Reduction of endothelial and smooth muscle density in the corpora cavernosa of the streptozotocin induced diabetic rat

PURPOSE: Erectile dysfunction is one of the most prevalent complications of diabetes in males. Because adequate vascular perfusion is needed for appropriate erectile tissue function a likely reason for the high incidence of this complication in diabetics is a pathological change associated with the disease in vascularization of erectile tissues. We investigate whether chronic diabetes may induce changes in vascularization of the corpora cavernosa using a computerized image analysis system to quantify changes in the smooth muscle and endothelial cell content of the corpora cavernosa of diabetic rats induced by streptozotocin 6 months previously, and compare these changes to those associated with aging. MATERIALS AND METHODS: We studied 3 groups of rats, including 10-week-old untreated controls, diabetic rats treated with streptozotocin for 6 months starting at age 10 weeks and 18-month-old rats (aged). Penile shafts from these groups were excised, fixed, sectioned and immunostained with anti-smooth muscle actin to identify smooth muscle cells and anti-CD31 to identify endothelial cells. Computerized image analysis was used to quantify the percent area within the corpora cavernosa occupied by smooth muscle cells or endothelial cells, and the data were compared among the groups. RESULTS: We identified a highly significant decrease in the percentage of smooth muscle and endothelial cells within the cavernosa areas of diabetic rats compared to control or aged rats. Mean cavernous smooth muscle cell content was 15.28 +/- 2.54% in control rats and 9.83 +/- 1.21% in diabetic rats (p = 0.0001). Likewise, cavernous endothelial cell content was 6.93 +/- 0.86% in the control group and 4.01 +/- 1.08% in the diabetic group (p = 0. 0001). However, no statistical difference of smooth muscle or endothelial cell content was found between control and aged rats. CONCLUSIONS: Using the streptozotocin treated rat as a model for diabetes, we showed that smooth muscle and endothelial cell density is significantly decreased in diabetic corpora cavernosa but not in normal aged rats. This observation is a further step toward the understanding of the pathomechanisms for diabetic related erectile dysfunction.     

可分泌表达人降钙素基因相关肽重组腺相关病毒对糖尿病大鼠阴茎勃起的作用

目的:探讨重组腺相关病毒(rAAV)介导人降钙素基因相关肽(hCGRP)基因转移在糖尿病大鼠阴茎海绵体平滑肌分泌表达及其对阴茎勃起的作用。方法:建立链佐脲菌素(STZ)糖尿病大鼠模型,随机分为3组,分别将VssHGCMV-hCGRP、VssCMV-GFP和rAAV空病毒液注射于阴茎海绵体。在注射后5 d,采用SMUP-PC型生物信号处理系统检测阴茎背神经电刺激诱发的阴茎勃起反应及海绵体内压(ICP)变化。切取海绵体组织,通过免疫组化技术和激光共聚焦显微镜分别检测hCGRP和绿色荧光蛋白(GFP)表达,以放射免疫法检测组织中环磷酸腺苷(cAMP)和环磷酸鸟苷(cGMP)变化。结果:在VssCMV-GFP转染后5 d,显示阴茎海绵体内几乎所有组织均有广泛的GFP表达,而rAAV空病毒转染的海绵体则无GFP表达。VssHGCMV-hCGRP转染STZ诱导的糖尿病大鼠后5d,电刺激阴茎背神经可诱发明显的阴茎勃起,监测ICP明显增高[(60.5±4.5)mm Hg,1 mm Hg=0.133kPa],而对rAAV空病毒转染的对照组STZ糖尿病大鼠以同样的参数电刺激阴茎背神经则无勃起反应,ICP无明显增加[(22.3±1.3)mm Hg],两组差异有显著性(P<0.01)。免疫组化观察显示在VssHGCMV-hCGRP转染的STZ糖尿病大鼠阴茎海绵体组织中hCGRP表达增强,同时当电刺激阴茎背神经诱发勃起反应时,海绵体内cAMP和cGMP水平均升高,分别为(48.4±6.5)nmol/L和(21.2±13.6)nmol/L,较rAAV空病毒组[(16.7±2.5)nmol/L和(0.42±0.12)nmol/L]明显增高(P<0.01)。结论:经阴茎海绵体内注射重组腺相关病毒VssHGCMV-hCGRP在糖尿病大鼠阴茎海绵体内获得了hCGRP转基因高效表达,其可增加阴茎背神经电刺激诱发的阴茎ICP和勃起反应。     

Vascular endothelial growth factor (VEGF) gene therapy using a nonviral gene delivery system improves erectile function in a diabetic rat model

Erectile dysfunction (ED) is a cause of decreased quality of life in more than 70% of diabetic men. Vascular endothelial growth factor (VEGF) has shown to improve overall endothelial and smooth muscle cell dysfunction in models of ED. We describe a novel technique for nonviral, in vivo gene transfection of VEGF in the rat corpus cavernosum. Diabetic rats were transfected with DNA encoding a fusion VEGF/green fluorescent protein (GFP) complex and fluorescence microscopy was used to monitor the expression of VEGF-GFP fusion protein. Western blot and PCR analyses confirmed the expression of the GFP-VEGF fusion protein and mRNA. Functional studies using cavernous nerve stimulation revealed maximal intracavernous pressures (ICPs) of 63.1 mm Hg, and 30.7 mm Hg in the normal and diabetic control groups, respectively, and 47.4 mm Hg in VEGF-GFP-transfected diabetic group. Immunohistochemical analysis of the cavernosal tissue from transfected rats showed increased smooth muscle content compared with the diabetic control group. We show for the first time in our animal model that expression of the transfected VEGF in cavernosal tissue leads to an overall improvement of maximal ICP and smooth muscle content. On the basis of these results, it is tempting to speculate that our nonviral vector system offers an excellent system for gene delivery into cavernosal tissue, and that VEGF gene therapy using this system could be useful in improving erectile function in diabetic men.     

Therapeutic effect of combination of alagebrium (ALT-711) and sildenafil on erectile function in diabetic rats

Recently, the relationship between advanced glycation end products (AGEs) and erectile dysfunction (ED) has been reported. The present study aimed to investigate whether a combination of an AGE cross-link breaker (alagebrium/ALT-711) and sildenafil could enhance the erectile capacity in streptozotocin (STZ) diabetic rats. Additionally, we assessed the effect of that treatment option on some molecules that have been suggested to have crucial roles in AGE-related ED pathways. Four groups of animals were utilized: (1) age-matched control rats, (2) STZ-induced diabetic rats (40 mg kg(-1) i.p.), (3) STZ rats+sildenafil (5 mg kg(-1) p.o.), (4) STZ rats treated with a combination of sildenafil (5 mg kg(-1) p.o)+alagebrium/ALT-711 (10 mg kg(-1) p.o.) for the final 1 month of the 2 months of diabetes period. At 2 months after i.p. injection of STZ, all animals underwent cavernosal nerve stimulation (CNS) to assess erectile function. Penile tissue AGEs, MDA (malondialdehyde), cyclic guanosine monophosphate (cGMP) (ELISA), endothelial nitric oxide (NO) synthase (eNOS), inducible NO synthase (iNOS) (western blot), nuclear factor (NF)-κB, mitogen-activated protein (MAP) kinase (immunohistochemistry) and apoptosis (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling) analyses were performed in all groups of rats. STZ diabetic rats had a significant decrease in erectile function as determined by the peak intracavernosal pressure (ICP) and total ICP (area under the erectile curve) after CNS when compared with control rats (P<0.05). The increase in both ICP and area under the erectile curve of STZ diabetic rats treated with a combination of sildenafil+alagebrium/ALT-711 as well as in STZ diabetic rats treated with sildenafil alone was significantly greater than STZ diabetic rats. Additionally, combination treatment decreased AGE, MDA, iNOS, NF-κB, MAP kinase and apoptosis levels, whereas it preserved cGMP contents in diabetic penile tissue. Decreased AGE, MDA, iNOS, NF-κB, MAP kinase and increased cGMP levels at the combination (sildenafil+alagebrium/ALT-711) therapy group increased both the peak ICP and total ICP to CNS in the STZ diabetic rats, which was similar to the response observed in control rats. These results may explain the role of AGEs in diabetes-related ED and the effect of an AGE cross-link breaker alagebrium/ALT-711+sildenafil therapy on some critical molecules related to AGE-related ED pathways.     

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.     

Valsartan treatment reverses erectile dysfunction in diabetic rats

In order to investigate the effect of angiotensin receptor blockage (ARB) for the treatment on diabetic erectile dysfunction (ED), we used male Sprague-Dawley rats injected with 65 mg/kg streptozotocin to induce diabetes mellitus. The diabetic rats with ED were selected by hypodermic injection of apomorphine (APO) after 8 weeks of model setting. All rats were divided into four groups: G1 (normal control rats), G2 (diabetic rats treated with normal saline), G3 (diabetic rats treated with valsartan) and G4 (diabetic rats treated with spironolactone). After treatment with drugs for 8 weeks, the rate of erection for each group was evaluated after the injection of APO. The intracavernous pressure (ICP) of each rat was then recorded before and after the electrostimulation of the major pelvic ganglion. The rates of erection and the ICP after electrostimulation for diabetic rats treated with valsartan were significantly higher than that in diabetic rats treated with normal saline and spironolactone. The ARB may be an effective therapy for diabetics with ED.     

VEGF165基因修饰脂肪干细胞对糖尿病大鼠骨缺损的修复研究

目的 :探讨采用基因转染大鼠脂肪干细胞构建血管化组织工程的方法对糖尿病骨质疏松性骨缺损的修复效果。方法:选取雄性Wistar大鼠78只,体重180~220 g,其中72只通过化学药物(STZ)诱导法建立糖尿病动物模型,成模大鼠血糖值均≥16.7 mmol/L。将实验动物随机分为5组,正常对照组6只,其他实验组各18只。正常对照组:在正常大鼠骨缺损内植入经VEGF165基因修饰的脂肪干细胞;糖尿病组:单纯糖尿病骨缺损大鼠;生长因子组:在糖尿病大鼠骨缺损内单纯植入VEGF生长因子;干细胞组:在糖尿病大鼠骨缺损内单纯植入脂肪干细胞;实验组:在糖尿病大鼠骨缺损内植入经VEGF165基因修饰的脂肪干细胞。将5×106个VEGF165-ADSCs细胞与凝胶海绵结合后,植入到糖尿病大鼠骨缺损模型中,在植入后第4周时,采用光学显微镜观察缺损修复组织大体形态;采用免疫组化SP法测定骨缺损区修复后局部微血管密度;应用美国IRIS IntrepidⅡXSP电感耦合等离子体发射光谱仪对修复骨痂内钙/磷含量和碱性磷酸酶(ALP)含量测定;统计分析上述测量结果验证VEGF165-ADSCs对糖尿病大鼠骨缺损的修复作用。结果:荧光染色结果显示,VEGF165表达定位于ADSCs的细胞浆,表达率在87﹪以上;大体组织学观察结果显示:实验组修复区内骨痂生成范围和质量接近正常组,糖尿病组、生长因子组、干细胞组修复效果欠佳。植入后第4周,实验组单位体积的修复组织钙、磷含量和ALP含量明显高于生长因子组、干细胞组(P0.05),与正常对照组组比较差异无统计学意义(P0.05);第4周时,实验组修复局部的血管密度低于正常对照组(P0.05),而显著高于其他组(P0.05)。结论 :VEGF165基因修饰的脂肪干细胞在糖尿病大鼠体内具有良好的成骨及成血管作用,有望成为修复糖尿病特定骨质条件下骨缺损的一种有效手段。     

Mobilisation of endothelial progenitor cells: one of the possible mechanisms involved in the chronic administration of melatonin preventing erectile dysfunction in diabetic rats

Diabetes-induced oxidative stress plays a critical role in the mobilisation of endothelial progenitor cells (EPCs) from the bone marrow to the circulation. This study was designed to explore the effects of chronic melatonin administration on the promotion of the mobilisation of EPCs and on the preservation of erectile function in type I diabetic rats. Melatonin was administered to streptozotocin-induced type I diabetic rats. EPCs levels were determined using flow cytometry. Oxidative stress in the bone marrow was indicated by the levels of superoxide dismutase and malondialdehyde. Erectile function was evaluated by measuring the intracavernous pressure during an electrostimulation of the cavernous nerve. The density of the endothelium and the proportions of smooth muscle and collagen in the corpus cavernosum were determined by immunohistochemistry. The administration of melatonin increased the superoxide dismutase level and decreased the malondialdehyde level in the bone marrow. This effect was accompanied by an increased level of circulating EPCs in the diabetic rats. The intracavernous pressure to mean arterial pressure ratio of the rats in the treatment group was significantly greater, compared with diabetic control rats. The histological analysis demonstrated an increase in the endothelial density of the corpus cavernosum after the administration of melatonin. However, melatonin treatment did not change the proportions of smooth muscle and collagen in the corpus cavernosum of diabetic rats. Chronic administration of melatonin has a beneficial effect on preventing erectile dysfunction (ED) in type I diabetic rats. Promoting the mobilisation of EPCs is one of the possible mechanisms involved in the improvement of ED.     

Effect of caffeine on erectile function via up-regulating cavernous cyclic guanosine monophosphate in diabetic rats

Erectile dysfunction (ED) is a common complication of diabetes mellitus. Phosphodiesterase-5 (PDE5) inhibitors, which inhibit the breakdown of intracellular cyclic guanosine monophosphate (cGMP), are used to treat diabetic ED. Caffeine, a nonselective PDE inhibitor used in our daily diet, is controversial regarding its effect on erectile function. To investigate the effect of caffeine on erectile function in diabetic rat models and explore the mechanism, male Sprague-Dawley rats were injected with streptozotocin to induce diabetes mellitus. The rats with blood glucose levels above 300 mg/dL were selected for the study. The rats were divided into 4 groups: group A (normal control rats), group B (diabetic rats treated with normal saline), group C (diabetic rats treated with caffeine, 10 mg/kg per day), and group D (diabetic rats treated with caffeine, 20 mg/kg per day). After 8 weeks of treatment, intracavernous pressure (ICP) was measured to assess erectile function. The radioimmunoassay was used to evaluate the level of cGMP in the cavernosum. The ICP and the cavernous cGMP decreased significantly in the diabetic rats compared with normal controls. An 8-week administration of caffeine at the given dosages increased the ICP and cavernous cGMP in diabetic rats. Caffeine consumption improved the erectile function of diabetic rats by up-regulating cavernous cGMP.     

Vascular endothelial growth factor restores erectile function through inhibition of apoptosis in diabetic rat penile crura

PURPOSE: Vascular endothelial growth factor (VEGF) is known as a multifunctional protein with roles in angiogenesis stimulation and apoptosis inhibition. We hypothesized that intracavernous administration of VEGF would recover erectile dysfunction due to diabetes by protection from apoptosis in the penile cavernosum. MATERIALS AND METHODS: A total of 30, 6-month-old male Sprague-Dawley rats were divided into 2 large groups, namely 20 with diabetes and 10 healthy controls. The diabetic group received intraperitoneal injection of streptozotocin (STZ) to induce diabetes. Intracavernous injection of VEGF was administered to randomly selected STZ diabetic rats 6 weeks after STZ injections. Erectile functional studies were performed in 10 STZ and 10 STZ plus VEGF rats at 12 weeks. After completion of the functional study the penile crura were collected for molecular and immunohistochemical studies. RESULTS: Mean intracavernous pressure in the diabetic group was significantly lower than in controls and low pressure was significantly recovered by VEGF treatment. Gene expression of pro-apoptotic and anti-apoptotic factors were present in the control, diabetic and VEGF treated groups. However, anti-apoptotic protein expression was lacking in the diabetic group and it was recovered by VEGF treatment. The apoptotic index in the diabetic group was significantly higher than in controls and this index was significantly decreased in the VEGF treated group. CONCLUSIONS: The decrease in and recovery of intracavernous pressure correlated significantly with a variation in anti-apoptotic protein expression in the diabetic and VEGF treated groups. To our knowledge this is the first study to show that intracavernous injection of VEGF restores erectile dysfunction through the inhibition of apoptosis in diabetic rats.     

Endothelial cell transplantation into the corpus cavernosum: moving towards cell-based gene therapy

PURPOSE: As a first step toward a cell based gene therapy for erectile dysfunction, we transplanted fluorescently labeled autologous microvessel endothelial cells (MVEC) into the rat corpus cavernosum. MATERIALS AND METHODS: MVEC were isolated from the epididymal fat pad, labeled with the membrane intercalating dye PKH 26, and injected into the corpus cavernosum. Two to 15 days after transplantation the penises were removed, cryosectioned, and examined under epifluorescent and phase contrast microscopy. RESULTS: In 7 consecutive animals transplanted fluorescent cells were identified in the corpora cavernosa. Bilateral distribution was noted in each animal, and staining with ED1 determined that the fluorescence was not due to engulfment of the MVEC by phagocytic cells. CONCLUSION: Transplanted endothelial cells adhere and persist in the corporal sinusoids and provide a rationale for cell-based gene therapy in the penis.     

Effects of Icariside II on Improving Erectile Function in Rats With Streptozotocin-Induced Diabetes

Icariin and icariside II (ICA II), 2 active components isolated from herba epimedii, have a closely structural relationship. There is evidence that icariin may be useful in the treatment of erectile dysfunction (ED); however, the study on the therapeutic efficacy of ICA II on ED is currently scant. We investigated the effects of ICA II on improving erectile function of rats with streptozocin-induced diabetes. Fifty 8-week-old Sprague-Dawley rats were randomly distributed into normal control and diabetic groups. Diabetes was induced by a one-time intraperitoneal injection of streptozocin (60 mg/kg). Three days later, the diabetic rats were randomly divided into 4 groups including a saline-treated placebo arm and 3 ICA II-treated models (1, 5, and 10 mg/kg/d). After 3 months, penile hemodynamics was measured by cavernous nerve electrostimulation (CNE) with real time intracorporal pressure assessment. Penises were harvested with subsequent histological examination (picrosirius red stain, Hart elastin stain, and immunohistochemical stain) and Western blots to explore the expression of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) and transforming growth factor β1 (TGFβ1)/Smad2 signaling pathways. Diabetes significantly attenuated erectile responses to CNE. Diabetic rats had decreased corpus cavernosum smooth muscle/collagen ratio and endothelial cell content relative to the control group. The ratio of collagen I to III was significantly lower in the corpora of diabetic rats; furthermore, cavernous elastic fibers were fragmented in the diabetic animals. Neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase, and vascular endothelial growth factor were expressed at lower levels in the diabetic group; ICA II-treated diabetic rats had higher expression in the penis relative to placebo-treated diabetic animals. Both the TGFβ1/Smad2/connective tissue growth factor (CTGF) signaling pathway and apoptosis were down-regulated in the penis from ICA II-treated rats. ICA II treatment attenuates diabetes-related impairment of penile hemodynamics, likely by increasing smooth muscle, endothelial function, and nNOS expression. ICA II could alter corpus cavernosum fibrous-muscular pathological structure in diabetic rats, which could be regulated by the TGFβ1/Smad2/CTGF and NO-cGMP signaling pathways.     

Antifibrogenic role of valproic acid in streptozotocin induced diabetic rat penis

We investigated the therapeutic effects of valproic acid (VPA) on erectile dysfunction and reducing penile fibrosis in streptozocin (STZ)‐induced diabetic rats. Eighteen male rats were divided into three experimental groups (Control, STZ‐DM, STZ‐DM plus VPA) and diabetes was induced by transperitoneal single dose STZ. Eight weeks after, VPA and placebo treatments were given according to groups for 15 days. All rats were anesthetised for the measurement of in vivo erectile response to cavernous nerve stimulation. Afterward penes were evaluated histologically in terms of immune labelling scores of endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF) and transforming growth factor‐β1 (TGF‐β1). Slides were also evaluated in terms of collagen/smooth muscle ratio and penile apoptosis. After the treatment with VPA, erectile responses were found as improved when compared with STZ‐DM rats but not statistically meaningful. eNOS and VEGF immune expressions diminished in penile corpora of STZ‐DM rats and improved with VPA treatment. VPA led to decrease in TGF‐β1 expression and collagen content of diabetic rats’ penes. Penile apoptosis was not diminished with VPA. In conclusion, VPA treatment seems to be effective for reducing penile fibrosis in diabetic rats and more prolonged treatment period may enhance erectile functions.     

Combined strategy of mesenchymal stem cell injection with vascular endothelial growth factor gene therapy for the treatment of diabetes-associated erectile dysfunction

This study was designed to investigate the effect of vascular endothelial growth factor 164 adenovirus (Ad-VEGF(164))-transfected mesenchymal stem cells (MSC) on improving erectile function in diabetic rats. Forty-five male Sprague-Dawley rats were injected with streptozotocin to develop type 1 diabetes, whereas 10 served as normal controls. Diabetic rats were randomly divided into 3 groups: rats that underwent intracavernous injection with phosphate-buffered saline (DM+PBS), unmodified MSCs (DM+MSC), and Ad-VEGF(164)-transfected MSCs (DM+VMSC). Normal controls received intracavernous injection of PBS. Four weeks after injection, erectile function was measured by cavernous nerve electrostimulation. Penile tissue was harvested for histology and enzyme-linked immunoassay. Prior to injection, high expression of VEGF was confirmed in Ad-VEGF(164)-transfected MSCs by enzyme-linked immunoassay. Four weeks after injection, the erectile function, as well as the content of smooth muscle and endothelium in corpus cavernosum increased significantly in the MSC-injected groups compared with the DM+PBS group. There was a significant improvement of erectile function, the content of smooth muscle and endothelium, and the VEGF concentration in the corpus cavernosum in the DM+VMSC group compared with the DM+MSC group. Our study validates the effect of intracavernous injection of MSCs for diabetes-associated erectile dysfunction in an animal model. The combined strategy of MSC injection with VEGF gene therapy-enhanced therapy of MSCs for the treatment of diabetes-associated erectile dysfunction.     

Chronic administration of phosphodiesterase 5 inhibitor improves erectile and endothelial function in a rat model of diabetes

This study was conducted to determine if the long-term administration of the phosphodiesterase type 5 (PDE 5) inhibitor, DA-8159, to diabetic rats can ameliorate the development of erectile dysfunction (ED) and endothelial dysfunction. After inducing diabetes with streptozotocin, DA-8159 was orally administered at a dose of 3 mg/kg or 10 mg/kg for 8 weeks. To examine the effect on erectile response, electrostimulation of the cavernous nerve with the parameters of 3 V, 5 ms, 5 Hz or 10 Hz, was performed to measure the intracavernous pressure (ICP) and mean arterial pressure (MAP). Thoracic aorta relaxation in vitro was evaluated by adding acetylcholine (Ach) cumulatively to the bathing medium. In addition, the plasma endothelin-1 (ET-1) levels were measured in order to investigate the effect of DA-8159 on endothelial dysfunction. The area under the curve (AUC) from the ICP/MAP ratio in the 10 Hz stimulation showed a significantly increased AUC after the 10 mg/kg treatment compared with the diabetic group (8891 +/- 619 vs. 6316 +/- 1016, respectively, p < 0.05). At the 5 Hz frequency, DA-8159 10 mg/kg also induced a significant increase in the AUC compared with the diabetic control. The maximum ICP/MAP ratio (%) of the 10 mg/kg treatment group was significantly higher in both the 10 Hz and 5 Hz frequency groups (p < 0.05). A treatment of 3 mg/kg tended to increase the AUC and peak ICP/MAP but was not statistically significant. The Ach EC50 value of the diabetic group was significantly higher than in the normal control (120.50 +/- 22.90 nm vs. 86.80 +/- 9.30 nm, respectively), and 10 mg/kg treatment group showed a significantly lower EC(50) value (88.38 +/- 19.7 nm). The ET-1 level was lower in groups treated with DA-8159, 3 mg/kg and 10 mg/kg treatment induced a statistical difference compared with the diabetic control (1.15 +/- 0.34 fmol/mL vs. 2.51 +/- 0.55 fmol/mL, respectively, p < 0.05). These results demonstrate that chronic administration of DA-8159 could attenuate the development of the ED in diabetes and its effect is associated with an improvement in the endothelial function.     

Neurotrophic effect of bone marrow mesenchymal stem cells for erectile dysfunction in diabetic rats

It has been demonstrated that intracavernous injection of bone marrow-derived mesenchymal stem cells (BM-MSCs) had beneficial effects on improving erectile function in type-1 diabetic rats. This study was designed to investigate the neurotrophic effect of BM-MSCs for type-1 diabetic rats. Streptozocin-induced type-1 diabetic rats were randomly divided into three groups: diabetic group, BM-MSCs-treated group and BM-MSCs-conditioned medium-treated group. At the 3d, 1 and 2w time points after BM-MSCs injection, three randomly selected rats in MSCs group were sacrificed and penile samples were harvested to detect BM-MSCs in penile tissue. Four weeks after intracavernous injection of BM-MSCs or BM-MSCs-conditioned medium, intracavernous pressure (ICP) was assessed to evaluate the erectile function. Immunohistochemistry was used to track labelled BM-MSCs in penile tissue and to detect neuronal nitric oxide synthase (nNOS) and neurofilament (NF) positive fibres in penile dorsal nerve. Enzyme lined immunosorbent assay (ELISA) was used to measure the concentrations of vascular endothelial growth factor (VEGF), nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in BM-MSCs-conditioned medium. BM- MSCs secreted detectable levels of VEGF, BDNF and NGF. Intracavernous injection of BM-MSCs improved erectile function in diabetic rats. The functional improvement was accompanied by promoted nNOS and NF positive nerve fibres within penile dorsal nerve in type-1 diabetic rats. Histological data revealed a time-dependent decrease in the number of BM-MSCs in the corpus cavernosum following injection. Furthermore, the beneficial effect of BM-MSCs was partially repeated by BM-MSCs-conditioned medium. Intracavernous injection of BM-MSCs is effective in improving nerve regeneration in diabetic rats. Paracrine effects of BM-MSCs are probably involved in the improvement.     

Increased estradiol levels in venous occlusive disorder: a possible functional mechanism of venous leakage

Venous insufficiency of the corpora cavernosa is the second most common cause of erectile dysfunction (ED). A functional insufficiency of the venous system has been hypothesised, but the cause is still unclear. To evaluate a possible endocrine mechanism, we have studied hormone profile in a group of nine patients with pure venous-leakage (VL) compared with a control group of 15 patients with ED of different origin. Prolactin, testosterone and gonadotropin levels did not differ among the two groups, while estradiol (E2) plasma concentration was significantly higher in VL patients compared to controls. Our data support the hypothesis that the steroid environment, in particular estradiol level, can influence venous vascular tone (via VEGF or NO), thus affecting venous leakage dysfunction. This point can explain a possible link between the high estradiol levels and a functional insufficiency of the venous system in ED.