were causally related to ED, while the potential connection between coffee intake, physical activity, recreational sedentary habits, and increased risk of ED needs to be further confirmed.

Heme-induced corpus cavernosum relaxation and its implications for priapism in sickle cell disease: a mechanistic insight

BACKGROUND

Patients with sickle cell disease (SCD) experience intravascular hemolysis, leading to elevated plasma heme levels. This phenomenon has been associated with increased priapism in men with SCD. The heme group can be metabolized by heme oxygenase (HO), generating carbon monoxide (CO), which is known to promote smooth muscle relaxation via soluble guanylyl cyclase (sGC)-cyclic guanosine monophosphate (cGMP). However, the effects of heme on the relaxation responses of corpus cavernosum (CC) have not been investigated.

OBJECTIVES

To evaluate the functional and biochemical effects of the heme group on mouse CC smooth muscle in vitro.

MATERIALS AND METHODS

Male C57BL/6 mice were used. CC tissues were mounted in organ baths. Measurement of cGMP in mice CC was evaluated.

RESULTS

The cumulative addition of heme concentrations promoted the relaxation of CC. HO inhibitor (1J, 100 μM) or sGC inhibitor (ODQ, 10 μM) blocked the relaxing effect of the heme group. Pre-incubation of CC with heme (100 μM) enhanced relaxation induced by acetylcholine, sodium nitroprusside, and nitrergic relaxation (electrical field stimulation), which was abolished by 1J or ODQ. The heme group increased the cGMP production in CC, which was abolished by 1J or ODQ. cGMP levels were significantly higher in CC treated with heme, and pre-incubation with compound 1J or ODQ abolished the effect of heme in raising cGMP levels.

DISCUSSION AND CONCLUSION

The HO-CO-sGC-cGMP pathway appears to play a crucial role in promoting CC relaxation. Our study provides novel insight into the role of group heme in CC relaxation and its potential contribution to priapism in SCD. Heme may serve as a pharmacological target for new therapies to prevent priapism.

Dual Strategy with Adipose-Derived Stem Cells and l-arginine Recovered Cavernosal Functions in a Rat Model of Radical Prostatectomy

As standard therapy for prostate cancer, radical prostatectomy causes cavernous nerve (CN) injury and increases fibrosis and hypoxia-induced penile structural alterations. This study aimed to determine the potential beneficial effects of adipose-derived stem cells (ADSCs) and l-arginine alone or in combination on the penile erection in a rat model of erectile dysfunction caused by bilateral cavernous nerve transection (CNT). Male rats (n = 35) were randomized into five groups: Sham-operated; CNT (4-weeks); CNT plus ADSCs (1 × 106 cells by intracavernosal injection); CNT plus l-arginine (4 weeks, 10 mg/kg/day, oral); and ADSCs combined with l-arginine in CNT. In vivo erectile responses and in vitro relaxant responses were measured. Western blot and immunohistochemistry analyses were used to determine the expression and localization of endothelial nitric oxide synthase, neuronal nitric oxide synthase, transforming growth factor-beta 1, hypoxia-inducible factor-1 alpha (HIF-1α), and apoptosis markers (Bax and Bcl-2). The ratio of smooth muscle to collagen and nerve regeneration were calculated using Masson's trichrome and nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase staining. The combined treatment restored diminished erectile responses, endothelium-dependent acetylcholine, and electrical field stimulation-induced relaxation of the corpus cavernosum in rats with CNT, whereas either monotherapy produced only partial improvements. All treatment regimens restored increases in the protein expression of HIF-1 and Bax in rats with CNT. The decrease in smooth muscle mass and NADPH-diaphorase-positive nerve fibers was partially ameliorated by monotherapy, whereas combined therapy led to recovery. These findings indicate that combined treatment with ADSCs and l-arginine may restore erectile function in rats with CNT by inhibiting hypoxia-induced neurotoxicity and preserving endothelium function and smooth muscle content.

Altered brain activity in diabetic patients with erectile dysfunction revealed by fractional amplitude of low-frequency fluctuation: A resting-state fMRI study

INTRODUCTION

Diabetes mellitus is one of the major chronic diseases, which enhances the risk of erectile dysfunction. However, the central pathological mechanisms of erectile dysfunction in diabetes mellitus patients are still unclear.

METHODS

Resting-state functional magnetic resonance imaging data were acquired in 30 type-2 diabetes mellitus, 31 type-2 diabetes mellitus with erectile dysfunction patients, and 31 healthy controls. The measure of fractional amplitude of low-frequency fluctuation was calculated and compared among groups.

RESULTS

Differences of fractional amplitude of low-frequency fluctuation values were found in the left superior frontal gyrus (medial) and middle temporal gyrus among three groups. Compared with healthy controls group, type-2 diabetes mellitus group exhibited lower fractional amplitude of low-frequency fluctuation values in the left superior frontal gyrus (dorsolateral), anterior cingulate gyrus, calcarine fissure, and increased fractional amplitude of low-frequency fluctuation values in the left post-central gyrus. Compared with healthy controls group, erectile dysfunction with type-2 diabetes mellitus group exhibited lower fractional amplitude of low-frequency fluctuation values in the left superior frontal gyrus (medial), middle temporal gyrus, temporal middle (pole), and increased fractional amplitude of low-frequency fluctuation values in the right post-central gyrus. Compared with type-2 diabetes mellitus group, erectile dysfunction with type-2 diabetes mellitus group exhibited increased fractional amplitude of low-frequency fluctuation values in the right median cingulum gyrus and left calcarine fissure.

CONCLUSION

Erectile dysfunction with type-2 diabetes mellitus patients showed functional changes in brain regions that were closely correlated with sexual dysfunction, which suggested that altered regional brain activity might be related to the pathophysiology of erectile dysfunction with type-2 diabetes mellitus.

Post-Finasteride Syndrome And Post-Ssri Sexual Dysfunction: Two Clinical Conditions Apparently Distant, But Very Close

Post-finasteride syndrome and post-SSRI sexual dysfunction, are two poorly explored clinical conditions in which men treated for androgenetic alopecia with finasteride or for depression with SSRI antidepressants show persistent side effects despite drug suspension (e.g., sexual dysfunction, psychological complaints, sleep disorders). Because of some similarities in the symptoms, common pathological mechanisms are proposed here. Indeed, as discussed, clinical studies and preclinical data obtained so far suggest an important role for brain modulators (i.e., neuroactive steroids), neurotransmitters (i.e., serotonin, and cathecolamines), and gut microbiota in the context of the gut-brain axis. In particular, the observed interconnections of these signals in these two clinical conditions may suggest similar etiopathogenetic mechanisms, such as the involvement of the enzyme converting norepinephrine into epinephrine (i.e., phenylethanolamine N-methyltransferase). However, despite the current efforts, more work is still needed to advance the understanding of these clinical conditions in terms of diagnostic markers and therapeutic strategies.

The Cavernous Nerve Injury Rat Model: A Pictorial Essay on Post-Radical Prostatectomy Erectile Dysfunction Research

Understanding and addressing post-radical prostatectomy (RP) erectile dysfunction (ED) is of paramount importance for clinicians. Cavernous nerve (CN) injury rat model studies have provided consistently promising experimental data regarding regaining erectile function (EF) after nerve damage-induced ED. However, these findings have failed to translate efficiently into clinical practice, with post-RP ED therapeutic management remaining cumbersome and enigmatic. This disparity highlights the need for further standardization and optimization of the elaborate surgical preparation protocols and multifaceted reporting parameters involved in reliable CN injury rat model experimentation. Even so, despite its technical complexity, this animal model remains instrumental in exploring the functional implications of RP, i.e., surgical lesions of the neurovascular bundles (NVBs). Herein, besides cavernous nerve (CN) dissection, injury, and electrostimulation, multiple pressure measurements, i.e., mean arterial pressure (MAP) and intra-cavernosal pressure (ICP), must also be achieved. A transverse cervical incision allows for carotid artery cannulation and MAP measurements. Conversely, ICP measurements entail circumcising the penis, exposing the ischiocavernous muscle, and inserting a needle into the corporal body. Finally, using an abdominal incision, the prostate is revealed, and the major pelvic ganglia (MPG) and CNs are dissected bilaterally. Specific surgical techniques are used to induce CN injuries. Herein, we provide a narrative and illustrative overview regarding these complex experimental procedures and their particular requirements, reflecting on current evidence and future research perspectives.

Neurovascular dysfunction associated with erectile dysfunction persists after long-term recovery from simulations of weightlessness and deep space irradiation

There has been growing interest within the space industry for long-duration manned expeditions to the Moon and Mars. During deep space missions, astronauts are exposed to high levels of galactic cosmic radiation (GCR) and microgravity which are associated with increased risk of oxidative stress and endothelial dysfunction. Oxidative stress and endothelial dysfunction are causative factors in the pathogenesis of erectile dysfunction, although the effects of spaceflight on erectile function have been unexplored. Therefore, the purpose of this study was to investigate the effects of simulated spaceflight and long-term recovery on tissues critical for erectile function, the distal internal pudendal artery (dIPA), and the corpus cavernosum (CC). Eighty-six adult male Fisher-344 rats were randomized into six groups and exposed to 4-weeks of hindlimb unloading (HLU) or weight-bearing control, and sham (0Gy), 0.75 Gy, or 1.5 Gy of simulated GCR at the ground-based GCR simulator at the NASA Space Radiation Laboratory. Following a 12-13-month recovery, ex vivo physiological analysis of the dIPA and CC tissue segments revealed differential impacts of HLU and GCR on endothelium-dependent and -independent relaxation that was tissue type specific. GCR impaired non-adrenergic non-cholinergic (NANC) nerve-mediated relaxation in the dIPA and CC, while follow-up experiments of the CC showed restoration of NANC-mediated relaxation of GCR tissues following acute incubation with the antioxidants mito-TEMPO and TEMPOL, as well as inhibitors of xanthine oxidase and arginase. These findings indicate that simulated spaceflight exerts a long-term impairment of neurovascular erectile function, which exposes a new health risk to consider with deep space exploration.

Effects of continuous use of Tadalafil on male sexual function after posterior urethroplasty: A clinical trial

INTRODUCTION

Posterior urethral injuries in men commonly occur following pelvic and perineal trauma. Erectile dysfunction (ED), whether brought on by the severity of the initial trauma or the surgery itself, is one of the complications in these patients.

MATERIALS AND METHODS

In this study, we divided candidates of posterior urethroplasty due to traumatic urethral injury into intervention and placebo groups; the former received continuous treatment with tadalafil (10 mg daily), and the latter received a placebo. Other services were provided equally to both groups. Before and after the intervention, both groups completed the International Index of Erectile Function version 5 (IIEF-5) questionnaire, and the findings were analyzed.

RESULTS

Forty patients were studied in groups of 20 with a mean age of 43.87 ± 15.70 years. The patient's most common cause of urethral injury was a pelvic fracture. Before the intervention, the mean scores of IIEF for patients in the intervention group and placebo group were 14.85 ± 7.39 and 14.77 ± 6.48, respectively with no statistical significance (p = 0.962) and patients of the groups were similar in terms of the severity of ED. The mean IIEF score in the intervention group was 20.12 ± 4.94 and in the placebo group, it was 18.05 ± 4.88 at the three-month follow-up, with no statistically significant difference (p = 0.063). In both the intervention and placebo groups, the IIEF score was significantly increased by 5.27 ± 4.04 (p < 0.001) and 3.27 ± 2.97 (p < 0.001), respectively. The rate of IIEF increase in the intervention group was higher than in the placebo group during the follow-up at 3-month follow-up with statistical significance. (p = 0.022).

CONCLUSION

The findings of this study suggest that tadalafil, in a 3-month treatment course, may improve erectile function in individuals with mild-to-moderate ED, significantly more than placebo. However, more studies, specifically with longer duration of follow-up and larger populations, are necessary for generalizing the current findings.

Substance abuse and male sexual dysfunction: what lies beneath?

INTRODUCTION

Substance abuse has become a worldwide health problem, leading to numerous consequences such as social problems among family members, abnormal behavior, adverse health effects, and psychological problems as well as economic consequences.

OBJECTIVES

We sought to assess the relationship between substance abuse and male sexual health.

METHODS

A search was carried out in the following databases: PubMed, MeSH (Medical Subject Headings), Science Direct, Scopus, Cochrane Library, EMBASE, CINAHL, Academic Search Complete, and the Egyptian Knowledge Bank. The following keywords were used to assess the outcomes for relevant associations: illicit drugs, addiction, substance abuse, sexual health, erectile dysfunction, ejaculatory disorders, impotence, orgasm disorders, and sexual performance.

RESULTS

The initial literature search identified a total of 148 articles in all searched databases. After removal of duplicate studies and application of inclusion/exclusion criteria, 75 reported studies were retained for review, including 38 case-control studies and 37 cross-sectional studies. These articles were classified into the following categories according to the type of abused substance addressed: cannabis/marihuana, 16 articles; opioids, 13 articles; heroin, 11 articles; cocaine, 5 articles; tramadol, 6 articles; ketamine, 2 articles; ecstasy, 4 articles; amphetamine, 2 articles; khat, 7 articles; androgen anabolic steroids, 2 articles; and polydrugs, 7 articles. Most of these recruited articles demonstrated a negative impact of the addressed substance on male sexual health, with variable levels.

CONCLUSION

Substance abuse has negative impacts on male sexual health that should be addressed. More studies conducted with proper methodological and statistical approaches, including logistic regression analysis, are needed to predict the effects of specific substances, considering the rapidly growing effects of non-substance-use disorders on male sexual health.

Oxidized soluble guanylyl cyclase causes erectile dysfunction in alcoholic mice

BACKGROUND AND PURPOSE

Alcohol abuse has been associated with erectile dysfunction (ED), but the implicated molecular mechanisms are unresolved. This study analyses the role of alterations in soluble guanylyl cyclase (sGC) in ED.

EXPERIMENTAL APPROACH

ED was analysed in adult male C57BL/6J mice subjected to the Chronic Intermittent Ethanol (CIE) paradigm. Erectile function was assessed in anaesthetised mice in vivo by evaluating intracavernosal pressure (ICP) and in vitro in isolated mice corpora cavernosa (CC) mounted in a myograph. Protein expression and reactive oxygen species were analysed by western blot and dihydroethidium staining, respectively.

KEY RESULTS

In CIE mice, we observed a significant decrease in the relaxant response of the CC to stimulation of NO release from nitrergic nerves by electrical field stimulation, to NO release from endothelial cells by acetylcholine, to the PDE5 inhibitor sildenafil, and to the sGC stimulator riociguat. Conversely, the response to the sGC activator cinaciguat, whose action is independent of the oxidation state of sGC, was significantly enhanced in these CC. The responses to adenylyl cyclase stimulation with forskolin were unchanged. We found an increase in reactive oxygen species in the CC from CIE mice as well as an increase in CYP2E1 and NOX2 protein expression. In vivo pre-treatment with tempol prevented alcohol-induced erectile dysfunction.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that alcoholic mice show ED in vitro and in vivo due to an alteration in the redox state of sGC and suggest that sGC activators may be effective in ED associated with alcoholism.

The Sexual Incentive Motivation Model and Its Clinical Applications

Sexual motivation (desire) requires the simultaneous presence of an active central motive state and a stimulus with sexual significance. Once activated, sexual motivation leads to visceral responses and approach behaviors directed toward the emitter of the sexual stimulus. In humans, such behaviors follow cognitive evaluation of the context, including predictions of the approached individual's response. After successful approach and establishment of physical contact, manifest sexual activities may be initiated. Sexual interaction is associated with and followed by a state of positive affect in most animals, whereas aversive consequences may be experienced by humans. The affective reactions may become associated with stimuli present during sexual interaction, and these stimuli may thereby alter their incentive properties. Here we show how the incentive motivation model can be used to explain the origins and possible treatments of sexual dysfunctions, notably disorders of desire. We propose that associations formed between negative outcomes of sexual interaction and the salient stimuli, for example, the partner, underlies hypoactive desire disorder. Highly positive outcomes of sexual interaction enhance the incentive value of the stimuli present, and eventually lead to hyperactive sexual desire. Treatments aim to alter the impact of sexual incentives, mainly by modifying cognitive processes.

Effects of transplantation of umbilical cord blood mononuclear cells into the scrotum on sexual function in elderly mice

Aim: This study investigated the effect of allografting umbilical cord blood mononuclear cells (UCBMCs) into the scrotum on sexual function in male elderly mice. Methods: UCBMCs were injected once into the scrotal sheath cavity of elderly mice. Results: The transplanted UCBMCs survived in the scrotal sheath cavity for 1 month. The mice had significantly increased blood testosterone concentrations, cyclic guanosine monophosphate (cGMP) levels and total nitric oxide synthase (T-NOS) activity in the corpus cavernosum and an increase in the number of mouse matings within 30 min (all p = 0.000). Conclusion: Scrotum-implanted UCBMCs improve the sexual function of male elderly mice through testosterone production and the NOS/cGMP pathway, which may provide an innovative transplantation approach for the treatment of erectile dysfunction.

Hydrogen sulfide regulates the redox state of soluble guanylate cyclase in CSE-/- mice corpus cavernosum microcirculation

The corpus cavernosum (CC) is a highly vascularized tissue and represents an excellent example of microcirculation. Indeed, erectile dysfunction is considered an early index of cardiovascular disease. Hydrogen sulfide (H2S) at the vascular level is endogenously produced from L-cysteine mainly by the action of cystathionine-γ-lyase (CSE) and plays a role in CC vascular homeostasis. Here we have evaluated the involvement of the endogenous H2S in the regulation of the soluble guanylate cyclase (sCG) redox state. The lack of CSE-derived endogenous H2S, in CSE-/- mice, disrupted the eNOS/NO/sGC/PDE pathway. Indeed, the absence of CSE-derived endogenous H2S caused a significant reduction of the relaxant response to riociguat, an sGC redox-dependent stimulator. Conversely, the response to cinaciguat, an sGC redox-independent activator, was not modified. The relevance of the role played at the redox level of the endogenous H2S was confirmed by the findings that in CC harvested from CSE-/- mice there was a significant reduction of GCβ1 expression coupled with a decrease in CYP5R3, a reductase involved in the regulation of the redox state of sGC. These molecular changes driven by the lack of endogenous H2S translate into a significant reduction in cGMP levels. The replenishment of the lack of H2S with an H2S donor rescued the relaxant response to riociguat in CC of CSE-/- mice. In conclusion, the endogenous CSE-derived H2S plays a physiological key role in the regulation of the redox state of sGC in CC microcirculation.

Beet leaf (beta vulgaris L.) extract attenuates iron-induced testicular toxicity: Experimental and computational approach

The purpose of this study was to investigate the protective effect of Beta vulgaris leaf extract (BVLE) on Fe2+-induced oxidative testicular damage via experimental and computational models. Oxidative testicular damage was induced via incubation of testicular tissue supernatant with 0.1 mM FeSO4 for 30 min at 37 °C. Treatment was achieved by incubating the testicular tissues with BVLE under the same conditions. The catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), and nitric oxide (NO) levels, acetylcholinesterase (AChE), sodium-potassium adenosine triphosphatase (Na+/K + ATPase), ecto-nucleoside triphosphate diphosphohydrolase (ENTPDase), glucose-6-phosphatase (G6Pase), and fructose-1,6-bisphosphatase (F-1,6-BPase) were all measured in the tissues. We identified the bioactive compounds present using high-performance liquid chromatography (HPLC). Molecular docking and dynamic simulations were done on all identified compounds using a computational approach. The induction of testicular damage (p < 0.05) decreased the activities of GSH, SOD, CAT, and ENTPDase. In contrast, induction of testicular damage also resulted in a significant increase in MDA and NO levels and an increase in ATPase, G6Pase, and F-1,6-BPase activities. BVLE treatment (p < 0.05) reduced these levels and activities compared to control levels. An HPLC investigation revealed fifteen compounds in BVLE, with quercetin being the most abundant. The molecular docking and MDS analysis of the present study suggest that schaftoside may be an effective allosteric inhibitor of fructose 1,6-bisphosphatase based on the interacting residues and the subsequent effect on the dynamic loop conformation. These findings indicate that B. vulgaris can protect against Fe2+-induced testicular injury by suppressing oxidative stress, acetylcholinesterase, and purinergic activities while regulating carbohydrate dysmetabolism.

Bioequivalence Studies of Sildenafil Citrate Orodispersible Film Administered with and without Water vs ViagraⓇ Film-Coated Tablets in Healthy Male Volunteers

Background

Orodispersible film (ODF) formulation offers ease of use, convenience of administration, and other advantages, especially for patients who have difficulty in swallowing or are on liquid restriction compared with conventional oral formulations for the treatment of erectile dysfunction.

Objectives

These studies compared the bioequivalence of 50 mg sildenafil citrate ODF formulation (test drug) with the marketed 50 mg sildenafil citrate film-coated tablet (FCT) (Viagra^Ⓡ; Pfizer, New York, NY) (reference drug), with and without water in 2 randomized cross-over studies.

Methods

Two randomized cross-over studies were conducted. The first study explored the bioequivalence of test drug administered with and without water compared with the reference drug with water. The second study investigated the bioequivalence of test drug, without water, compared with the reference drug with water. Forty-two and 80 healthy male volunteers were recruited in the first and second study, respectively. All volunteers fasted for 10 hours pre-dose. A 1-day washout period between doses was observed. Blood samples were collected at both before (up to 120 minutes before dosing) and after dosing (at different intervals up to 14 hours) stages. Statistical analyses on pharmacokinetic parameters were performed. Safety and tolerability for both the formulations were evaluated.

Results

In the first study, bioequivalence was demonstrated for sildenafil citrate ODF administered with water when compared with the Viagra^Ⓡ FCT. The ratios of adjusted geometric means (90% confidence interval (CI)) were maximum plasma concentration: 1.02 (94.91-108.78) and area under the plasma concentration-time curve: 1.09 (104.49-113.21) for sildenafil citrate ODF administered with water vs Viagra^Ⓡ FCT. These ratios were within the bioequivalence acceptance range of 80% to 125%, indicating that the bioequivalence criteria were met. The pharmacokinetic parameters for the second study also showed bioequivalence for sildenafil citrate ODF (without water) compared with Viagra^Ⓡ FCT. The ratios of adjusted geometric means (90% CI) were maximum plasma concentration: 1.02 (95.47-109.36) and area under the plasma concentration-time curve: 1.06 (103.42-108.40) for sildenafil citrate ODF administered without water vs Viagra^Ⓡ FCT. Adverse events in both the studies occurred at similar rates for the 2 formulations and were mild in intensity.

Conclusions

These results suggest that the new ODF formulation can be used interchangeably with the marketed FCT formulation. Sildenafil citrate ODF administered with and without water met bioequivalence criteria compared with Viagra^Ⓡ FCT administered with water under fasted conditions in healthy adult male volunteers. The new ODF formulation can be used as a suitable alternative to the conventional oral solid dosage form.

Erectile Dysfunction: Treatments, Advances and New Therapeutic Strategies

Erectile dysfunction (ED) is the inability to get and maintain an adequate penile erection for satisfactory sexual intercourse. Due to its negative impacts on men's life quality and increase during aging (40% of men between 40 and 70 years), ED has always attracted researchers of different disciplines, from urology, andrology and neuropharmacology to regenerative medicine, and vascular and prosthesis implant surgery. Locally and/or centrally acting drugs are used to treat ED, e.g., phosphodiesterase 5 inhibitors (first in the list) given orally, and phentolamine, prostaglandin E1 and papaverine injected intracavernously. Preclinical data also show that dopamine D4 receptor agonists, oxytocin and α-MSH analogues may have a role in ED treatment. However, since pro-erectile drugs are given on demand and are not always efficacious, new strategies are being tested for long lasting cures of ED. These include regenerative therapies, e.g., stem cells, plasma-enriched platelets and extracorporeal shock wave treatments to cure damaged erectile tissues. Although fascinating, these therapies are laborious, expensive and not easily reproducible. This leaves old vacuum erection devices and penile prostheses as the only way to get an artificial erection and sexual intercourse with intractable ED, with penile prosthesis used only by accurately selected patients.

Guaiazulene and related compounds: A review of current perspective on biomedical applications

BACKGROUND

Thousands of people worldwide pass away yearly due to neurological disorders, cardiovascular illnesses, cancer, metabolic disorders, and microbial infections. Additionally, a sizable population has also been impacted by hepatotoxicity, ulcers, gastroesophageal reflux disease, and breast fissure. These ailments are likewise steadily increasing along with the increase in life expectancy. Finding innovative therapies to cure and consequently lessen the impact of these ailments is, therefore, a global concern.

METHODS AND MATERIALS

All provided literature on Guaiazulene (GA) and its related compounds were searched using various electronic databases such as PubMed, Google Scholar, Web of Science, Elsevier, Springer, ACS, CNKI, and books via the keywords Guaiazulene, Matricaria chamomilla, GA-related compounds, and Guaiazulene analogous.

RESULTS

The FDA has approved the bicyclic sesquiterpene GA, commonly referred to as azulon or 1,4-dimethyl-7-isopropylazulene, as a component in cosmetic colorants. The pleiotropic health advantages of GA and related substances, especially their antioxidant and anti-inflammatory effects, attracted a lot of research. Numerous studies have found that GA can help to manage various conditions, including bacterial infections, tumors, immunomodulation, expectorants, diuretics, diaphoresis, ulcers, dermatitis, proliferation, and gastritis. These conditions all involve lipid peroxidation and inflammatory response. In this review, we have covered the biomedical applications of GA. Moreover, we also emphasize the therapeutic potential of guaiazulene derivatives in pre-clinical and clinical settings, along with their underlying mechanism(s).

CONCLUSION

GA and its related compounds exhibit therapeutic potential in several diseases. Still, it is necessary to investigate their potential in animal models for various other ailments and establish their safety profile. They might be a good candidate to advance to clinical trials.

Does Testosterone Salvage PDE5i Non-Responders? A Scoping Review

Erectile physiology, in order to function normally, requires the complex coordination of endocrine, neurocognitive, neuromuscular and vascular mechanisms. Testosterone (T) influences male sexuality as well as penile erections at multiple levels, including a direct influence on the nitric oxide synthase (NOS)/cGMP/phosphodiesterase 5 pathway in the penis. However, the precise role of testosterone replacement (TRT) to “salvage” men with mixed ED failing phosphdiesterase-5 inhibitors (PDE5i) remains unclear. We conducted a scoping review identifying the rationale for TRT in ED failing PDE5i, and we critically discuss clinical trials that have examined TRT in the setting of PDE5i use. Overall, TRT replacement appears to be well tolerated and may enhance the response to PDE5i and quality of life, particularly for men with mixed ED, and particularly among men with very low levels of testosterone. However, most of the available literature examines concurrent TRT alone or simultaneous TRT + PDE5i usage, without necessarily selecting for PDE5i failure cases. The present studies are limited to heterogenous studies with small sample sizes, without an exact predominant etiologic factor causing ED. Furthermore, studies showing the most benefit are non-placebo-controlled trials; however, the correction of more profound hypogonadism may lead to an improved response to PDE5i. Stronger conclusions would require properly selected patient populations and larger placebo-controlled RCTs.

Effect of phosphodiesterase type 5 inhibitors on major adverse cardiovascular events and overall mortality in a large nationwide cohort of men with erectile dysfunction and cardiovascular risk factors: A retrospective, observational study based on healthcare claims and national death index data

BACKGROUND

Treatment with phosphodiesterase type 5 inhibitors (PDE-5is) is effective in treating erectile dysfunction (ED).

AIM

The objective of this study was to determine the effect of PDE-5is on the incidence of major adverse cardiovascular (CV) events (MACE; composite outcome of CV death, hospitalization for myocardial infarction, coronary revascularization, stroke, heart failure, and unstable angina pectoris) and overall mortality.

METHODS

A retrospective observational cohort study was conducted in a large US claims database in men with ≥1 diagnosis of ED without prior MACE within 1 year, from January 1, 2006, to October 31, 2020. The exposed group had ≥1 claim for PDE-5i and the unexposed group had no claims for PDE-5i, and the groups were matched up to 1:4 on baseline risk variables.

OUTCOME

The primary outcome was MACE and the secondary outcomes were overall mortality and individual components of MACE, determined by multivariable Cox proportional hazard modeling.

RESULTS

Matched plus multivariable analyses showed that MACE was lower by 13% in men exposed (n = 23 816) to PDE-5is (hazard ratio [HR] 0.87; 95% CI 0.79-0.95; P = .001) vs nonexposure (n = 48 682) over mean follow-up periods of 37 and 29 months, respectively, with lower incidence of coronary revascularization (HR 0.85; 95% CI 0.73-0.98; P = .029), heart failure (HR 0.83; 95% CI 0.72-0.97; P = .016), unstable angina (HR 0.78; 95% CI 0.64-0.96; P = .021), and CV death (HR 0.61; 95% CI 0.41-0.90; P = .014) with PDE-5i exposure. Phosphodiesterase type 5 inhibitor-exposed men had a 25% lower incidence of overall mortality (HR 0.75; 95% CI 0.65-0.87; P < .001). Men without coronary artery disease (CAD) but with CV risk factors at baseline showed a similar pattern. In the main study cohort, men in the highest quartile of PDE-5i exposure had the lowest incidence of MACE (HR 0.45; 95% CI 0.37-0.54; P < .001) and overall mortality (HR 0.51; 95% CI 0.37-0.71; P < .001) vs the lowest exposure quartile. In a subgroup with baseline type 2 diabetes (n = 6503), PDE-5i exposure was associated with a lower MACE risk (HR 0.79; 95% CI 0.64-0.97; P = .022).

CLINICAL IMPLICATIONS

PDE-5is may have cardioprotective effects.

STRENGTHS AND LIMITATIONS

Strengths are the large numbers of participants and consistency of the data; limitations include the retrospective nature of the study and unknown confounders.

CONCLUSIONS

In a large population of US men with ED, PDE-5i exposure was associated with lower incidence of MACE, CV death, and overall mortality risk compared to non-exposure. Risk reduction correlated with PDE-5i exposure level.

Cigarette smoking and erectile dysfunction: an updated review with a focus on pathophysiology, e-cigarettes, and smoking cessation

Introduction

Cigarette smoking has major health implications and causes substantial damage to all organ systems. Approximately one-third of men are active smokers worldwide, and most men are unaware that cigarette smoking can contribute to erectile dysfunction (ED).

Objectives

This article aims to provide a comprehensive overview of research conducted on cigarette smoking and ED, with a particular focus on pathophysiology, electronic cigarettes (e-cigarettes), and smoking cessation.

Methods

A manual literature search was conducted on all research conducted on cigarette smoking and ED up to October 2022.

Results

Substantial evidence is now available showing that past and current cigarette smoking has dose-dependent associations with ED in studies controlling for age and important health comorbidities. Cigarette smoke contains nicotine, carbon monoxide, oxidant chemicals, and metals that can damage the endothelium and disrupt erectile processes. For current smokers, smoking abstinence can strengthen the endothelium and reverse diminished erectile function. The effect of e-cigarettes on endothelial damage and ED remains largely untested. E-cigarettes expose users to fine and ultrafine particles and toxins that can increase risk of cardiovascular injury, but these acute effects appear less potent than conventional cigarettes (long-term cardiovascular effects are still unknown). E-cigarettes are therefore likely to have less harmful effects on ED than conventional cigarettes.

Conclusions

Smoking cessation programs that focus on nicotine replacement therapy (transdermal patches, gum, or inhalers), behavioral counseling, social support, and education programs can be effective approaches to ED treatment in active smokers. Temporarily transferring from regular cigarettes to e-cigarettes—which transmit some of the same carcinogens as conventional cigarettes and are likely to have some long-term cardiovascular effects that disrupt erectile function—might also be useful for long-term smoking cessation and treatment of ED.

Expression and Distribution of Free Zinc in Penile Erectile Tissue

PURPOSE

Several studies have shown that zinc has a significant influence on erectile function. However, no studies evaluating the cellular distribution of free zinc in penile erectile tissue have been performed. Therefore, this study aimed to test whether free zinc is present in penile tissue and whether it may be involved in the electrical stimulation (ES)-induced penile erection.

MATERIALS AND METHODS

The subjects for this study were 26 young (8-week-old) male C57BL/6J mice. After the cavernous nerve was exposed through a midline stomach incision, 14 mice received ES of the cavernous nerve (ES group), whereas 12 mice did not (control group). Intracavernous pressure (ICP) (consisting of 10 V at a duration of 1 min, frequency of 12 Hz and a pulse width of 1 m/s) was recorded during ES. Immediately after ICP was recorded, penile tissues were harvested for histological and biochemical analysis, including analysis of zinc transporter 3 (ZnT3) and intracellular free zinc levels.

RESULTS

The expression of neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS) in penile tissue was significantly greater in the ES group than in the control group (p=0.036 and 0.016, respectively). And then, ZnT3 and intracellular free zinc were present in the penile tissue of both groups. However, ZnT3 immunofluorescence in the ES group was more intense in the dorsal nerve bundle (22% increase, p=0.032). The ES group also showed higher intensity N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide (TSQ) fluorescence signals indicative of intracellular free zinc level in the penile tissue compared to the control group (49% increase in dorsal nerve bundle, p=0.001; 50% increase in corpus cavernosum, p=0.001).

CONCLUSIONS

The results of the study supported the expression and distribution of free zinc in penile tissue and increased levels after penile erection. Therefore, this study provides anatomical evidence for the potential role of free zinc in penile erection.

Sexual dysfunction precedes motor defects, dopaminergic neuronal degeneration, and impaired dopamine metabolism: Insights from Drosophila model of Parkinson's disease

Sexual dysfunction (SD) is one of the most common non-motor symptoms of Parkinson's disease (PD) and remains the most neglected, under-reported, and under-recognized aspect of PD. Studies have shown that Dopamine (DA) in the hypothalamus plays a role in regulating sexual behavior. But the detailed mechanism of SD in PD is not known. Drosophila melanogaster shares several genes and signaling pathways with humans which makes it an ideal model for the study of a neurodegenerative disorder such as PD. Courtship behavior of Drosophila is one such behavior that is closely related to human sexual behavior and so plays an important role in understanding sexual behavior in diseased conditions as well. In the present study, a sporadic SD model of PD using Drosophila was developed and SD phenotype was observed based on abnormalities in courtship behavior markers. The Drosophila SD model was developed in such a way that at the window of neurotoxin paraquat (PQ) treatment [PQ is considered a crucial risk factor for PD due to its structural similarity with 1-methyl-4-phenyl pyridinium (MPP+), the active form of PD-inducing agent, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)], it does not exhibit mobility defects but shows SD. The whole brain tyrosine hydroxylase immunostaining showed no observable dopaminergic (DAergic) degeneration (number of DA neurons and fluorescence intensity of fluorescently labeled secondary antibodies that target anti-TH primary antibody) of the SD model. Similarly, there was no significant depletion of brain DA and its metabolite levels (HVA and DOPAC) as determined using HPLC-ECD (High-Performance Liquid Chromatography using Electrochemical Detector). The present study illustrates that the traits associated with courtship and sexual activity provide sensitive markers at the earlier stage of PD onset. This PQ-induced SD fly model throws an opportunity to decipher the molecular basis of SD under PD conditions and to screen nutraceuticals/potential therapeutic molecules to rescue SD phenotype and further to DAergic neuroprotection.

Study on the mechanism of Jin Gui Shen Qi Pill in the treatment of erectile dysfunction based on bioinformatics analysis

Erectile dysfunction (ED) is a male disease, which is easy to cause disharmony in sexual life. However, at present, there are few drugs with small side effects in clinic. Jin Gui Shen Qi Pill (JGSQP) is a traditional Chinese medicine compound with obvious clinical effect in treating ED. Therefore, it is imperative to explore clinical drugs based on inhibiting the pathological characteristics of ED. First, the active ingredients and action targets in JGSQP were screened by applying Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and SWISS Target Prediction. Further, a systematic pharmacological analysis platform for traditional Chinese medicine, and the ED targets were screened by applying Gene Cards and Online Mendelian Inheritance in Man databases to construct drug active ingredient-target-disease mapping, followed by gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein-protein interaction (PPI) network analysis. Finally, Molecular docking and molecular dynamics simulations were used to screen the active ingredients of JGSQP acting on PDE-5, and analyze the ligand-receptor interaction relationship and binding free energy. The results showed that there were 212 potential targets of JGSQP for ED disease, and GO analysis revealed that the main pathways were positive regulation of DNA-binding transcription factor activity, regulation of vascular diameter, and negative regulation of vascular diameter, etc. KEGG analysis revealed that the main pathways were HIF-1 signaling pathway, prolactin signaling pathway, fluid shear stress, and atherosclerosis, etc. PPI network analysis revealed that the core targets TGFB1 and EGFR have important roles. Molecular docking and molecular dynamics simulations showed that the main components acting on PDE-5 were MOL000546, MOL011169, MOL000279, MOL000273 and Sildenafil. MOL000546 was able to bind stably to PDE-5. The multi-component, multi-target, and multi-pathway action characteristics of JGSQP were confirmed by network pharmacology, which predicted the possible mechanism of action of JGSQP in the treatment of ED and provided a theoretical reference for further experimental validation.

Prostaglandins as a Topical Therapy for Erectile Dysfunction: A Comprehensive Review

INTRODUCTION

Erectile dysfunction (ED) is a substantial cause of dissatisfaction among many men. This discontentment has led to the emergence of various drug treatment options for this problem.

OBJECTIVES

Unfortunately, due to various interactions, contraindications, and side effects, systemic therapies such as phosphodiesterase-5 inhibitors (including sildenafil, tadalafil, vardenafil, avanafil, etc.) are not welcomed in many patients. These problems have led researchers to look for other ways to reduce these complications.

METHODS

This article holistically reviews the efficacy of topical prostaglandins and their role in treating ED. We sought to provide a comprehensive overview of recent findings on the current topic by using the extensive literature search to identify the latest scientific reports on the topic.

RESULTS

In this regard, topical and transdermal treatments can be suitable alternatives. In diverse studies, prostaglandins, remarkably PGE1 (also known as alprostadil), have been suggested to be an acceptable candidate for topical treatment.

CONCLUSION

Numerous formulations of PGE1 have been used to treat patients so far. Still, in general, with the evolution of classical formulation methods toward modern techniques (such as using nanocarriers and skin permeability enhancers), the probability of treatment success also increases.

L-Arginine reverses maternal and pre-pubertal codeine exposure-induced sexual dysfunction via upregulation of androgen receptor gene and NO/cGMP signaling

Background

Although codeine has been reported to enhance sexual activity by improving penile reflexes, it has been shown to impair fertility indices. Also, codeine impairs ovarian steroidogenesis and folliculogenesis. Nonetheless, whether or not codeine exerts an epigenetic effect remains unclear. On the other hand, arginine has been speculated to enhance penile reflexes by upregulating NO/cGMP Signaling.

Aim

The study evaluated the effect of maternal codeine exposure and prepubertal codeine and arginine treatments on F1 male sexual function and fertility indices, as well as the outcome of F2 progenies. In addition, the epigenetic programming mechanism was also explored.

Methods

Forty three-week-old female rats were randomized into two groups (n = 20 rats/group); the control that received 0.5 ml of distilled water and the codeine-treated that received 5 mg/kg of codeine via gavage for eight weeks. Afterward, the female rats were paired for mating with sexually mature male rats. Rats were maintained on their pre-pregnancy treatments throughout pregnancy and lactation. FI progenies from each cohort (control and codeine-treated cohorts) were weaned at three weeks and randomized into four groups; the control, codeine-treated, L-arginine-treated (300mg/kg), and codeine + L-arginine-treated (n = 10 rats/group). Administration commenced a week post-weaning and lasted for eight weeks via gavage.

Key findings

Maternal codeine exposure did not alter body weight, but significantly reduced anogenital distance and anogenital index of F1 male offspring. Also, maternal codeine delayed preputial membrane separation, impaired male sexual competence, and penile reflexes of F1 male offsprings. These were associated with reduced dopamine, gonadotropins, and testosterone levels as well as suppressed expression of androgen receptor mRNA. In addition, maternal codeine downregulated NO/cGMP signaling, impaired fertility indices, and reduced the litter size, weight, and survival of F2 progenies. These alterations were observed to be aggravated by prepubertal codeine exposure but improved by prepubertal arginine treatment.

Significance

In conclusion, codeine programmed sexual dysfunction by suppressing the levels of dopamine and testosterone, as well as repressing the expression of androgen receptor mRNA. In addition, codeine-induced epigenetic reprogramming was expressed in the F2 offsprings as reduced litter size and weight, and survival rate. Notably, these observations were worsened by prepubertal codeine exposure, but dampened by prepubertal arginine treatment.

Haptoglobin treatment contributes to regulating nitric oxide signal and reduces oxidative stress in the penis: A preventive treatment for priapism in sickle cell disease

Background: In sickle cell disease (SCD), reduced bioavailability of endothelial NO and cGMP results in reduced expression of phosphodiesterase type 5 (PDE5), thus impairing the penile erection control mechanism and resulting in prolonged penile erection (priapism). In SCD, reduced NO bioavailability is associated with excess plasma hemoglobin due to intravascular hemolysis and increased oxidative stress. Haptoglobin is the plasma protein responsible for reducing plasma hemoglobin levels, but in SCD, haptoglobin levels are reduced, which favors the accumulation of hemoglobin in plasma. Therefore, we aimed to evaluate the effects of haptoglobin treatment on functional and molecular alterations of erectile function, focusing on the contractile and relaxant mechanisms of corpus cavernosum (CC), as well as oxidative stress.

Methods: SCD mice were treated with haptoglobin (400 mg/kg, subcutaneous) or vehicle of Monday, Wednesday and Friday for a period of 1 month. Corpus cavernosum strips were dissected free and placed in organ baths. Cumulative concentration-response curves to the acetylcholine, sodium nitroprusside, phenylephrine and KCL, as well as to electrical field stimulation (EFS), were obtained in CC. Protein expressions of eNOS, phosphorylation of eNOS at Ser-1177, nNOS, PDE5, ROCK1, ROCK2, gp91^phox, 3-nitrotyrosine, and 4-HNE were measured by western blot in CC.

Results: Increased CC relaxant responses to acetylcholine, sodium nitroprusside and electrical-field stimulation were reduced by haptoglobin in SCD mice. Reduced CC contractile responses to phenylephrine and KCl were increased by haptoglobin in SCD mice. Haptoglobin prevented downregulated eNOS, p-eNOS (Ser-1177), PDE5, and ROCK2 protein expressions and reduced protein expressions of reactive oxygen species markers, NADPH oxidase subunit gp91phox, 3-nitrotyrosine and 4-HNE in penises from SCD mice. Haptoglobin treatment did not affect ROCK1 and nNOS protein expressions in penises from SCD mice. Basal cGMP production was lower in the SCD group, which was normalized by haptoglobin treatment.

Conclusion: Treatment with haptoglobin improved erectile function due to up-regulation of eNOS-PDE5 expression and down-regulation of the gp91phox subunit of NADPH oxidase and oxidative/nitrosative stress in the penises of SCD mice. Treatment with haptoglobin also increased contractile activity due to up-regulation of ROCK2. Therefore, haptoglobin treatment may be an additional strategy to prevent priapism in SCD.

Opioid-Induced Sexual Dysfunction in Cancer Patients

Simple Summary

Sexual disorders affect up to 80% of cancer patients, depending on the type of cancer, yet they are commonly overlooked and untreated. Opioid-induced sexual dysfunction (OISD) is reported in half of opioid users. The pathophysiology of OISD—still a subject for research—may include disorders of both the endocrine and nervous systems, expressed in, among other things, erectile dysfunction and declined sexual desire, sexual arousal, orgasm, and general satisfaction with one’s sex life. The etiology of sexual dysfunction in cancer patients is usually multifactorial, so the management should be multifaceted and individualized by targeting pathophysiological factors. The treatment options for OISD are few and include testosterone replacement therapy, bupropion, opioid antagonists, phosphodiesterase type 5 inhibitors, plant-derived substances, and non-pharmacological treatments, although the evidence is insufficient. One of the treatment options may also be a choice of an opioid that is less likely to cause sexual dysfunction, yet further research is necessary.

Abstract

Sexual dysfunction is common in patients with advanced cancer, although it is frequently belittled, and thus consistently underdiagnosed and untreated. Opioid analgesics remain fundamental and are widely used in cancer pain treatment. However, they affect sexual functions primarily due to their action on the hypothalamus–pituitary–gonadal axis. Other mechanisms such as the impact on the central and peripheral nervous systems are also possible. The opioid-induced sexual dysfunction includes erectile dysfunction, lack of desire and arousal, orgasmic disorder, and lowered overall sexual satisfaction. Around half of the individuals taking opioids chronically may be affected by sexual dysfunction. The relative risk of sexual dysfunction in patients on chronic opioid therapy and opioid addicts increased two-fold in a large meta-analysis. Opioids differ in their potential to induce sexual dysfunctions. Partial agonists and short-acting opioids may likely cause sexual dysfunction to a lesser extent. Few pharmaceutical therapies proved effective: testosterone replacement therapy, PDE5 inhibitors, bupropion, trazodone, opioid antagonists, and plant-derived medicines such as Rosa damascena and ginseng. Non-pharmacological options, such as psychosexual or physical therapies, should also be considered. However, the evidence is scarce and projected primarily from non-cancer populations, including opioid addicts. Further research is necessary to explore the problem of sexuality in cancer patients and the role of opioids in inducing sexual dysfunction.

Effect of Flavonoid-Rich Extract From Dalbergiella welwitschii Leaf on Redox, Cholinergic, Monoaminergic, and Purinergic Dysfunction in Oxidative Testicular Injury: Ex Vivo and In Silico Studies

The antioxidant, cholinergic, monoaminergic, and purinergic activities of flavonoid-rich extract from Dalbergiella welwitschii leaf (FEDW) were investigated on oxidative testicular injury (ex vivo) due to the local report on the use of this plant as anti-testicular injury. Flavonoid extract was obtained from FEDW using a standard procedure. Five male albino rats were used, testes harvested and incubated with FeSO₄ for accessing the cholinergic, monoaminergic, and purinergic activities of the FEDW (ex vivo). Testicular tissues incubated with FeSO₄ demonstrated a significant decrease in antioxidant biomarkers, arginase, ATPase, ENTPDase, 5'-nucleotidase, and PDE-5 activities, as well as Zn and sialic acid levels with an upsurge in malondialdehyde (MDA), and NO levels, myeloperoxidase, cholinesterases, monoamine oxidase (MAO), and angiotensin-converting enzyme (ACE) activities. Treatment of testicular tissues incubated with FeSO₄ via different concentrations of FEDW significantly increased the activities of antioxidant, arginase, ATPase, E-NTPDase, 5'-nucleotidase, phosphodiesterase-5 (PDE-5), as well as Zn and sialic acid levels with a significant decrease in MDA, nitric oxide (NO), myeloperoxidase, cholinesterases, MAO, and ACE levels. Molecular docking revealed the molecular interactions of cyclooxygenase-2 (COX-2) with ellagic acid, piperine, and caffeine with piperine and caffeine obeyed the druggability and pharmacokinetic. These findings point to FEDW as a possible potential for the treatment of oxidative testicular injury.

MYPT1 reduction is a pathogenic factor of erectile dysfunction

Erectile dysfunction (ED) is closely associated with smooth muscle dysfunction, but its underlying mechanisms remains incompletely understood. We here reported that the reduced expression of myosin phosphatase target subunit 1 (MYPT1), the main regulatory unit of myosin light chain phosphatase, was critical for the development of vasculogenic ED. Male MYPT1 knockout mice had reduced fertility and the penises displayed impaired erections as evidenced by reduced intracavernous pressure (ICP). The penile smooth muscles of the knockout mice displayed enhanced response to G-Protein Couple Receptor agonism and depolarization contractility and resistant relaxation. We further identified a natural compound lotusine that increased the MYPT1 expression by inhibiting SIAH1/2 E3 ligases-mediated protein degradation. This compound sufficiently restored the ICP and improved histological characters of the penile artery of Mypt1 haploinsufficiency mice. In diabetic ED mice (db/db), the decreased expression of MYPT1 was measured, and ICP was improved by lotusine treatment. We conclude that the reduction of MYPT1 is the major pathogenic factor of vasculogenic ED. The restoration of MYPT1 by lotusine improved the function of injured penile smooth muscles, and could be a novel strategy for ED therapy.

A Systematic Review on the Effect of Nutraceuticals on Antidepressant-Induced Sexual Dysfunctions: From Basic Principles to Clinical Applications

Sexual dysfunctions are common side effects reported by patients during antidepressant treatment. When they occur, patients often discontinue psychopharmacological therapy, with a negative impact on the underlying psychiatric disease. Recently, great attention has been paid to the use of nutraceuticals in the management of psychiatric disorders, although a systematic review on their effects as a treatment option for antidepressant-induced sexual dysfunctions (AISD) is lacking. Here, we conducted a systematic search in the following databases: MEDLINE (through PubMed), EMBASE, PsycINFO, Cochrane Central Register of Controlled Trials, and Web of Science. We searched eligible studies among parallel or crossover randomized controlled trials (RCTs) in adult populations. After this process, a total of 10 articles that evaluated the effect of six different nutraceuticals versus placebo were included: Maca Root, S-adenosyl-L-methionine (SAMe), Rosa Damascena, Ginkgo Biloba, Saffron, and Yohimbine. Overall, a high dose of Maca Root and the use of SAMe or Saffron may improve AISD. Additionally, the administration of Rosa Damascena seemed to be more effective in men than in women, whereas no evidence of effects emerged for Gingko Biloba and Yohimbine. Given the mixed results still available, future RCTs should consider larger samples and confounding factors, such as depressive status and individual vulnerability.

Supplementation with Spirulina platensis Prevents Damage to Rat Erections in a Model of Erectile Dysfunction Promoted by Hypercaloric Diet-Induced Obesity

Erectile dysfunction (ED) is the inability to achieve and/or maintain a penile erection sufficient for sexual satisfaction. Currently, many patients do not respond to the pharmacotherapy. The effects of a supplementation with Spirulina platensis, were evaluated in a model of ED induced by hypercaloric diet consumption. Wistar rats were divided into groups fed with standard diet (SD) or hypercaloric diet (HD) and supplemented with this alga at doses of 25, 50 or 100 mg/kg. Experimental adiposity parameters and erectile function were analyzed. In SD groups, Spirulina platensis reduced food intake, final body mass and adiposity index, and increased the total antioxidant capacity (TAC) of adipose tissue. However, no change was observed in erectile function. In the HD group, without Spirulina supplementation, a decrease in food intake was observed, in addition to an increase of final body mass, weight gain, adipose reserves, and adiposity index. Additionally, reduction in the number and increase in the latency of penile erection and adipose malondialdehyde levels, as well as a reduction in TCA was noted. Furthermore, cavernous contractility was increased, and the relaxing response was decreased. Interestingly, these deleterious effects were prevented by the algae at doses of 25, 50 and/or 100 mg/kg. Therefore, the supplementation with S. platensis prevents damages associated to a hypercaloric diet consumption and emerges as an adjuvant the prevention of ED.

Erectile Dysfunction: Key Role of Cavernous Smooth Muscle Cells

Erectile dysfunction is increasingly affecting men, from the elderly to young adults, being a sexual disorder related to the inability to generate or maintain a penile erection. This disorder is related to psychosocial factors such as anxiety, depression, and low self-esteem, to organic factors such as the presence of preexisting conditions like hypertension, diabetes and dyslipidemia. The pathophysiology of the disease is related to changes in the neurotransmission of the autonomic or the non-cholinergic non-adrenergic nervous system, as well as the release of local mediators, such as thromboxane A₂ and endothelin, and hormonal action. These changes lead to impaired relaxation of cavernous smooth muscle, which reduces local blood flow and impairs penile erection. Currently, therapy is based on oral vasodilation, such as sildenafil, tadalafil, vardenafil and iodenafil, or by direct administration of these agents into the corpus cavernosum or by intraurethral route, such as alprostadil and papaverine. Despite this, studies that consolidate the understanding of its pathophysiological process contribute to the discovery of new more efficient drugs for the treatment of erectile dysfunction. In this sense, in the present work an extensive survey was carried out of the mechanisms already consolidated and the most recent ones related to the development of erectile dysfunction.

Resting Rates of Blood Flow and Glucose Use per Neuron Are Proportional to Number of Endothelial Cells Available per Neuron Across Sites in the Rat Brain

We report in a companion paper that in the mouse brain, in contrast to the 1,000-fold variation in local neuronal densities across sites, capillary density (measured both as capillary volume fraction and as density of endothelial cells) show very little variation, of the order of only fourfold. Here we confirm that finding in the rat brain and, using published rates of local blood flow and glucose use at rest, proceed to show that what small variation exists in capillary density across sites in the rat brain is strongly and linearly correlated to variations in local rates of brain metabolism at rest. Crucially, we show that such variations in local capillary density and brain metabolism are not correlated with local variations in neuronal density, which contradicts expectations that use-dependent self-organization would cause brain sites with more neurons to have higher capillary densities due to higher energetic demands. In fact, we show that the ratio of endothelial cells per neuron serves as a linear indicator of average blood flow and glucose use per neuron at rest, and both increase as neuronal density decreases across sites. In other words, because of the relatively tiny variation in capillary densities compared to the large variation in neuronal densities, the anatomical infrastructure of the brain is such that those sites with fewer neurons have more energy supplied per neuron, which matches a higher average rate of energy use per neuron, compared to sites with more neurons. Taken together, our data support the interpretation that resting brain metabolism is not demand-based, but rather limited by its capillary supply, and raise multiple implications for the differential vulnerability of diverse brain areas to disease and aging.

Dopamine, Erectile Function and Male Sexual Behavior from the Past to the Present: A Review

Early and recent studies show that dopamine through its neuronal systems and receptor subtypes plays different roles in the control of male sexual behavior. These studies show that (i) the mesolimbic/mesocortical dopaminergic system plays a key role in the preparatory phase of sexual behavior, e.g., in sexual arousal, motivation and reward, whereas the nigrostriatal system controls the sensory-motor coordination necessary for copulation, (ii) the incertohypothalamic system is involved in the consummatory aspects of sexual behavior (penile erection and copulation), but evidence for its role in sexual motivation is also available, (iii) the pro-sexual effects of dopamine occur in concert with neural systems interconnecting the hypothalamus and preoptic area with the spinal cord, ventral tegmental area and other limbic brain areas and (iv) D₂ and D₄ receptors play a major role in the pro-sexual effects of dopamine. Despite some controversy, increases or decreases, respectively, of brain dopamine activity induced by drugs or that occur physiologically, usually improves or worsens, respectively, sexual activity. These findings suggest that an altered central dopaminergic tone plays a role in mental pathologies characterized by aberrant sexual behavior, and that pro-erectile D₄ receptor agonists may be considered a new strategy for the treatment of erectile dysfunction in men.

Curcumin slow-release membrane promotes erectile function and penile rehabilitation in a rat model of cavernous nerve injury

Male erectile dysfunction (ED) caused by cavernous nerve injury is a common complication of pelvic surgery, radiotherapy, transurethral surgery or other operations. However, clinical treatment for iatrogenic or traumatic male ED is difficult and not satisfactory. Many studies have shown that curcumin can promote the repair and regeneration of peripheral nerves; however, whether curcumin can rescue cavernous nerve injury is unknown, and the poor bioavailability of curcumin limits its application in vivo. Hence, the study was conducted. A curved slow-release membrane was produced, and the properties were examined. In addition, the effects of the curcumin slow-release membrane on cavernous nerve-injured SD rats were studied. We found that polylactic acid-glycolic acid-polyethylene glycol (PLGA-PEG) can be used as a good carrier material for curcumin, and curcumin-loaded PLGA-PEG membranes can effectively rescue the cavernous nerve in SD rats, restore the continuity of the cavernous nerve, and increase the expression of nNOS mRNA and proteins in penile tissue, which can improve the penile erectile function of injured SD rats, reduce the degree of penile tissue fibrosis, and effectively promote penis rehabilitation. The curcumin slow-release membrane is proposed to be a new therapeutic approach for penile rehabilitation of cavernous nerve injury.

Resveratrol-nitric oxide donor hybrid effect on priapism in sickle cell and nitric oxide-deficient mouse

Background

Children and adult with sickle cell disease (SCD) display priapism associated with low nitric oxide (NO) bioavailability and oxidative stress in penis.

Aim

This study aimed to evaluate the effects of hybrid compound RVT-FxMe, derived from resveratrol bearing a NO-donor subunit, on two murine model that display priapism phenotype, SCD transgenic mice and endothelial NO synthase gene-deficient (eNOS^-/-) mice.

Methods

Wild-type, SCD, and eNOS^-/- mice were treated with RVT-FxMe (25 mg/kg/d, 2 weeks).

Outcomes

Hematological parameters, concentration-response curves to acetylcholine (ACh) and sodium nitroprusside (SNP), as well as to electrical field stimulation (EFS), were obtained in mice corpus cavernosum strips.

Results

Corpus cavernosum relaxations to SNP and EFS were increased in eNOS^-/- group, which were normalized by RVT-FxMe treatment. SCD mice exhibited an excessive CC relaxant response induced by ACh, EFS and SNP RVT-FxMe treatment did not change the increased relaxant responses to ACh, EFS and SNP in corpus cavernosum from SCD group.

Clinical translation

Excess of plasma hemoglobin in SCD may interfere in pharmacological activity of NO donors compounds.

Strength/Limitations

While mechanistic data with promising potential is showed, the current study is not without limitations. RVT-FxMe effects in the mid- and long-term warrant complementary studies.

Conclusion

Treatment with RVT-FxMe reversed the enhanced NO-cGMP-mediated CC relaxations in eNOS^-/- mice, but not in SCD mice; it is likely that excess of plasma hemoglobin in SCD mice act to inactivate NO before it reaches soluble guanylyl cyclase, avoiding restoration of NO bioavailability in penis.

Intracavernosal OnabotulinumtoxinA Exerts a Synergistic Pro-Erectile Effect When Combined With Sildenafil in Spontaneously Hypertensive Rats

BACKGROUND

Botulinum toxin A (BTX-A) has a variety of uses in medicine. Some evidence suggests that intracavernosal (ic) BTX-A injection administered in addition to phosphodiesterase type 5 inhibitors (PDE5-Is) could effectively treat erectile dysfunction (ED) in insufficient responders to PDE5-Is.

AIM

To provide experimental pharmacological evidence for the use of onabotulinumtoxinA ic alone or in combination with PDE5-Is for difficult-to-treat ED. We thus compared the effects of BTX-A ic alone and BTX-A ic combined with PDE5-I iv, and a placebo treatment ic or iv.

METHODS

Erectile function was evaluated following cavernous nerve electrical stimulation (6 V, 1-millisecond pulse, 45-second duration) at different frequencies (0, 2, 3, 4, 5, 7.5, and 10 Hz) in 4 groups (n = 8 / group) of anesthetized, spontaneously hypertensive rats, a robust animal model of ED of vascular origin. Rats were treated by onabotulinumtoxinA 10U or saline ic 1 week prior to erectile function testing and sildenafil (0.3 mg/kg) or saline iv 4 minutes prior to testing. Frequency-response curves were compared with a 2 way ANOVA.

OUTCOMES

Both onabotulinumtoxinA ic, and sildenafil iv significantly improved erectile responses in spontaneously hypertensive rats, however the effect was greatly amplified when the treatments were combined.

RESULTS

Intracavernosal pressure and/or mean arterial pressure ratios were significantly increased by sildenafil and onabotulinumtoxinA ic versus the control condition. OnabotulinumtoxinA 10U ic combined with sildenafil iv significantly potentiated erectile responses. Area under the curve and/or mean arterial pressure ratio increased by 19% with sildenafil iv, by 15% with onabotulinumtoxinA ic and by 58% with the combined treatment following cavernous nerve electrical stimulation at 6V, 1 ms, 10 Hz: these stimulation parameters elicited the maximal erectile response.

CLINICAL TRANSLATION

These data provide a pharmacological rationale for the combined administration of onabotulinumtoxinA ic and sildenafil iv since the effects of both treatments were potentiated when their administration was combined.

STRENGTHS & LIMITATIONS

First evidence of a synergistic pro-erectile effect of BTX-A combined with PDE5-I, however the mechanism behind the pro-erectile effect of BTX-A ic remains hypothetical.

CONCLUSIONS

These results support further studies into the mechanisms behind the pro-erectile effect of BTX-A ic, as well as multicenter randomized control trials to evaluate the safety and efficacy of BTX-A ic combined with sildenafil for difficult-to-treat ED. Giuliano F., Joussain C., Denys P., et al. Intracavernosal OnabotulinumtoxinA Exerts a Synergistic Pro-Erectile Effect When Combined With Sildenafil in Spontaneously Hypertensive Rats. J Sex Med 2022;19:899-906.

Preparation and evaluation of radioiodinated avanafil: A novel potential radiopharmaceutical for the diagnostic evaluation of erectile dysfunction

Avanafil, a selective second-generation phosphodiesterase-5 inhibitor, was successfully labeled with iodine-125 via electrophilic and different factors affecting the labeling efficiency were studied. The labeled compound exhibited in-vitro stability of more than 24 h with a maximum labeling yield of up to 98.4 ± 1.9 %. Molecular modeling and in-vitro assessment of tracer inhibitory activity were performed to ensure that radiolabeling did not affect its binding ability to the target. Biodistribution studies were performed in normal rats and models of erectile dysfunction. The tracer specifically accumulated in the penis, and the clearance appeared to take place via the hepatobiliary route. Results suggested the usefulness of radiolabeled avanafil as a promising tracer for erectile dysfunction.

In vitro inhibition of phosphodiesterase type 4 enhances rat corpus cavernosum nerve-mediated relaxation induced by gasotransmitters

AIMS

Nitric oxide (NO) and hydrogen sulfide (H2S) are involved in nerve-mediated corpus cavernosum (CC) relaxation. Expression of phosphodiesterase type 5 (PDE5) and type 4 (PDE4), cyclic guanosine monophosphate (cGMP)- and cyclic adenosine monophosphate (cAMP)-specific, respectively, has been described and PDE5- and PDE4-inhibitors induce cavernous smooth muscle relaxation. Whereas the NO/cGMP signaling pathway is well established in penile erection, the cAMP-mediated mechanism is not fully elucidated. The aim of this study is to investigate the localization and the functional significance of PDE4 in rat CC tone regulation.

MAIN METHODS

We performed immunohistochemistry for the detection of the PDE4A isoenzyme. Isometric tension recordings for roflumilast and tadalafil, PDE4 and PDE5 inhibitors, respectively, electrical field stimulation (EFS) and β-adrenoceptor agonist isoproterenol and endogenous H2S production measurement.

KEY FINDINGS

A marked PDE4A expression was detected mainly localized in the nerve cells of the cavernous smooth muscle. Furthermore, roflumilast and tadalafil exhibited strong corpus cavernous relaxations. Endogenous H2S production was decreased by NO and H2S synthase inhibitors and increased by roflumilast. Isoproterenol- and EFS-induced relaxations were increased by roflumilast.

SIGNIFICANCE

These results indicate that PDE4A is mainly expressed within the nerves cells of the rat CC, where roflumilast induces a potent corpus cavernous relaxation per se and potentiates the response induced by β-adrenoceptor activation. The fact that roflumilast enhances H2S production, as well as EFS-elicited responses suggests that PDE4 inhibitors modulate, in a positive feedback fashion, nerve-mediated relaxation induced by gasotransmitters, thus indicating a key role for neuronal PDE4 in penile erection.

Breath chemical markers of sexual arousal in humans

The chemical composition of exhaled breath was examined for volatile organic compound (VOC) indicators of sexual arousal in human beings. Participants (12-male, 12-female) were shown a randomized series of three emotion-inducing 10-min film clips interspersed with 3-min neutral film clips. The films caused different arousals: sports film (positive-nonsexual); horror film (negative-nonsexual); and erotic (sexual) that were monitored with physiological measurements including genital response and temperature. Simultaneously the breath was monitored for VOC and CO₂. While some breath compounds (methanol and acetone) changed uniformly irrespective of the film order, several compounds did show significant arousal associated changes. For both genders CO₂ and isoprene decreased in the sex clip. Some male individuals showed particularly strong increases of indole, phenol and cresol coincident with sexual arousal that decreased rapidly afterwards. These VOCs are degradation products of tyrosine and tryptophan, precursors for dopamine, noradrenalin, and serotonin, and therefore represent potential breath markers of sexual arousal.

From the PnTx2-6 Toxin to the PnPP-19 Engineered Peptide: Therapeutic Potential in Erectile Dysfunction, Nociception, and Glaucoma

The venom of the “armed” spider Phoneutria nigriventer comprises several potent toxins. One of the most toxic components from this venom is the neurotoxin PnTx2-6 (LD50 = ∼ 0.7 μg/mouse, 48 residues, five disulfide bridges, MW = 5,289.31 Da), which slows down the inactivation of various Na+ channels. In mice and rats, this toxin causes priapism, an involuntary and painful erection, similar to what is observed in humans bitten by P. nigriventer. While not completely elucidated, it is clear that PnTx2-6 potentiates erectile function via NO/cGMP signaling, but it has many off-target effects. Seeking to obtain a simpler and less toxic molecule able to retain the pharmacological properties of this toxin, we designed and synthesized the peptide PnPP-19 (19 residues, MW = 2,485.6 Da), representing a discontinuous epitope of PnTx2-6. This synthetic peptide also potentiates erectile function via NO/cGMP, but it does not target Na+ channels, and therefore, it displays nontoxic properties in animals even at high doses. PnPP-19 effectively potentiates erectile function not only after subcutaneous or intravenous administration but also following topical application. Surprisingly, PnPP-19 showed central and peripheral antinociceptive activity involving the opioid and cannabinoid systems, suggesting applicability in nociception. Furthermore, considering that PnPP-19 increases NO availability in the corpus cavernosum, this peptide was also tested in a model of induced intraocular hypertension, characterized by low NO levels, and it showed promising results by decreasing the intraocular pressure which prevents retinal damage. Herein, we discuss how was engineered this smaller active non-toxic peptide with promising results in the treatment of erectile dysfunction, nociception, and glaucoma from the noxious PnTx2-6, as well as the pitfalls of this ongoing journey.