REDUCTION OF ENDOTHELIAL AND SMOOTH MUSCLE DENSITY IN THE CORPORA CAVERNOSA OF THE STREPTOZOTOCIN INDUCED DIABETIC RAT

A possible mechanism of erectile dysfunction in coronavirus disease-19: Cavernosal smooth muscle damage: A pilot study

INTRODUCTION

Studies have reported that coronavirus disease 2019 (COVID-19) may cause erectile dysfunction (ED), however, its role in the pathophysiology of ED has not yet been fully elucidated. We aimed to elucidate COVID-19's effects on cavernosal smooth muscle, which has a pretty important role in erection physiology, by corpus cavernosum electromyography (cc-EMG).

MATERIALS AND METHODS

Twenty-nine male patients aged 20-50 years who applied to the urology outpatient clinic due to ED were included in the study. Nine patients that had COVID-19 and were treated as outpatients were classified as group 1, 10 patients who were hospitalized due to COVID-19 were classified as group 2, and 10 patients who did not have COVID-19 were classified as the control group (group 3). Patients underwent diagnostic evaluation including International Index of Erectile Function (IIEF)-5 form, penile color Doppler ultrasonography (CDUS), cc-EMG, and fasting serum levels of reproductive hormones (07-11am).

RESULTS

According to penile CDUS and hormonal values results, there was no significant difference between the groups. According to cc-EMG results, amplitudes and relaxation capacities of the cavernosal smooth muscle of patients in group 3 were significantly higher than those in the other groups.

CONCLUSIONS

COVID-19 can cause ED not only by psychogenic and hormonal factors but also with cavernosal smooth muscle damage.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04980508.

Altered Regional Homogeneity in Patients With Diabetic Erectile Dysfunction: A Resting-State fMRI Study

INTRODUCTION

Erectile dysfunction (ED) is a common complication of Type-2 Diabetes Mellitus (T2DM) for male patients and it is considered to be associated with different causes including hyperglicemia-induced vascular endothelial cell damages. However, the possible central neural mechanisms shared by these two diseases remain unclear. This study aimed to explore the changes of brain activity and their relationships with the clinical characteristics in patients with diabetic ED.

METHODS

The data of resting-state functional magnetic resonance imaging were acquired in 31 T2DM patients with ED (DM-ED) and 31 matched healthy controls (HCs). The whole-brain regional homogeneity (ReHo) values were calculated and compared between groups. In addition, Pearson correlation analysis was performed to evaluate the relationships between brain regions with altered ReHo values and clinical characteristics in the patient group.

RESULTS

The DM-ED group exhibited increased ReHo values in the right middle frontal gyrus (orbital part) and decreased ReHo values in the left superior frontal gyrus (dorsolateral), paracentral lobule, precuneus and bilateral supplementary motor area when compared with the HCs group. Moreover, significantly negative correlations were found between ReHo values of the left superior frontal gyrus (dorsolateral) and IIEF-5 scores, as well as the level of HbA1c in the DM-ED group.

CONCLUSION

The altered spontaneous brain activity in cognitive-related regions revealed by ReHo values might provide new insights into the neurological pathophysiology underlying DM-ED and serve as potential neuroimaging biomarkers for detecting and evaluating ED in diabetes patients.

miR-195-5p Regulates the Phenotype Switch of CCSM Cells by Targeting Smad7

Introduction

Phenotype switch refers to the process in which smooth muscle cells change from contractile type to synthetic type and acquire the ability of proliferation. Phenotypic transformation involves many changes of cell function, such as collagen deposition and fibrosis, which affect the normal erectile function of penis.

Aim

To investigate the role of miR-195-5p in regulating the Phenotype switch of the corpus cavernosum smooth muscle (CCSM) cells.

Methods

A small mother against decapentaplegic 7(Smad7) virus vector and a miR-195-5p mimics or an si-Smad7 viral vector and a miR-195-5p inhibitor were transfected into CCSM cells. The cells were obtained by primary culture of rat corpus cavernosum smooth muscle tissue. Real-time polymerase chain reaction (PCR) experiments, Western blotting, hematoxylin-eosin (HE) staining, transwell experiments, MTT assays, and flow cytometry were used to detect miR-195-5p, Smad7, phenotype switch markers of CCSM cells and related protein expression, as well as changes in cell morphology, migration, proliferation and apoptosis.

Main Outcome Measure

To study the regulation of miR-195-5p in CCSM cells by overexpression and silencing strategies.

Results

Overexpressed miR-195-5p promoted the transformation of CCSM cells from a contractile type to a synthetic type. Meanwhile, the migration ability and proliferation ability of CCSM cells increased, and the apoptosis rate decreased. The expression-silencing of miR-195-5p gave rise to the opposite effect. The results of the rescue experiment demonstrated that overexpressed Smad7 rescued the inhibitory of the switch of the CCSM cell phenotype from the contractile type to the synthesis type caused by overexpression of miR-195-5p alone. Moreover, the enhancement effect of the migration ability and proliferation ability of CCSM cells was also eliminated, and the apoptosis rate was increased. Silencing miR-195-5p and Smad7 at the same time resulted in the opposite effect.

Conclusion

miR-195-5p may regulate the phenotype switch of CCSM cells by targeting Smad7.

Zhang J, Zhang X, Zhang J, et al. miR-195-5p Regulates the Phenotype Switch of CCSM Cells by Targeting Smad7. Sex Med 2021;9:100349.

Pericyte-Derived Dickkopf2 Regenerates Damaged Penile Neurovasculature Through an Angiopoietin-1-Tie2 Pathway

Penile erection requires well-coordinated interactions between vascular and nervous systems. Penile neurovascular dysfunction is a major cause of erectile dysfunction (ED) in patients with diabetes, which causes poor response to oral phosphodiesterase-5 inhibitors. Dickkopf2 (DKK2), a Wnt antagonist, is known to promote angiogenesis. Here, using DKK2-Tg mice or DKK2 protein administration, we demonstrate that the overexpression of DKK2 in diabetic mice enhances penile angiogenesis and neural regeneration and restores erectile function. Transcriptome analysis revealed that angiopoietin-1 and angiopoietin-2 are target genes for DKK2. Using an endothelial cell-pericyte coculture system and ex vivo neurite sprouting assay, we found that DKK2-mediated juxtacrine signaling in pericyte-endothelial cell interactions promotes angiogenesis and neural regeneration through an angiopoietin-1-Tie2 pathway, rescuing erectile function in diabetic mice. The dual angiogenic and neurotrophic effects of DKK2, especially as a therapeutic protein, will open new avenues to treating diabetic ED.

Penile alterations at early stage of type 1 diabetes in rats

Objective

Diabetes affects the erectile function significantly. However, the penile alterations in the early stage of diabetes in experimental animal models have not been well studied. We examined the changes of the penis and its main erectile components in diabetic rats.

Materials and methods

Male Sprague-Dawley rats were divided into 2 groups: streptozotocin (STZ)-induced diabetics and age-matched controls. Three or nine weeks after diabetes induction, the penis was removed for immunohistochemical staining of smooth muscle and neuronal nitric oxide synthase (nNOS) in midshaft penile tissues. The cross-sectional areas of the whole midshaft penis and the corpora cavernosa were quantified. The smooth muscle in the corpora cavernosa and nNOS in the dorsal nerves were quantified.

Results

The weight, but not the length, of the penis was lower in diabetics. The cross-sectional areas of the total midshaft penis and the corpora cavernosa were lower in diabetic rats compared with controls 9 weeks, but not 3 weeks after diabetes induction. The cross-sectional area of smooth muscle in the corpora cavernosa as percentage of the overall area of the corpora cavernosa was lower in diabetic rats than in controls 9 weeks, but not 3 weeks after diabetes induction. Percentage change of nNOS in dorsal nerves was similar at 3 weeks, and has a decreased trend at 9 weeks in diabetic rats compared with controls.

Conclusions

Diabetes causes temporal alterations in the penis, and the significant changes in STZ rat model begin 3-9 weeks after induction. Further studies on the reversibility of the observed changes are warranted.

An experimental study: evaluating the tissue structure of penis with 2D-ShearWave™ Elastography

The aim of this study was to investigate the feasibility of two-dimensional-ShearWave™ Elastography (2D-SWE) on evaluating the change of tissue structure of penis. Twenty healthy male Sprague Dawley rats were divided into penis-developed group (PDG, 52 weeks) and penis-underdeveloped group (PUDG, 5 weeks). The ultrafast ultrasound device-Aixplorer® (SuperSonic Imagine) was used for 2D-SWE imaging of the penis, the measurement index was shear wave stiffness (SWS, kPa). All rat penises were cut off immediately after ultrasonic examination. After paraffin embedding, slicing and hematoxylin-eosin staining, the tissue structure of the penis was observed under light microscope. SWS of all rat penises were measured successfully. The results showed that SWS of PDG was significantly lower than PUDG (P=0.008). At the same time, the pathological results found that there were significant differences in the tissue structures (sinusoids, smooth muscle cells and fibrocytes) of the penises between the two groups. These results suggest that there are significant differences in SWS between different tissue structures of penis. 2D-SWE is expected to be used on the etiological diagnosis of erectile dysfunction by serving as a new noninvasive method of evaluating the change of tissue structure of penis.

Sac-1004, a Pseudo-Sugar Derivative of Cholesterol, Restores Erectile Function through Reconstruction of Nonleaky and Functional Cavernous Angiogenesis in the Streptozotocin Induced Diabetic Mouse

PURPOSE

We examined whether and how Sac-1004, a vascular leakage blocker, would restore erectile function in an animal model of diabetic erectile dysfunction.

MATERIALS AND METHODS

Eight-week-old C57BL/6J mice were used. Diabetes was induced by intraperitoneal injection of streptozotocin. Eight weeks after diabetes induction the animals were divided into 6 groups, including controls, diabetic mice that received repeat intracavernous injections of phosphate buffered saline (20 μl) on days -3 and 0, and diabetic mice that received repeat intracavernous injections of Sac-1004 on days -3 and 0 (1, 2, 5 and 10 μg, respectively, in 20 μl phosphate buffered saline). One week after injection erectile function was measured by cavernous nerve stimulation. The penis was then harvested for histological examinations and Western blot analysis.

RESULTS

Local delivery of Sac-1004 in the corpus cavernosum restored erectile function in diabetic mice. The highest erectile response was noted at a dose of 5 μg with a response comparable to that in the control group. Sac-1004 significantly increased cavernous endothelial and smooth muscle contents, and induced endothelial nitric oxide synthase phosphorylation (Ser1177). Sac-1004 decreased extravasation of oxidized low density lipoprotein by restoring endothelial cell-cell junction proteins and pericyte content. Sac-1004 also promoted tube formation in primary cultured mouse cavernous endothelial cells in vitro. Sac-1004 mediated cavernous angiogenesis and erectile function recovery was abolished by inhibiting angiopoietin-1-Tie2 signaling with soluble Tie2 antibody.

CONCLUSIONS

With the effects of angiogenesis and antipermeability Sac-1004 reestablishes structural and functional cavernous sinusoids. This is highly promising for future treatment of erectile dysfunction from vascular causes.

Intracavernous delivery of clonal mesenchymal stem cells rescues erectile function in the streptozotocin-induced diabetic mouse

The major hurdle for the clinical application of stem cell therapy is the heterogeneous nature of the isolated cells, which may cause different treatment outcomes. The aim of this study was to examine the effectiveness of mouse clonal bone marrow-derived stem cells (BMSCs) obtained from a single colony by using subfractionation culturing method for erectile function in diabetic animals. Twelve-week-old C57BL/6J mice were divided into four groups: controls, diabetic mice, and diabetic mice treated with a single intracavernous injection of PBS (20 μL) or clonal BMSCs (3 × 10(5) cells/20 μL). Clonal BMSCs were isolated from 5-week-old C3H mice. Two weeks after treatment, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was stained with antibodies to PECAM-1, smooth muscle α-actin, neuronal nitric oxide synthase (nNOS), neurofilament, and phosphorylated endothelial NOS (phospho-eNOS). We also performed Western blot for phospho-eNOS, and eNOS in the corpus cavernosum tissue. Local delivery of clonal BMSCs significantly restored cavernous endothelial and smooth muscle cell contents, and penile nNOS and neurofilament contents, and induced eNOS phosphorylation (Ser1177) in diabetic mice. Intracavernous injection of clonal BMSCs induced significant recovery of erectile function, which reached 80-90% of the control values. Clonal BMSCs successfully restored erectile function through dual angiogenic and neurotrophic effects in diabetic mice. The homogenous nature of clonal mesenchymal stem cells may allow their clinical applications and open a new avenue through which to treat diabetic erectile dysfunction.

Animal models of erectile dysfunction

Erectile dysfunction (ED) is a prevalent male sexual dysfunction with profound adverse effects on the physical and the psychosocial health of men and, subsequently, on their partners. The expanded use of various types of rodent models has produced some advances in the study of ED, and neurophysiological studies using various animal models have provided important insights into human sexual dysfunction. At present, animal models play a key role in exploring and screening novel drugs designed to treat ED.

The pericyte as a cellular regulator of penile erection and a novel therapeutic target for erectile dysfunction

Pericytes are known to play critical roles in vascular development and homeostasis. However, the distribution of cavernous pericytes and their roles in penile erection is unclear. Herein we report that the pericytes are abundantly distributed in microvessels of the subtunical area and dorsal nerve bundle of mice, followed by dorsal vein and cavernous sinusoids. We further confirmed the presence of pericytes in human corpus cavernosum tissue and successfully isolated pericytes from mouse penis. Cavernous pericyte contents from diabetic mice and tube formation of cultured pericytes in high glucose condition were greatly reduced compared with those in normal conditions. Suppression of pericyte function with anti-PDGFR-β blocking antibody deteriorated erectile function and tube formation in vivo and in vitro diabetic condition. In contrast, enhanced pericyte function with HGF protein restored cavernous pericyte content in diabetic mice, and significantly decreased cavernous permeability in diabetic mice and in pericytes-endothelial cell co-culture system, which induced significant recovery of erectile function. Overall, these findings showed the presence and distribution of pericytes in the penis of normal or pathologic condition and documented their role in the regulation of cavernous permeability and penile erection, which ultimately explore novel therapeutics of erectile dysfunction targeting pericyte function.

A comprehensive review of urologic complications in patients with diabetes

Diabetes Mellitus (DM) is a chronic disease characterized by hyperglycemia, as a result of abnormal insulin production, insulin function, or both. DM is associated with systemic complications, such as infections, neuropathy and angiopathy, which involve the genitourinary tract. The three most significant urologic complications include: bladder cystopathy, sexual dysfunction and urinary tract infections. Almost half of the patients with DM have bladder dysfunction or cystopathy, which can be manifested in women as hypersensitivity (in 39-61% of the diabetic women) or neurogenic bladder. In males it can be experienced as lower urinary tract symptoms (in 25% of diabetic males with a nearly twofold increased risk when seen by age groups). Additionally, an increased prostate volume affects their micturition as well as their urinary tract. Involving sexual dysfunction in women, it includes reduced libido, decreased arousal, clitoral erectile dysfunction and painful or non-sensitive intercourse; and in diabetic males it varies from low libido, ejaculatory abnormalities and erectile dysfunction. Globally, sexual disorders have a prevalence of 18-42%. Erectile dysfunction is ranked as the third most important complication of DM. Urinary tract infections are observed frequently in diabetic patients, and vary from emphysematous infections, Fournier gangrene, staghorn infected lithiasis to repetitive bacterial cystitis. The most frequent finding in diabetic women has been lower urinary tract infections. Because of the high incidence of obesity worldwide and its association with diabetes, it is very important to keep in mind the urologic complication associated with DM in patients, in order to better diagnose and treat this population.

Inhibition of Ninjurin 1 restores erectile function through dual angiogenic and neurotrophic effects in the diabetic mouse

Penile erection is a neurovascular phenomenon, and erectile dysfunction (ED) is caused mainly by vascular risk factors or diseases, neurologic abnormalities, and hormonal disturbances. Men with diabetic ED often have severe endothelial dysfunction and peripheral nerve damage, which result in poor response to oral phosphodiesterase-5 inhibitors. Nerve injury-induced protein 1 (Ninjurin 1, Ninj1) is known to be involved in neuroinflammatory processes and to be related to vascular regression during the embryonic period. Here, we demonstrate in streptozotocin-induced diabetic mice that inhibition of the Ninj1 pathway by administering Ninj1-neutralizing antibody (Ninj1-Ab) or by using Ninj1-knockout mice successfully restored erectile function through enhanced penile angiogenesis and neural regeneration. Angiopoietin-1 (Ang1) expression was down-regulated and angiopoietin-2 expression was up-regulated in the diabetic penis compared with that in controls, and these changes were reversed by treatment with Ninj1-Ab. Ninj1 blockade-mediated penile angiogenesis and neural regeneration as well as recovery of erectile function were abolished by inhibition of Ang1-Tie2 (tyrosine kinase with Ig and epidermal growth factor homology domain-2) signaling with soluble Tie2 antibody or Ang1 siRNA. The present results suggest that inhibition of the Ninj1 pathway will be a novel therapeutic strategy for treating ED.

Myocardin restores erectile function in diabetic rats: phenotypic modulation of corpus cavernosum smooth muscle cells

This study aimed to investigate whether gene transfer of myocardin to the penis of diabetic rats can modulate corpus cavernosum smooth muscle (CCSM) cells phenotype and restore erectile function. Five normal control rats, and 22 diabetic rats were randomly divided into four groups: rats transfected with adCMV-myocardin (N = 6), treated with empty vector (N = 6), injected with medium (N = 5), and sham-operated rats (N = 5). The erectile response was measured 7 days after transfection. The percent of smooth muscle and the expressions of SMα-actin, smooth muscle myosin heavy chain (SMMHC), calponin were evaluated. The increases in intracorporal pressure(ICP)/mean arterial pressure and total ICP in response to nerve stimulation in the adCMV-myocardin treated rats were significantly greater than those in the empty vector (P < 0.001 and P < 0.001), medium only (P < 0.001 and P < 0.001), and sham-operated rats (P < 0.001 and P < 0.001). The suppressed expressions of SMα-actin, SMMHC and calponin were completely restored, and the amount of smooth muscle in diabetic rats were not restored after treatment. It is concluded that myocardin ameliorated erectile responses in diabetic rats mainly via promoting phenotypic modulation of CCSM cells from a proliferative to a contractile state.

Energy restriction ameliorates metabolic syndrome-induced cavernous tissue structural modifications in aged rats

High-fat (HF) diet regular intake along life highly contributes to vascular dysfunction and to an increment in prevalence of metabolic syndrome (MetS) and erectile dysfunction (ED), a surrogate symptom of occult vascular disease, in the elderly. However, little is known about the effects of energy restriction (ER) alone/or after an HF-feeding period. We show here that in male Sprague-Dawley rats, 16 months of HF-diet consumption led to an increase in body adiposity, blood pressure, lipidemia, C-reactive protein, and insulin resistance and to hypoadiponectinemia, conditions that cluster in MetS. In addition, this treatment strongly favored collagen deposition in cavernous tissue and myocardium. Conversely, for the same time period, the ingestion of 75 % of ad libitum energy intake by controls (ER) extensively counteracted these outcomes. The impact of 6-month ER after 10-month HF period was also analyzed, and despite the decrease in body weight, adiposity, blood pressure, lipidemia, and C-reactive protein and improvement of insulin sensitivity, no differences were observed either in adiponectin blood levels or in retroperitoneal fat pad mass. Moreover, this treatment led to a reduction in cavernous tissue collagen deposition, but not in the myocardium, and evidenced differential mobilization of adipose tissue accretions. The data show the ability of HF diet to cause MetS and produce unwanted effects on myocardium and corpora vascular structure. They also indicate that these consequences are preventable upon ER diet starting early, but not later, in life.

Effect of intracavernous administration of angiopoietin-4 on erectile function in the streptozotocin-induced diabetic mouse

INTRODUCTION

Erectile dysfunction (ED) is a highly prevalent complication of diabetes, and the severity of endothelial dysfunction is one of the most important factors in reduced responsiveness to oral phosphodiesterase type 5 inhibitors.

AIM

To study the effects of human angiopoietin-4 (Ang-4) protein on erectile function in diabetic mice.

METHODS

Diabetes was induced by intraperitoneal injection of streptozotocin into 8-week-old C57BL/6J male mice. At 8 weeks after the induction of diabetes, the animals were divided into four groups: control nondiabetic mice and diabetic mice receiving two successive intracavernous injections of phosphate buffered saline (days -3 and 0), a single intracavernous injection of Ang-4 protein (day 0), or two successive intracavernous injections of Ang-4 protein (days -3 and 0).

MAIN OUTCOME MEASURES

One week after treatment, we measured erectile function by electrical stimulation of the cavernous nerve. The penis was harvested and stained with hydroethidine or antibodies to Ang-4, platelet/endothelial cell adhesion molecule-1, and phosphorylated endothelial nitric oxide synthase (eNOS). We also determined the differential expression of Ang-4 in cavernous tissue in the control and diabetic mice. The effect of Ang-4 protein on the phosphorylation of Tie-2, Akt, and eNOS was determined in human umbilical vein endothelial cells (HUVECs) by Western blot.

RESULTS

The cavernous expression of Ang-4 was downregulated in diabetic mice; Ang-4 was mainly expressed in endothelial cells. Local delivery of Ang-4 protein significantly increased cavernous endothelial content, induced eNOS phosphorylation, and decreased the generation of superoxide anion and apoptosis in diabetic mice. Ang-4 protein strongly increased the phosphorylation of Tie-2, Akt, and eNOS in HUVECs. Repeated intracavernous injections of Ang-4 induced significant restoration of erectile function in diabetic mice (87% of control values), whereas a single intracavernous injection of Ang-4 protein elicited modest improvement.

CONCLUSIONS

Cavernous endothelial regeneration by use of Ang-4 protein may have potential for the treatment of vascular disease-induced ED, such as diabetic ED.

A study of the early changes of the level of calcitonin gene-related Peptide and histopathology of penises of rats with experimentally induced type I diabetes mellitus by streptozocin

Introduction

Diabetes mellitus (DM) is a multiorgan disease that leads to neurovascular complications that disturb the normal erectile function.

Aim

The aim of the current work was to study the early changes occurring in the level of calcitonin gene-related peptide (CGRP) and histopathological changes in penile tissues of uncontrolled diabetic rats.

Materials and Methods

This study was carried on 50 adult male Sprague-Dawley rats divided into two main groups: group I (control, n = 10) and group II (diabetic, n = 40). Type I DM was induced by a single intraperitoneal injection of streptozotocin (60 mg/kg). The tissue level of CGRP and histopathological examination of rat penises were assessed at 2, 4, 6, and 8 weeks after induction of DM.

Results

CGRP was higher in the diabetic group at 4, 6, and 8 weeks than in the control group. However, endothelial changes and decreased smooth muscles mass started only 2 weeks after induction of DM.

Conclusion

Deterioration of histopathological features of the uncontrolled diabetic rats corporeal tissues is time dependent. Furthermore, vascular changes seem to precede the neurological changes. El-Kamshoushi AAM, Abdallah WI, Helal SF, El Azhary NM, and Hassan EM. A study of the early changes of the level of calcitonin gene-related peptide and histopathology of penises of rats with experimentally induced type I diabetes mellitus by streptozocin. Sex Med 2013;1:21–29.

Morphological analysis of rat ureteric terminal arterioles in situ

Confocal imaging of Fluo-4, Propidium iodide, and di-8-Anepps loaded ureter were used to study the morphology of terminal arterioles with an inner diameter <50 μm in intact rat ureter. Optical sectioning showed that the muscle coat of the terminal arterioles consisted of a monolayer of highly curved smooth muscle cells which run circumferentially around the endothelium. This technique allowed not only to measure the inner diameter of the terminal arterioles but also to define the orientation and number of revolutions an individual smooth muscle cell made around the endothelium. We measured thickness, width, length, and morphological profile of the myocytes and endothelial cells. Propidium iodide staining showed nuclei of individual cells by continuous imaging at high resolution in serial optical sections. Conventional haematoxylin-eosin, Masson's tri-chrome staining, and transmission electron microscopy were also used in this study to compare the measurements obtained from live confocal imaging with histological standard methods. Parameters obtained from live imaging were significantly different. This technique of live staining allowed measuring the cellular and nuclear dimensions of the terminal arterioles in their natural environment which are important in studying the effects of vascular disease or aging on vascular structure.

The influence of promoter -202 A/C polymorphism (rs2854744) of the IGFBP-3 gene on erectile dysfunction risk and serum levels of IGF-I and IGFBP-3

PURPOSE

We studied whether the IGFBP-3 gene polymorphism rs2854744 is associated with erectile dysfunction.

MATERIALS AND METHODS

We investigated the association of this polymorphism with erectile dysfunction in 176 cases and 352 controls. We genotyped rs2854744 using polymerase chain reaction-restriction fragment length polymorphism. Circulating concentrations of IGF-I and IGFBP-3 were also measured.

RESULTS

Allelic frequencies were 0.474 (A allele) and 0.526 (C allele) in men with erectile dysfunction, and 0.457 (A allele) and 0.543 (C allele) in normal controls (adjusted OR 1.74, 95% CI 0.82-2.43, p = 0.08). The frequency of the IGFBP-3 A-202C polymorphism genotype was 0.273 (CC), 0.506 (AC) and 0.221 (AA) in the case group, and 0.296 (CC), 0.494 (AC) and 0.210 (AA) in the control group (chi-square test p = 0.08). Neither the IGFBP-3 A-202C polymorphism nor serum IGF-I and IGFBP-3 levels were significantly associated with the risk of erectile dysfunction. Carriers of the AA genotype had the highest age adjusted serum IGFBP-3. This demonstrated a stepwise decrease in the presence of 1 or 2 copies of the C allele (mean ± SD 4,541 ± 796.2, 3,552 ± 642.4 and 3,314 ± 669.3 ng/ml, respectively). There was a positive correlation between serum IGFBP-3 and serum IGF-I concentrations (Spearman correlation coefficient r = 0.34, p for trend = 0.001).

CONCLUSIONS

The IGFBP-3 gene A-202C polymorphism does not modulate the risk of erectile dysfunction.

Intracavernous delivery of freshly isolated stromal vascular fraction rescues erectile function by enhancing endothelial regeneration in the streptozotocin-induced diabetic mouse

INTRODUCTION

Men with diabetic erectile dysfunction (ED) often have severe endothelial dysfunction and respond poorly to oral phosphodiesterase-5 inhibitors.

AIM

To examine whether and how freshly isolated stromal vascular fraction (SVF) promotes cavernous endothelial regeneration and restores erectile function in diabetic animals.

METHODS

Eight-week-old C57BL/6J mice were used. Diabetes was induced by intraperitoneal injection of streptozotocin. SVF was isolated from epididymal adipose tissues of green fluorescence protein transgenic mice. At 8 weeks after the induction of diabetes, the animals were divided into six groups: controls, diabetic mice, and diabetic mice treated with a single intracavernous injection of phosphate-buffered saline (PBS) or SVF (1 × 10(4) cells, 1 × 10(5) cells, or 2 × 10(5) cells/20 µL, respectively).

MAIN OUTCOME MEASURES

Two weeks later, erectile function was measured by cavernous nerve stimulation. The penis was stained with antibodies to CD31, CD34, phosphohistone H3, phospho-endothelial nitric oxide synthase (eNOS), and vascular endothelial growth factor-A (VEGF-A). We also performed Western blot for phospho-eNOS and eNOS, and determined cyclic guanosine monophosphate (cGMP) concentration in the corpus cavernosum tissue.

RESULTS

Significant improvement in erectile function was noted in diabetic mice treated with SVF at concentrations of 1 × 10(5) and 2 × 10(5) cells, which reached up to 82% of the control values. Local delivery of SVF significantly increased cavernous endothelial cell proliferation, eNOS phosphorylation, and cGMP expression compared with that in the untreated group and the PBS-treated diabetic group. Intracavernous injection of SVF increased cavernous VEGF-A expression and induced recruitment of CD34(+)CD31(-) progenitor cells. Some SVF underwent differentiation into cavernous endothelial cells. SVF-induced promotion of cavernous angiogenesis and erectile function was abolished in the presence of VEGF-Trap, a soluble VEGF-A neutralizing antibody.

CONCLUSION

The results support the concept of cavernous endothelial regeneration by use of SVF as a curative therapy for diabetic ED.

Differential expression of nerve injury-induced protein 1 (ninjurin 1) in in vivo and in vitro models for diabetic erectile dysfunction

Purpose

Endothelial dysfunction and peripheral neuropathy are important mechanisms responsible for diabetes-induced erectile dysfunction (ED). Nerve injury-induced protein 1 (Ninjurin 1) is known to be related to neuroinflammatory processes and is also reported to induce vascular regression during the developmental period. In the present study, we determined the differential expression of Ninjurin 1 in penile tissue of streptozotocin (STZ)-induced diabetic mice with ED.

Materials and Methods

Diabetes was induced in 8-week-old C57BL/6J mice by intraperitoneal injections of STZ (50 mg/kg for 5 days). Eight weeks later, erectile function was measured by electrical stimulation of the cavernous nerve (n=6 per group). The penis was then harvested for immunohistochemical analysis and Western blot analysis for Ninjurin 1 (n=4 per group). We also determined Ninjurin 1 expression in primary cultured mouse cavernous endothelial cells (MCECs) incubated under the following conditions: normal glucose condition (5 mM), high-glucose condition (30 mM), and high-glucose condition (30 mM)+insulin (1 nM).

Results

The expression of Ninjurin 1 protein was significantly higher in both cavernous endothelial cells and the dorsal nerve bundle of diabetic mice than in those of controls. In the in vitro study in MCECs, Ninjurin 1 expression was also significantly increased by the high-glucose condition and was returned to baseline levels by treatment with insulin.

Conclusions

Regarding the role of Ninjurin 1 in neuropathy and vascular regression, it would be interesting to examine the effects of inhibition of Ninjurin 1 on erectile function in animal models of ED with a vascular or neurogenic cause.

Characterization of corpus cavernosum smooth muscle cell phenotype in diabetic rats with erectile dysfunction

Phenotypic modulation from a contractile to a proliferative state within vascular smooth muscle cells has a critical role in the pathogenesis of a variety of cardiovascular diseases. To investigate the characterization of corpus cavernosum smooth muscle cell phenotype in diabetic rats with erectile dysfunction, a group of Sprague-Dawley rats (n=30) were induced by intraperitoneal injection of streptozotocin (60 mg kg(-1)) and screened by subcutaneous injection of apomorphine (100 μg kg(-1)) for the measurement and comparison of the penile erections, and then three different groups were defined. Primary corpus cavernosum smooth muscle cells were cultured and passaged. The cavernous tissue segments were subjected to quantitative real-time polymerase chain reaction to determine the expressions of smooth muscle α-actin (SMA), SM myosin heavy chain (SMMHC), smoothelin, calponin and myocardin. Cell contractility in vitro and western blot analysis of SMA and SMMHC in the cavernous tissues and cells were determined. Compared with the control group (n=8) and the diabetes mellitus group (n=5), the expressions of SMA, calponin, SMMHC, smoothelin and myocardin mRNA were decreased in the cavernous tissues in rats of the diabetic erectile dysfunction group (n=15; P=0.001 and 0.02, P=0.014 and 0.012, both P<0.001, P=0.005 and <0.001, P=0.003 and 0.035, respectively). The levels of SMA and SMMHC proteins showed a significant decrease in cavernous tissues and cultured cells in rats of the diabetic erectile dysfunction group. Cells of the diabetic erectile dysfunction group exhibited significantly less contractility compared with those of other groups (P<0.001). Corpus cavernosum SM cell possesses the ability to modulate the phenotype under hyperglycemic conditions, which could have a key role in the pathogenesis of diabetic erectile dysfunction.

Intracavernous delivery of a designed angiopoietin-1 variant rescues erectile function by enhancing endothelial regeneration in the streptozotocin-induced diabetic mouse

OBJECTIVE

Patients with diabetic erectile dysfunction often have severe endothelial dysfunction and respond poorly to oral phosphodiesterase-5 inhibitors. We examined the effectiveness of the potent angiopoietin-1 (Ang1) variant, cartilage oligomeric matrix protein (COMP)-Ang1, in promoting cavernous endothelial regeneration and restoring erectile function in diabetic animals.

RESEARCH DESIGN AND METHODS

Four groups of mice were used: controls; streptozotocin (STZ)-induced diabetic mice; STZ-induced diabetic mice treated with repeated intracavernous injections of PBS; and STZ-induced diabetic mice treated with COMP-Ang1 protein (days -3 and 0). Two and 4 weeks after treatment, we measured erectile function by electrical stimulation of the cavernous nerve. The penis was harvested for histologic examinations, Western blot analysis, and cGMP quantification. We also performed a vascular permeability test.

RESULTS

Local delivery of the COMP-Ang1 protein significantly increased cavernous endothelial proliferation, endothelial nitric oxide (NO) synthase (NOS) phosphorylation, and cGMP expression compared with that in the untreated or PBS-treated STZ-induced diabetic group. The changes in the group that received COMP-Ang1 restored erectile function up to 4 weeks after treatment. Endothelial protective effects, such as marked decreases in the expression of p47(phox) and inducible NOS, in the generation of superoxide anion and nitrotyrosine, and in the number of apoptotic cells in the corpus cavernosum tissue, were noted in COMP-Ang1-treated STZ-induced diabetic mice. An intracavernous injection of COMP-Ang1 completely restored endothelial cell-cell junction proteins and decreased cavernous endothelial permeability. COMP-Ang1-induced promotion of cavernous angiogenesis and erectile function was abolished by the NOS inhibitor, N-nitro-L-arginine methyl ester, but not by the NADPH oxidase inhibitor, apocynin.

CONCLUSIONS

These findings support the concept of cavernous endothelial regeneration by use of the recombinant Ang1 protein as a curative therapy for diabetic erectile dysfunction.

Intracavernous delivery of synthetic angiopoietin-1 protein as a novel therapeutic strategy for erectile dysfunction in the type II diabetic db/db mouse

INTRODUCTION

Patients with erectile dysfunction (ED) associated with type II diabetes often have impaired endothelial function and tend to respond poorly to oral phosphodiesterase type 5 inhibitors. Therefore, neovascularization is a promising strategy for curing diabetic ED.

AIM

To determine the effectiveness of a soluble, stable, and potent angiopoietin-1 (Ang1) variant, cartilage oligomeric matrix protein (COMP)-Ang1, in promoting cavernous angiogenesis and erectile function in a mouse model of type II diabetic ED. Methods.  Sixteen-week-old male db/db mice (in which obesity and type II diabetes are caused by a mutation in the leptin receptor) and control C57BL/6J mice were used and divided into four groups (N=14 per group): age-matched controls; db/db mice receiving two successive intracavernous injections of phosphate-buffered saline (PBS) (days -3 and 0; 20 µL); db/db mice receiving a single intracavernous injection of COMP-Ang1 protein (day 0; 5.8 µg/20 µL); and db/db mice receiving two successive intracavernous injections of COMP-Ang1 protein (days -3 and 0; 5.8 µg/20 µL).

MAIN OUTCOME MEASURES

Two weeks later, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was then harvested and stained with antibodies to platelet/endothelial cell adhesion molecule-1 (PECAM-1) (endothelial cell marker), phosphohistone H3 (PH3, a nuclear protein indicative of cell proliferation), phospho-endothelial nitric oxide synthase (eNOS), and eNOS. Penis specimens from a separate group of animals were used for cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) quantification.

RESULTS

Local delivery of COMP-Ang1 protein significantly increased eNOS phosphorylation and cGMP and cAMP expression compared with that in the group treated with PBS. Repeated intracavernous injections of COMP-Ang1 protein completely restored erectile function and cavernous endothelial content through enhanced cavernous neoangiogenesis as evaluated by PECAM-1 and PH3 immunohistochemistry and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assay, whereas a single injection of COMP-Ang1 protein elicited partial improvement.

CONCLUSION

Cavernous neovascularization using recombinant Ang1 protein is a novel therapeutic strategy for the treatment of ED resulting from type II diabetes.

Characterization of the expression of Ang1, Ang2, and Tie2 in the Corpus Cavernosum of the rat during aging

Aging is the single most significant risk factor for erectile dysfunction (ED), leading to structural modification of cavernous tissue and altering expression of vascular growth factors. The angiopoietin/Tie2 system has been recently considered as a potential target for therapy of vascular disorders, including ED. Hence, the aim of this study was to analyze expression of angiopoietin1 (Ang1), angiopoietin2 (Ang2), and their receptor Tie2 in corpus cavernosum (CC) of rat during aging (6, 12, 18, and 24 months). The expression of Ang1, Ang2, and Tie2 was studied by immunohistochemistry and immunofluorescence, followed by semiquantification after Western blotting. Both Ang1 and Ang2 were localized mainly in perivascular smooth muscle and endothelial cells, while Tie2 was strictly detected at the vascular endothelium. A significant decrease in Ang2's expression was observed at 12 months when compared with 6-month-old rats, a tendency that reverses in older animals. No significant differences were demonstrated for Ang1 or Tie2, which is consistent with their constitutive expression in CC. The ratios Ang1/Tie2 and Ang2/Tie2 were also calculated and both decrease during aging, while no marked variation was observed for Ang1/Ang2. Our results suggest that the angiopoietin/Tie2 system participate in the vascular maintenance and remodeling of the CC during aging.

Intracavernous transplantation of bone marrow-derived mesenchymal stem cells restores erectile function of streptozocin-induced diabetic rats

INTRODUCTION

Erectile dysfunction (ED) is a frequent complication of diabetes mellitus. The efficacy of common ED therapies is low for diabetes-associated ED.

AIM

To explore the effects of transplantation of bone marrow-derived mesenchymal stem cells (BM-MSCs) on improving erectile function of streptozocin (STZ)-induced diabetic rats.

METHODS

Male Sprague Dawley rats were injected either with STZ to induce diabetes or with citrate buffer as controls. Rat BM-MSCs were harvested and labeled with CM-DiI (Chloromethylbenzamido derivatives of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate), and then transplanted into corporal cavernosum of STZ-induced diabetic rats. Four weeks after transplantation, all rats were analyzed for erectile function and penile histology.

MAIN OUTCOME MEASURES

Erectile function was evaluated by the ratio between intracavernous pressure (ICP) and mean arterial pressure (MAP) during electrostimulation of cavernous nerve. Fate of transplanted BM-MSCs was identified using immunofluorescence staining. Smooth muscle and endothelium in corpora cavernosum were assessed using immunohistochemistry.

RESULTS

After BM-MSCs transplantation, the ICP/MAP ratio was increased significantly compared with diabetic controls. Content of smooth muscle and endothelium in corporal cavernosa of BM-MSCs transplanted rats was significantly increased compared to diabetic controls. Immunofluorescence analysis demonstrated that CM-DiI-labeled BM-MSCs could stay in corporal cavernosa for at least 4 weeks and some of them expressed von Willebrand Factor, CD31, calponin, or α-smooth muscle actin, cells markers for endothelial cells or smooth muscle cells, respectively.

CONCLUSION

Intracavernous transplantation of BM-MSCs had beneficial effects on erectile function of diabetic rats and increased the content of endothelium and smooth muscle in corporal cavernosum.

Testosterone and chronic sildenafil/tadalafil anti-apoptotic role in aged diabetic rats

This work aimed to assess the cavernous anti-apoptotic role of using chronic low-dose sildenafil/tadalafil with and without testosterone (T) in aged diabetic rats. In all, 140 Sprague-Dawley aged rats were divided into the following groups: controls; induced diabetic rats; diabetic rats that received intramuscular depot T once every 4 weeks; diabetic rats on sildenafil 2 mg kg(-1) orally daily; diabetic rats on T and daily sildenafil; diabetic rats on tadalafil 0.45 mg kg(-1) orally every other day; diabetic rats on every-other-day tadalafil and T; diabetic rats on alternate sildenafil and tadalafil; and diabetic rats on alternate sildenafil, tadalafil and T. After 12 weeks, Bax (apoptotic factor), Bcl(2) (B-cell lymphoma 2; anti-apoptotic factor), cGMP (cyclic guanosine monophosphate) were estimated in their cavernous tissues. Compared with the controls, aged diabetic rats showed significant increased cavernous tissue Bax and significant decreased Bcl(2), in which diabetic rats injected with T showed the reverse compared with the diabetic rats. Diabetic rats on sildenafil or tadalafil showed significant increased cavernous Bcl(2) and decreased Bax with upgraded Bcl(2)/Bax ratio that was improved being on T. Diabetic rats on alternate sildenafil/tadalafil with or without T showed further significant increased cavernous tissue Bcl(2) with upgraded Bcl(2)/Bax ratio. It is concluded that frequent low-dose use of sildenafil and/or tadalafil combined with T would be predicted to have a pronounced anti-apoptotic cavernous tissue effect on the cavernous tissues of aged diabetic rats.

Molecular targets for diabetes mellitus-associated erectile dysfunction

Protein expression profiles in rat corporal smooth muscle tissue were compared between animal models of streptozotocin-induced diabetes mellitus (STZ-DM) and age-matched controls (AMCs) at 1 week and 2 months after induction of hyperglycemia with STZ treatment. At each time point, protein samples from four STZ-DM and four AMC rat corpora tissues were prepared independently and analyzed together across multiple quantitative two-dimensional gels using a pooled internal standard sample to quantify expression changes with statistical confidence. A total of 170 spots were differential expressed among the four experimental groups. A subsequent mass spectrometry analysis of the 170 spots identified a total of 57 unique proteins. Network analysis of these proteins using MetaCore suggested altered activity of transcriptional factors that are of too low abundance to be detected by the two-dimensional gel method. The proteins that were down-regulated with diabetes include isoforms of collagen that are precursors to fibril-forming collagen type 1; Hsp47, which assists and mediates the proper folding of procollagen; and several proteins whose abundance is controlled by sex hormones (e.g. CRP1 and A2U). On the other hand, proteins seen or predicted to be up-regulated include proteins involved in cell apoptosis (e.g. p53, 14-3-3-gamma, Serpinf1, Cct4, Cct5, and Sepina3n), proteins that neutralize the biological activity of nerve growth factor (e.g. anti-NGF 30), and proteins involved in lipid metabolism (e.g. apoA-I and apoA-IV). Subsequent Western blot validation analysis of p53, 14-3-3-gamma, and Hsp47 confirmed increased p53 and 14-3-3-gamma and decreased Hsp47 levels in separate samples. According to the results from the Western blot analysis, Hsp47 protein showed a approximately 3-fold decrease at 1 week and was virtually undetectable at 2 months in diabetic versus control. Taken together, our results identify novel candidate proteins playing a role in erectile dysfunction in diabetes resulting from STZ treatment.

Functional and morphologic characterizations of the diabetic mouse corpus cavernosum: comparison of a multiple low-dose and a single high-dose streptozotocin protocols

INTRODUCTION

With the advent of genetically modified mice, it seems particularly advantageous to develop a mouse model of diabetic erectile dysfunction.

AIM

To establish a mouse model of type I diabetes by implementation of either multiple low-dose streptozotocin (STZ) protocol or single high-dose STZ protocol and to evaluate morphologic alterations in the cavernous tissue and subsequent derangements in penile hemodynamics in vivo.

METHODS

Eight-week-old C57BL/6J mice were divided into three groups: a control group, a group administered the multiple low-dose STZ protocol (50 mg/kg x 5 days), and a group administered the single high-dose STZ protocol (200 mg/kg).

MAIN OUTCOME MEASURES

After 8 weeks, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was then harvested and stained with hydroethidine (in situ analysis of superoxide anion), TUNEL, or antibodies to nitrotyrosine (marker of peroxynitrite formation), PECAM-1, smooth muscle alpha-actin, and phospho-eNOS. Penis specimens from a separate group of animals were used for phospho-eNOS and eNOS western blot or cGMP determination.

RESULTS

Erectile function was significantly less in diabetic groups than in control group. The generation of superoxide anion and nitrotyrosine and the number of apoptotic cells in both cavernous endothelial and smooth muscle cells were significantly higher in diabetic groups than in control group. Cavernous tissue phospho-eNOS and cGMP expression and the number of endothelial and smooth muscle cells were lower in diabetic groups than in control group. Both diabetic models resulted in similar structural and functional derangements in the corpus cavernosum; however, the mortality rate was higher in mice receiving single high-dose of STZ than in those receiving multiple low-doses.

CONCLUSION

The mouse model of type I diabetes is useful and technically feasible for the study of the pathophysiologic mechanisms involved in diabetic erectile dysfunction.

Early onset of fibrosis within the arterial media in a rat model of type 2 diabetes mellitus with erectile dysfunction

OBJECTIVES

To determine, in the obese Zucker fa/fa rat (OZR), whether the loss in smooth muscle cells (SMCs) as well as the increase in fibrosis that occurs within the corpora cavernosa accompanying corporal veno-occlusive dysfunction (CVOD), also occurs within the media of the arterial tree.

MATERIALS AND METHODS

The penis and aorta from both 7-month-old male diabetic OZR (5 months of diabetes) and aged-matched nondiabetic lean Zucker rats (LZR) rats were harvested (eight per group). The penis and aorta were subjected to histo- or immnohistochemistry, followed by quantitative image analysis (QIA) to determine the contents of SMC, collagen and the pro-fibrotic transforming growth factor (TGF)beta1. The turnover of SMCs was assessed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) assays. Quantitative Western blots determined calponin (SMC marker) and PCNA, and hydroxyproline was used for collagen. In vitro relaxation of corporal strips was measured.

RESULTS

In vitro relaxation of corporal tissue from OZR was considerably less than in the LZR. In the media of the penile dorsal artery (PDA) of OZR, there was a considerable reduction in the SMC content and the SMC/collagen ratio, as well as an increase in apoptosis, but there were no changes in PCNA or TGFbeta1 expression, or in the intima-media/lumen ratio. In the aorta of the OZR, in contrast to the PDA, there was a reduction in PCNA as well as a more pronounced decrease in the SMC/collagen ratio, mainly from an increase in collagen, but there were no changes in TGFbeta1 or the wall/lumen morphometry. In the OZR, Western blots of aortic tissue confirmed the decrease in PCNA and a reduction in the SMC marker calponin.

CONCLUSIONS

These data show that 5 months after the onset of hyperglycaemia in the OZR, the rats develop both abnormal corporal SMC relaxation and a generalized fibrosis of the arterial media of both the large and small diameter vessels. It is possible that this pan-fibrosis of the media of the arterial system might contribute to the diabetes-related ED that occurs during this period in this rat model.

Localization of increased insulin-like growth factor binding protein-3 in diabetic rat penis: implications for erectile dysfunction

OBJECTIVES

Diabetes-induced erectile dysfunction (ED) is assumed to result from neurovascular abnormalities. However, the entire picture of the molecular mechanisms underlying ED has not yet been clarified. To elucidate the possible elements involved in ED in diabetes mellitus, we performed broad-scale gene expression profiling using cDNA array in the penis of streptozotocin-induced diabetic rats.

METHODS

Northern blot analysis was performed to examine the course of the mRNA expression encoded by the identified gene. Immunohistochemistry was performed to identify the cellular localization of the encoded protein.

RESULTS

Of the genes investigated, the expression level of insulin-like growth factor binding protein 3 (IGFBP-3) was greatly increased at 12 weeks after streptozotocin treatment. The levels of ErbB3 epidermal growth factor receptor-related proto-oncogene, G1/S-specific cyclin D2, hepatic neutral cholesteryl ester hydrolase precursor, UDP-galactose ceramide galactosyltransferase, and serine protease RNK-Met-1 were markedly decreased. Increased levels of IGFBP-3 mRNA were demonstrated as early as 2 weeks after induction of hyperglycemia. Increased IGFBP-3 protein was localized to the epithelium of the urethra, penile endothelium, and smooth muscle in the corpus cavernosum. Significant depletion of the smooth muscle density relative to the connective tissue was first observed in the penis of the 8-week diabetic rats, and a significant reduction in the intracavernous pressure was demonstrated only at 12 weeks after the induction of hyperglycemia.

CONCLUSIONS

These results suggest that the increased expression of IGFBP-3 during hyperglycemia might play an important role in the development of ED.

The mouse as a model for the study of penile erection: moving towards a smaller animal

We evaluated erectile haemodynamics in mice and characterized the corpus cavernosum morphologically. Four-month-old male BALB/c mice and Sprague-Dawley rats were used. The following stimulation parameters were tested to achieve maximal erectile responses: voltage, 1-6 V; frequency, 6-24 Hz; pulse width, 1 msec; duration, 1 min (n = 7 per group). In a separate group of mice and rats (n = 10 per group), we measured systemic arterial pressure by use of either a 24-gauge angiocatheter or smaller calibre PE-10 tubing. Cavernous tissues from mice, rats or patients with psychogenic erectile dysfunction were stained for factor VIII, alpha-actin and Masson trichrome. Electrical stimulation of the cavernous nerve in mice produced voltage-dependent erectile responses of up to 5 V, with the highest response at a frequency of 12 Hz. The maximal intracavernous pressure recorded at this stimulation parameter was comparable with that in rats. A PE-10 catheter was more reliable for measuring systemic arterial pressure in mice than was a 24-gauge angiocatheter, and the values recorded were similar between mice and rats. The content of endothelial cells, smooth muscle cells and collagen was similar between mice and rats. However, the cavernous tissue of both animals contained lesser amounts of smooth muscle cells and greater amounts of collagen than that of humans (p < 0.01). These results suggest that the mouse is a useful and technically feasible model for the study of penile erection and has functional and structural properties similar to those of rats.

Improvement in erectile dysfunction after insulin-like growth factor-1 gene therapy in diabetic rats

AIM

To determine whether adenoviral gene transfer of insulin like growth factor-1 (IGF-1) to the penis of streptozotocin (STZ)-induced diabetic rats could improve erectile capacity.

METHODS

THE STZ diabetic rats were transfected with AdCMV-betagal or AdCMV-IGF-1. These rats underwent cavernous nerve stimulation to assess erectile function and their responses were compared with those of age-matched control rats 1 to 2 days after transfection. In control and transfected STZ diabetic rats, IGF-1 expression were examined by reverse transcription polymerase chain reaction (RT-PCR), Western blot and histology. The penis beta-galactosidase activity and localization of the STZ diabetic rats were also determined.

RESULTS

One to two days after transfection, the beta-galactosidase was found in the smooth muscle cells of the diabetic rat penis transfected with AdCMV-betagal. One to 2 days after administration of AdCMV-IGF-1, the cavernosal pressure, as determined by the ratio of maximal intracavernous pressure-to-mean arterial pressure (ICP/MAP) and total intracavernous pressure (ICP), was increased in response to cavernous nerve stimulation. Transgene expression was confirmed by RT-PCR, Western blot and histology.

CONCLUSION

Gene transfer of IGF-1 significantly increased erectile function in the STZ diabetic rats. These results suggest that in vivo gene transfer of IGF-1 might be a new therapeutic intervention for the treatment of erectile dysfunction (ED) in the STZ diabetic rats.

Regulation of cavernous nerve injury-induced apoptosis by sonic hedgehog

Thirty to eighty-seven percent of patients treated by radical prostatectomy experience erectile dysfunction (ED). The reduced efficacy of treatments in this population makes novel therapeutic approaches to treat ED essential. We propose that abundant apoptosis observed in penile smooth muscle when the cavernous nerve (CN) is cut (mimicking the neural injury which can result from prostatectomy) is a major contributing factor to ED development. We hypothesize that decreased Sonic hedgehog (SHH) signaling is a cause of ED in neurological models of impotence by increasing apoptosis in penile smooth muscle. We examined this hypothesis in a bilateral CN injury model of ED. We found that the active form of SHH protein was significantly decreased 1.2-fold following CN injury, that SHH inhibition causes a 12-fold increase in smooth muscle apoptosis in the penis, and that SHH treatment at the time of CN injury was able to decrease CN injury-induced apoptosis (1-3-fold) in a dose-dependent manner. These results show that SHH stabilizes the alterations of the corpora cavernosal smooth muscle following nerve injury.

Endothelial and erectile dysfunction, diabetes mellitus, and the metabolic syndrome: common pathways and treatments?

The past decade has witnessed a dramatic increase in the prevalence of obesity. Comorbidities of obesity include type 2 diabetes mellitus, hypertension, and lipid abnormalities, all of which contribute to cardiovascular disease (CVD) and are associated with endothelial dysfunction. These abnormalities frequently cluster in individuals, and the term metabolic syndrome is now widely used to define this cluster. The syndrome is frequently (although not invariably) associated with insulin resistance and CVD. Diabetes is associated with CVD, which may be asymptomatic in some cases, particularly when associated with autonomic neuropathy. This has implications for guidelines on the evaluation of patients with erectile dysfunction (ED) and CVD. Treatment of ED in men with diabetes has been revolutionized by the introduction of phosphodiesterase 5 inhibitors. However, men with diabetes tend to respond less positively to these agents, at least as currently prescribed. This decreased responsiveness may be related to the severity of endothelial function in patients with diabetes. Additional therapeutic strategies may be needed to overcome this problem.

Application of angiogenic factors for therapy of erectile dysfunction: Protein and DNA transfer of VEGF 165 into the rat penis

OBJECTIVES

To establish a laboratory animal model for vascular endothelial growth factor (VEGF) transfer in the rat penis to invent a curative therapy for erectile dysfunction (ED). Vascular insufficiency is a common pathomechanism of ED. Previous investigations have shown neovascularization of ischemic organs after gene transfer of VEGF.

METHODS

For VEGF-protein transfer, osmotic pumps were connected to the renal arteries of rats. The pumps were filled with human VEGF 165 protein (n = 20) or sterile saline (n = 20). After 28 days, a VEGF serum immunoassay was performed to document successful delivery. For VEGF-DNA transfer, liposome complexes containing VEGF 165 expression vectors were injected into rat corpora cavernosa. After immunostaining, computerized image analysis was performed to quantify the percentage of area (within the corpora cavernosa) covered by smooth muscle or endothelial cells.

RESULTS

The immunoassay of the VEGF-protein transfer showed a 10-fold greater VEGF concentration in the serum of rats carrying VEGF pumps than in the control group. In the VEGF-DNA transfer, the penes transfected with VEGF 165 vectors showed a 283-bp polymerase chain reaction product according to specific primers for human VEGF. Although statistical trends were measured in the VEGF protein-treated group, no statistically significant difference in smooth muscle or endothelial cell content was found between the control and VEGF-treated rats.

CONCLUSIONS

Our findings have established proof of principle for successful delivery of VEGF protein and VEGF-DNA transfer in the rat penis. This study was a prelude to attempt to manipulate genetically expression of angiogenic factors in insufficient erectile tissue as a curative therapy for ED.

Neointimal hyperplasia and vascular endothelial growth factor expression are increased in normoglycemic, insulin resistant, obese fatty rats

OBJECTIVE

Insulin resistance is associated with a constellation of factors that enhance the artherosclerotic process. Vessel injury results in the formation of a markedly increased neointima in type 2 diabetes. Increased neointimal hyperplasia (NH) and vascular endothelial growth factor (VEGF) expression may lead to restenosis post angioplasty. We studied NH and VEGF expression in an obese, insulin resistant, but normoglycemic rat model, after carotid balloon injury.

METHODS AND RESULTS

Diabetic rats (ZDF, n=10), normoglycemic, insulin-resistant rats (ZDF-normoglycemic, n=6) as well as Zucker fatty rats (FZ, n=6), and lean Zucker rats (LZ, n=6), all 13-16 weeks old, were subjected to right carotid injury by an angioplasty catheter introduced via the femoral artery. Three weeks later the rats were sacrificed and serum and carotids obtained. The intima-media ratio (I/M) was then calculated. ZDF-normoglycemic, FZ and ZDF-diabetic rats were all hyperinsulinemic and hypertriglyceridemic when compared to LZ rats. ZDF diabetic rats were hyperglycemic while FZ, ZDF-normoglycemic and LZ rats were normoglycemic. The I/M ratio for ZDF and FZ rats were significantly greater than for LZ rats. The VEGF expression was significantly greater in ZDF and FZ rats than LZ rats.

CONCLUSIONS

In conclusion, insulin resistance increases neointimal hyperplasia and VEGF expression even with normoglycemia, after carotid angioplasty in rats.

Effect of basic fibroblast growth factor incorporating gelatin microspheres on erectile function in the diabetic rat

PURPOSE

We report the potential of basic fibroblast growth factor (bFGF) incorporating gelatin microspheres to preserve erectile function in a diabetic rat model.

MATERIALS AND METHODS

A total of 48 adult male rats were divided into 3 groups, namely control (nondiabetic rats), diabetes mellitus (DM) (diabetic rats that received gelatin microspheres with saline) and bFGF (diabetic rats that received gelatin microspheres with bFGF). After 4 and 8 weeks we examined intracavernous pressure responses with electrical stimulation to the cavernous nerve. For histological examination of the penis we performed Azan-Mallory staining for smooth muscle and collagen, and immunohistochemistry for endothelial nitric oxide synthase (NOS) in endothelium and neuronal NOS in cavernous nerve fiber.

RESULTS

Although the intracavernous pressure response was significantly lower in the DM group than in the control group, pressure in the bFGF group was maintained at the normal level found in controls. Azan-Mallory staining showed a mass decrease in smooth muscle in cavernous tissue in the DM group. However, that in the bFGF group was maintained. There was no significant difference in endothelial NOS positive areas and the distribution of the diameter of neuronal NOS positive nerve fibers in cavernous tissue among the 3 groups.

CONCLUSIONS

We report the maintenance of erectile function with bFGF incorporating gelatin microspheres in diabetic rats. The rationale of this maneuver is smooth muscle preservation by the long-term release of bFGF. This is a novel therapeutic option that is clinically applicable for diabetes induced erectile dysfunction.

The neurovascular mechanism of clitoral erection: nitric oxide and cGMP-stimulated activation of BKCa channels

Female sexual function is under-studied, and mechanisms of clitoral engorgement-relaxation are incompletely understood. Penile erection results from nitric oxide (NO) -induced cyclic guanosine monophosphate (cGMP) accumulation. cGMP-dependent protein kinase (PKG) activates large-conductance, calcium-activated potassium channels (BK(Ca)), thereby hyperpolarizing and relaxing vascular and trabecular smooth muscle cells, allowing engorgement. We hypothesize rat clitorises relax by a similar mechanism. Rat clitorises express components of the proposed pathway: neuronal and endothelial NO synthases, soluble guanylyl cyclase (sGC), type 5 phosphodiesterase (PDE-5), and BK(Ca) channels. The NO donor diethylamine NONOate (DEANO), the PKG activator 8-pCPT-cGMP, and the PDE-5 inhibitor sildenafil, cause dose-dependent clitoral relaxation that is inhibited by antagonists of PKG (Rp-8-Br-cGMPS) or BK(Ca) channels (iberiotoxin). Electrical field stimulation induces tetrodotoxin-sensitive NO release and relaxation that is inhibited by the Na+ channel blocker tetrodotoxin or sGC inhibitor 1H-(1,2,4)oxadiozolo(4,3-a)quinoxalin-1-one. Human BK(Ca) channels, transferred to Chinese hamster ovary cells via an adenoviral vector, and endogenous rat clitoral smooth muscle K+ current are activated by this PKG-dependent mechanism. Laser confocal microscopy reveals protein expression of BK(Ca) channels on clitoral smooth muscle cells; these cells exhibit BK(Ca) channel activity that is activated by both DEANO and sildenafil. We conclude that neurovascular derived NO causes clitoral relaxation via a PKG-dependent activation of BK(Ca) channels. The BK(Ca) channel is an appealing target for drug therapy of female erectile dysfunction.

The effect of PDE5 inhibition on the erectile function in streptozotocin-induced diabetic rats

The aim of this study was to assess the effect of phosphodiesterase 5 inhibitor, DA-8159, on erectile function throughout the quantitative analysis of vascular endothelial cell, smooth muscle (SM), TGF-beta1 expression in rat corpus cavernosum and measurement of intracavernous pressure (ICP) in diabetic rats. DA-8159 (0, 5, 10, 20 mg/kg) was administered orally once a day to diabetic rats. After 8 weeks, immunohistochemistry and computerized image analysis were performed to quantify the percent area within the Corpora Cavernosa occupied by the endothelial cells, SM cells and fibrotic tissues. ICP/mean arterial pressure (MAP) was also measured by electrostimulation of the cavernous nerve. Diabetic rats showed a significant decrease in the SM and endothelial cell content, and an increase in the TGF-beta1 expression level within the cavernosa areas compared to the normal rats. The mean cavernous SM, endothelial cell content and TGF-beta1 expression level were 9.7+/-0.7, 4.5+/-0.7 and 17.9+/-2.1%, respectively. DA-8159 prevented reduction of SM (12.3+/-0.4% (5 mg/kg), 13.8+/-0.4% (20 mg/kg)) and endothelial cell content (5.6+/-0.5% (5 mg/kg), 6.3+/-0.6% (20 mg/kg)). Immunoreactivity of TGF-beta1 and intracorporal fibrosis were also significantly lower in DA-8159-treated groups (11.8+/-1.2% (5 mg/kg), 9.5+/-1.1% (20 mg/kg)). Electrostimulation of the cavernous nerve induced significant increase in maximum ICP (62.2+/-13.6 mmHg in 10 mg/kg vs 37.5+/-17.5 mmHg in diabetic group) and area under the curve of the ratio of ICP/MAP (8891.09+/-1957 in 10 mg/kg vs 6315.87+/-2272 in diabetic group). These results suggest that subchronic treatment of DA-8159 can prevent the development of erectile dysfunction (ED), and provides a rationale for the use of DA-8159 as treatment of diabetic ED.

Effect of PDE5 inhibition combined with free oxygen radical scavenger therapy on erectile function in a diabetic animal model

Phosphodiesterase (PDE) inhibitors represent an important advance in the treatment of erectile dysfunction (ED). In spite of widespread use and generally good efficacy, as a class they remain ineffective in 15-57% of men. Specific cohorts of patients with severe vascular or neurogenic basis to their ED, such as diabetic men or those who have undergone radical pelvic surgery, demonstrate lower response rates with PDE inhibition treatment. We believe that circulating levels of nitric oxide (NO) may be enhanced through delivery of adequate concentrations of free oxygen radical scavenger molecules such as vitamin E. Higher levels of NO, theoretically, should produce increased penile blood flow with the potential for a synergistic effect when combined with a PDE5 inhibitor. With this hypothesis in mind, 20 adult male Sprague-Dawley streptozotocin-induced (60 mg/kg i.p.) diabetic rats were divided into four therapeutic groups (n=5). Group I--control animals received peanut oil, group II--vitamin E 20 IU/day, group III--sildenafil 5 mg/kg/day and group IV--vitamin E 20 IU/day plus sildenafil 5 mg/kg/day, by oral gavage daily for 3 weeks. Erectile function was assessed as a rise in intracavernous pressure following cavernous nerve electrostimulation. Penile tissue was harvested to determine the changes in tissue morphology including neuronal nitric oxide synthase, smooth muscle alpha-actin and endothelial cell integrity. PDE5 protein content and activity were measured. Significant increases in intracavernous pressure were measured in the animals receiving combined vitamin E plus sildenafil treatment. Immunohistochemical staining showed increases of neuronal nitric oxide synthase, endothelial cell and smooth muscle cell staining. Western blot analysis did not show significant differences of PDE5 protein between the groups. However, higher PDE5 activity was measured in the sildenafil group and lower activity of PDE5 was recorded in the cohort receiving vitamin E with sildenafil. Vitamin E enhanced the therapeutic effect of the PDE5 inhibitor in a meaningful way in this animal model of diabetes. This study indicates a potential means of salvaging erectile function among patients who are refractory to sildenafil.

Altered Sonic hedgehog signaling is associated with morphological abnormalities in the penis of the BB/WOR diabetic rat

Erectile dysfunction (ED) is a common and debilitating pathological development that affects up to 75% of diabetic males. Neural stimulation is a crucial aspect of the normal erection process. Nerve injury causes ED and disrupts signaling of the Sonic hedgehog (Shh) cascade in the smooth muscle of the corpora cavernosa. Shh and targets of its signaling establish normal corpora cavernosal morphology during postnatal differentiation of the penis and regulate homeostasis in the adult. Interruption of the Shh cascade in the smooth muscle of the corpora cavernosa results in extensive changes in corpora cavernosal morphology that lead to ED. Our hypothesis is that the neuropathy observed in diabetics causes morphological changes in the corpora cavernosa of the penis that result in ED. Disruption of the Shh cascade may be involved in this process. We tested this hypothesis by examining morphological changes in the penis, altered gene and protein expression, apoptosis, and bromodeoxyuridine incorporation in the BB/WOR rat model of diabetes. Extensive smooth muscle and endothelial degradation was observed in the corpora cavernosa of diabetic penes. This degradation accompanied profound ED, significantly decreased Shh protein in the smooth muscle of the corpora cavernosa, and increased penile Shh RNA expression in the intact penis (nerves, corpora, and urethra). Localization and expression of Shh targets were also disrupted in the corpora cavernosa. Increasing our understanding of the molecular mechanisms that regulate Shh signaling may provide valuable insight into improving treatment options for diabetic impotence.