Effect of Intracavernous Administration of Angiopoietin‐4 on Erectile Function in the Streptozotocin‐Induced Diabetic Mouse

IntroductionErectile 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.AimTo study the effects of human angiopoietin‐4 (Ang‐4) protein on erectile function in diabetic mice.MethodsDiabetes 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 MeasuresOne 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.ResultsThe 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.ConclusionsCavernous endothelial regeneration by use of Ang‐4 protein may have potential for the treatment of vascular disease‐induced ED, such as diabetic ED. Kwon M‐H, Ryu J‐K, Kim WJ, Jin H‐R, Song K‐M, Kwon K‐D, Batbold D, Yin GN, Koh GY, and Suh J‐K. Effect of intracavernous administration of angiopoietin‐4 on erectile function in the streptozotocin‐induced diabetic mouse. J Sex Med 2013;10:2912–2927.     

Intracavernous Delivery of Freshly Isolated Stromal Vascular Fraction Rescues Erectile Function by Enhancing Endothelial Regeneration in the Streptozotocin‐Induced Diabetic Mouse

IntroductionMen with diabetic erectile dysfunction (ED) often have severe endothelial dysfunction and respond poorly to oral phosphodiesterase‐5 inhibitors.AimTo examine whether and how freshly isolated stromal vascular fraction (SVF) promotes cavernous endothelial regeneration and restores erectile function in diabetic animals.MethodsEight‐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 × 10⁴ cells, 1 × 10⁵ cells, or 2 × 10⁵ cells/20 µL, respectively).Main Outcome MeasuresTwo 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.ResultsSignificant improvement in erectile function was noted in diabetic mice treated with SVF at concentrations of 1 × 10⁵ and 2 × 10⁵ 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.ConclusionThe results support the concept of cavernous endothelial regeneration by use of SVF as a curative therapy for diabetic ED. Ryu J‐K, Tumurbaatar M, Jin H‐R, Kim WJ, Kwon M‐H, Piao S, Choi MJ, Yin GN, Song K‐M, Kang Y‐J, Koh YJ, Koh GY, and Suh J‐K. Intracavernous delivery of freshly isolated stromal vascular fraction rescues erectile function by enhancing endothelial regeneration in the streptozotocin‐induced diabetic mouse. J Sex Med 2012;9:3051–3065.     

Effects of Low‐Energy Shockwave Therapy on the Erectile Function and Tissue of a Diabetic Rat Model

IntroductionLow‐energy shockwave therapy (LESWT) has been shown to improve erectile function in patients suffering from diabetes mellitus (DM)‐associated erectile dysfunction (ED). However, the underlying mechanism remains unknown.AimThe aim of this study is to investigate whether LESWT can ameliorate DM‐associated ED in a rat model and examine the associated changes in the erectile tissues.MethodsNewborn male rats were intraperitoneally injected with 5‐ethynyl‐2‐deoxyuridine (EdU; 50 mg/kg) for the purpose of tracking endogenous mesenchymal stem cells (MSCs). Eight weeks later, eight of these rats were randomly chosen to serve as normal control (N group). The remaining rats were injected intraperitoneally with 60 mg/kg of streptozotocin (STZ) to induce DM. Eight of these rats were randomly chosen to serve as DM control (DM group), whereas another eight rats were subject to shockwave (SW) treatment (DM+SW group). Each rat in the DM+SW group received 300 shocks at energy level of 0.1 mJ/mm² and frequency of 120/minute. This procedure was repeated three times a week for 2 weeks. Another 2 weeks later, all 24 rats were evaluated for erectile function by intracavernous pressure (ICP) measurement. Afterward, their penile tissues were examined by histology.Main Outcome MeasuresErectile function was measured by ICP. Neuronal nitric oxide synthase (nNOS)‐positive nerves and the endothelium were examined by immunofluorescence staining. Smooth muscle and MSCs were examined by phalloidin and EdU staining, respectively.ResultsSTZ treatment caused a significant decrease in erectile function and in the number of nNOS‐positive nerves and in endothelial and smooth muscle contents. These DM‐associated deficits were all partially but significantly reversed by LESWT. MSCs (EdU‐positive cells) were significantly more numerous in DM+SW than in DM rats.ConclusionLESWT can partially ameliorate DM‐associated ED by promoting regeneration of nNOS‐positive nerves, endothelium, and smooth muscle in the penis. These beneficial effects appear to be mediated by recruitment of endogenous MSCs. Qiu X, Lin G, Xin Z, Ferretti L, Zhang H, Lue TF, and Lin C‐S. Effects of low‐energy shockwave therapy on the erectile function and tissue of a diabetic rat model. J Sex Med 2013;10:738–746.     

Poly(ADP‐Ribose) Polymerase Inhibition Improves Erectile Function in Diabetic Rats

IntroductionErectile dysfunction (ED) is a common and hard‐to‐treat complication of diabetes mellitus (DM). Multiple lines of evidence have shown that poly(ADP‐ribose) polymerase (PARP) activation plays an important role in neurovascular dysfunction in diabetes, which is the crucial mechanism for diabetic ED.AimTo investigate the preventive benefit of a PARP inhibitor in a rat model of ED induced by diabetes.MethodsEstablished streptozotocin‐diabetic male Sprague‐Dawley rats were given PJ‐34, a selective PARP inhibitor, by oral gavage at a dose of 10 mg/kg twice daily for 8 weeks. Erectile responses under electrical stimulation of the cavernous nerve, PARP activity and reactive oxygen species (ROS) production were measured. Nitric oxide synthase (NOS) isoforms were evaluated by Western blot and real‐time quantitative PCR. Nuclear factor‐kappa B activition and apoptosis in corpus cavernosa (CC) were also investigated.Main Outcome MeasuresThe effects of PARP inhibition on the development of diabetic ED were determined.ResultsDiabetes markedly attenuated the erectile responses (intracavernosal pressure/mean systemic arterial blood pressure) and these were partially prevented by PJ‐34 treatment. Promoted oxidative stress associated PARP activation was found in CC from vehicle‐treated diabetic rats. PJ‐34 blocked PARP activity and the diabetes‐associated ROS generation. Decreased expression and activity of constitutive NOS (cNOS), including endothelial NOS (eNOS) and neuronal NOS (nNOS), associated with enhanced inducible NOS (iNOS) expression and activity were observed in vehicle‐treated diabetic rats. Although PJ‐34 had no effect on eNOS expression, it significantly prevented the decrease in nNOS expression and cNOS activity, and inhibited iNOS expression and activity in diabetic rats. PARP blockade by PJ‐34 to some extent prevented diabetes‐associated apoptosis and NF‐κB activation.ConclusionsOur results indicate that PARP activation plays an important role in the pathogenesis of diabetic ED and PARP inhibition may be a promising strategy to prevent development of diabetic ED. Wan ZH, Li WZ, Li YZ, Chen L, Li GH, Hu WF, Peng S, Yu JJ, and Guo F. Poly(ADP‐Ribose) polymerase inhibition improves erectile function in diabetic rats.     

Oral l‐Citrulline Supplementation Improves Erectile Function in Rats with Acute Arteriogenic Erectile Dysfunction

IntroductionOral l‐citrulline supplementation increases serum l‐arginine levels more efficiently than l‐arginine itself and increases nitric oxide (NO) production.AimTo investigate whether oral l‐citrulline supplementation improves erectile function in rats with acute arteriogenic erectile dysfunction (ED).MethodsWe divided 8‐week‐old male Wistar‐ST rats into 3 groups: sham‐operated rats (control group), arteriogenic ED rats who underwent ligation of both internal iliac arteries (ligation group), and arteriogenic ED rats receiving oral 2% l‐citrulline water supplementation (citrulline group). Citrulline water was given to arteriogenic ED rats for 3 weeks from 1 week after surgery. Erectile function was evaluated by maximum intracavernous pressure/mean arterial pressure (ICP/MAP) ratios via cavernous nerve stimulation at 4 weeks after surgery. Then, the penises were resected, stained with Masson's trichrome, and observed microscopically. Serum nitrogen oxides (NOx) levels were measured by high‐performance liquid chromatography. Bonferroni's multiple t‐test was used for statistical analysis.Main Outcome MeasuresThe main outcome measures were changes in ICP/MAP, smooth muscle (SM)/collagen ratios, and NOx levels following l‐citrulline supplementation.ResultsThe ICP/MAP ratio in the ligation group was significantly lower than that in the control group (P < 0.05), denoting ED. The ICP/MAP ratio of the citrulline group was significantly higher than that of the ligation group (P < 0.05), indicating ED amelioration. Levels of NOx in the ligation group were significantly lower than in the control group (P < 0.05), while those in the citrulline group were significantly higher than in the ligation group (P < 0.05). SM/collagen ratios in the ligation group were significantly lower than in the control group (P < 0.05), while ratios in the citrulline group were significantly higher than those in the ligation group (P < 0.05).ConclusionsOral l‐citrulline supplementation improved ICP/MAP and SM/collagen ratios and increased NOx. Therefore, oral l‐citrulline supplementation might be a useful novel therapy for acute arteriogenic ED. Shiota A, Hotta Y, Kataoka T, Morita M, Maeda Y, and Kimura K. Oral l‐citrulline supplementation improves erectile function in rats with acute arteriogenic erectile dysfunction. J Sex Med 2013;10:2423–2429.     

Chronic Treatment with an Oral Rho‐Kinase Inhibitor Restores Erectile Function by Suppressing Corporal Apoptosis in Diabetic Rats

IntroductionIt has been suggested that the up‐regulation of the contractile RhoA/Rho‐kinase (ROCK) signaling pathway is one of the important mechanisms for diabetes‐associated erectile dysfunction (ED). However, the exact role of RhoA/ROCK signaling in the pathogenesis of diabetes‐related ED has not been fully delineated.AimTo determine whether the RhoA/ROCK pathway is involved in the regulation of corporal apoptosis and whether administration of insulin or fasudil, a specific ROCK inhibitor, could ameliorate ED in streptozotocin‐induced diabetic rats.Main Outcome MeasuresAt 16 weeks after diabetes induction, erectile function was assessed by cavernous nerve stimulation. Penile tissue was assessed for apoptosis with terminal deoxynucleotidyl transferase‐mediated 2′‐deoxyuridine 5′‐triphosphate (dUTP) nick end labeling assay. Expression of myosin phosphatase target subunit 1 (MYPT1), protein kinase B (Akt), and phospho‐endothelial nitric oxide synthase (eNOS) were evaluated by Western blot. Immunohistochemical study was carried out for smooth muscle alpha‐actin, B‐cell leukemia/lymphoma 2 (Bcl‐2), and Bcl‐2‐associated X Protein (Bax). Activity of caspase‐3 and phosphatase and tensin homolog deleted on chromosome ten (PTEN) was also determined.MethodsMale Sprague‐Dawley rats (8 weeks old) were randomly divided into four groups: age‐matched controls, diabetic controls, and diabetic rats treated with insulin (10 U/day, subcutaneous injection) or fasudil (30 mg/kg/day, oral) for the last 4 weeks of the 16 weeks after diabetes induction.ResultsDiabetic rats showed impairment of erectile function, increased MYPT1 phosphorylation, and corporal apoptosis. Expression of phospho‐Akt, phospho‐eNOS, and Bcl‐2 were decreased, whereas activity of PTEN and caspase‐3 and expression of Bax were increased. Treatment with fasudil normalized these molecular and histologic alterations, and restored erectile function. Insulin treatment showed similar effects to those of fasudil, however, the effects were smaller than fasudil.ConclusionsThis study indicates that up‐regulation of the penile RhoA/ROCK pathway in diabetic rats enhances corporal apoptosis via the PTEN/Akt pathway resulting in ED, which could be prevented by chronic treatment with fasudil. Li WJ, Park K, Paick J‐S, and Kim SW. Chronic treatment with an oral rho‐kinase inhibitor restores erectile function by suppressing corporal apoptosis in diabetic rats.     

Assessment of Androgen Replacement Therapy for Erectile Function in Rats with Type 2 Diabetes Mellitus by Examining Nitric Oxide‐Related and Inflammatory Factors

IntroductionType 2 diabetes mellitus (T2DM) has become a major public health issue and is considered a risk factor for erectile dysfunction (ED). T2DM is also associated with androgen deficiency. However, there have been few basic studies on androgen replacement therapy (ART) for ED treatment in T2DM animal models, and the mechanism underlying the effect of ART on T2DM‐induced ED is unclear.AimTo investigate the effect of ART on ED in T2DM rats by examining inflammatory and nitric oxide (NO)‐related factors.MethodsOtsuka Long‐Evans Tokushima Fatty (OLETF) rats and their controls, Long‐Evans Tokushima Otsuka (LETO) rats, were distributed into three groups: LETO, OLETF, and ART. In the ART group, OLETF rats were treated daily with testosterone (3 mg/kg/day, subcutaneously) from 20 to 25 weeks of age; LETO and OLETF rats received vehicle only.Main Outcome MeasuresWe measured erectile function by using measurements of the ratio between intracavernosal pressure (ICP) and mean arterial pressure (MAP) following electrical stimulation of the cavernous nerve and by evaluating the endothelial function of the corpus cavernosum in an isometric tension study. Expression of endothelial NO synthase (eNOS), inducible NO synthase (iNOS), sirtuin‐1 (Sirt1), interleukin‐6 (IL‐6), and tumor necrosis factor alpha (TNF‐α) mRNA was detected using polymerase chain reaction.ResultsThe ICP/MAP ratio in the OLETF group was significantly decreased and that in the ART group was significantly improved (P < 0.01). The response to acetylcholine was significantly decreased in the OLETF group and improved in the ART group (P < 0.01). Although expression of eNOS and Sirt1 mRNA was decreased and that of iNOS, IL‐6, and TNF‐α mRNA was increased in the OLETF group, ART improved mRNA expression.ConclusionsART suppressed inflammation in rats with T2DM and metabolic disorders and improved their endothelial and erectile functions. ART could be effective for T2DM‐induced ED and may be considered a potential ED treatment method. Kataoka T, Hotta Y, Maeda Y, and Kimura K. Assessment of androgen replacement therapy for erectile function in rats with type 2 diabetes mellitus by examining nitric oxide‐related and inflammatory factors. J Sex Med 2014;11:920–929.     

Incomplete Recovery of Erectile Function in Rat after Discontinuation of Dual 5‐Alpha Reductase Inhibitor Therapy

AimThe association of 5‐alpha reductase inhibitor (5ARI) therapy and sexual dysfunction has been reported. Some patients claim persistent erectile dysfunction despite long‐term discontinuation of 5ARI treatment. The aim of this study was to assess erectile function after cessation of 5ARI therapy using a rat model.MethodsTwenty‐six adult male Sprague‐Dawley rats were randomized into three groups: (i) control (N = 10); (ii) 8‐week dutasteride treatment (0.5 mg/rat/day, in drinking water, N = 8); and (iii) 6‐week dutasteride treatment followed by a 2‐week washout period (N = 8). The experiments were performed after 8 weeks from the initiation of treatment in all groups. In vivo erectile activity and in vitro contractile and relaxant responses of cavernosal smooth muscle were investigated.ResultsIn vivo erectile activity (intracavernosal pressure [ICP]/mean arterial pressure [MAP] and total ICP) in treatment groups were significantly decreased compared with controls (ICP/MAP: P < 0.001 for 2.5 v, 5 v, and 7.5 v; total ICP: P < 0.001 for 5 v and P < 0.01 for 7.5 v). Acetylcholine‐induced relaxations were diminished in treatment groups (P < 0.05). Relaxant responses to electrical field stimulation (EFS) were decreased in the 8‐week treatment group (P < 0.05) but were similar to controls in the washout group. Sodium nitroprusside (SNP)‐induced endothelium‐independent relaxations were reduced in the 8‐week dutasteride treatment group (P < 0.01), while these responses were restored in the washout group. The contractile responses to the alpha1‐adrenergic agonist phenylephrine were decreased in treatment groups compared with controls (P < 0.01). Direct neurogenic contractile responses in the dutasteride groups were significantly lower than controls between 1 and 15 Hz frequencies (but not at 20 Hz) and washout partially restored the responses at 10 and 15 Hz.ConclusionDiscontinuation of dutasteride improved the relaxant responses to EFS and SNP, while cholinergic and adrenergic responses remained depressed. Our findings suggest a time‐dependent detriment of dutasteride on erectile function. The withdrawal/washout effect of 5ARIs on parameters of human sexual function warrants further investigation. Öztekin ÇV, Gur S, Abdulkadir NA, Lokman U, Akdemir AÖ, Cetinkaya M, and Hellstrom WJG. Incomplete recovery of erectile function in rat after discontinuation of dual 5‐alpha reductase inhibitor therapy. J Sex Med 2012;9:1790–1798.     

Poly(ADP‐Ribose) Polymerase Inhibition Improves Erectile Function by Activation of Nitric Oxide/Cyclic Guanosine Monophosphate Pathway in Diabetic Rats

IntroductionEndothelial dysfunction‐induced abnormalities of the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway in the corpus cavernosum are thought to be the main factors involved in the pathogenesis of diabetes‐induced erectile dysfunction (ED). Recent studies have shown that the poly(adenosine diphosphate ribose) polymerase (PARP) pathway plays a critical role in diabetic endothelial dysfunction.AimThe aim of this study is to determine whether activation of the PARP pathway is involved in diabetic cavernosal endothelial dysfunction and abnormalities of the NO/cGMP pathway.MethodsMale Sprague‐Dawley rats were randomly divided into three groups: age‐matched controls, diabetic controls (DM), and the 3‐aminobenzamide (3‐AB, a PARP inhibitor)‐treated diabetic group (DM+3‐AB). Diabetes was induced by intraperitoneal injection of streptozotocin. Eight weeks after inducing diabetes, the DM+3‐AB group was treated with 3‐AB for 4 weeks.Main Outcome MeasuresErectile function was assessed at 12 weeks after inducing diabetes by stimulating the cavernous nerve. Expression of poly(ADP‐ribose), protein kinase B (Akt), phospho‐Akt, endothelial nitric oxide synthase (eNOS), phospho‐eNOS, and neuronal nitric oxide synthase (nNOS) were evaluated by Western blot. Cavernous NO generation and cGMP levels were also determined.ResultsThe DM group showed impaired erectile function and significantly increased PARP activity. Expression of total eNOS and nNOS, phospho‐Akt, and eNOS decreased significantly in the DM group compared with those in the control group. In addition, cavernous NO generation and cGMP levels decreased significantly in the DM group compared with those in the control group. Treatment with 3‐AB restored erectile function and significantly reversed all molecular alterations except decreased nNOS expression.ConclusionOveractivation of the PARP pathway in the corpus cavernosum of diabetic rats was involved in cavernosal endothelial dysfunction and abnormalities of the NO/cGMP pathway resulting in ED. These findings may be applied to develop novel therapies for patients with diabetic ED. Li WJ, Peng Y, Zhou J, Li B, Wang H, Zhang J, and Wang Z. Poly(ADP‐ribose) polymerase inhibition improves erectile function by activation of nitric oxide/cyclic guanosine monophosphate pathway in diabetic rats. J Sex Med 2012;9:1319–1327.     

TNF‐α, Erectile Dysfunction,and NADPH Oxidase‐Mediated ROS Generation in Corpus Cavernosum in High‐Fat Diet/Streptozotocin‐Induced Diabetic Rats

IntroductionPatients with diabetes‐associated erectile dysfunction (ED) are characterized by an increase in circulating tumor necrosis factor‐alpha (TNF‐α). However, no study has indicated whether and how TNF‐α plays a role in the pathogenesis of ED associated with diabetes.AimWe examined the effects and potential mechanism of infliximab (INF), a chimeric monoclonal antibody to TNF‐α, on reactive oxygen species (ROS) generation in corpus cavernosum and ED in diabetic rats.MethodsFour groups of male rats were used: age‐matched normal controls; diabetic rats induced by a high‐fat diet (HFD) combined with a single streptozotocin (STZ) injection (35 mg/kg body weight, intraperitoneal [i.p.]); nondiabetic rats receiving INF (5 mg/kg body weight/week, i.p.), and diabetic rats receiving INF. Erectile function was assessed with electrical stimulation of the cavernous nerve after 8 weeks. The blood and penile tissues were harvested for plasma biochemical determinations, serum TNF‐α measurement, penile ROS detection, and molecular assays of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, endothelial nitric oxide synthase (eNOS), phospho‐eNOS, and neural nitric oxide synthase (nNOS) in the penis.Main Outcome MeasuresThe effect of INF on HFD/STZ‐induced diabetic ED and NADPH oxidase‐mediated ROS generation was studied in diabetic corpus cavernosum.ResultsUntreated diabetic rats displayed significantly decreased erectile parameters, and increased plasma TNF‐α levels, penile ROS production, p47^phox and gp91^phox expression compared with nondiabetic controls. INF neutralized TNF‐α and significantly reduced ED in diabetic rats, in which marked decreases in p47^phox and gp91^phox expression and ROS generation in corpus cavernosum were noted. The ratio of phospho‐eNOS to eNOS and expression of nNOS in the penis were significantly increased in INF‐treated vs. untreated diabetic rats.ConclusionsIncreased TNF‐α expression associated with diabetes contributes to ED by promoting NAPDH oxidase‐mediated ROS generation in corpus cavernosum. INF protects against diabetic ED by neutralizing TNF‐α. Long T, Liu G, Wang Y, Chen Y, Zhang Y, and Qin D. TNF‐α, erectile dysfunction, and NADPH oxidase‐mediated ROS generation in corpus cavernosum in high‐fat diet/streptozotocin‐induced diabetic rats. J Sex Med 2012;9:1818–1831.     

Combination of Psychological Intervention and Phosphodiesterase‐5 Inhibitors for Erectile Dysfunction: A Narrative Review and Meta‐Analysis

IntroductionErectile dysfunction (ED) is an increasing health problem that demands effective treatment. There is evidence that phosphodiesterase‐5 inhibitors (PDE5‐Is) and psychological intervention (PI) are effective treatment options; however, little is known about their comparative efficacy and the efficacy of combined treatments.AimThe aim of this systematic review and meta‐analysis is to evaluate the comparative efficacy of PI, PDE5‐Is, and their combination in the treatment of ED.Main Outcome MeasuresPrimary outcome was ED symptoms, and secondary outcome was sexual satisfaction of the patient.MethodsA systematic literature search was conducted in order to identify relevant articles published between 1998 and 2012. We included randomized controlled trials and controlled trials comparing PI with PDE5‐I treatment or one of them against a combination of both.ResultsEight studies with a total number of 562 patients were included in the meta‐analysis. The results of the included studies are inconclusive, though they show a trend towards a larger effect of combined treatment compared with PI or PDE5‐I treatment alone. The meta‐analysis found that, overall, combined treatment was more efficacious for ED symptoms than PDE5‐I treatment or PI alone. Combined treatment was more efficacious than PDE5‐I use alone on sexual satisfaction. No differences were found between PDE5‐Is and PI as stand‐alone treatments. None of the moderators (treatment duration, methodological quality, or researcher allegiance) altered the effects.ConclusionsThe combination of PI and PDE5‐Is is a promising strategy for a favorable outcome in ED and can be considered as a first‐choice option for ED patients. Stronger RCTs are required to confirm this initial finding. Schmidt HM, Munder T, Gerger H, Frühauf S, and Barth J. Combination of psychological intervention and phosphodiesterase‐5 inhibitors for erectile dysfunction: A narrative review and meta‐analysis. J Sex Med 2014;11:1376–1391.     

P144, A TGF‐β1 Antagonist Peptide,Synergizes with Sildenafil and Enhances Erectile Response via Amelioration of Cavernosal Fibrosis in Diabetic Rats

IntroductionPatients with diabetes exhibit more severe erectile dysfunction (ED) and are less responsive to first‐line oral phosphodiesterase type 5 inhibitor (PDE5i). It has been suggested that increased collagen deposition and reduced smooth muscle content in the corpus cavernosum are important mechanisms for diabetes‐associated ED and that transforming growth factor‐β1 (TGF‐β1) is a potent fibrotic factor responsible for the structural alterations in the corpus cavernosum.AimsThe aims of this study are to determine whether activation of TGF‐β1 and its downstream pathways is responsible for the reduced efficacy of the PDE5is in diabetic ED via abnormalities in cavernosal structures and to investigate the synergistic effects of the TGF‐β1 antagonist P144 and sildenafil on erectile response.MethodsSix weeks after inducting diabetes with streptozotocin in male Sprague‐Dawley rats, age‐matched control and diabetic rats were treated with vehicle, sildenafil, or P144 alone or in combination for 4 weeks, respectively.Main Outcome MeasuresIntracavernous pressure, dynamic infusion cavernosometry, and histological and molecular alterations of the corpus cavernosum were analyzed.ResultsDiabetic rats exhibited a decreased erectile response, severe corporal veno‐occlusive dysfunction (CVOD), and structural alterations including cavernosal fibrosis and decreased smooth muscle content. Expression and activation of TGF‐β1 and its downstream Smad and non‐Smad pathways increased in diabetic rats. Treatment with sildenafil showed modest effect on erectile response and a less suppressive effect on CVOD, cavernosal fibrosis, and molecular alterations. Treatment with P144 had lower effect on erectile response, even greatly improved the histological and molecular alterations and CVOD than sildenafil. The combined treatment with P144 and sildenafil effectively restored erectile response, CVOD, and histological and molecular alterations.ConclusionAn insufficient suppressive effect of sildenafil on cavernosal fibrosis, severe CVOD, and TGF‐β1 pathways was implicated in reduced efficacy of the PDE5i in diabetic ED. Treatment with P144 synergized sildenafil and significantly increased erectile response by the potential antifibrotic activity. Li WJ, Wang H, Zhou J, Li B, Zhang J, Lu M, and Wang Z. P144, a TGF‐β1 antagonist peptide, synergizes with sildenafil and enhances erectile response via amelioration of cavernosal fibrosis in diabetic rats. J Sex Med 2013;10:2942–2951.     

The Self‐Estimation Index of Erectile Function‐No Sexual Intercourse (SIEF‐NS): A Multidimensional Scale to Assess Erectile Dysfunction in the Absence of Sexual Intercourse

IntroductionA new concept of Erectile Dysfunction with No Sexual Intercourse (ED‐NS) is proposed to acknowledge the subpopulation of patients who are unable to achieve or sustain an erection in the absence of sexual intercourse. Since the commonly used ED diagnostic tool, International Index of Erectile Function Questionnaire is not able to adequately assess the erectile function (EF) in the absence of intercourse, the researchers developed a new 10‐item questionnaire to better evaluate the EF in this special patient subpopulation: Self‐Estimation Index of Erectile Function‐No Sexual Intercourse (SIEF‐NS).AimTo validate the reliability, sensitivity and specificity of SIEF‐NS.MethodsThe study was carried out in three phases. Phase one applied component analysis to 126 ED‐NS patients to search for the primary factors and Cronbach's alpha standardized statistic values for SIEF‐NS. Phase two applied discriminant analysis to participants' (212 ED‐NS patients and 193 normal controls) scores on each question item, each factor and the overall 10‐item questionnaire. Phase three investigated SIEF‐NS's capability of evaluating treatment effect on 41 ED‐NS patients.Main Outcome MeasuresReliability, sensitivity and specificity were defined and used to evaluate the performance of SIEF‐NS.ResultsEF by autonomic response (factor 1) and EF with potential sexual partners (factor 2) are the two primary factors with eigenvalues greater than 1.0. High degree of internal consistency was observed for the two factors and the 10‐item questionnaire (Cronbach's alpha values: 0.871 for 10 items, 0.84 for factor 1, and 0.823 for factor 2). SIEF‐NS demonstrated adequate construct validity, high sensitivity (0.925) and specificity (0.829) to diagnose ED‐NS. The EF scores of ED‐NS patients post treatment showed significant improvement (P < 0.05).ConclusionSIEF‐NS can be used to identify ED‐NS patients and detect treatment‐related EF changes in ED‐NS patients. Yuan Y, Zhang Z, Gao B, Peng J, Cui W, Song W, Xin Z, and Guo Y. The Self‐Estimation Index of Erectile Function‐No Sexual Intercourse (SIEF‐NS): A multidimensional scale to assess erectile dysfunction in the absence of sexual intercourse. J Sex Med 2014;11:1201–1207.     

Calcification of the Internal Pudendal Artery and Development of Erectile Dysfunction in Adenine‐Induced Chronic Kidney Disease: A Sentinel of Systemic Vascular Changes

IntroductionChronic kidney disease (CKD), erectile dysfunction (ED), and cardiovascular disease share common vascular etiologies and risk factors.AimUsing a rat model, this is the first study to characterize the consequences of CKD in the onset and development of ED associated with differential regional vascular calcification and circulatory changes.MethodsStable CKD was generated at 3 weeks in male Sprague‐Dawley rats given dietary adenine and progressed until 7 weeks. Mineral content and morphometry were assessed in the internal pudendal arteries (IPAs), thoracic aorta, and carotid artery. Endothelial function was determined via changes in serum von Willebrand factor (VWF) and endothelium‐dependent relaxation of the thoracic aorta.ResultsIn severe CKD rats, calcium and phosphate content in all arteries increased, and pulse wave velocity was elevated. Distal IPA segments, in particular, were the first to calcify, but penile tissue per se did not. CKD rats had endothelial dysfunction, as indicated by a decrease in acetylcholine‐mediated relaxation (∼40%) and an increase in serum VWF (∼40%), as well as increased lumen diameter (20%) of the distal IPA. Erectile function, assessed using a centrally acting dopaminergic agent, was significantly impaired by 7 weeks (∼40%).ConclusionsIn CKD, the distal IPA appears to be more susceptible to vascular dysfunction and calcification. Additionally, the onset of ED may be an important sentinel of impending systemic vascular disease. To confirm this concept, future experimental and clinical studies will need to examine a range of vessel types and the use of supplementary methods to assess erectile function. Maio MT, McCabe KM, Pruss CM, Pang JJ, Laverty K, Holden RM, and Adams MA. Calcification of the internal pudendal artery and development of erectile dysfunction in adenine‐induced chronic kidney disease: A sentinel of systemic vascular changes. J Sex Med 2014;11:2449–2465.     

The Role of Regulatory Proteins and S‐nitrosylation of Endothelial Nitric Oxide Synthase in the Human Clitoris: Implications for Female Sexual Function

IntroductionDuring female sexual arousal, clitoral blood flow is controlled by endothelial nitric oxide synthase (eNOS) and its product, nitric oxide (NO). The mechanisms regulating eNOS activity and NO bioavailability in the clitoris are largely unknown.AimTo identify proteins involved in regulation of eNOS activity within the clitoris and to evaluate the effects of S‐nitrosoglutathione reductase (GSNO‐R) and eNOS nitrosylation/denitrosylation on clitoral blood flow.MethodsImmunohistochemistry for eNOS, caveolin‐1 (Cav1), heat shock protein‐90 (Hsp90), phosphodiesterase type 5 (PDE5), GSNO‐R, and soluble guanylate cyclase (sGC) was performed on human and murine clitoral tissue. Western blot analysis was performed for eNOS, phosphorylated eNOS (phospho‐eNOS, Ser1177), Cav1, Hsp90, sGC, PDE5, phosphoinositide 3‐kinase (PI3K), Akt (protein kinase B), and GSNO‐R on protein from human clitoral tissue. A biotin switch assay was used to analyze the S‐nitrosylation of eNOS, nNOS, and GSNO‐R. Clitoral blood flow was measured in wild‐type and GSNO‐R^‐/‐ mice at baseline and during cavernous nerve electrical stimulation (CNES).Main Outcome MeasuresLocalization of eNOS regulatory proteins and clitoral blood flow.ResultseNOS and GSNO‐R co‐localized to the vascular endothelium and sinusoids of human clitoral tissue. Immunohistochemistry also localized Cav1 and Hsp90 to the endothelium and PDE5 and sGC to the trabecular smooth muscle. Expression of S‐nitrosylated (SNO)‐eNOS and SNO‐GSNO‐R was detected by biotin switch assays. Wild‐type control mice exhibited increased clitoral blood flow with CNES whereas GSNO‐R^‐/‐ animals failed to show an increase in blood flow.ConclusionsSeveral key eNOS regulatory proteins are present in the clitoral tissue in a cellular specific pattern. S‐nitrosylation of eNOS may also represent a key regulatory mechanism governing eNOS activation/deactivation since mice deficient in GSNO‐R failed to increase clitoral blood flow. Additional studies are necessary to define the role of S‐nitrosylation in the genital vascular response and its subsequent impact on female sexual function. Oliver JL, Kavoussi PK, Smith RP, Woodson RI, Corbett ST, Costabile RA, Palmer LA, and Lysiak JJ. The role of regulatory proteins and s‐nitrosylation of endothelial nitric oxide synthase in the human clitoris: Implications for female sexual function. J Sex Med 2014;11:1927–1935.     

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

Introduction

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

A Randomized,Double‐Blind,Placebo‐Controlled Evaluation of the Safety and Efficacy of Avanafil in Subjects with Erectile Dysfunction

IntroductionPhosphodiesterase type 5 (PDE5) inhibitors have become standard treatment for erectile dysfunction (ED).AimTo prospectively evaluate the safety and efficacy of avanafil, a novel PDE5 inhibitor, in men with mild to severe ED.MethodsIn this multicenter, double‐blind, Phase 3 trial, 646 subjects were randomized to receive avanafil (50 mg, 100 mg, 200 mg) or placebo throughout a 12‐week treatment period. Subjects were instructed to take study drug 30 minutes prior to initiation of sexual activity. At least a 12‐hour separation time between doses was required; no restrictions were placed on food or alcohol intake.Main Outcome MeasuresImprovement in erectile function (EF) was measured by Sexual Encounter Profile questions 2 and 3 (SEP2 and SEP3) and by the EF domain of the International Index of Erectile Function (IIEF) questionnaire.ResultsMean change in percentage of successful sexual attempts (SEP2 and SEP3) and IIEF‐EF domain score significantly favored all doses of avanafil over placebo (P ≤ 0.001). Secondary analyses demonstrated achievement of successful intercourse by subjects within 15 minutes of dosing. Of the 300 sexual attempts made during this interval, 64% to 71% were successful in avanafil‐treated subjects compared with 27% in placebo‐treated subjects. Successful intercourse was also demonstrated >6 hours post dosing, with 59% to 83% of the 80 sexual attempts successful in avanafil‐treated subjects compared with 25% of placebo‐treated subjects. The most commonly reported adverse events in subjects taking avanafil included headache, flushing, and nasal congestion; there were no drug‐related serious adverse events.ConclusionFollowing 12 weeks of avanafil treatment without food or alcohol restrictions, significant improvements in sexual function were observed with all 3 doses of avanafil compared with placebo. Successful intercourse was observed as early as 15 minutes and >6 hours after dosing in some subjects. Avanafil was generally well tolerated for the treatment of ED. Goldstein I, McCullough AR, Jones LA, Hellstrom WJ, Bowden CH, DiDonato K, Trask B, and Day WW. A randomized, double‐blind, placebo‐controlled evaluation of the safety and efficacy of avanafil in subjects with erectile dysfunction. J Sex Med 12;9:1122–1133.     

Functional and Morphologic Characterizations of the Diabetic Mouse Corpus Cavernosum: Comparison of a Multiple Low‐Dose and a Single High‐Dose Streptozotocin Protocols

IntroductionWith the advent of genetically modified mice, it seems particularly advantageous to develop a mouse model of diabetic erectile dysfunction.AimTo 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.MethodsEight‐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 × 5 days), and a group administered the single high‐dose STZ protocol (200 mg/kg).Main Outcome MeasuresAfter 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 α‐actin, and phospho‐eNOS. Penis specimens from a separate group of animals were used for phospho‐eNOS and eNOS western blot or cGMP determination.ResultsErectile 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.ConclusionThe mouse model of type I diabetes is useful and technically feasible for the study of the pathophysiologic mechanisms involved in diabetic erectile dysfunction. Jin H‐R, Kim WJ, Song JS, Choi MJ, Piao S, Shin SH, Tumurbaatar M, Tuvshintur B, Nam M‐S, Ryu J‐K, and Suh, J‐K. Functional and morphologic characterizations of the diabetic mouse corpus cavernosum: comparison of a multiple low‐dose and a single high‐dose streptozotocin protocols.     

Superoxide Anion Production by NADPH Oxidase Plays a Major Role in Erectile Dysfunction in Middle‐Aged Rats: Prevention by Antioxidant Therapy

Introduction.Prevalence of erectile dysfunction (ED) increases progressively with aging, but the ED pathophysiology at its early stages is still poorly investigated.Aim.This study aimed to evaluate the functional and molecular alterations of erectile function at middle age, focusing on the contribution of oxidative stress in erectile tissue for the ED.Methods.Young (3.5‐month) and middle‐aged (10‐month) male Wistar rats were used. Rat corpus cavernosum (RCC) was dissected free and mounted in 10‐mL organ baths containing Krebs solution. Intracavernosal pressure (ICP) in anesthetized rats was evaluated.Main Outcome Measures.Concentration–response curves to endothelium‐dependent and endothelium‐independent agents, as well as to electrical field stimulation (EFS), were obtained in RCC strips. Measurement of cyclic guanosine monophosphate (cGMP) and expressions of neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS), gp91^phox and superoxide dismutase‐1 (SOD‐1) expressions in RCC were evaluated.Results.ICP was significantly reduced in middle‐aged compared with young rats. RCC relaxations to acetylcholine (10^?8 to 10^?2 M), sodium nitroprusside (10^?8 to 10^?2 M), sildenafil (10^?9 to 10^?5 M), BAY 41‐2272 (10^?9 to 10^?5 M), and EFS (4–32 Hz) were decreased in middle‐aged group, which were nearly normalized by apocynin (NADPH oxidase inhibitor; 10^?4 M) or SOD (75 U/mL). Prolonged treatment with apocynin (85 mg/rat/day, 4 weeks) also restored the impaired relaxations in middle‐aged rats. Relaxations to 8‐bromoguanosine 3′,5′‐cyclic monophosphate sodium salt (8‐Br‐cGMP; 10^?8 to 3 × 10^?4 M) remained unchanged between groups. Basal and stimulated cGMP production were lower in middle‐aged group, an effect fully restored by apocynin and SOD. Protein expression of nNOS and phosphorylated eNOS (p‐eNOS) (Ser‐1177) reduced, whereas gp^91phox mRNA expression increased in RCC from middle‐aged rats.Conclusions.ED in middle‐aged rats is associated with decreased NO bioavailability in erectile tissue due to upregulation of NADPH oxidase subunit gp91^phox and downregulation of nNOS/p‐eNOS. Antioxidant therapies may be a good pharmacological approach to prevent ED at its early stages.