Arteriogenic Erectile Dysfunction Alters Protein Expression within the Cavernosal Tissue in an Animal Model

Molecular and Histologic Evidence of Novel Erectile Dysfunction Rat Model as an Aging Atherosclerosis Model: A Preliminary Study

Purpose

To validate a novel arteriogenic erectile dysfunction (ED) model with atherosclerosis (AS) based on molecular and histologic evidence induced by chronic pelvic ischemia (CPI) and determine effect of phosphodiesterase-5 inhibitor treatment.

Materials and Methods

Twenty 16-week-old male Sprague–Dawley rats were divided into three experimental groups (Group I, untreated sham-operated rats with regular diet; Group II, CPI with cholesterol diet; Group III, CPI model with cholesterol diet and mirodenafil). Erectile function was accessed using maximum intracavernous pressure (ICP) and ICP/mean arterial pressure (MAP). Molecular changes were examined by western blot analysis using hypoxia inducible factor 1-alpha (HIF-1α), endothelial nitric oxide synthase (eNOS), and transforming growth factor beta-1 (TGF-β1) antibodies. Collagen change was evaluated by Masson's trichrome staining.

Results

In vivo measurements of ICP and ICP/MAP in Group II were significantly lower than those in Group I (p<0.01). Smooth muscle/collagen ratio in Group II was significantly lower than that in Group I (p<0.05). After treatment with mirodenafil for four weeks, Group III showed significantly higher levels of ICP and ICP/MAP than Group II (p<0.05). Western blot analysis showed that HIF-1α and TGF-β1 levels were significantly higher in Group II whereas eNOS levels were significantly lower in Group II than those in Group I or III.

Conclusions

A novel arteriogenic ED with AS model is successfully induced by CPI and validated based on molecular and histologic evidences.

Intracavernous administration of bone marrow mononuclear cells: a new method of treating erectile dysfunction?

While PDE5 inhibitors have revolutionized treatment of ED, approximately 30% of patients are non-responsive. A significant cause of this is vascular and smooth muscle dysfunction, as well as nerve atrophy. Autologous administration of bone marrow mononuclear cells (BMMC) has been performed in over 2000 cardiac patients without adverse effects, for stimulation of angiogenesis/regeneration. Despite its ease of access, and dependence on effective vasculature for function, comparatively little has been perform in terms of BMMC therapy for ED. Here we outline the rationale for use of autologous BMMC in patients with ED, as well as provide early safety data on the first use of this procedure clinically.

Animal models of erectile dysfunction (ED): potential utility of non-human primates as a model of atherosclerosis-induced vascular ED

Erectile dysfunction (ED) is a prevalent medical condition affecting 18 million men and their sexual partners in the United States alone. In the majority of patients, ED is related to alterations in the flow of blood to or from the penis. Undeniably, significant progress has been made in understanding the multifactorial mechanisms that modulate erectile capacity and predispose one to ED, and this, in turn, has led to the availability of more effective treatment options. Nonetheless, all current therapies have untoward side effects, and moreover, there are still no satisfactory treatments for many patients with ED. Further enhancements in the treatment of ED would logically result from both early intervention and more detailed mechanistic insight into the characteristics of the disease process per se. This fact underscores the importance of improved understanding of the initiation, development and progression of ED. However, to do so requires longitudinal studies on animal models that more closely approximate the corresponding clinical features and time course of human disease. The goal of this report is twofold. First, to provide a brief general overview of the applicability of commonly used animal models for the study of ED. The second and primary goal is to highlight the scientific rationale for using non-human primates to evaluate the impact of atherosclerosis-induced vascular disease on the penile and systemic circulatory systems. This latter goal seems especially relevant in light of the recent literature documenting a link between ED and systemic vascular disease, a finding that has major implications in an aging US male population consuming a high fat diet.

Transplantation of endothelial progenitor cells transfected with VEGF165 to restore erectile function in diabetic rats

The present study investigated the effect of transplanting endothelial progenitor cells (EPCs) transfected with the vascular endothelial growth factor gene (VEGF165) into the corpora cavernosa of rats with diabetic erectile dysfunction (ED). A rat model of diabetic ED was constructed via intraperitoneal injection of streptozotocin. After streptozotocin treatment, pre-treated EPCs from each of three groups of rats were transplanted into their corpora cavernosa. Our results, following intracavernosal pressure (ICP) monitoring, showed that ICP increased significantly among rats in the trial group when compared to the results from rats in the blank-plasmid and control groups during basal conditions and electrical stimulation (P<0.01 for both comparisons). Histological examination revealed extensive neovascularisation in the corpora cavernosa of rats in the trial group. Fluorescence microscopy indicated that many of the transplanted EPCs in the trial group survived, differentiated into endothelial cells and integrated into the sites of neovascularisation. Based on the results of this study, we conclude that transplantation of VEGF165-transfected EPCs into the corpora cavernosa of rats with diabetic ED restores erectile function.

Chronic inhibition of nitric-oxide synthase induces hypertension and erectile dysfunction in the rat that is not reversed by sildenafil

STUDY TYPE

Aetiology (case control) Level of Evidence 3b OBJECTIVE To evaluate the effect of N(G)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension (HT) on erectile function in the rat and determine if the phosphodiesterase (PDE)-5 inhibitor, sildenafil, can reverse the effects of nitric oxide (NO) deficiency, as HT is a risk factor for erectile dysfunction (ED) and the NO synthase (NOS) inhibitor L-NAME induces NO-deficient HT.

MATERIALS AND METHODS

Thirty-six adult Sprague-Dawley male rats were divided into three groups, i.e. a control, L-NAME-HT (40 mg/rat/day in the drinking water for 4 weeks), and sildenafil-treated L-NAME-HT (1.5 mg/rat/day sildenafil, by oral gavage concomitantly with L-NAME). The erectile response expressed as a ratio of intracavernosal pressure (ICP)/mean arterial pressure (MAP), evaluated after electrical stimulation of the right cavernous nerve. The isometric tension of corpus cavernosum smooth muscle (CCSM) was measured in organ-bath experiments. NOS expression was determined immunohistochemically for neuronal (n)NOS and by Western blot analysis for endothelial (e) and inducible (i) NOS protein. cGMP levels were evaluated by enzyme-linked immunosorbent assay.

RESULTS

The erectile response was diminished in the HT group. Nitrergic and endothelium-dependent relaxation was reduced, while the relaxation response to sodium nitroprusside and contractile response to phenylephrine were not altered in CCSM from L-NAME-treated rats. HT rats showed decreased expression of nNOS, whereas eNOS and iNOS protein expression was increased. Sildenafil partly restored endothelial and molecular changes in CCSM from HT rats, but did not reverse the decreased erectile response, even as cGMP levels returned to normal levels.

CONCLUSIONS

Sildenafil treatment did not correct the ED in L-NAME-treated HT rats. Under sustained high blood pressure, up-regulation of PDE5 expression failed to reverse the depletion of neuronal NO and/or impaired nNOS activity. However, endothelium-dependent relaxation was restored. Drug targeting of neuronal dysfunction might delay the onset of ED in HT.

High cholesterol feeding in C57/Blc6 mice alters expression within the VEGF receptor-ligand family in corporal tissue

INTRODUCTION

Angiogenesis, the growth and proliferation of blood vessels from existing vascular structures, is mediated by many cytokine growth factors and receptors, among the most important are the vascular endothelial growth factor (VEGF) family.

AIM

Decreases in VEGF receptor signaling have been linked to abnormalities in vasoreactivity in corporal tissue, but it is unknown if alterations in the VEGF ligands and/or receptors contribute to this process.

MAIN OUTCOME MEASURES

We sought to determine changes in vasoreactivity and the expression of the family of VEGF ligands and receptors in corporal tissue with cholesterol feeding in C57BL6 mice. Methods. Twenty-four mice (N = 8/group) were fed a normal diet (Group 1) or a 1.25% high cholesterol diet for 4 (Group 2) or 12 (Group 3) weeks. Isometric tension studies were performed on corporal strips and dose response curves were generated to evaluate endothelium-dependent and endothelium-independent vasoreactivities. Levels of VEGF-A, B, C, D, VEGF receptors (VEGFRs) were detected by PCR (polymerase chain reaction) and/or western blot/enzyme-linked immunosorbent assay (ELISA). Endothelial and smooth muscle cell contents were determined by immunohistochemistry.

RESULTS

At 4 weeks there was a small but significant decrease in endothelium-dependent vasoreactivity. Both mRNA and protein levels of VEGFR-1 were decreased, while VEGF-B was increased in Group 2 vs. Group 1, with no change in VEGF-A or endothelial cell content. By 12 weeks, decreases in both endothelium-dependent and endothelium-independent vasoreactivity were evident with decrease in most VEGF ligands (except VEGF-B), receptors, and receptor signaling.

CONCLUSIONS

Cholesterol feeding in C57BL6 mice results in alterations in the VEGF receptor-ligand family that may initially serve to limit the degree of vascular injury but these adaptations fail with the continuation of cholesterol feeding.

ORIGINAL RESEARCH—ERECTILE DYSFUNCTION: Association of Risk Factors and Medical Comorbidities with Male Sexual Dysfunctions

INTRODUCTION

Conventionally, little attention has been given to the association of risk factors and medical comorbidities with male sexual dysfunctions. Although that association has been recently shown in many studies, it is not yet well investigated in the Saudi community.

AIM

To investigate the association of risk factors and medical comorbidities with male sexual dysfunctions in the Saudi community.

METHODS

A total of 1,464 male patients with a clinical diagnosis of sexual dysfunctions were enrolled in this study. All patients were assessed for sexual functions using different domains of the International Index for Erectile Function. Patients were also interviewed for sociodemographic data, medical history, and risk factors for erectile dysfunction (ED). Routine laboratory investigations, plus total testosterone and prolactin assessments, were offered to all patients. Assessments of penile vasculature using Doppler ultrasonography and rigidometer were performed.

RESULTS

A total of 92.6% of the patients had ED, 50.8% had premature ejaculation (PE), and 7.6% had low sexual desire. There was a significant association between increased age and increased severity of ED. In total, 20% had psychogenic cause, whereas 80% had organic cause of ED. Of the patients, 10.2% had mild, 41% had moderate, and 48.8% had severe ED. There were significant associations between endocrinopathy and both low sexual desire and PE (P < 0.05). There were significant associations between increased severity of ED and presence of diabetes, hypertension, dyslipidemia, ischemic heart disease, myocardial infarction, and psychological disorders. There were significant associations between increased severity of ED and increased values of end diastolic velocity, decreased values of peak systolic velocity, resistive index, rigidometer, and decreased response to intracavernosal injection (P < 0.001).

CONCLUSION

This study provides an assessment of the association of risk factors and medical comorbidities with male sexual dysfunctions in ambulatory service in this community.

Is There a Role for Proteomics in Peyronie's Disease?

INTRODUCTION

Peyronie's disease (PD) continues to be a major source of sexual dysfunction among the 3-9% of affected men. The challenge in treating PD is determining the natural history and clinical course for the individual patient. Currently, there exists no reliable means to predict whether a penile plaque of PD will progress, regress, or remain stable. This represents a significant deficiency in contemporary management, one that may be addressed with newer technologies such as proteomic profiling.

AIM

This review assesses the potential use of protein alterations measured by various novel technologies, to predict progression, regression, or stabilization of PD in an affected individual.

METHODS

A comprehensive literature review of the past decade in the field of gene profiling and protein expression of PD was performed.

MAIN OUTCOME MEASURES

A critical analysis of the existing worldwide literature evaluating surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS or SELDI) and other proteonomic techniques.

RESULTS

SELDI and other technologies can provide the clinician with innovative data indicating the presence of unique individual factors that act to suppress or promote the fibrotic process in PD. Determining the clinical implications of altered protein expression in an individual is not yet defined.

CONCLUSIONS

The area of proteomics has begun to revolutionize the study of medicine in the postgenomic era, by allowing researchers to study the role that proteins play in health and disease. Applying this knowledge clinically has already led to innovative discoveries in early cancer detection in a number of malignancies, including prostate, ovarian, and bladder. Prior to the widespread use and acceptance of proteomic technology in PD, a critical assessment of its therapeutic and diagnostic value will be required.

The use of proteomics in identifying differentially expressed serum proteins in humans with type 2 diabetes

Background

The aim of the study was to optimize protocols for finding and identifying serum proteins that are differentially expressed in persons with normal glucose tolerance (NGT) compared to individuals with type 2 diabetes mellitus (T2DM).

Serum from persons with NGT and persons with T2DM was profiled using ProteinChip arrays and time-of-flight mass spectra were generated by surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS).

Results

Mass spectra from NGT- and T2DM-groups were compared. Fifteen proteins ranging from 5 to 79 kDa were differentially expressed (p < 0.05). Five of these proteins showed decreased and ten showed increased serum levels in individuals with T2DM. To be able to identify the proteins, the complexity of the sample was reduced by fractionation approaches. Subsequently, the purified fractions containing biomarkers were separated by one-dimensional SDS-polyacrylamide gel electrophoresis (SDS-PAGE) in two identical lanes. Protein bands of the first lane were excised and subjected to passive elution to recapture the biomarkers on ProteinChip arrays. The corresponding bands of the second lane were subjected to peptide-mass fingerprinting (PMF). Using this approach four of the differentially expressed proteins were identified as apolipoprotein C3 (9.4 kDa), transthyretin (13.9 kDa), albumin (66 kDa) and transferrin (79 kDa). Whereas apolipoprotein C3 and transthyretin were up-regulated, albumin and transferrin were down-regulated in T2DM.

Conclusion

Protocols for protein profiling by SELDI-TOF MS and protein identification by fractionation, SDS-PAGE and PMF were optimized for serum from humans with T2DM. With these protocols differentially expressed proteins were discovered and identified when serum from NGT- and T2DM-individuals was analyzed.

Chronic Administration of an Oral Rho Kinase Inhibitor Prevents the Development of Vasculogenic Erectile Dysfunction in a Rat Model

INTRODUCTION

It has been shown that the Rho/Rho kinase calcium sensitizing pathway has been implicated in the pathogenesis of erectile dysfunction as well as systemic atherosclerosis.

AIMS

To test whether chronic treatment of an oral Rho kinase inhibitor (fasudil, 5-Isoquinolinesulfonyl homopiperazine) could prevent the development of both vasculogenic erectile dysfunction and pelvic atherosclerosis in a rat model.

METHODS

Rats (3 months old) were divided into three groups (N = 10 in each group): control (group 1); atherosclerosis (group 2); and fasudil-treated (group 3). Groups 2 and 3 received atherosclerosis-prone treatment (6 weeks of 1% cholesterol diet and early 2 weeks of N(G)-nitro-L-arginine methyl ester [3 mg/mL/day] treatment, but group 3 was concurrently treated with fasudil (30 mg/kg/day) for 6 weeks.

MAIN OUTCOME MEASURES

The amount of systemic endothelial injury (plasma von Willebrand factor) and pelvic atherosclerosis was determined. Erectile function, cavernosal Rho kinase activity, and expressions of total and phosphorylated endothelial nitric oxide synthase (eNOS) were also determined.

RESULTS

Group 2 showed a significant amount of pelvic atherosclerosis and endothelial injury. The rats also showed elevated cavernosal Rho kinase activity and impaired erectile function. Immunoblot showed a decreased total as well as phosphorylated eNOS expression. The treatment with fasudil partly but significantly ameliorated the development of pelvic atherosclerosis and plasma level of von Willebrand factor. The treatment also normalized the erectile function, cavernosal Rho kinase activity, and total eNOS expression. The overexpression of phospho-eNOS was observed in group 3.

CONCLUSIONS

These results indicate that the Rho/Rho kinase pathway is substantially involved in the development of erectile dysfunction and pelvic atherosclerosis, both of which could be prevented by chronic treatment with fasudil. Thus, Rho kinase might be considered a novel target for the prevention of vasculogenic erectile dysfunction.