PDE5 inhibitors: targeting erectile dysfunction in diabetics

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.

Nitro-oleic acid ameliorates erectile dysfunction in a streptozotocin-induced rat model of diabetes by inhibiting oxidative stress and apoptosis and activating the NO/cGMP pathway

The major vascular complications associated with diabetes make the management of diabetic mellitus erectile dysfunction (DMED) a challenging endeavor. Notable factors contributing to DMED include oxidative stress, nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway activation, and apoptosis, while nitro-oleic acid (NO 2 -OA) has been shown to be beneficial in treating these aspects of this condition. We, herein, investigated the effects and possible mechanisms of NO 2 -OA on erectile function as assessed in a streptozotocin-induced rat model of diabetes. Our results revealed that the erectile function of DMED rats was significantly impaired compared with that of the control group. However, in response to 4 weeks of NO 2 -OA treatment, there was an improvement in erectile function. The expression of oxidative stress-related indicators was significantly increased and the NO/cGMP pathway was impaired in the DMED group. The expression of proapoptotic factors was increased, while that of antiapoptotic factors was decreased in the DMED group. Moreover, the cell morphology in the cavernous tissue of the DMED group also changed adversely. NO 2 -OA treatment significantly reversed all these changes observed in the DMED group. In conclusion, NO 2 -OA treatment partially improved erectile function in DMED rats through mechanisms that included inhibition of oxidative stress, activation of the NO/cGMP pathway, and a reduction in apoptosis.

A Review on Penile Doppler and Ultrasonography for Erectile Dysfunction

PURPOSE OF REVIEW

Herein, we seek to review the clinical applications of penile duplex Doppler ultrasound (PDDU) in sexual medicine practices and discuss the indications, protocols, advantages, and limitations of this diagnostic modality. Other more outdated diagnostic tests, such as cavernosometry, are briefly discussed to provide the reader a background of understanding on the evolution of diagnostic testing within the realm of sexual medicine.

RECENT FINDINGS

PDDU has become a key diagnostic tool in the clinical evaluation of both erectile dysfunction (ED) and Peyronie's disease (PD). With the assistance of intracavernosal injections such as alprostadil, clinicians can utilize ultrasound technology to produce a detailed description of the hemodynamics of the patient's erection cycle. This information plays a pivotal role in establishing an accurate diagnosis and creating a sensible management plan for the patient. This review aims to provide a better understanding regarding the technique and interpretation of PDDU as it pertains to male sexual function.

Erectile Dysfunction Severity: The Role of Glycometabolic Compensation and Antihyperglycemic Drugs

Background: The aim of this study was to evaluate the prevalence of DM among patients with ED and the impact of glycometabolic compensation and antihyperglycemic treatment on ED severity. Methods: In total, 1332 patients with ED were enrolled. The diagnosis was performed through the International-Index-of-Erectile-Function questionnaire. ED severity was considered according to presence/absence of spontaneous erections, maintenance/achievement deficiency and response to PDE5-i. DM patients were clustered according to antihyperglycemic treatment: “metformin”/“insulin”/“old antihyperglycemic drugs”/“new antihyperglycemic drugs”. Results: The prevalence of DM patients was 15.8% (Group A, patients with ED and DM). Among these, the prevalence of spontaneous erections (21.0%) was lower than in the remaining patients (Group B, patients with ED without DM) (32.0%, p < 0.001). The prevalence of poor response to PDE5-i was lower in Group B (10.0%) than in Group A (35.0%, p < 0.001). Patients with good response to PDE5-i therapy showed lower HbA1c values than patients with poor/no response (6.6 ± 1.1% vs. 7.7 ± 1.9%, p = 0.02). The prevalence of absent response to PDE5-i was higher in patients treated with old antidiabetic drugs than in the population treated with new drugs (p = 0.03). Conclusion: The severity of ED and lower response to PDE5-i were higher in DM patients. A better glycometabolic profile, as well as new antihyperglycemic drugs, seem to have a positive effect on ED.

Erectile dysfunction and diabetes: A melting pot of circumstances and treatments

Diabetes mellitus (DM), a chronic metabolic disease characterised by elevated levels of blood glucose, is among the most common chronic diseases. The incidence and prevalence of DM have been increasing over the years. The complications of DM represent a serious health problem. The long-term complications include macroangiopathy, microangiopathy and neuropathy as well as sexual dysfunction (SD) in both men and women. Erectile dysfunction (ED) has been considered the most important SD in men with DM. The prevalence of ED is approximately 3.5-fold higher in men with DM than in those without DM. Common risk factors for the development of DM and its complications include sedentary lifestyle, overweight/obesity and increased caloric consumption. Although lifestyle changes may help improve sexual function, specific treatments are often needed. This study aims to review the definition and prevalence of ED in DM, the impact of DM complications and DM treatment on ED and, finally, the current and emerging therapies for ED in patients with DM.

JAK2 deficiency improves erectile function in diabetic mice through attenuation of oxidative stress, apoptosis, and fibrosis

Background

Janus kinase 2 (JAK2) is activated in diabetic mellitus (DM) conditions and may enhance oxidative stress, apoptosis and fibrosis in many tissues. Whether JAK2 activation is involved in the occurrence of diabetic erectile dysfunction (ED) is unknown.

Objectives

We performed this study to investigate the effect of JAK2 deficiency on diabetic ED.

Materials and methods

Conditional JAK2 gene knockout mice (Cre^+/+‐JAK2^fl/fl) were used, in which JAK2 gene knockout could be induced by tamoxifen. Mice fell into four groups: control, JAK2 knockout (JAK2^−/−), DM, and DM with JAK2^−/−. DM was induced by intraperitoneal injection of streptozotocin. Two months later, JAK2 gene knockout was induced with tamoxifen in Cre^+/+‐JAK2^fl/fl mice. After another 2 months, erectile function was measured by electrical stimulation of the cavernous nerve, and penile tissues were harvested. Ratio of maximal intracavernosal pressure (MIP) to mean arterial blood pressure (MAP), expression and phosphorylation of JAK2, oxidative stress level, NO/Cyclic Guanosine Monophosphate (cGMP) pathway, apoptosis, fibrosis, and transforming growth factor beta 1 (TGF‐β1)/Smad/Collagen IV pathway in corpus cavernosum, were measured.

Results

JAK2 expression was remarkably decreased after induction with tamoxifen. JAK2 was activated in penile tissues of diabetic mice, and JAK2 deficiency could improve the impaired erectile function caused by DM. However, in mice without DM, JAK2 deficiency had no apparent influence on erectile function. Levels of oxidative stress, apoptosis, fibrosis, and TGF‐β1/Smad/Collagen IV pathway were all elevated by DM, whereas JAK2 deficiency lessened these alterations in diabetic mice. Moreover, JAK2 deficiency improved the expression of the down‐regulated NO/cGMP pathway in diabetic mice. In non‐diabetic mice, no apparent changes were found in aforementioned parameters after JAK2 gene knockout.

Discussion and conclusion

Our study showed that JAK2 deficiency could improve erectile function in diabetic mice, which might be mediated by reduction in oxidative stress, apoptosis, and fibrosis in corpus cavernosum.

Advantages of Phosphodiesterase Type 5 Inhibitors in the Management of Glucose Metabolism Disorders: A Clinical and Translational Issue

Among metabolic diseases, carbohydrate metabolism disorders are the most widespread. The most common glucose pathological conditions are acquired and may increase the risk of type 2 diabetes, obesity, heart diseases, stroke, and kidney insufficiency. Phosphodiesterase type 5 inhibitors (PDE5i) have long been used as an effective therapeutic option for the treatment of erectile dysfunction (ED). Different studies have demonstrated that PDE5i, by sensitizing insulin target tissues to insulin, play an important role in controlling the action of insulin and glucose metabolism, highlighting the protective action of these drugs against metabolic diseases. In this review, we report the latest knowledge about the role of PDE5i in the metabolic diseases of insulin resistance and type 2 diabetes, highlighting clinical aspects and potential treatment approaches. Although various encouraging data are available, further in vivo and in vitro studies are required to elucidate the mechanism of action and their clinical application in humans.

Rapamycin Supplementation May Ameliorate Erectile Function in Rats With Streptozotocin-Induced Type 1 Diabetes by Inducing Autophagy and Inhibiting Apoptosis, Endothelial Dysfunction, and Corporal Fibrosis

INTRODUCTION

Erectile dysfunction (ED), which is common in patients with diabetes mellitus (DM), seriously affects quality of life. Previous studies on the treatment of DM-induced ED (DMED) involve autophagy, but the specific effect and mechanism of treatment are not yet clear.

AIM

To investigate the effect and mechanism of rapamycin, an autophagy inducer, in ameliorating DMED.

METHODS

45 male Sprague-Dawley rats (7 weeks old) were used in the experiment. 8 rats were randomly selected as the control group; the other rats were treated with streptozotocin to induce type 1 DM. After 10 weeks, an apomorphine test was used to confirm DMED. Rats with DMED were intraperitoneally injected with rapamycin or vehicle for 3 weeks. Rats in the control group were injected with saline. Erectile function in rats was measured by electrically stimulating the cavernous nerve. The penises were then harvested for histologic examinations, ribonucleic acid (RNA), and protein levels of related factors by immunohistochemistry, immunofluorescence, real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blot.

MAIN OUTCOME MEASURE

Erectile function was evaluated by maximum intracavernous pressure and mean arterial pressure. Penile tissues were used to perform histologic examinations and to determine the RNA and protein levels.

RESULTS

Erectile function, which was impaired in rats with DMED, was significantly ameliorated in the DMED + rapamycin group. The nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway was inhibited in the DMED group, and rapamycin significantly reduced this inhibition. The DMED group showed increased autophagy and apoptosis level compared with the non-diabetic group, and rapamycin increased the autophagy level and decreased the apoptosis level in the penis. Penile fibrosis was more severe in the DMED group than in the control group and was partially but significantly improved in the DMED + rapamycin group compared with the DMED group. The adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin kinase (mTOR) and PI3K/AKT/mTOR pathways were activated, and the mTOR (regulatory associated protein of mTOR, complex 1 [raptor])/p70 ribosomal protein S6 kinase (p70S6K) pathway was inhibited in the DMED group. Compared with DMED group, rapamycin led to lower AMPK/mTOR and AKT/mTOR pathways expression, a higher degree of mTOR (raptor)/p70S6K pathway inhibition, and no change in the mTORC2-related pathway.

CLINICAL IMPLICATIONS

Rapamycin was effective in restoring erectile function in type 1 DMED models.

STRENGTH AND LIMITATIONS

This study suggested for the first time that rapamycin, an autophagy inducer, is effective in restoring erectile function in rats with diabetes. However, the rat model might not represent the human condition.

CONCLUSION

Rapamycin improved erectile function in rats with DMED, likely by promoting autophagy, inhibiting apoptosis and fibrotic activity, and ameliorating endothelial function. These findings provide evidence of a potential treatment option for DMED. Lin H, Wang T, Ruan Y, et al. Rapamycin supplementation may ameliorate erectile function in rats with streptozotocin-induced type 1 diabetes by inducing autophagy and inhibiting apoptosis, endothelial dysfunction, and corporal fibrosis. J Sex Med 2018;15:1246-1259.

Intracavernosal Adeno-Associated Virus-Mediated S100A1 Gene Transfer Enhances Erectile Function in Diabetic Rats by Promoting Cavernous Angiogenesis via VEGF-A/VEGFR2 Signaling

INTRODUCTION

Novel therapeutic targets for diabetes-induced erectile dysfunction (DED) are urgently needed. Previous studies have proved that S100A1, a small Ca²⁺-binding protein, is a pluripotent regulator of cardiovascular pathophysiology. Its absence is associated with endothelial dysfunction, the central event linking cardiovascular changes in diabetes. However, the role of S100A1 in DED remains unknown.

AIM

To explore the effect and underlying mechanisms of S100A1 in restoring erectile function in type I diabetic rat model.

METHODS

Diabetes was induced by intraperitoneal injection of streptozotocin and then screened by apomorphine (APO) to confirm erectile dysfunction. Rats that met the criteria of penile erection were marked as APO-positive; otherwise, the result was APO-negative. In experiment 1, S100A1 gene expression alterations in the corpus cavernosum in moderate and established stages of DED were analyzed. In experiment 2, S100A1 and control GFP gene were delivered into the corpus cavernosum in APO-negative rats by adeno-associated virus (AAV) serotype 9. Erectile function was assessed at 4 weeks after gene therapy.

MAIN OUTCOME MEASURES

Erectile response, histologic and molecular alterations.

RESULTS

S100A1 protein was localized to the area surrounding the cavernosal sinusoids in the penis, and it was gradually downregulated synchronized with the progression of DED. Compared with an injection of AAV-GFP, a single injection of AAV-S100A1 significantly restored erectile function in diabetic rats. S100A1 overexpression significantly upregulated the expression of endogenous VEGF-A, promoted VEGFR2 internalization, and subsequently triggered the protein kinase B-endothelial nitric oxide synthase pathway in diabetic erectile tissues. Marked increases in nitric oxide and endothelial content were noted in AAV-S100A1-treated diabetic rats.

CLINICAL IMPLICATIONS

Local S100A1 overexpression may be an alternative therapy for DED and should be further investigated by future clinical studies.

STRENGTH & LIMITATIONS

This is the first study demonstrating the angiogenic role of S100A1 in DED, but does not preclude the contribution of the effects of S100A1 in other tissues such as the neuronal tissue on the functional effects observed in erectile responses.

CONCLUSION

The decreased expression of S100A1 during hyperglycemia might be important in the development of erectile dysfunction. S100A1 may play a potential role in restoring erectile function in rats with DED through modulating cavernous angiogenesis. Yu Z, Zhang Y, Tang Z, et al. Intracavernosal Adeno-Associated Virus-Mediated S100A1 Gene Transfer Enhances Erectile Function in Diabetic Rats by Promoting Cavernous Angiogenesis via VEGF-A/VEGFR2 Signaling. J Sex Med 2019;16:1344-1354.

Lipoxin A4 improves erectile dysfunction in rats with type I diabetes by inhibiting oxidative stress and corporal fibrosis

Previous studies have shown that oxidative stress and corporal fibrosis in penile tissues of rats were key pathological factors of erectile dysfunction induced by diabetic mellitus (DMED). Lipoxin A4 (LXA4) was reported to inhibit oxidative stress and fibrosis diseases, while whether it could exert a protective role on erectile function was not clear. Type I diabetic mellitus (DM) was induced in thirty male 10-week-old Sprague-Dawley rats using streptozotocin. Ten weeks later, twenty-two rats with DMED confirmed by an apomorphine test were divided into two groups: the DMED group (n = 11) and the DMED + LXA4 group (n = 11; LXA4 injection daily for 4 weeks). In addition, another ten age-matched rats formed the Control group. We found that erectile function was significantly impaired in the DMED group compared with the Control group, but was improved in the DMED + LXA4 group. Similarly, the over-activated oxidative stress and impaired endothelial function in the DMED group were both improved in the DMED + LXA4 group. Moreover, the DMED group showed serious corporal fibrosis, which was also inhibited by the treatment of LXA4 in the DMED + LXA4 group. Taken together, LXA4 could exert an inhibition role on oxidative stress and fibrosis to improve DMED effectively.

Phenolic-rich extracts of Eurycoma longifolia and Cylicodiscus gabunensis inhibit enzymes responsible for the development of erectile dysfunction and are antioxidants

BACKGROUND

Herbs have been used from ages to manage male sexual dysfunction. Hence, this study sought to investigate the effects of Eurycoma longifolia (EL) and Cylicodiscus gabunensis (CG) stem bark extracts on some enzymes implicated in erectile dysfunction in vitro.

METHODS

The extracts were prepared, and their effects on phosphodiesterase-5 (PDE-5), arginase, and angiotensin-1-converting enzyme (ACE) as well as pro-oxidant-induced lipid peroxidation were assessed. Furthermore, phenolic contents were determined, and their components were characterized and quantified using high-performance liquid chromatography with diode array detector (HPLC-DAD).

RESULTS

The results revealed that the extracts inhibited PDE-5, arginase, and ACE in a concentration-dependent manner. However, IC50 values revealed that CG had higher inhibitory potential on PDE-5 (IC50=204.4 μg/mL), arginase (IC50=39.01 μg/mL), and ACE (IC50=48.81 μg/mL) than EL. In addition, the extracts inhibited pro-oxidant-induced lipid peroxidation in penile tissue homogenate. HPLC-DAD analysis showed that CG is richer in phenolic compounds than EL, and this could be responsible for higher biological activities observed in CG than EL.

CONCLUSIONS

Hence, the observed antioxidant property and inhibitory action of CG and EL on enzymes relevant to erectile dysfunction in vitro could be part of possible mechanisms underlying their involvement in traditional medicine for the management of male sexual dysfunction.

Comparison of Improving Effects for Diabetic Erectile Dysfunction according to the Anti-Glycemic Agents: Phlorizin and Insulin

Purpose

To compare the improving effects of diabetic erectile dysfunction with two anti-glycemic agents; phlorizin and insulin.

Materials and Methods

Sixty Sprague-Dawley rats were divided into four groups (n=15 in each group): normal control (C), untreated diabetic rats (D), and diabetic rats treated by phlorizin (P) or insulin (I). Ten weeks after the diabetic induction using an injection of streptozotocin (55 mg/kg), four weeks of diabetic control was conducted. Erectile response, Western blot, and immunohistochemistry were assessed.

Results

During the experiment, the C-group showed continuous weight gain, while the other groups suffered from weight loss. After start of diabetic control, the body weight of I-group was increased; whereas, there was no meaningful change in the P-group. Meanwhile, comparable blood glucose levels were achieved in the P- and I-groups. The erectile response was markedly decreased in the D-group, whereas the P- and I-groups were similar as good as the C-group. In addition, D-group showed the significant decrease in the cavernosal smooth muscle content and increased apoptosis. Platelet endothelial cell adhesion molecule-1 protein expression, phosphorylation of endothelial nitric oxide synthase and myosin phosphatase target subunit 1 were significantly distorted in the D-group, while the P- and I-groups were comparable with the C-group.

Conclusions

Phlorizin treatment resulted in the improvement of erectile function as same as insulin despite the lack of anabolic weight gains. These results suggest that control of blood glucose level rather than a type of anti-glycemic agents is more important for the prevention and treatment of diabetic erectile dysfunction

Decreased expression of pigment epithelium-derived factor within the penile tissues contributes to erectile dysfunction in diabetic rats

Increased production of reactive oxygen species (ROS) and inflammation are major contributors to the development and progression of diabetes-associated erectile dysfunction (DMED). As an endogenous antioxidant and anti-inflammatory factor, the potential implication of pigment epithelium-derived factor (PEDF) in DMED has not been revealed. To assess the potential antioxidant and anti-inflammatory functions of PEDF in DMED, we first demonstrated that PEDF was significantly decreased at the levels of the mRNA and protein in the penis of diabetic rats compared with normal controls. To test the hypothesis that decreased the penile levels of PEDF are associated with oxidative stress and inflammation in DMED, an adenovirus expressing PEDF (Ad-PEDF) or the same titer of control virus (Ad-GFP) was intracavernously administered at 2 weeks after diabetic onset. After 6 weeks of treatment, we found that administration of Ad-PEDF could significantly increase erectile response to cavernosal nerve stimulation in the diabetic rats by restoring the endothelial NO synthase (eNOS), P-eNOS, and neuronal NO synthase (nNOS) protein levels to the standard levels represented in normal rats and by suppressing the levels of tumor necrosis factor-α (TNF-α) and oxidative stress. In conclusion, the present data indicated that the antioxidant and anti-inflammatory potential of PEDF plays important role in restoring erectile function by the inhibition of oxidative stress and TNF-α production.

Low dose daily versus on-demand high dose tadalafil in diabetic patients with erectile and ejaculatory dysfunction

The aim was to compare the differences between daily 5 mg and on-demand 20 mg tadalafil use in diabetic patients with erectile dysfunction (ED), and the effects of two different tadalafil protocols on ejaculatory and lower urinary tract symptoms (LUTS). Of the 63 diabetic patients with ED, 31 were given 5 mg tadalafil once a day, and 32 were given 20 mg tadalafil on-demand four times a month over three months. Erectile function, erectile hardness, ejaculatory function, and LUTS were assessed at pretreatment, first- and third-month controls. Both tadalafil protocols increased International Index of Erectile Function (IIEF) scores in all patients under 65 years, whereas patients older than 65 years did not benefit. Ejaculatory function, the quality of the hardness of an erection, and LUTS improved in both groups in the study. Tadalafil improved sexual function with acceptable side effects in diabetic men with ED. Both protocols equally improved LUTS and the quality of the erection. Daily use of 5 mg of tadalafil significantly improved the quality of ejaculation and LUTS more than the on-demand use of 20 mg of tadalafil. It may be beneficial to give 5 mg tadalafil daily to patients over 65 years old who do not benefit from treatment with 20 mg of tadalafil or in patients who have LUTS over 65 years old.

Is Hba1c level of diabetic patients associated with penile prosthesis implantation infections?

BACKGROUND AND OBJECTIVES

Diabetes mellitus is an important risk factor for erectile dysfunction (ED). Penile prosthesis implantation surgery is the final solution for diabetic patients with ED, but infections thereof are still a serious risk factor. While some studies suggest that most infections associated with penile prosthesis implantation are associated to high glycated hemoglobin (HbA1c) levels, other research did support such relationship.

MATERIALS AND METHODS

The current study assessed retrospectively, the association between HbA1c level and penile prosthesis surgery infection. We retrieved and reviewed the records of 300 diabetic patients who had penile prosthesis surgery at our Institution (January 2012-November 2016). Patients' mean age was 55.26 ± 10.9 years (31% patients were <50 years of age), and mean HbA1c was 7.60 ± 1.90%.

RESULTS

Infection rate among diabetics was 0.67%. Prevalence of prosthesis infection among patients with HbA1c ≤ 9% was 0.9%, compared with 0% among patients with HbA1c > 9%. Prosthesis infection risk did not significantly increase with higher HbA1c levels, with no meaningful difference in the median or mean level of HbA1c in the infected and non-infected diabetic patients.

CONCLUSION

Findings do not support the use of HbA1c values among diabetic patients who are candidates for penile prosthesis implantation surgery in order to identify and exclude those who might be prone to increased risk of prosthesis infections. Future studies would benefit from larger sample sizes in order to support or refute our findings.

The phosphodiesterase 5 inhibitor tadalafil regulates lipidic homeostasis in human skeletal muscle cell metabolism

PURPOSE

Tadalafil seems to ameliorate insulin resistance and glucose homeostasis in humans. We have previously reported that tadalafil targets human skeletal muscle cells with an insulin (I)-like effect. We aim to evaluate in human fetal skeletal muscle cells after tadalafil or I: (i) expression profile of I-regulated genes dedicated to cellular energy control, glycolitic activity or microtubule formation/vesicle transport, as GLUT4, PPARγ, HK2, IRS-1, KIF1C, and KIFAP3; (ii) GLUT4, Flotillin-1, and Caveolin-1 localization, all proteins involved in energy-dependent cell trafficking; (iii) activation of I-targeted paths, as IRS-1, PKB/AKT, mTOR, P70/S6K. Free fatty acids intracellular level was measured. Sildenafil or a cGMP synthetic analog were used for comparison; PDE5 and PDE11 gene expression was evaluated in human fetal skeletal muscle cells.

METHODS

RTq-PCR, PCR, western blot, free fatty acid assay commercial kit, and lipid stain non-fluorescent assay were used.

RESULTS

Tadalafil upregulated I-targeted investigated genes with the same temporal pattern as I (GLUT4, PPARγ, and IRS-1 at 3 h; HK2, KIF1C, KIFAP3 at 12 h), re-localized GLUT4 in cell sites positively immune-decorated for Caveolin-1 and Flotillin-1, suggesting the involvement of lipid rafts, induced specific residue phosphorylation of IRS-1/AKT/mTOR complex in association with free fatty acid de novo synthesis. Sildenafil or GMP analog did not affect GLUT4 trafficking or free fatty acid levels.

CONCLUSION

In human fetal skeletal muscle cells tadalafil likely favors energy storage by modulating lipid homeostasis via IRS-1-mediated mechanisms, involving activation of I-targeted genes and intracellular cascade related to metabolic control. Those data provide some biomolecular evidences explaining, in part, tadalafil-induced favorable control of human metabolism shown by clinical studies.

Treatment of diabetes mellitus-induced erectile dysfunction using endothelial progenitor cells genetically modified with human telomerase reverse transcriptase

The efficacy of treatments for diabetes mellitus-induced erectile dysfunction (DMED) is quite poor, and stem cell therapy is emerging as a useful method. In this study, we used endothelial progenitor cells (EPCs) overexpressing human telomerase reverse transcriptase (hTERT) for the treatment of DMED. Rat EPCs were transfected with hTERT (EPCs-hTERT). EPCs-hTERT secreted more growth factors and demonstrated enhanced proliferation and resistance to oxidative stress. Twenty-four male DMED rats were subjected to four treatments: DMED (DMED group), EPCs (EPCs group), EPCs transduced with control lentivirus (EPC-control group) and EPCs-hTERT (EPCs-hTERT group). A group of healthy rats were used as the normal control group. The erectile function in the EPCs-hTERT group was markedly increased compared with the EPCs and EPCs-control groups. The EPCs-hTERT group exhibited more growth factors, smooth muscle content and retained stem cells in penile tissues. The degree of apoptosis and collagen/smooth muscle ratio in penile tissues of the EPCs-hTERT group was considerably reduced. Endothelial nitric oxide synthase (eNOS) expression increased significantly in the EPCs-hTERT group. Taken together, these data showed that the enhanced paracrine effect, resistance to oxidative stress and proliferation of EPCs-hTERT may contribute to the improvements of erectile function in DMED rats.

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

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

Skin autofluorescence (a marker for advanced glycation end products) and erectile dysfunction in diabetes

AIM

Although diabetes-related erectile dysfunction (ED) has many etiological factors, little is known about the putative pathophysiological role of advanced glycation end products (AGEs). Skin autofluorescence is a noninvasive marker of AGEs. Recent studies have evidenced a relationship between skin autofluorescence and several complications of diabetes. We hypothesized that AGEs (assessed by skin autofluorescence) are associated with ED in diabetes patients.

METHODS

Between March 2014 and April 2015, 42 patients with type 1 diabetes (T1D) and 44 patients with type 2 diabetes (T2D) were consecutively enrolled in a descriptive, cross-sectional study and compared to 54 healthy controls. ED was evaluated via the 5-item version of the International Index of Erectile Function (IIEF-5). Skin autofluorescence was measured on the volar aspect of the arm with an AGE-Reader.

RESULTS

Patients with diabetes had a mean±standard deviation age of 50±15 and a mean duration of diabetes of 16±12years. Skin autofluorescence was strongly and significantly correlated with the IIEF-5 score in the T1D subgroup (r=-0.52; P=0.004), the T2D subgroup (r=-0.32; P<0.03) and in the whole group of diabetic patients (r=-0.49; P<0.0001). In multivariate analyses that controlled for potentially confounding clinical and biochemical factors, only skin autofluorescence was still significantly correlated with the IIEF-5 score (P<0.0001). A receiver operating characteristic analysis revealed that a skin autofluorescence value ≥3.2AU determined severe ED with a sensitivity of 60% and a specificity of 87% in diabetic patients.

CONCLUSION

Skin autofluorescence is significantly associated with ED in diabetes, independently of classical confounding factors.

Effects of prolonged ingestion of epigallocatechin gallate on diabetes type 1-induced vascular modifications in the erectile tissue of rats

Diabetes Mellitus type 1 is a metabolic disease that predisposes to erectile dysfunction, partly owing to structural and molecular changes in the corpus cavernosum (CC) vessels. The aim of this study was to determine the effects of early treatment with the antioxidant epigallocatechin gallate (EGCG) in cavernous diabetes-induced vascular modifications. Diabetes was induced in two groups of young Wistar rats; one group was treated with EGCG for 10 weeks. A reduction in smooth muscle content was observed in the CC of diabetic rats, which was significantly attenuated with EGCG consumption. No differences were observed among groups, neither in the expression of VEGF assayed by western blotting nor in the immunofluorescent labeling of vascular endothelial growth factor (VEGF) and its receptors (VEGFR1 and VEGFR2). VEGFR2 was restricted to the endothelium, whereas VEGF and VEGFR1 co-localized in the smooth muscle layer. With regard to the Angiopoietin/Tie-2 system, no quantitative differences in Angiopoietin 1 were observed among the experimental groups. Ang1 localization was restricted to the smooth muscle layer, and receptor Tie2 and Angiopoietin 2 were both expressed in the endothelium. In brief, our results suggest that EGCG consumption prevented diabetes-induced loss of cavernous smooth muscle but does not affect vascular growth factor expression in young rats.

PDE5 expression in human thyroid tumors and effects of PDE5 inhibitors on growth and migration of cancer cells

Recent studies have revealed in normal thyroid tissue the presence of the transcript of several phosphodiesterases (PDEs), enzymes responsible for the hydrolysis of cyclic nucleotides. In this work, we analyzed the expression of PDE5 in a series of human papillary thyroid carcinomas (PTCs) presenting or not BRAF V600E mutation and classified according to ATA risk criteria. Furthermore, we tested the effects of two PDE5 inhibitors (sildenafil, tadalafil) against human thyroid cancer cells. PDE5 gene and protein expression were analyzed in two different cohorts of PTCs by real-time PCR using a TaqMan micro-fluid card system and Western blot. MTT and migration assay were used to evaluate the effects of PDE5 inhibitors on proliferation and migration of TPC-1, BCPAP, and 8505C cells. In a first series of 36 PTCs, we found higher expression levels of PDE5A in tumors versus non-tumor (normal) tissues. PTCs with BRAF mutation showed higher levels of mRNA compared with those without mutation. No significant differences were detected between subgroups with low and intermediate ATA risk. Upregulation of PDE5 was also detected in tumor tissue proteins. Similar results were obtained analyzing the second cohort of 50 PTCs. Moreover, all tumor tissues with high PDE5 levels showed reduction of Thyroglobulin, TSH receptor, Thyroperoxidase, and NIS transcripts. In thyroid cancer cells in vitro, sildenafil and tadalafil determined a reduction of proliferation and cellular migration. Our findings demonstrate for the first time an overexpression of PDE5 in PTCs, and the ability of PDE5 inhibitors to block the proliferation of thyroid cancer cells in culture, therefore, suggesting that specific inhibition of PDE5 may be proposed for the treatment of these tumors.

Hepatocyte growth factor-modified adipose tissue-derived stem cells improve erectile function in streptozotocin-induced diabetic rats

TGFβ1-Smad signaling pathway is closely related to various tissues fibrosis. Hepatocyte growth factor (HGF) has been shown to antagonize TGFβ1-Smad signaling and may improve kidney tissue fibrosis in diabetic models. Penile fibrosis is a pathological condition which occurs during diabetic erectile dysfunction (ED). The aim of this study was to examine the effect of the treatment of ED in diabetic rats with a combination of HGF and adipose tissue-derived stem cells (ADSC). In this diabetes model, rats were injected intraperitoneally with 60 mg streptozotocin (STZ) to induce diabetes. Three months later, the diabetic rats were divided into a negative control(NC) group, an ADSC-treated group and an ADSC + HGF-treated group while normal rats were assigned into a sham group. Rats in the sham and NC groups were injected in the corpus cavernosum with phosphate-buffered saline, while rats in the other groups were injected with either ADSC or ADSC + HGF. One month later, erectile function was examined in each group and penile tissues were collected for experiments. The expression of smooth muscle actin (SMA) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) was analyzed by Western blotting. The smooth muscle and collagen deposition in corpus cavernosum was evaluated by Masson staining, while endothelial changes were assessed immunohistochemically. Cell apoptosis was detected by the TdT-mediated dUTP nick-end labeling (TUNEL) assay. The results revealed that ADSC alone can significantly improve erectile function in diabetic rats, but in combination with HGF the improvement was more prominent, showing higher content of smooth muscle and endothelial cells and lower cell apoptotic index in corpus cavernosum. Treatment with HGF can significantly enhance the beneficial effect of ADSC on erectile function in diabetic rats, and this effect might be closely related to the down-regulation of TGFβ1-Smad signaling.

Cyclic nucleotide phosphodiesterases: important signaling modulators and therapeutic targets

By catalyzing hydrolysis of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), cyclic nucleotide phosphodiesterases are critical regulators of their intracellular concentrations and their biological effects. As these intracellular second messengers control many cellular homeostatic processes, dysregulation of their signals and signaling pathways initiate or modulate pathophysiological pathways related to various disease states, including erectile dysfunction, pulmonary hypertension, acute refractory cardiac failure, intermittent claudication, chronic obstructive pulmonary disease, and psoriasis. Alterations in expression of PDEs and PDE-gene mutations (especially mutations in PDE6, PDE8B, PDE11A, and PDE4) have been implicated in various diseases and cancer pathologies. PDEs also play important role in formation and function of multimolecular signaling/regulatory complexes, called signalosomes. At specific intracellular locations, individual PDEs, together with pathway-specific signaling molecules, regulators, and effectors, are incorporated into specific signalosomes, where they facilitate and regulate compartmentalization of cyclic nucleotide signaling pathways and specific cellular functions. Currently, only a limited number of PDE inhibitors (PDE3, PDE4, PDE5 inhibitors) are used in clinical practice. Future paths to novel drug discovery include the crystal structure-based design approach, which has resulted in generation of more effective family-selective inhibitors, as well as burgeoning development of strategies to alter compartmentalized cyclic nucleotide signaling pathways by selectively targeting individual PDEs and their signalosome partners.

Advances in targeting cyclic nucleotide phosphodiesterases

Cyclic nucleotide phosphodiesterases (PDEs) catalyse the hydrolysis of cyclic AMP and cyclic GMP, thereby regulating the intracellular concentrations of these cyclic nucleotides, their signalling pathways and, consequently, myriad biological responses in health and disease. Currently, a small number of PDE inhibitors are used clinically for treating the pathophysiological dysregulation of cyclic nucleotide signalling in several disorders, including erectile dysfunction, pulmonary hypertension, acute refractory cardiac failure, intermittent claudication and chronic obstructive pulmonary disease. However, pharmaceutical interest in PDEs has been reignited by the increasing understanding of the roles of individual PDEs in regulating the subcellular compartmentalization of specific cyclic nucleotide signalling pathways, by the structure-based design of novel specific inhibitors and by the development of more sophisticated strategies to target individual PDE variants.

Diabetes and sexual dysfunction: current perspectives

Diabetes mellitus is one of the most common chronic diseases in nearly all countries. It has been associated with sexual dysfunction, both in males and in females. Diabetes is an established risk factor for sexual dysfunction in men, as a threefold increased risk of erectile dysfunction was documented in diabetic men, as compared with nondiabetic men. Among women, evidence regarding the association between diabetes and sexual dysfunction are less conclusive, although most studies have reported a higher prevalence of female sexual dysfunction in diabetic women as compared with nondiabetic women. Female sexual function appears to be more related to social and psychological components than to the physiological consequence of diabetes. Hyperglycemia, which is a main determinant of vascular and microvascular diabetic complications, may participate in the pathogenetic mechanisms of sexual dysfunction in diabetes. Moreover, diabetic people may present several clinical conditions, including hypertension, overweight and obesity, metabolic syndrome, cigarette smoking, and atherogenic dyslipidemia, which are themselves risk factors for sexual dysfunction, both in men and in women. The adoption of healthy lifestyles may reduce insulin resistance, endothelial dysfunction, and oxidative stress - all of which are desirable achievements in diabetic patients. Improved well-being may further contribute to reduce and prevent sexual dysfunction in both sexes.