Effects of stem cell-derived exosome therapy on erectile dysfunction: a systematic review and meta-analysis of preclinical studies.

Introduction: Erectile dysfunction (ED) is a common disease among elderly men, and novel therapy methods are needed for drug-refractory ED. As an extracellular vesicle, stem cell-derived exosomes displayed erectile function improvement in rat ED models in some preclinical studies. However, the therapeutic efficacy has not been comprehensively evaluated. Aim: To study the therapeutic effects of stem cell-derived exosomes on ED in preclinical studies and to investigate the potential mechanisms responsible for the efficacy. Methods: The systematic literature search was conducted in Web of Science, PubMed, and Embase to retrieve studies utilizing stem cell-derived exosomes for ED treatment. We extracted data of intracavernous pressure/mean artery pressure (ICP/MAP), and cavernosum structural changes in rat ED models before and after stem cell-derived exosome therapy. RevMan 5.3 was used to perform meta-analyses of ICP/MAP and cavernosum microstructural changes. Publication bias was assessed with the Egger test and funnel plot by Stata 15.0 (StataCorp). Main Outcome Measures: Outcomes included ICP/MAP, smooth muscle, and endothelial markers-such as the ratio of smooth muscle to collagen and the expression of α-SMA (alpha smooth muscle actin), CD31 (cluster of differentiation 31), nNOS and eNOS (neuronal and endothelial nitric oxide synthase), TGF-ß1 (transforming growth factor ß1), and caspase 3 protein-to evaluate erectile function and microstructural changes. Forest plots of effect sizes were performed. Results: Of 146 studies retrieved, 11 studies were eligible. Pooled analysis showed that stem cell-derived exosomes ameliorated damaged ICP/MAP (standardized mean difference, 3.68; 95% CI, 2.64-4.72; P < .001) and structural changes, including the ratio of smooth muscle to collagen and the expression of α-SMA, CD31, nNOS, eNOS, TGF-ß1, and caspase 3 protein. Subgroup analysis indicated that exosome type and ED model type made no difference to curative effects. Conclusion: This meta-analysis suggests the therapeutic efficacy of stem cell-derived exosomes for ED. Exosomes may restore erectile function by optimizing cavernosum microstructures.

Effects of platelet-rich plasma glue placement at the prostatectomy site on erectile function restoration and cavernous nerve preservation in a nerve-sparing prostatectomy rat model.

BACKGROUND: Despite the widespread use of nerve-sparing prostatectomy techniques, the incidence of post-operative erectile dysfunction (ED) remains high. Early intracavernous (IC) injection of platelet-rich plasma (PRP) after nerve crushing improves erectile function (EF) in rats by promoting cavernous nerve (CN) regeneration and preventing structural changes in the corpus cavernosum. However, the neuroprotective effects of the in situ application of PRP glue in rats after CN-sparing prostatectomy (CNSP) remain unclear. AIM: This study aimed to investigate the effects of PRP glue treatment on EF and CN preservation in rats after CNSP. METHODS: After prostatectomy, male Sprague-Dawley rats were treated with PRP glue, IC PRP injection, or their combination. The intracavernous pressure (ICP), mean arterial pressure (MAP), and CN preservation status in the rats were evaluated after 4 weeks. Results were corroborated using histology, immunofluorescence, and transmission electron microscopy. RESULTS: The PRP glue-treated rats showed 100% CN preservation and significantly higher ICP responses (the ratio of maximum ICP to MAP (0.79 ± 0.09)) than the CNSP rats (the ratio of maximum ICP to MAP (0.33 ± 0.04)). PRP glue also significantly increased neurofilament-1 expression, indicating its positive effect on the CNs. Furthermore, this treatment significantly increased the expression of α-smooth muscle actin. Electron micrographs revealed that PRP glue preserved the myelinated axons and prevented atrophy of the corporal smooth muscle by maintaining the adherens junctions. CONCLUSIONS: These results indicate that PRP glue is a potential solution for EF preservation by neuroprotection in patients with prostate cancer who are likely to undergo nerve-sparing radical prostatectomy.

Ipidacrine (Axamon), A Reversible Cholinesterase Inhibitor, Improves Erectile Function in Male Rats With Diabetes Mellitus-Induced Erectile Dysfunction.

BACKGROUND: Management of diabetes mellitus-induced erectile dysfunction (DMED) is challenging because of its insufficient responses to phosphodiesterase type 5 inhibitors. AIM: To compare the effects of ipidacrine, a reversible cholinesterase inhibitor, and sildenafil on DMED in a rat model of streptozotocin (STZ)-induced diabetes. METHODS: Erectile dysfunction (ED) caused by STZ-induced diabetes mellitus was modeled in adult male Wistar rats, which were randomized to 4 groups: untreated diabetic rats, sildenafil (5 mg/kg), ipidacrine (3.6 mg/kg) and ipidacrine (6.7 mg/kg). The test drug (ipidacrine), comparator (sildenafil) or control substance (1% starch solution) were administered orally for 5 days or 14 days. Erectile function was assessed by the change in the maximum intracavernous pressure (ICPmax) following cavernous nerve electrical stimulation. The mean arterial pressure (MAP) was recorded, and the ICPmax/MAP ratio was calculated. Sexual behavior, cholinesterase activity and blood testosterone level tests assessed. MAIN OUTCOME MEASURE: The quantitative value of ICPmax/MAP 14 days after the start of administration of the test drug and the comparison drug. RESULTS: Animals with STZ-induced diabetes mellitus showed a significant decrease in ICPmax and ICPmax/MAP ratio compared to the intact control group. When ipidacrine was administered to rats with DMED for 14 days, an increase in these indicators was noted. It was proved that ipidacrine at a dose of 6.7 mg/kg has noninferiority compared to sildenafil on the DMED model. Significant increase in ICPmax compared to STZ-control after electrostimulation of the cavernous nerve was recorded following administration of ipidacrine at a dose of 6.7 mg/kg (P < .05) and sildenafil at a dose 5 mg/kg (P < .05). Neither the test drug, nor the comparator were associated with increase in testosterone levels in blood; as well both drugs did not promote activation of sexual behavior. CLINICAL IMPLICATIONS: Ipidacrine may be considered as an effective therapy for DMED but needs to be verified in human investigations. STRENGTHS & LIMITATIONS: The role of ipidacrine, was firstly demonstrated in rats with DMED. However, the results were obtained in animal experiments, and will be further tested in the study of receptor interactions and the determination of cellular targets. CONCLUSION: This is the first study to show that administration of ipidacrine, the reversible cholinesterase inhibitor, improved erectile function in diabetic rats and these results may be beneficial in further studies using ipidacrine for treatment of DMED, particularly in non-responders to PDE5 inhibitors. Bykov V, Gushchina E, Morozov S, et al. Ipidacrine (Axamon), A Reversible Cholinesterase Inhibitor, Improves Erectile Function in Male Rats With Diabetes Mellitus-Induced Erectile Dysfunction. Sex Med 2022;10:100477.

Prolonged isoflurane anesthesia-induced acidosis decreases penile intracavernous pressure in rats.

BACKGROUND: Intracavernous pressure measurement following cavernous nerve electrostimulation has been extensively adopted for the evaluation of erectile function in animals. However, the effect of measurement time and acidosis during anesthesia is still lacking. OBJECTIVE: To explore the effect of measurement time and acidosis during anesthesia. MATERIALS AND METHODS: Fifty-six male Sprague-Dawley rats were used and anesthetized by a spontaneous inhalation of isoflurane. In the first step, rats were randomly divided into four groups: a control group and three time-delayed measurement groups (intracavernous pressure measurement beginning at 15, 30, and 45 min after cavernous nerve exposure). In the second step, rats were randomly divided into three groups: a control group and two time-delayed measurement groups. Two intravenous fluid support strategies were used in time-delayed measurement groups: a normal saline solution and an isotonic Na2 CO3 solution. RESULTS: Isoflurane-anesthetized rats developed systemic acidosis that worsens with time during intracavernous pressure measurement, which results in a significant decrease in the maximum intracavernous pressure value, intracavernous pressure/mean arterial pressure ratio, and total intracavernous pressure measured. The Na2 CO3 infusion could effectively correct acidosis. The decrease in intracavernous pressure was related to the reduced nitric oxide synthase activity, decreased cyclic guanosine monophosphate concentration, and reactive oxygen species activation in rat penis under acidosis conditions. DISCUSSION AND CONCLUSION: Prolonged isoflurane anesthesia-induced acidosis markedly depresses the erectile response to cavernous nerve electrostimulation in rats. In this situation, it is recommended to supplement with a Na2 CO3 infusion to maintain a normal acid-base balance.

Comparative study of intracavernous pressure and cavernous pathology after bilateral cavernous nerve crushing and resection in rats.

This study aimed to compare the effects of bilateral cavernous nerve crushing (BCNC) and bilateral cavernous nerve resection (BCNR) on intracavernous pressure (ICP) and cavernous pathology in rats and to explore the optimal treatment time for the BCNC and BCNR models. Seventy-two male rats aged 12 weeks were randomly divided into three equal groups: Sham (both cavernous nerves exposed only), BCNC (BCN crushed for 2 min), and BCNR (5 mm of BCN resected). Erectile function was then measured at 1 week, 3 weeks, and 5 weeks after nerve injury, and penile tissues were harvested for histological and molecular analyses by immunohistochemistry, immunofluorescence, Western blot, and cytokine array. We found that erectile function parameters including the maximum, area, and slope of ICP/mean arterial pressure (MAP) significantly decreased after BCNR and BCNC at 1 week and 3 weeks. At 5 weeks, no significant differences were observed in ICP/MAP between the BCNC and Sham groups, whereas the ICP/MAP of the BCNR group remained significantly lower than that of the Sham group. After BCNC and BCNR, the amount of neuronal-nitric oxide synthase-positive fibers, smooth muscle cells, and endothelial cells decreased, whereas the amount of collagen III content increased. These pathological changes recovered over time, especially in the BCNC group. Our findings demonstrate that BCNC leads to acute and reversible erectile dysfunction, thus treatment time should be restricted to the first 3 weeks post-BCNC. In contrast, the self-healing ability of the BCNR model is poor, making it more suitable for long-term treatment research.

Comparative study of intracavernous pressure and cavernous pathology after bilateral cavernous nerve crushing and resection in rats / 亚洲男科学杂志(英文版)

This study aimed to compare the effects of bilateral cavernous nerve crushing (BCNC) and bilateral cavernous nerve resection (BCNR) on intracavernous pressure (ICP) and cavernous pathology in rats and to explore the optimal treatment time for the BCNC and BCNR models. Seventy-two male rats aged 12 weeks were randomly divided into three equal groups: Sham (both cavernous nerves exposed only), BCNC (BCN crushed for 2 min), and BCNR (5 mm of BCN resected). Erectile function was then measured at 1 week, 3 weeks, and 5 weeks after nerve injury, and penile tissues were harvested for histological and molecular analyses by immunohistochemistry, immunofluorescence, Western blot, and cytokine array. We found that erectile function parameters including the maximum, area, and slope of ICP/mean arterial pressure (MAP) significantly decreased after BCNR and BCNC at 1 week and 3 weeks. At 5 weeks, no significant differences were observed in ICP/MAP between the BCNC and Sham groups, whereas the ICP/MAP of the BCNR group remained significantly lower than that of the Sham group. After BCNC and BCNR, the amount of neuronal-nitric oxide synthase-positive fibers, smooth muscle cells, and endothelial cells decreased, whereas the amount of collagen III content increased. These pathological changes recovered over time, especially in the BCNC group. Our findings demonstrate that BCNC leads to acute and reversible erectile dysfunction, thus treatment time should be restricted to the first 3 weeks post-BCNC. In contrast, the self-healing ability of the BCNR model is poor, making it more suitable for long-term treatment research.

Mirabegron elicits rat corpus cavernosum relaxation and increases in vivo erectile response.

Mirabegron is the first ß3-adrenoceptor agonist approved on the market and may offer beneficial pharmacological action in patients with overactive bladder and erectile dysfunction. Here, we further investigate the mechanisms by which mirabegron induces rat corpus cavernosum (CC) relaxation. Adult male Wistar rats were used. The CC were isolated for in vitro functional assays and ß-adrenoceptors subtypes mRNA expression evaluation. Animals were treated orally with mirabegron (30 mg/kg, 3 h), tadalafil (10 mg/kg, 3 h) or both for intracavernous pressure (ICP). Intracellular levels of cAMP and cGMP were also determined. The ß1-, ß2- and ß3-adrenoceptors subtypes were expressed in rat CC. Mirabegron produced concentration-dependent CC relaxations that were unaffected by the ß1-, ß2- or ß3-adrenoceptor antagonists atenolol (1 µM), ICI-118,551 (1 µM) and L748,337 (10 µM), respectively. Mirabegron-induced relaxations were not affected by the phosphodiesterase type 4 inhibitor, rolipram, or the adenylyl cyclase selective inhibitor, SQ 22,536. Potassium channel- or calcium influx-blockade are not involved in mirabegron-induced relaxations. In contrast, mirabegron produced rightward shifts in the contractile response induced by the α1-adrenoceptor agonist, phenylephrine. Finally, cavernous nerve stimulation caused frequency-dependent ICP increases, which were significantly increased in rats treated with mirabegron in a similar degree of tadalafil-treated rat, without promoting a significant cAMP or cGMP accumulation. Together, our results demonstrate that mirabegron induced CC relaxation through α1-adrenoceptor blockade. Care should be taken to translate the effect of mirabegron into the clinic, especially when using rat as an animal model of erectile dysfunction.

Hydro-Jet Dissection of the Cavernous Nerves Preserves Erection Function in a Radical Prostatectomy Animal Model.

BACKGROUND: Postoperative erectile dysfunction (ED) remains a prevalent consequence of radical prostatectomy (RP) that significantly impacts patient quality of life. Water-jet technology is widely used for dissection in neurosurgical procedures but novel to urologic surgery. AIM: To establish the impact of hydro-jet dissection (HJD) of the cavernous nerves (CN) on postoperative erectile function in an animal model of RP-induced ED. METHODS: 32 male Sprague-Dawley rats were randomized to 4 groups: Sham surgery (n = 8), bilateral HJD of CN (n = 8), blunt CN injury (n = 8), or stretch CN injury (n = 8). After 4 weeks, erectile function was assessed by measuring intracavernous pressure (ICP), and penile tissues were harvested for immunohistologic studies. MAIN OUTCOME MEASURE: The peak ICP and the area under the curve were calculated for each group. Immunohistologic studies were performed for α-smooth muscle actin and neuronal nitric oxide synthase on cross-sections of penile tissue. RESULTS: Rats in the HJD group demonstrate a significantly higher mean peak ICP and area under the curve compared with both CN injury groups (P = .001). Postoperative erectile function in the HJD group returned to baseline function. Preservation of α-smooth muscle actin and neuronal nitric oxide synthase was observed in the HJD group compared with the other surgical trauma groups. CLINICAL IMPLICATIONS: Hydro-jet dissection used in an RP animal model maintains erectile function and offers a potential benefit that warrants further human studies. STRENGTHS & LIMITATIONS: This is a novel animal study comparing a new technology to established CN dissection techniques. This study uses an animal model, which may not completely translate to post-RP ED in humans. CONCLUSION: Hydro-jet dissection of the CN during RP in an animal model is associated with significantly better postoperative erectile function when compared with other CN injury. Clinical studies are needed to further investigate the putative benefit of HJD on erectile function in patients undergoing RP. Campbell JD, Alenezi H, DeYoung LX, et al. Hydrojet Dissection of the Cavernous Nerves Preserves Erection Function in a Radical Prostatectomy Animal Model. Sex Med 2019;7:104-110.

Prostate-Confined Radiation Decreased Pelvic Ganglia Neuronal Survival and Outgrowth.

BACKGROUND: Erectile dysfunction (ED) is common following radiation therapy (RT) for prostate cancer. Although the cause of RT-induced ED is unknown, damage to both the neuronal and vascular components supporting erections are often implicated. AIM: To determine the effects of prostatic RT on erections, penile vascular physiology, and major pelvic ganglia (MPG) neuron growth and survival in a rat model. METHODS: Male rats underwent 0 Gy or 22 Gy single fraction of prostate-confined, conformal RT. At 2 weeks or 10 weeks post-RT (n = 10/group), cavernous nerve stimulation was performed and erections were assessed. Tissue bath experiments were performed to assess both penile artery and internal pudendal artery (IPA) function. MPGs were dissociated and neurons grown in culture for 72 hours. Immunofluorescence staining was done to quantify neuron survival (terminal deoxynucleotidyl transferase nick-end labeling), outgrowth (beta-tubulin III), type (nitric oxide synthase [nNOS] and tyrosine hydroxylase [TH]), and nerve injury markers (small GTPase Rac1 and ninjurin-1 [Ninj-1]). Whole MPG real-time quantitative polymerase chain reaction (qPCR) was performed to measure expression of genes related to nerve type, neuron injury, repair, and myelination, such as Ninj-1, Rac1, ATF3, GAP43, GFAP, SOX10, and KROX20. OUTCOMES: Intracavernosal pressure (ICP) to mean arterial pressure (MAP) ratio, smooth muscle contractility and relaxation, gene expression, neuritogenesis, and apoptosis. RESULTS: Following RT, ICP/MAP was unchanged at 2 weeks or 10 weeks. Nerve-mediated penile contraction was increased at 2 weeks, whereas adrenergic contraction was reduced at 10 weeks. Penile relaxation and IPA vasoreactivity were unchanged. Neuronal apoptosis was more than doubled both early and late post-RT. RT caused a progressive decrease in neurite branching but an early increase and then late decrease in neurite lengthening. RT reduced the numbers of nNOS-positive neurons both early and late and also decreased MPG nitrergic gene expression. TH neurons and gene expression were unchanged at 2 weeks; however, both were decreased after 10 weeks. Although most markers of gene injury and repair were unaffected early post-RT, MPG expression of Ninj1 and GFAP increased. After 10 weeks, Ninj1 and GFAP remained elevated while markers of neuron injury (ATF3), outgrowth (GAP43 and Rac1), and myelin regulation (SOX10) were decreased. CLINICAL TRANSLATION: RT-induced ED may result from damage to the ganglia controlling erections. STRENGTHS & LIMITATIONS: This study used a clinically relevant, prostate-confined model to examine neurovascular structures not accessible in human studies. Unfortunately, rats did not exhibit ED at this time point. CONCLUSION: This is the first study to demonstrate impaired health and regeneration potential of dissociated MPG neurons following RT. Neuronal injury was apparent early post-RT and persisted or increased over time but was insufficient to cause ED at the time points examined. Powers SA, Odom MR, Pak ES, et al. Prostate-Confined Radiation Decreased Pelvic Ganglia Neuronal Survival and Outgrowth. J Sex Med 2019;16:27-41.

Reflex erection in the rat: reciprocal interplay between hemodynamic and somatic events.

BACKGROUND: Penile erection is a complex reflex under spinal control and modulated by the brain. The hemodynamic events under autonomic control and the perineal muscles somatic activity are interconnected during the reflex erection at the spinal level, however if the afferent feedback on the corpus cavernosum pressure during an erection affects the somatic activity (perineal muscles contractions) and vice versa is not known. This study was aimed to test this hypothesis using a rat model. METHODS: Intracavernous pressure (ICP) and bulbocavernosus (BC) muscle EMG were recorded during reflex erections elicited with dorsal penile nerve (DNP) electrical stimulation in anaesthetized acutely spinalized SD rats with surgically (bilateral cavernous nerve section, CnX, n = 8) and pharmacologically (trimetaphan infusion, TMPh, n = 8) abolished pressor response, or with surgically (bilateral section of the motor branch of the pudendal nerve, PnX, n = 7) and pharmacologically (1 mg/kg d-tubocurarine, n = 8) blocked perineal muscles contractions, or with interrupted afferent input from the penis (bilateral crush of the dorsal penile nerve, DPnX, n = 7). Control rats (n = 8) received no intervention. RESULTS: Moderate positive correlations were found between net parameters of pressor and somatic activity during DNP-stimulation induced reflex erection in spinal rats, particularly the speed of pressor response development was positively correlated to EMG parameters. No changes of EMG activity were found in CnX rats, while the decrease of BC EMG in TMPh-treated males can be attributed to direct inhibitory action of TMPh on neuromuscular transmission. Pressor response latency was increased and ICP front slope decreased in dTK and PnX rats, indicating that perineal muscles contraction augment pressor response. DPN crush had little effect on ICP and EMG. CONCLUSION: Afferent input on the level of intracavernous pressure and the perineal muscles activity has minimal impact on, correspondingly, the somatic and the autonomic components of the reflex erection in spinal males, once the reflex has been initiated.

Pancreatic kininogenase improves erectile function in streptozotocin-induced type 2 diabetic rats with erectile dysfunction.

Erectile dysfunction (ED) associated with type 2 diabetes is a severe problem that requires effective treatment. Pancreatic kininogenase (PK) has the potential to improve the erectile function of ED patients. This study aims to investigate the effect of PK on erectile function in streptozotocin-induced type 2 diabetic ED rats. To achieve this goal, we divided male Sprague-Dawley rats into five groups. One group was not treated, and the other four groups were treated with saline, sildenafil, PK or sildenafil, and PK, respectively, for 4 weeks after the induction of type 2 diabetic ED. Then, intracavernous pressure under cavernous nerve stimulation was measured, and penile tissue was collected for further study. Endothelial nitric oxide synthase levels, smooth muscle content, endothelium content, cyclic guanosine monophosphate (cGMP) levels in the corpus cavernosum, and neuronal nitric oxide synthase levels in the dorsal penile nerve were measured. Improved erectile function and endothelium and smooth muscle content in the corpus cavernosum were observed in diabetic ED rats. When treating diabetic ED rats with PK and sildenafil at the same time, a better therapeutic effect was achieved. These data demonstrate that intraperitoneal injection of PK can improve erectile function in a rat model of type 2 diabetic ED. With further research on specific mechanisms of erectile function improvement, PK may become a novel treatment for diabetic ED.

Do penile haemodynamics change in the presence of hydrogen sulphide (H2 S) donor in metabolic syndrome-induced erectile dysfunction?

Erectile dysfunction (ED) is defined in relation to the metabolic syndrome (metS). Hydrogen sulphide (H2 S), a gasotransmitter, has been revealed to get involved in hypertension, insulin secretion and regulation of vascular tone especially in erectile physiology. This study aimed to investigate the effect of H2 S on metS-induced ED. Animals were divided into two groups as control and metS, which were fed with standard diet or 60% high-fructose diet for 10 weeks respectively. The metS model was evaluated with biochemical analyses, waist circumference/tibia length ratio and HOMA index. Penile hemodynamic parameters were evaluated by the measurement of intracavernous pressure/mean arterial pressure ratio during cavernous nerve stimulation in the presence and absence of intracavernous injection of NaHS (100 µg/50 µl) and its control 0.9%NaCl (50 µl) in both groups. H2 S levels were measured in penile tissues by methylene blue assay. H2 S levels were significantly decreased in the penile tissues of the metS group. Decreased intracavernous pressure/mean arterial pressure ratio improved after intracavernous administration of NaHS in the metS group. These results suggest the significant role of H2 S in the metS-induced erectile dysfunction that could be a new therapeutic target.

Pancreatic kininogenase improves erectile function in streptozotocin-induced type 2 diabetic rats with erectile dysfunction / 亚洲男科学杂志(英文版)

Erectile dysfunction (ED) associated with type 2 diabetes is a severe problem that requires effective treatment. Pancreatic kininogenase (PK) has the potential to improve the erectile function of ED patients. This study aims to investigate the effect of PK on erectile function in streptozotocin-induced type 2 diabetic ED rats. To achieve this goal, we divided male Sprague-Dawley rats into five groups. One group was not treated, and the other four groups were treated with saline, sildenafil, PK or sildenafil, and PK, respectively, for 4 weeks after the induction of type 2 diabetic ED. Then, intracavernous pressure under cavernous nerve stimulation was measured, and penile tissue was collected for further study. Endothelial nitric oxide synthase levels, smooth muscle content, endothelium content, cyclic guanosine monophosphate (cGMP) levels in the corpus cavernosum, and neuronal nitric oxide synthase levels in the dorsal penile nerve were measured. Improved erectile function and endothelium and smooth muscle content in the corpus cavernosum were observed in diabetic ED rats. When treating diabetic ED rats with PK and sildenafil at the same time, a better therapeutic effect was achieved. These data demonstrate that intraperitoneal injection of PK can improve erectile function in a rat model of type 2 diabetic ED. With further research on specific mechanisms of erectile function improvement, PK may become a novel treatment for diabetic ED.

Pancreatic kininogenase improves erectile function in streptozotocin-induced type 2 diabetic rats with erectile dysfunction / 亚洲男科学杂志(英文版)

Erectile dysfunction (ED) associated with type 2 diabetes is a severe problem that requires effective treatment. Pancreatic kininogenase (PK) has the potential to improve the erectile function of ED patients. This study aims to investigate the effect of PK on erectile function in streptozotocin-induced type 2 diabetic ED rats. To achieve this goal, we divided male Sprague-Dawley rats into five groups. One group was not treated, and the other four groups were treated with saline, sildenafil, PK or sildenafil, and PK, respectively, for 4 weeks after the induction of type 2 diabetic ED. Then, intracavernous pressure under cavernous nerve stimulation was measured, and penile tissue was collected for further study. Endothelial nitric oxide synthase levels, smooth muscle content, endothelium content, cyclic guanosine monophosphate (cGMP) levels in the corpus cavernosum, and neuronal nitric oxide synthase levels in the dorsal penile nerve were measured. Improved erectile function and endothelium and smooth muscle content in the corpus cavernosum were observed in diabetic ED rats. When treating diabetic ED rats with PK and sildenafil at the same time, a better therapeutic effect was achieved. These data demonstrate that intraperitoneal injection of PK can improve erectile function in a rat model of type 2 diabetic ED. With further research on specific mechanisms of erectile function improvement, PK may become a novel treatment for diabetic ED.

Antioxidative mechanism of Lycium barbarum polysaccharides promotes repair and regeneration following cavernous nerve injury.

Polysaccharides extracted from Lycium barbarum exhibit antioxidant properties. We hypothesized that these polysaccharides resist oxidative stress-induced neuronal damage following cavernous nerve injury. In this study, rat models were intragastrically administered Lycium barbarum polysaccharides for 2 weeks at 1, 7, and 14 days after cavernous nerve injury. Serum superoxide dismutase and glutathione peroxidase activities significantly increased at 1 and 2 weeks post-injury. Serum malondialdehyde levels decreased at 2 and 4 weeks. At 12 weeks, peak intracavernous pressure, the number of myelinated axons and nicotinamide adenine dinucleotide phosphate-diaphorase-positive nerve fibers, levels of phospho-endothelial nitric oxide synthase protein and 3-nitrotyrosine were higher in rats administered at 1 day post-injury compared with rats administered at 7 and 14 days post-injury. These findings suggest that application of Lycium barbarum polysaccharides following cavernous nerve crush injury effectively promotes nerve regeneration and erectile functional recovery. This neuroregenerative effect was most effective in rats orally administered Lycium barbarum polysaccharides at 1 day after cavernous nerve crush injury.

Optimization of platelet-rich plasma and its effects on the recovery of erectile function after bilateral cavernous nerve injury in a rat model.

Platelet-rich plasma (PRP) containing autologous growth factors is applied in regenerative medicine, but the lack of an optimized PRP preparation protocol causes unstable therapeutic effects. The aim of this study was to optimize the PRP preparation method and compare the effects of PRP from different preparation methods in restoration of erectile function in a rat model. The in vivo experiments used Sprague-Dawley male rats (n = 24), which were randomly divided into four groups of equal numbers: group I underwent sham operation, while the remaining three groups underwent bilateral CN crush. Crush injury groups were treated at the time of injury with an application of general PRP, optimized PRP [with the largest amount of platelet-derived growth factor (PDGF)-AB] or normal saline-only injection in the corpus cavernosum, respectively. Four weeks later, erectile function was assessed by CN electrosimulation, and penile tissue was collected for histology. Results demonstrated that in the PRP group prepared with the ACD-A anticoagulant, chitosan and incubated at -20°C for 15 days had the largest amount of PDGF-AB and showed a synergistic effect on release (p < 0.05). Functional outcome measurement and immunofluorescence staining for the dorsal nerve revealed that improvement after bilateral CN injury occurred in the optimized PRP group (p < 0.05). It was concluded that optimized PRP with a high level of growth factors was more stable, and its injection into the corpus cavernosum facilitated recovery of erectile function. Copyright © 2013 John Wiley & Sons, Ltd.

Effect of DDAH/ADMA/NOS regulation pathway on cavernae corporum cavernosorum rat penis of different age.

The effect of DDAH/ADMA/NOS pathway in penile tissue of rats of different age was investigated to better understand the mechanism of age-related erectile dysfunction (ED). The Sprague Dawley male rats were assigned as the young group (3 month old, n = 10) and the old group (18 month old, n = 10) respectively. Intracavernous pressure (ICP) was measured before and after papaverine intracavernous injection. Pathology structure of penile tissue was evaluated under transmission electron microscope. The expression amounts of asymmetric dimethylarginine (ADMA) and cyclic guanosine monophosphate (cGMP) in penile tissue were detected by ELISA; the expression levels of isoform-specific DDAH and NOS were assessed via Western blot. Compared with the young group, the ICP in the old group rat decreased significantly (33.46 ± 5.37 versus 39.71 ± 3.67 mmHg, P = 0.02) after papaverine injection. Diffused fibrosis and impairment of endothelial cell were observed in corpus cavernosum in the old group rats. Higher level of ADMA (10.83 ± 0.96 versus 7.51 ± 1.39 µmol per gpro, P = 3.14 × 10(-4) ) and lower level of cGMP (29.42 ± 3.84 versus 47.09 ± 6.07 nmol per gpro, P = 1.57 × 10(-6) ) were detected in penile tissue of the old group compared with those of the young group. Expression of DDAH1, DDAH2, endothelial NOS (eNOS) and neuronal NOS(nNOS) all decreased significantly in penile tissue of the old group rat. The DDAH/ADMA/NOS regulation pathway changes dramatically accompanying with lower ICP in old group rat compared with those of the young group. Such findings in rats are suggestive in understanding the mechanism of age-related ED in humans.

Application of a modified intracavernous cannulation in monitoring the intracavernous pressure of rats / 中华泌尿外科杂志

Objective To investigate the modified method of intracavernous cannulation in monitoring intracavernous pressure (ICP) of rats.Methods The present study was conducted from October to December 2014.Twenty male Sprague-Dawley rats were randomly divided into 2 groups,the conventional group (cannulated in the crus of the penis) and the modified group (cannulated in the corporal body of the penis).The erectile function of the rats was assessed by measuring ICP/MAP (mean arterial pressure) ratio.The electrical-stimulation (ES) parameters were 5 V,15 Hz,5 ms,and 60 s for each stimulation.Results The differences in the basic ICP (14.9 ± 2.7 versus 15.5 ± 3.1 mmHg),ES-ICP (87.6 ± 7.5 versus 85.0 ± 6.2 mmHg),and ICP/MAP (71.3％ ± 6.6％ versus 72.5％ ± 6.3％) were not significant between the 2 groups (P ＞0.05 for all).Compared with the conventional group,the modified group could accurately cannulate the corpus cavernosum under direct vision,with an improved successful rate (100％ versus 80％),but there was no significant difference (P ＞ 0.05) in intracavernous pressure measurement.Conclusion The modified method of cannulating in the corpus cavernosum could have the advantage of higher successful rate,suggesting a feasible way for basic research of erectile dysfunction in rats.

Prolonged therapy with the soluble guanylyl cyclase activator BAY 60-2770 restores the erectile function in obese mice.

INTRODUCTION: Cardiovascular and endocrine-metabolic diseases associated with increased oxidative stress such as obesity lead to erectile dysfunction (ED). Activators of soluble guanylyl cyclase (sGC) such as BAY 60-2770 reactivate the heme-oxidized sGC in vascular diseases. AIM: This study aimed to evaluate the effects of 2-week oral intake with BAY 60-2270 on a murine model of obesity-associated ED. METHODS: C57BL/6 male mice were fed for 12 weeks with standard chow or high-fat diet. Lean and obese mice were treated with BAY 60-2770 (1 mg/kg/day, 2 weeks). MAIN OUTCOME MEASURES: Measurements of intracavernosal pressure (ICP), along with acetylcholine (10(-9) to 10(-5) M) and electrical field stimulation (EFS; 4-10 Hz)-induced corpus cavernosum relaxations in vitro, were obtained. Levels of cyclic guanosine monophosphate (cGMP), reactive oxygen species (ROS), and sGC protein expressions in cavernosal tissues were measured. RESULTS: Cavernous nerve stimulation caused frequency-dependent ICP increases, which were significantly lower in obese compared with lean mice (P < 0.05). Two-week therapy with BAY 60-2770 fully reversed the decreased ICP in obese group. Acetylcholine-induced cavernosal relaxations were 45% lower (P < 0.001) in obese mice, which were fully restored by BAY 60-2770 treatment. Likewise, the EFS-induced relaxations in obese mice were restored by BAY 60-2770. Basal cGMP content in erectile tissue was 68% lower (P < 0.05) in obese mice, an effect normalized by BAY 60-2770. Levels of ROS were 52% higher (P < 0.05) whereas protein expression of α1 sGC subunit was reduced in cavernosal tissue of obese mice, both of which were normalized by BAY 60-2770. In lean group, BAY 60-2770 did not significantly affect any functional, biochemical, or molecular parameter analyzed. CONCLUSIONS: Two-week therapy with BAY 60-2770 restores the erectile function in obese mice that is associated with reduced ROS levels, up-regulation of α1 sGC subunit, and increased cGMP levels in the erectile tissue.

Erectile dysfunction precedes other systemic vascular diseases due to incompetent cavernous endothelial cell-cell junctions.

PURPOSE: Erectile dysfunction is often a harbinger of cardiovascular disease. We sought to gain mechanistic insight at the cellular and molecular levels into why erectile dysfunction precedes the clinical consequences of cardiovascular disease. MATERIALS AND METHODS: Diabetes was induced by intraperitoneal streptozotocin injection in 8-week-old C57BL/6J mice. At 8 weeks after diabetes induction, we determined the expression of endothelial cell-cell junction proteins and vascular endothelial permeability in the penis, heart and hind limb by systemic injection of various vascular space markers (350 Da to 2,000 kDa) or by immunohistochemical staining with antibody to oxidized low density lipoprotein. We also investigated the effect of recombinant Ang1 protein on cavernous endothelial permeability. RESULTS: Alterations in the integrity of the endothelial cell-cell junction, including a decrease in endothelial cell-cell junction proteins and an increase in vascular permeability to fluorescent tracers or oxidized low density lipoprotein, were prominent in the cavernous tissue of diabetic mice. In contrast, no significant changes in endothelial cell-cell junction proteins or vascular permeability were noted in heart or hind limb tissue according to the diabetic condition. Intracavernous injection of Ang1 protein, an anti-permeability factor, significantly decreased cavernous endothelial permeability to oxidized low density lipoprotein by restoring endothelial cell-cell junction proteins in diabetic mice. CONCLUSIONS: The incompetent cavernous endothelial cell-cell junction in the diabetic condition provides an important clue to why erectile dysfunction is highly prevalent and often precedes other systemic vascular diseases.