Ginsenoside Rg3 Improves Erectile Function in Streptozotocin‐Induced Diabetic Rats

IntroductionGinsenoside Rg3 is one of the active ingredients isolated from Panax ginseng C.A. Meyer. Previous studies demonstrated that Rg3 has antioxidant and neuroprotective abilities.AimThe purpose of this study was to evaluate the protective effect of Rg3 on erectile function in streptozotocin (STZ)‐induced diabetic rats.MethodsTwo‐month‐old Sprague‐Dawley male rats received a one‐time intraperitoneal (IP) STZ (60 mg/kg) or vehicle injection after a 16‐hour fast. Three days later, rats were randomly divided into four groups and were treated with daily gavage feedings of a mix of distilled saline water and 0.5% carboxymethylcellulose or Rg3 dissolved in the mix at doses of 10 mg/kg and 100 mg/kg for 3 months. A sham group underwent IP injection of saline followed by daily gavage of the above mix for 3 months.Main Outcome MeasureErectile function was assessed by cavernosal nerve electrostimulation at 3 months. The penis was then harvested and deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was performed. Western blot was performed to examine cleaved caspase‐3, platelet endothelial cell adhesion molecule (PECAM)‐1, and smooth muscle actin (SMA). Neural regeneration was measured by nicotinamide adenine dinucleotide phosphate (NADPH)‐diaphorase staining. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected by colorimetry.ResultsIn the negative control group, the functional evaluation showed a lower mean intracavernosal pressure (ICP) with cavernosal nerve stimulation than in the sham group; there was a significant change in the expression of cleaved caspase‐3, bcl‐2, bcl‐xl, PECAM‐1, and SMA, as well as in the SOD and MDA production in the corpus cavernosum. Histological analysis of specimens stained for NADPH showed a significant change in the staining quality of the neurons in the dorsal nerves; TUNEL showed a greater apoptotic index in corpus cavernosum cells. With daily oral gavage with 100 mg/kg Rg3, the ICP/mean arterial pressure value was significantly higher than in the controls. The level of cleaved caspase‐3, bcl‐2, bcl‐xl, PECAM‐1, and SMA and the number of positively stained nerve fibers tended to revert to normal after Rg3 treatment. The apoptotic index in corpus cavernosum cells was lowered.ConclusionOral gavage with Rg3 appears to both prevent degeneration of neurons in the dorsal nerves and exert an antioxidant effect in the corpus cavernosum of rats. Liu T, Peng Y‐F, Jia C, Yang B‐H, Tao X, Li J, and Fang X. Ginsenoside Rg3 improves erectile function in streptozotocin‐induced diabetic rats. J Sex Med 2015;12:611–620.     

Apocynin Improves Erectile Function in Diabetic Rats through Regulation of NADPH Oxidase Expression

IntroductionDiabetes is a risk factor for erectile dysfunction (ED). The proposed mechanisms responsible for diabetic ED are associated with an increase in reactive oxygen species (ROS) production, overactivity of RhoA/ROCK signaling pathway and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, as seen in experimental models of diabetic rats.AimThe aim of this study was to investigate whether NADPH oxidase inhibitor apocynin can ameliorate Streptozotocin (STZ)‐induced diabetes‐related ED by reducing the ROS production and inhibiting the activity of RhoA/ROCK signaling pathway.MethodsThe diabetic rats were treated with and without the NADPH oxidase inhibitor apocynin.Main Outcome MeasuresErectile responses were evaluated by determining mean arterial blood pressure (MAP) and intracavernosal pressure (ICP) with electrical stimulation of the cavernous nerve. Levels of mRNA expression were measured by real‐time polymerase chain reaction (RT‐PCR). Levels of protein expression were examined by Western Blot. ROS production was measured by dihydroethidium (DHE) staining and thiobarbituric acid reactive substances assay.ResultsThe ratio of Maximum ICP‐to‐MAP (MaxICP/MAP) was significantly decreased in diabetic ED rats, compared to that of age‐matched control rats (P < 0.05). Apocynin improved erectile function of diabetic rats (P < 0.05). Expression levels of RhoA (cytosol), nNOS and eNOS were reduced, compared to those of control rats (P < 0.05). Apocynin significantly elevated their expression levels in diabetic rats (P < 0.05). Expression levels of ROCK1, RhoA (membrane fraction), p‐MYPT1 and NADPH oxidase subunits p47^phox and p67^phox were increased in diabetic rats when compared to those of control rats (P < 0.05), and it was observed that apocynin significantly reduced their expression levels in diabetic rats (P < 0.05). ROS production was increased in diabetic rats when compared to that of control rats (P < 0.05), the effect of apocynin was a reduction in the ROS production in diabetic rats (P < 0.05).ConclusionNADPH oxidase inhibitor apocynin can ameliorate diabetes‐related ED by reducing the ROS production and inhibiting the activity of RhoA/ROCK signaling pathway. Li M, Zhuan L, Wang T, Rao K, Yang J, Yang J, Quan W, Liu J, and Ye Z. Apocynin improves erectile function in diabetic rats through regulation of NADPH oxidase expression. J Sex Med 2012;9:3041–3050.     

A Protein Tyrosine Kinase Inhibitor,Imatinib Mesylate (Gleevec), Improves Erectile and Vascular Function Secondary to a Reduction of Hyperglycemia in Diabetic Rats

IntroductionErectile dysfunction (ED) afflicts 50% of diabetic men, many of whom experience poor results with phosphodiesterase type 5 inhibitors. The protein tyrosine kinase (PTK) inhibitor imatinib (Gleevec, Novartis Pharmaceuticals, Basel, Switzerland) has therapeutic potential in diabetic men by maintaining β-cell function.AimTo determine if imatinib has a beneficial effect on erectile and vascular function in diabetic rats.MethodsMale Sprague-Dawley rats were divided into six groups: (i) control; (ii) imatinib (50 mg/kg, daily gavage)-treated control; (iii) diabetic; (iv) preventive imatinib (8 weeks); (v) reversal imatinib (4 weeks untreated diabetes and 4 weeks of treatment); and (vi) insulin (8 weeks)-treated diabetic rats.Main Outcome MeasuresAfter 8 weeks, all groups underwent cavernosal nerve stimulation and measurements of intracavernosal pressure (ICP) and mean arterial pressure (MAP). Contractile and relaxation responses were evaluated using isolated strips of corpus cavernosum smooth muscle (CCSM) and aorta.ResultsDiabetic rats exhibited a 32% decrease in weight and fivefold increase in blood glucose levels. Imatinib-treated diabetic rats gained weight and partially improved blood glucose levels. Diabetic rats displayed a decrease in ICP/MAP. While maximum electrical field stimulation- and acetylcholine (ACh)-induced relaxations in CCSM strips from the diabetics were reduced, preventive imatinib or insulin treatment normalized ICP/MAP ratios and improved relaxation responses. ACh responses in diabetic aortas were diminished by 50.1% and restored by imatinib. While contractile responses to phenylephrine in diabetic CCSM were not altered, there was a significant enhancement (59.4 %) in the aortic contractile response in diabetic rats, which was restored by imatinib and insulin treatment.ConclusionsIn diabetic rats, prolonged therapy with imatinib improves diabetes-related ED and vascular function, which may involve normalization of high glucose levels and restoration of PTK activation. Future studies are needed to elaborate on the actions of imatinib on diabetic vascular complications. Gur S, Kadowitz PJ, and Hellstrom WJG. A protein tyrosine kinase inhibitor, imatinib mesylate (Gleevec), improves erectile and vascular function secondary to a reduction of hyperglycemia in diabetic rats.     

NOX1/4 Inhibitor GKT-137831 Improves Erectile Function in Diabetic Rats by ROS Reduction and Endothelial Nitric Oxide Synthase Reconstitution

BackgroundPrevious studies have shown that oxidative stress contributes to hyperglycemia-induced erectile dysfunction. A preferential direct inhibitor of NOX1 and NOX4, GKT-137831, exhibited a strong anti‑oxidative role via blockade of reactive oxygen species (ROS) generation in endothelial cells, but whether GKT-137831 could improve erectile function was not clear.AimOur study was designed to investigate the effect of NOX1/4 inhibition on improving diabetic erectile dysfunction (ED) in rats.MethodsWe used streptozotocin to induce type 1 diabetes mellitus (DM) in 32 male Sprague Dawley (SD) rats (8 weeks old). Eight weeks later, type 1 diabetes mellitus-induced erectile dysfunction (DMED) in rats was confirmed using an apomorphine test. Our study consisted of 3 groups: (i) nondiabetic control group (n = 8), (ii) DMED + vehicle group (DMED group; n = 8), and (iii) DMED + GKT-137831 group (n = 9); GKT-137831 was given as a once-daily intraperitoneal injection for 4 weeks. Cavernous nerve electrostimulation was used to evaluate erectile function. Western blot, ELISA, immunohistochemistry, and immunofluorescence were used to measure expression of specific proteins, and DHE fluorescent probe was performed to detect ROS level.OutcomesIntracavernous pressure (ICP), nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway, oxidative stress level, inflammatory response, corporal autophagy, and apoptosis were measured.ResultsErectile function in the DMED group was significantly impaired compared to the nondiabetic control group, whereas this impairment was improved with GKT-137831 treatment by 70%. Similarly, endothelial function and overactivated oxidative stress in the corpus cavernosum (CC) of the DMED + GKT-137831 group were improved. The DMED group showed serious inflammatory responses and excessive autophagy, which were inhibited by GKT-137831 treatment in the DMED + GKT-137831 group.Clinical TranslationOur study showed improvement in erectile function with GKT-137831 in a diabetic rat ED model.Strength and LimitationsThis study suggested for the first time that GKT-137831, an NOX1/4 inhibitor undergoing clinical trials, is effective in improving erectile function in rats with type 1 DMED. However, we only investigated GKT-137831 treatment of streptozotocin-induced type 1 diabetic rats, and therapeutic evidence in other types of diabetes is lacking.ConclusionGKT-137831 improves erectile function by 70% in type 1 DMED rats and constitutes a promising compound for the treatment of type 1 DMED, likely by inhibition of overactivated oxidative stress, down-regulation of proinflammatory factors, and amelioration of excessive autophagy and endothelial function.B Zhou, Y Chen, H Yuan, et al. NOX1/4 Inhibitor GKT-137831 Improves Erectile Function in Diabetic Rats by ROS Reduction and Endothelial Nitric Oxide Synthase Reconstitution. J Sex Med 2021;18:1970–1983.     

Metformin Treatment Improves Erectile Function in an Angiotensin II Model of Erectile Dysfunction

IntroductionIncreased angiotensin II (AngII) levels cause hypertension, which is a major risk factor for erectile dysfunction (ED). Studies have demonstrated that increased AngII levels in penile tissue are associated with ED. A recent study showed that metformin treatment restored nitric oxide synthase (NOS) protein expression in penile tissue in obese rats; however, whether metformin treatment can be beneficial and restore erectile function in a model of ED has not yet been established.AimThe goal of this study was to test the hypothesis that AngII induces ED by means of increased corpus cavernosum contraction, and that metformin treatment will reverse ED in AngII-treated rats.MethodsMale Sprague-Dawley rats were implanted with mini-osmotic pumps containing saline or AngII (70 ng/minute, 28 days). Animals were then treated with metformin or vehicle during the last week of AngII infusion.Main Outcome MeasuresIntracavernosal pressure; corpus cavernosum contraction and relaxation; nNOS protein expression; extracellular signal-regulated kinase (ERK1/2), AMP-activated protein kinase (AMPK), and eNOS protein expression and phosphorylation.ResultsAngII-induced ED was accompanied with an increase in corpus cavernosum contractility, decreased nitrergic relaxation, and increased ERK1/2 phosphorylation. Metformin treatment improved erectile function in the AngII-treated rats by reversing the increased contraction and decreased relaxation. Metformin treatment also resulted in an increase in eNOS phosphorylation at ser1177.ConclusionsMetformin treatment increased eNOS phosphorylation and improved erectile function in AngII hypertensive rats by reestablishing normal cavernosal smooth muscle tone. Labazi H, Wynne BM, Tostes R, and Webb RC. Metformin treatment improves erectile function in an angiotensin II model of erectile dysfunction. J Sex Med 2013;10:2154–2164.     

Putative Role of Carbon Monoxide Signaling Pathway in Penile Erectile Function

IntroductionErectile response depends on nitric oxide (NO) generated by NO synthase (NOS) enzyme of the nerves and vascular endothelium in the cavernous tissue. NO activates soluble guanylate cyclase (sGC), leading to the production of cyclic guanosine monophosphate (cGMP). cGMP activates cGMP-dependent protein kinase that activates Ca²⁺/ATPase pump that activates Ca²⁺/K efflux pump extruding Ca²⁺ across the plasma membrane with consequent smooth muscle cell relaxation. A role similar to that of NOS/NO signaling has been postulated for carbon monoxide (CO) produced in mammals from heme catabolism by heme oxygenase (HO) enzyme.AimTo assess CO signaling pathway for erectile function by reviewing published studies.MethodsA systematic review of published studies on this affair based on Pubmed and Medical Subject Heading databases, with search for all concerned articles.Main Outcome MeasuresDocumentation of positive as well as negative criteria of CO/HO signaling focused on penile tissue.ResultsThe concept that HO-derived CO could play a role in mediating erectile function acting in synergism with, or as a potentiator for, NOS/NO signaling pathway is gaining momentum. CO/HO signaling pathway has been shown to partially mediate the actions of oral phosphodiesterase type 5 inhibitors. In addition, it was shown that the use of CO releasing molecules potentiated cavernous cGMP levels. However, increased CO production or release was reported to be associated, in some studies, with vasoconstriction.ConclusionThis review sheds a light on the significance of cavernous tissue CO signaling pathway that may pave the way for creation of therapeutic modalities based on this pathway. Abdel Aziz MT, Mostafa T, Atta H, Wassef MA, Fouad HH, Rashed LA, and Sabry D. Putative role of carbon monoxide signaling pathway in penile erectile function.     

Intracavernous Injection of Human Umbilical Cord Blood Mononuclear Cells Improves Erectile Dysfunction in Streptozotocin-Induced Diabetic Rats

IntroductionErectile dysfunction (ED) worsens in men with diabetes. Human umbilical cord blood (HUCB), because of its widespread availability and low immunogenicity, is a valuable source for stem cell-based therapies.AimTo determine the effect of intracavernous injection of HUCB mononuclear cells (MNCs) on ED in rats with diabetes induced by streptozotocin.MethodsThirty adult male Sprague-Dawley rats were equally divided into three groups: (i) control, (ii) diabetes induced by streptozotocin (35 mg/kg intravenously for 8 weeks), and (iii) diabetic rats treated with MNCs (1 × 10⁶ cells by intracavernosal injection). The HUCB-MNCs isolated by the Ficoll-Hypaque technique were obtained from eight healthy donors and administered to diabetic rats after 4 weeks.Main Outcome MeasuresThe ratio of intracavernosal pressure to mean arterial pressure ratio; the protein expression of endothelial and neuronal markers, such as von Willebrand factor, neuronal nitric oxide synthase, hypoxia-inducible factor-1α, and vascular endothelium growth factor; and the relative area of smooth muscle to collagen using western blotting and Masson trichrome staining were determined.ResultsDiabetic rats demonstrated a significantly decreased ratio of intracavernosal pressure to mean arterial pressure (0.26 ± 0.04; P < .01) and treatment with MNCs restored erectile function in diabetic rats (0.67 ± 0.05) compared with control rats (0.56 ± 0.02). In bath studies, neurogenic relaxant and contractile responses were significantly decreased in diabetic cavernosal tissues, which were restored by treatment. The ratio of smooth muscle to collagen was partly recovered by treatment, whereas von Willebrand factor levels were not altered in any group. Neuronal nitric oxide synthase and vascular endothelium growth factor levels were decreased, which were not restored by treatment. Increased hypoxia-inducible factor-1α protein expression in the diabetic group was completely normalized in MNC-treated diabetic samples.ConclusionThese results suggest that HUCB-MNC treatment can enhance the recovery of erectile function and promote numerous activities such the contribution of the hypoxia-inducible factor-1α and von Willebrand factor pathway to the neurogenic erectile response of diabetic rats. HUCB-MNCs in the healing process could involve an adaptive regenerative response and appear to be a potential candidate for cell-based therapy in ED of men with diabetes. It is evident that HUCB could provide a realistic therapeutic modality for the treatment of diabetic ED.     

Losartan,an Angiotensin Type I Receptor,Restores Erectile Function by Downregulation of Cavernous Renin-Angiotensin System in Streptozocin-Induced Diabetic Rats

IntroductionThe high incidence of erectile dysfunction (ED) in diabetes highlights the need for good treatment strategies. Recent evidence indicates that blockade of the angiotensin type I receptor (AT1) may reverse ED from various diseases.AimTo explore the role of cavernous renin-angiotensin system (RAS) in the pathogenesis of diabetic ED and the role of losartan in the treatment of diabetic ED.MethodsThe AT1 blocker (ARB) losartan (30 mg/kg/d) was administered to rats with streptozocin (65 mg/kg)-induced diabetes. Erectile function, cavernous structure, and tissue gene and protein expression of RAS in the corpora cavernosa were studied.Main Outcome MeasureWe sought to determine the changes of cavernous RAS in the condition of diabetes and after treatment with losartan.ResultsRAS components (angiotensinogen, [pro]renin receptor, angiotensin-converting enzyme [ACE], and AT1) were expressed in cavernosal tissue. In diabetic rats, RAS components were upregulated, resulting in the increased concentration of angiotensin II (Ang II) in the corpora. A positive feedback loop for Ang II formation in cavernosum was also identified, which could contribute to overactivity of cavernous RAS in diabetic rats. Administration of losartan blocked the effect of Ang II, downregulated the expression of AT1 and Ang II generated locally, and partially restored erectile function (losartan-treated group revealed an improved intracavernous pressure/mean systemic arterial pressure ratio as compared with the diabetic group (0.480 ± 0.031 vs. 0.329 ± 0.020, P < 0.01). However, losartan could not elevate the reduced smooth muscle/collagen ratio in diabetic rats.ConclusionsThe cavernous RAS plays a role in modulating erectile function in corpora cavernosa and is involved in the pathogenesis of diabetic ED. ARB can restore diabetic ED through downregulating cavernous RAS. Yang R, Yang B, Wen Y, Fand F, Cui S, Lin G, Sun Z, Wang R, and Dai Y. Losartan, an angiotensin type I receptor blocker, restores erectile function by down-regulation of cavernous renin-angiotensin system in streptozocin-induced diabetic rats. J Sex Med 2009;6:696–707.     

Effects of Losartan,HO‐1 Inducers or HO‐1 Inhibitors on Erectile Signaling in Diabetic Rats

IntroductionActivation of the renin‐angiotensin system which is common in diabetes mellitus might affect heme oxygenase (HO‐1) gene expression.AimAssessment of the effects of administration of angiotensin II (Ang II) receptor antagonist (losartan) with HO‐1 inducer or inhibitor on erectile signaling in diabetic rats.Materials and MethodsSeventy male rats were divided equally into seven groups; healthy controls, streptozotocin‐induced diabetic rats, rats on citrate buffer, diabetic rats on losartan, diabetic rats on HO‐1 inducer (cobalt protoporphyrin [CoPP]), diabetic rats on losartan and CoPP, and diabetic rats on losartan and HO‐1 inhibitor (stannus mesoporphyrin [SnMP]).Main Outcome MeasureHO enzyme activity, HO‐1 gene expression, cyclic guanosine monophosphate (cGMP) assay, intracavernosal pressure (ICP), and cavernous tissue sinusoids surface area.ResultsHO‐1 gene expression, HO enzymatic activity, and cGMP were significantly decreased in the cavernous tissue of diabetic rats. These parameters were significantly elevated with the use of CoPP that restored the normal control levels of HO enzyme activity. Administration of losartan exhibited a significant enhancing effect on these parameters compared with the diabetic group, but not restored to the control levels, whereas administration of CoPP combined with losartan led to the restoration of their normal levels. ICP demonstrated significant decline in diabetic rats. The use of CoPP and/or losartan led to its significant improvement compared with diabetic rats. Administration of either losartan and/or CoPP led to a significant increase in the cavernous sinusoids surface area of diabetic rats. Administration of losartan with SnMP significantly decreased the enhancing effect of losartan on the studied parameters.ConclusionThe decline in erectile function in diabetes mellitus could be attributed to the downregulation of HO‐1 gene expression. HO‐1 induction added to Ang II receptor antagonist could improve erectile function. Abdel Aziz MT, El Asmer MF, Mostafa T, Atta H, Mahfouz S, Fouad H, Rashed L, Sabry D, Hassouna A, Abdel Aziz AT, Senbel A, and Demery A. Effects of losartan, HO‐1 inducers or HO‐1 inhibitors on erectile signaling in diabetic rats.     

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

IntroductionNovel therapeutic targets for diabetes-induced erectile dysfunction (DED) are urgently needed. Previous studies have proved that S100A1, a small Ca²⁺-binding protein, is a pluripotent regulator of cardiovascular pathophysiology. Its absence is associated with endothelial dysfunction, the central event linking cardiovascular changes in diabetes. However, the role of S100A1 in DED remains unknown.AimTo explore the effect and underlying mechanisms of S100A1 in restoring erectile function in type I diabetic rat model.MethodsDiabetes was induced by intraperitoneal injection of streptozotocin and then screened by apomorphine (APO) to confirm erectile dysfunction. Rats that met the criteria of penile erection were marked as APO-positive; otherwise, the result was APO-negative. In experiment 1, S100A1 gene expression alterations in the corpus cavernosum in moderate and established stages of DED were analyzed. In experiment 2, S100A1 and control GFP gene were delivered into the corpus cavernosum in APO-negative rats by adeno-associated virus (AAV) serotype 9. Erectile function was assessed at 4 weeks after gene therapy.Main Outcome MeasuresErectile response, histologic and molecular alterations.ResultsS100A1 protein was localized to the area surrounding the cavernosal sinusoids in the penis, and it was gradually downregulated synchronized with the progression of DED. Compared with an injection of AAV-GFP, a single injection of AAV-S100A1 significantly restored erectile function in diabetic rats. S100A1 overexpression significantly upregulated the expression of endogenous VEGF-A, promoted VEGFR2 internalization, and subsequently triggered the protein kinase B–endothelial nitric oxide synthase pathway in diabetic erectile tissues. Marked increases in nitric oxide and endothelial content were noted in AAV-S100A1-treated diabetic rats.Clinical ImplicationsLocal S100A1 overexpression may be an alternative therapy for DED and should be further investigated by future clinical studies.Strength & LimitationsThis is the first study demonstrating the angiogenic role of S100A1 in DED, but does not preclude the contribution of the effects of S100A1 in other tissues such as the neuronal tissue on the functional effects observed in erectile responses.ConclusionThe decreased expression of S100A1 during hyperglycemia might be important in the development of erectile dysfunction. S100A1 may play a potential role in restoring erectile function in rats with DED through modulating cavernous angiogenesis.Yu Z, Zhang Y, Tang Z, et al. Intracavernosal Adeno-Associated Virus-Mediated S100A1 Gene Transfer Enhances Erectile Function in Diabetic Rats by Promoting Cavernous Angiogenesis via VEGF-A/VEGFR2 Signaling. J Sex Med 2019;16:1344–1354.     

Platelet-Rich Plasma (PRP) Improves Erectile Function: A Double-Blind,Randomized, Placebo-Controlled Clinical Trial

BackgroundAnimal studies postulate that platelet-rich plasma (PRP) injections improve key elements of the pathophysiologic mechanisms leading to erectile dysfunction (ED).AimTo conduct the first double-blind, randomized, placebo-controlled trial assessing the efficacy and safety of PRP injections in patients with mild and moderate ED.MethodsSixty sexually active patients with mild and moderate ED were randomly assigned to two sessions, with a one-month difference, of 10 mL PRP (n = 30) or placebo (n = 30) intracavernosal injections. An FDA-approved separation system was used. Patients were evaluated at 1, 3 and 6 months after completion of the treatment protocol. A per-protocol analysis was applied. All participants withheld any ED treatment during the trial.OutcomesThe achievement of minimal clinically important difference (MCID) in the International Index of Erectile Function – Erectile Domain (IIEF-EF) from baseline to 6 months after final treatment. Erectile function at all time points, as well as safety of PRP injections, were also evaluated.ResultsAt 6 months, a MCID was achieved by 20/29 (69%) patients in the PRP group compared to 7/26 (27%) in the placebo group. The risk difference between the two groups was 42% (95%CI: 18?66), P < 0.001 and the baseline-adjusted mean between-group-difference in the IIEF-EF score was 3.9 points (95%CI: 1.8?5.9). Similarly, a statistically significant difference of both the number of participants attaining a MCID and the IIEF-EF score was also observed at the 1- and 3-month evaluation between the two groups. Accordingly, patients receiving PRP were more satisfied with the treatment. No adverse events were observed during the study period.Clinical implicationsIntracavernosal PRP injection therapy used as outlined in this trial appears to be a safe and effective short-term treatment for the management of mild to moderate ED.Strengths & LimitationsWe conducted the first clinical trial exploring the role of PRP in the management of ED. Conversely, our findings lack external validity due to single-center design. Furthermore, our results cannot be extrapolated to other PRP separation systems.ConclusionsPRP intracavernosal injections may be a promising addition to the urologist's armamentarium for the management of ED. Still, further high-quality studies are warranted to corroborate our findings. Evangelos P, Mykoniatis I, Pyrgidis N, et al. Platelet-Rich Plasma (PRP) Improves Erectile Function: A Double-Blind, Randomized, Placebo-Controlled Clinical Trial. J Sex Med 2021;18:926–935.     

Chronic Administration of Sildenafil Modified the Impaired VEGF System and Improved the Erectile Function in Rats with Diabetic Erectile Dysfunction

IntroductionMen frequently develop diabetic erectile dysfunction (DMED), as a result of endothelial dysfunction. DMED patients often have reduced efficacy with phosphodiesterase type 5 inhibitors therapy.AimTo determine whether chronic sildenafil administration can modify the impaired vascular endothelial growth factor (VEGF) system and improve the erectile function in rats with diabetic erectile dysfunction.MethodsA group of Sprague Dawley rats (n = 30) with DMED were induced by intraperitoneal injection of streptozotocin (40 mg/kg) and screened by subcutaneous injection of Apomorphine (100 mg/kg). They were then exposed to either vehicle or sildenafil (prescribed in our hospital, 5 mg/kg and 10 mg/kg, respectively) for 10 weeks. An additional nondiabetic and age-matched control group (n = 10) was also allocated and given the routine diet for the same period. Assessments were performed to both groups at 36 hours after the last dose of sildenafil. Penile intracavernous pressure (ICP), mean arterial pressure (MAP), penile tissue morphology, immunohistologic analysis, and Western blot analysis of VEGF, VEGFR1, and eNOS were determined.Main Outcome MeasureFunctional, morphological, and proteomical changes on penile structures by the chronic Sildenafil (5 mg/kg and 10 mg/kg, respectively) administration were determined.ResultsA significant increase of ICP, ICP/MAP ratio, and area under the curve were observed in the both groups treated by sildenafil (5 mg/kg and 10 mg/kg, respectively), compared with the DMED rats without receiving Sildenafil. Immunohistochemical staining of their penile tissue showed a decrease in VEGF, VEGFR1, and eNOS staining in the controlled group compared with an improvement in the chronic sildenafil administration group. Western blot analysis demonstrated exactly the same results.ConclusionWe demonstrated that daily sildenafil administration can restore the impaired VEGF system in the penis of DMED rats and progressively improve both erectile function and endothelial function, suggesting a potential general mechanism of improved signaling through the VEGF/eNOS signaling cascade. Liu G, Sun X, Dai Y, Zheng F, Wang D, Huang Y, Bian J, and Deng C. Chronic administration of sildenafil modified the impaired VEGF system and improved the erectile function in rats with diabetic erectile dysfunction.     

Nebivolol Dilates Human Penile Arteries and Reverses Erectile Dysfunction in Diabetic Rats through Enhancement of Nitric Oxide Signaling

IntroductionTraditional beta-blockers have sometimes been associated with erectile dysfunction (ED). Nebivolol is a cardioselective β₁-adrenoceptor antagonist that promotes vasodilation through a nitric oxide (NO)-dependent mechanism.AimWe evaluated the effects of nebivolol on the NO/cyclic guanosine monophosphate (cGMP) signaling pathway, on erectile function and dysfunction, and in human penile vascular tissues.MethodsErectile response to cavernosal nerve electrical stimulation in control and diabetes-induced ED rats were evaluated, along with serum nitrite/nitrate (NOx) concentration and plasma/tissue cGMP levels. Endothelium-dependent and sildenafil-induced relaxation of isolated human corpus cavernosum (HCC) and human penile resistance arteries (HPRA) were also determined.Main Outcome MeasuresThe effects of nebivolol on erectile function and dysfunction and on NO/cGMP-mediated responses.ResultsTreatment with nebivolol significantly potentiated erectile response in control rats, regardless of its effects on blood pressure. Nebivolol increased NOx and plasma cGMP by 3-fold and 2.75-fold, respectively, and significantly augmented the elevation of plasma cGMP produced by sildenafil. Nebivolol enhanced endothelium-dependent and sildenafil-induced relaxations of HCC tissue, and produced endothelium-dependent vasodilation of HPRA. Nebivolol, but not atenolol, significantly improved erectile response in diabetic rats (51.6%, 53.2%, and 87.1% of response at 3 Hz in nondiabetic rats, for vehicle-treated, atenolol-treated, and nebivolol-treated diabetic rats, respectively); after sildenafil administration, ED was completely reversed in nebivolol-treated diabetic rats (69.6% and 112% for diabetic rats treated with sildenafil and nebivolol plus sildenafil, respectively). Accordingly, nebivolol restored systemic NOx levels and cGMP content in penile tissue from these animals.ConclusionsNebivolol in vivo activated the NO/cGMP pathway, enhanced erectile response and reversed ED in diabetic rats. Moreover, nebivolol in vitro potentiated NO/cGMP-mediated relaxation of human erectile tissues. These effects may account for the low incidence of ED in nebivolol-treated hypertensive patients. Nebivolol therefore may have utility in the treatment of ED, particularly ED associated with diabetes. Angulo J, Wright HM, Cuevas P, González-Corrochano R, Fernández A, Cuevas B, La Fuente JM, Gupta S, and de Tejada IS. Nebivolol dilates human penile arteries and reverses erectile dysfunction in diabetic rats through enhancement of nitric oxide signaling.     

Investigation of the Effects of the Level of Glycemic Control on Erectile Function and Pathophysiological Mechanisms in Diabetic Rats

IntroductionPoor glycemic control is associated with erectile dysfunction (ED); however, differences in ED according to the level of glycemic control have been poorly investigated.AimThe aim of this paper is to investigate the change in erectile function according to the level of glycemic control and to clarify the pathophysiological mechanism of diabetes-associated ED.MethodsStreptozotocin was injected into 55 male Sprague-Dawley rats classified into four groups: control (group 1), diabetes with multiple insulin injections (group 2), diabetes with a single injection (group 3), and untreated diabetes (group 4). Daily insulin injections in groups 2 and 3 were administered for 4 weeks after 10 weeks of diabetic induction.Main Outcome MeasuresThe main outcome measures are the anova or Kruskal–Wallis tests to evaluate glycosylated hemoglobin (HbA1c), testosterone levels, the ratios of intracavernosal pressure to mean arterial pressure (ICP/MAP), area under the ICP curve to MAP (AUC/MAP), and changes in cavernous tissue and protein expression related to Rho kinase and nitric oxide pathways.ResultsHbA1c levels were different between pairs of groups. Group 4 showed the lowest erectile parameters and group 2 showed near normal level. No differences in erectile parameters were found between groups 1 and 2 or between groups 3 and 4, except the ratio of AUC to MAP for group 1 was significantly higher than that of group 2 (20 Hz stimulation). Decrease in erectile function of group 2 was related to decreased expression of nitrergic nitric oxide synthase or decreased testosterone level compared with group 1. Groups 2 and 3 showed significant differences in erectile parameters, which were associated with difference in apoptotic index. Groups 3 and 4 showed no differences in erectile parameters, although these groups had significant differences in apoptotic index, smooth muscle component, and protein expression ratios of phosphorylated to total myosin phosphatase target subunit 1, endothelial nitric oxide synthase, and Akt.ConclusionsImprovement in glycemic control assists recovery from diabetes-associated ED; however, only tight glycemic control can provide recovery from ED to a near normal status. Cho SY, Chai JS, Lee SH, Park K, Paick J-S, and Kim SW. Investigation of the effects of the level of glycemic control on erectile function and pathophysiological mechanisms in diabetic rats. J Sex Med 2012;9:1550–1558.     

Role of JAK2 in the Pathogenesis of Diabetic Erectile Dysfunction and an Intervention With Berberine

BackgroundOxidative stress is a significant contributor to the poor treatment efficacy on erectile dysfunction induced by diabetes mellitus (DMED). Thus, understanding the mechanism underlying oxidative stress will aid in the identification of novel therapeutic targets.AimTo define the role of Janus kinase 2 (JAK2) in mediating oxidative stress in the corpus cavernosum smooth muscle cells (CCSMCs) and to investigate the therapeutic effect of monomeric berberine (BB), which inhibits JAK2, in the pathogenesis of DMED.MethodsStreptozotocin was used to establish type I diabetic rat models and apomorphine tests were conducted to determine DMED rats. Eighteen DMED rats were divided into the DMED group and the DMED+BB group, whereas another 10 age-matched rats formed the control group. CCSMCs were isolated from the corpus cavernosum of rats and were treated with the JAK2 inhibitor alpha cyanano-(3,4-hydroxyl)N-benzophenylamine (AG490) and/or BB.OutcomesMetabolic parameters; erectile function; histologic and molecular alterations.ResultsErectile function was impaired and excessive oxidative stress was found in the DMED group. Excessive oxidative stress led to decreased expression level of phosphorylated endothelial nitric oxide synthase at serine 1177/endothelial nitric oxide synthase and increased expression level of Ras homolog gene family and Rho kinase 1/2. Meanwhile, the relative expression ratio of phosphorylated JAK2/JAK2 was significantly greater in the DMED group than that in the other groups. In vitro, oxidative stress was significantly reduced along with reduced intracellular calcium upon treatment with the JAK2 inhibitor, AG490. Moreover, the CCSMCs treated with BB showed changes similar to those upon treatment with AG490. In vivo experiments also confirmed that the erectile function of the DMED+BB group was improved, accompanied by decreased phosphorylated JAK2/JAK2 and decreased oxidative stress.Clinical TranslationJAK2 can be used as a therapeutic target and BB can be used as a potential drug for the clinical treatment of DMED.Strengths and LimitationsThis study examines the promoting effect of JAK2 on oxidative stress occurrence in the corpus cavernosum and on the development of DMED in both animal experiments and cell experiments, as well evaluates the inhibitory effect of BB on JAK2 and its therapeutic effect on DMED. The main limitation of our current study is the lack of an appropriate means for activating JAK2.ConclusionsJAK2 can induce DMED by enhancing oxidative stress and BB can play a role in treating DMED by inhibiting JAK2 and reducing oxidative stress. Our study provides an option and an idea for further studies on the pathogenesis and treatment of DMED.Song J, Tang Z, Li H, et al. Role of JAK2 in the Pathogenesis of Diabetic Erectile Dysfunction and an Intervention With Berberine. J Sex Med 2019;16:1708–1720     

Effect of Chronic Administration of PDE5 Combined with Glycemic Control on Erectile Function in Streptozotocin‐Induced Diabetic Rats

IntroductionChronic treatment with phosphodiesterase type 5 inhibitors (PDE5) is effective in an animal model of diabetes‐induced erectile dysfunction (DMED). In addition, recent research indicates that glycemic control can restore DMED.AimsWe evaluated the effect of chronic administration of PDE5 combined with glycemic control on DMED.MethodsSprague‐Dawley rats (8 weeks old) were divided into five groups (n = 10 each): normal control (C), diabetes (DM), DM treated with insulin (DM‐I), DM treated with PDE5 (DM‐P), and DM treated with insulin and PDE5 (DM‐I + P). Rats in the diabetic groups received an injection of streptozotocin (45 mg/kg). After 10 weeks of induced diabetes, the DM‐I group was treated with a daily injection of neutral protamine Hagedorn, and the DM‐P group was treated with a daily dosage of 20 mg/kg PDE5 (DA‐8159) for 4 weeks. The DM‐I + P group was treated with both treatments simultaneously. After 14 weeks of induced diabetes, an evaluation of erectile function and histological and biochemical markers of corporal tissue was performed.Main Outcome MeasuresErectile function and histological and biochemical markers in corporal tissue.ResultsRats in the DM group showed markedly lower erectile parameters than those in the C group, whereas rats in the DM‐I and DM‐P groups showed intermediate erectile function between the DM and C groups. Rats in the DM‐I + P group showed restored erectile function, comparable with group C. A comparison of apoptotic index, expression of the endothelial marker, and phosphorylation of endothelial nitric oxide synthase and Akt displayed a similar pattern with the results from cavernosometry (DM < DM‐I = DM‐P < DM‐I + P = C, P < 0.05). The distribution of phosphorylated myosin phosphatase target subunit 1 was in the reverse order.ConclusionsChronic administration of PDE5 or glycemic control with insulin resulted in restoration of overt DMED. The combination of both treatments was superior to monotherapy with insulin or PDE5. Choi WS, Kwon OS, Cho SY, Paick J‐S, and Kim SW. Effect of chronic administration of PDE5 combined with glycemic control on erectile function in streptozotocin‐induced diabetic rats. J Sex Med 2015;12:600–610.     

Vardenafil Improves Penile Erection in Type 2 Diabetes Mellitus Patients with Erectile Dysfunction: Role of Tropomyosin

IntroductionEvidences have been suggested that phosphodiesterase type 5 (PDE5) inhibition promotes vasculoprotective benefits in patients with cardiovascular diseases.AimThe aim of this study is to analyze the systemic effect of PDE5 inhibition in type 2 diabetes mellitus patients with erectile dysfunction (ED) determining changes in the expression levels of plasma proteins.MethodsSeventeen patients with controlled type 2 diabetes mellitus and ED were included in the study. Patients received vardenafil hydrochloride 20 mg on demand during 12 weeks. At the beginning and 12 weeks after vardenafil administration, plasma samples were collected and analyzed using proteomics.Main Outcome MeasuresInternational Index of Erectile Function-Erectile Function Domain (IIEF-EFD) and plasma protein expression before and after vardenafil administration. Nitrate/nitrite release, PDE5, and soluble guanylate cyclase (sGC) expression and cyclic guanosine monophosphate (cGMP) content in cultured bovine aortic endothelial cells (BAECs).ResultsThe IIEF-EFD score was markedly improved after 12 weeks of vardenafil administration. Plasma levels of alpha 1-antitrypsin isotypes 4 and 6 and β-tropomyosin were decreased, whereas apolipoprotein AI isoype 5 was increased 12 weeks after vardenafil administration. Only β-tropomyosin plasma levels were inversely correlated with IIEF-EFD score. Tropomyosin has been added to cultured BAECs and after 24 hours reduced the protein expression level of sGC-β₁ subunit and decreased the cGMP content. Tropomyosin did not modify PDE5 expression and nitric oxide release in BAECs as compared with control BAECs. Vardenafil (10 μg/mL) did not modify sGC-β₁ subunit expression in tropomyosin + vardenafil-incubated BAECs; however, vardenafil significantly reversed the reduction of cGMP content induced by tropomyosin.ConclusionVardenafil administration improved erectile functionality in controlled type 2 diabetes mellitus patients with ED, which was associated with reduction of circulating plasma β-tropomyosin levels. Tropomyosin affected by itself the cGMP generating system suggesting a possible new mechanism involved in ED. Vardenafil reversed the reduction effect of cGMP content elicited by tropomyosin in BAECs. Zamorano-León JJ, Olivier C, de las Heras N, Mateos-Cáceres PJ, Brime Menéndez R,Rodríguez-Sierra P, Martín Palacios N, Manso LSJ, Modrego J, Segura A, Macaya C, and López-Farré AJ. Vardenafil improves penile erection in type 2 diabetes mellitus patients with erectile dysfunction: Role of tropomyosin. J Sex Med 2013;10:3110–3120.     

Effect of BKCa Channel Opener LDD175 on Erectile Function in an In Vivo Diabetic Rat Model

IntroductionThe development of novel therapeutic options is imperative in patients with erectile dysfunction, especially those non-responsive to phosphodiesterase type 5 inhibitors. LDD175, a potent BKCa channel opener, has a relaxation effect on the in vitro cavernosal smooth muscle strip.AimTo investigate the effect of LDD175 on erectile function using in vivo animal disease model.MethodsMale Sprague-Dawley rats were assigned to a normal control group and seven diabetic groups: diabetic control, sildenafil (1 and 5 mg/kg), LDD175 (5 and 10 mg/kg), LDD175 5 mg/kg plus sildenafil 1 mg/kg, and LDD175 10 mg/kg plus tetraethylammonium.Main Outcome MeasuresIntracavernosal pressure (ICP), ratio of ICP to mean arterial pressure (MAP), and the area under curve of ICP/MAP of eight groups were compared using in vivo pelvic nerve stimulation.ResultsThe ICP, ICP/MAP ratio, and area under curve of the ICP/MAP ratio of the normal control rats increased with an increase in electrical field stimulation voltage. All parameters in the diabetic control group were significantly lower than those in the normal control rats, with an electrical field stimulation ranging from 1 to 5 V (P < .05). LDD175 improved the erectile response in diabetic rats in a dose-dependent manner. The combination of sildenafil (1 mg/kg) and LDD175 (5 mg/kg) showed a significant additive effect (P < .05) on the improvement of erectile function compared with sildenafil (1 mg/kg) alone. The enhancement of erectile function by LDD175 was completely blocked by tetraethylammonium.ConclusionThe results showed that the BKCa channel opener LDD175 improved erectile function in an in vivo diabetic rat model. Furthermore, combination therapy of LDD175 and sildenafil had an additive effect on the improvement of erectile function in diabetic rats. LDD175 could be a new candidate for the treatment of erectile dysfunction.