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

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

Effect of mesenchymal stem cell penile transplantation on erectile signaling of aged rats

Stem cell‐based therapy targeted at the penile tissue has been lately considered in preclinical studies. This work aimed to assess the effect of intracavernous administration of mesenchymal stem cells (MSCs) in aged rats (n = 100). They were subjected to single intracavernous injection (ICI) of 1.0 million MSCs, followed up for 3, 4 weeks, 3 and 4 months (each group 25 rats) and compared with both adult and aged controls (n = 50). In dissected cavernous tissues, cGMP and histopathology were assessed in addition to intracavernous pressure (ICP) measurement in some anaesthetised rats. The results showed that cavernous tissue cGMP was significantly increased in MSCs transplanted rats in all investigated groups compared with the controls. The mean cavernous cGMP levels after 3 and 4 months of MSCs transplantation were significantly increased compared with those after 3 or 4 weeks. Cavernous tissue ICP measurement showed significant increase in MSCs transplanted groups compared with the controls, more in the long‐term follow up than in the shorter one. Histopathological examination detected markedly dilated sinusoidal vascular spaces in the long‐term follow‐up study. It is concluded that stem cell‐based therapy is feasible for age‐associated erectile dysfunction and could improve erectile signaling.     

Decrease of the insulin‐like growth factor‐1 bioavailability in spontaneously hypertensive rats with erectile dysfunction

We investigated the role of insulin‐like growth factor‐1 (IGF‐1) in spontaneously hypertensive rats with erectile dysfunction. Firstly, we evaluated intracavernous pressure. The bioavailability of IGF‐1 at both mRNA and protein levels were measured by quantitative real‐time PCR and Western blot respectively. Then, cavernous cyclic guanosine monophosphate concentrations were detected by enzyme‐linked immunosorbent assay. The cavernosal pressure was significantly decreased in the hypertensive and the propranolol treatment groups compared to the normal control group (P < 0.01). Cavernous IGF‐1 bioavailability and the concentrations of cavernous cyclic guanosine monophosphate were both significantly decreased in the hypertensive and the propranolol treatment groups compared to the normal control group (P < 0.01). This study suggests that an obvious decrease in cavernous IGF‐1 levels might play an important role in spontaneously hypertensive rats with erectile dysfunction.     

Longitudinal studies of time‐dependent changes in both bladder and erectile function after streptozotocin‐induced diabetes in Fischer 344 male rats

OBJECTIVES

To provide sensitive physiological endpoints for the onset and long‐term progression of deficits induced by diabetes mellitus (DM) in bladder and erectile function in male rats, and to evaluate parallel changes in urogenital and nerve function induced by hyperglycaemia over a protracted period as a model for chronic deficits in patients with diabetes.

MATERIALS AND METHODS

The study comprised in 877 male, 3‐month‐old, Fischer 344 rats; 666 were injected intraperitoneally with 35 mg/kg streptozotocin (STZ) and divided into insulin‐treated and untreated diabetic groups. The rats were studied over 8 months and measurements made of both erectile and bladder function, as well as nerve conduction studies over the duration of the study.

RESULTS

There was an early (first month) abnormality of both erectile and bladder function that persisted through the 8 months of the study. The erectile dysfunction was manifest as reduced intracavernous pressure/blood pressure ratio, and the bladder dysfunction as a persistent increase in detrusor overactivity with no detrusor decompensation. Insulin treatment prevented or modified the abnormality in each organ. Hyperglycaemia caused a progressive decrease in caudal nerve conduction velocity. The mean digital sensory and tibial motor nerve conduction velocity did not deteriorate over time. Correlation measurements of nerve and organ function were not consistent.

CONCLUSIONS

The results of this extensive long‐term study show early and profound effects of hyperglycaemia on the smooth muscle of the penis and bladder, that were persistent and stable in surviving rats over the 8 months. The physiological changes did not correlate well with neurological measurements of those organs. Significantly, diverse smooth‐muscle cellular and subcellular events antedated the measured neurological manifestations of the hyperglycaemia by several months. Although autonomic diabetic neuropathy is a primary life‐threatening complication of long‐term diabetes in humans, this rat model of STZ‐induced diabetes showed that the rapid onset of physiological manifestations was based on many molecular changes in the smooth muscle cells in this model of type 1 DM.     

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

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

Ganoderma lucidum polysaccharide ameliorated diabetes mellitus-induced erectile dysfunction in rats by regulating fibrosis and the NOS/ERK/JNK pathway

BackgroundDiabetes mellitus-induced erectile dysfunction (DMED) is a frequent complication of diabetes mellitus (DM), with limited therapy at present. This study aimed to explore the role and mechanism of Ganoderma lucidum polysaccharide (GLP) on DMED.MethodsDMED was induced in the experimental rats [male 12-week-old Sprague-Dawley (SD) rats] by treatment with streptozotocin (60 mg/kg) and apomorphine (APO). Next, rats in the GLP low dose (GLP-L)/GLP high dose (GLP-H) groups were treated with GLP (100 or 400 mg/kg/d, respectively) for 8 weeks. Subsequently, erectile function was assessed by APO and electrostimulation of the cavernous nerve (CN). Serum or penile testosterone (T), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and cyclic guanosine monophosphate (cGMP) contents were evaluated by enzyme-linked immunosorbent assay (ELISA). The levels of oxidative stress indicators in the corpus cavernosum (CC) were measured by corresponding kits, and histological changes in the CC were observed by hematoxylin-eosin (HE) and Masson staining. Additionally, the apoptosis index, caspase-3, caspase-9, and eNOS expression, and mitochondrial membrane potential (MMP) were also detected. Furthermore, quantitative polymerase chain reaction (qPCR) and western blot assays were conducted to determine the NOS, TGF-β1 mRNA expression, ERK1/2, eNOS, JNK phosphorylation, and arginase II protein expression.ResultsThe erectile function test revealed that erectile dysfunction (ED) was alleviated in the DMED rats following treatment with GLP. Moreover, GLP upregulated the T and cGMP content, improved the oxidative stress and histological injuries of CC, and also inhibited the apoptosis and MMP loss of penile tissues in DMED rats. Furthermore, GLP treatment enhanced the mRNA expression of NOS and TGF-β1 and suppressed the phosphorylation of ERK1/2, eNOS, and JNK, as well as the protein expression of arginase II in DMED rats.ConclusionsGLP ameliorated DMED by repairing the CC pathological damage and upregulating NOS expression and ERK/JNK phosphorylation, indicating that GLP may be a candidate drug for DMED therapy.     

糖尿病性勃起功能障碍研究进展

勃起功能障碍是糖尿病常见并发症。糖尿病性勃起功能障碍发病率为20%~75%。糖尿病引起的血管、神经病变,肌肉组织的改变导致勃起功能障碍。控制血糖、血压和血脂是糖尿病性勃起功能障碍治疗的基础。半数的糖尿病性勃起功能障碍患者用磷酸二酯酶-5抑制剂治疗有效,海绵体内注射血管活性剂有效率大于90%,阴茎假体植入手术适用于经其他治疗效果不满意的各种勃起功能障碍患者。     

Reduction in Peyronie's‐like plaque size using a vacuum erection device in a rat model of Peyronie's disease via the TGF‐β/SMAD signalling pathway

Peyronie's disease (PD) is a fibrotic disorder of the tunica albuginea (TA). This study aimed to determine the therapeutic effects of a vacuum erection device (VED) in an animal model of PD and explore the possible mechanisms. Twenty‐seven male Sprague‐Dawley rats were used. The sham group (group A) (N = 9) received a 50‐μl‐saline vehicle injection into the TA, while the remaining 18 rats (groups B and C) received a TGF‐β1 injection into the TA. The treatment group (group C) underwent VED therapy for 10 days after the TGF‐β1 injection. Erectile function was then assessed at day 42. Rats injected with TGF‐β1 showed significantly lower intracavernous pressures than those in the sham group (p < 0.0001). After VED therapy, erectile function was significantly better in the treatment group than in the PD group (group B) (p < 0.0147). Masson's trichrome staining confirmed Peyronie's‐like plaques at the TGF‐β1 injection site in the PD group. Furthermore, the treatment group showed markedly smaller fibrotic plaque sizes than the PD group. A significant increase in TGF‐β1, SMAD2, SMAD3 and p‐SMAD2/3 protein expression was observed 6 weeks after the TGF‐β1 injection. However, the expression of the same proteins decreased after VED therapy. Protein expression trends were confirmed using immunohistochemistry analysis. The findings of this study demonstrate that VED therapy can reduce Peyronie's‐like plaque size in a rat model of PD while simultaneously improving erectile function.     

Short hairpin ribonucleic acid constructs targeting insulin‐like growth factor binding protein‐3 rehabilitated dyslipidaemia in diabetic rats

It was investigated whether short hairpin ribonucleic acid constructs targeting insulin‐like growth factor binding protein‐3 (IGFBP‐3 shRNA) can rehabilitate dyslipidaemia in streptozotocin‐induced diabetic rats. After 12 weeks of intracavernous administration of IGFBP‐3 shRNA, intracavernous pressure responses to electrical stimulation of cavernous nerves were evaluated. The concentrations of serum low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol, triglyceride and cavernous cyclic guanosine monophosphate were all detected by enzyme‐linked immunosorbent assay. The per cent of smooth muscle in corpus cavernous tissue was also evaluated. It was found that the cavernosal pressure was significantly increased in the IGFBP‐3 shRNA treatment group compared to the diabetic control group after 12 weeks of intracavernous administration of IGFBP‐3 shRNA (P < 0.01). The concentrations of serum low‐density lipoprotein cholesterol and triglyceride were significantly decreased in the IGFBP‐3 shRNA treatment group compared to the diabetic control group, while no significant changes of serum high‐density lipoprotein cholesterol concentration were found (P < 0.01). At the same time, cavernous cyclic guanosine monophosphate concentrations and the percentage of cavernosal smooth muscle were both significantly increased in the IGFBP‐3 shRNA treatment group compared to the diabetic control group (P < 0.01). This study indicated that IGFBP‐3 shRNA might rehabilitate erectile function via a decrease in concentrations of serum low‐density lipoprotein and triglyceride, an increase in the percentage of cavernosal smooth muscle and an improvement in the nitric oxide‐cyclic guanosine monophosphate signalling activities in streptozotocin‐induced diabetic rats.     

Nocturnal penile tumescence activity unchanged after long-term intracavernous injection therapy

PURPOSE: Anecdotal evidence suggests that some men have restored erectile function after long-term intracavernous injection therapy for erectile dysfunction. We objectively assessed this phenomenon using nocturnal penile tumescence testing. MATERIALS AND METHODS: In our retrospective study 19 men with a mean age of 53.5 years who had organic erectile dysfunction underwent nocturnal penile tumescence testing before and after prostaglandin E1 based intracavernous injection at least 6 months in duration. The nocturnal penile tumescence parameters measured included the number of erectile episodes, base and tip tumescence, and percent of time with rigidity greater than 70% at the penile base and tip. A 5-item questionnaire was given to all patients after the intracavernous injection period to assess subjective changes in erectile quality. RESULTS: Mean time on intracavernous injection was 2.42 years and mean injection frequency was 3.74 times monthly. Prostaglandin E1 only, and combined prostaglandin E1, phentolamine and papaverine were used in 7 and 9 cases, respectively. Nine patients believed that unaided erection improved after intracavernous injection and 6 achieved intercourse without injection who were unable to do so before injection. No statistically significant changes were noted in any of the 5 objectively measured nocturnal penile tumescence parameters. CONCLUSIONS: Long-term prostaglandin E1 based intracavernous injection may provide subjective improvement in erectile function in some men. However, as measured by nocturnal penile tumescence testing, no objective improvement in spontaneous erectile function occurs.     

Diabetes induced erectile dysfunction and apoptosis in penile crura are recovered by insulin treatment in rats

PURPOSE: We hypothesized that apoptosis is a downstream event in erectile dysfunction, and pro-apoptotic (Bak and Bax) and anti-apoptotic (Bcl-2 and Bcl-x) factors are involved in the etiology of diabetes induced erectile dysfunction. To test this hypothesis the intracavernous pressure of diabetic and insulin treated rats was measured to assess erectile function. Molecular and immunohistochemical analyses for apoptosis were then performed in rat crura to assess their role in diabetes induced erectile dysfunction and insulin treatment. MATERIALS AND METHODS: A total of 70, 6-month-old male Sprague-Dawley rats were divided into 2 groups, including a diabetic (50) and a healthy control (20) group. The diabetic group received intraperitoneal injection of streptozotocin (STZ) (Sigma-Aldrich Co., St. Louis, Missouri) to induce diabetes. Subcutaneous injection of insulin was administered daily to 9 diabetic rats 4 and 8 weeks after STZ injections for 4 and 8 weeks, respectively. Functional studies were performed in 9 diabetic rats each 4, 8 and 12 weeks after STZ injections, in 6 age matched control rats and in insulin treated rats at the termination of therapy. After the completion of functional study the penile crura were collected from rats for molecular and immunohistochemical studies. RESULTS: Mean intracavernous pressure of diabetic rats was significantly lower than in control rats and the decrease in intracavernous pressure was significantly recovered by insulin treatment. Gene expressions of pro-apoptotic and anti-apoptotic factors were present in control, diabetic and insulin treated rat crura. However, anti-apoptotic protein expression was lacking in diabetic rat crura and pro-apoptotic protein expression was lost in insulin treated rat crura. The apoptotic index of diabetic rat crura was significantly higher than that of control rat crura and this index was significantly decreased in insulin treated rat crura. CONCLUSIONS: There was a significant correlation between the decrease and recovery in intracavernous pressure, and protein expression of apoptotic factors in diabetic and insulin treated rat crura. To our knowledge this is the first report demonstrating that the relief of diabetes associated erectile dysfunction by insulin treatment is due to alterations in the protein expression of apoptotic factors in rat crura.     

Transplantation of adipose tissue‐derived stem cell‐derived exosomes ameliorates erectile function in diabetic rats

Mesenchymal stem cells (MSCs) have been considered as an attractive tool for the therapy of diseases. Accumulating evidence indicates that the healing effects of MSCs are mainly related to paracrine action rather than transdifferentiation. Exosomes excreted from MSCs have emerged as physiologically relevant and powerful components of the MSC secretome. However, whether MSC‐derived exosomes can improve erectile function of streptozotocin‐induced diabetic rats and its mechanism remains unknown. Our previous work showed that adipose tissue‐derived stem cells (ADSCs) transplantation could increase endothelial and smooth muscle contents and improve erectile function of diabetic rats. In this study, ADSC‐derived exosomes (ADSC‐Exo) exhibited in vitro proangiogenic properties, induced the proliferation of endothelial cells and restored erectile function in vivo, as well as decreased fibrosis of corpus cavernosum. In further experiments, we found that ADSC‐Exo contained some proangiogenic (miR‐126, miR‐130a and miR‐132) microRNAs and an antifibrotic microRNA family (miR‐let7b and miR‐let7c). Thus, it is reasonable to postulate that ADSC‐Exo transports key functional miRNAs to target cells in a specific manner to improve functional recovery or to activate endogenous repair mechanisms. This proof‐of‐concept study provides a novel approach for the treatment of diabetic erectile dysfunction.     

Protective effect of annexin‐A1 against irreversible damage to cavernous tissue after cavernous nerve injury in the rat

Study Type – Aetiology (case control) Level of Evidence 3b What's known on the subject? and What does the study add? Penile rehabilitation is still controversial regarding good results. Our study shows a non‐invasive treatment option to recovery after cavernous nervous damage. The assessment of changes in the intracavernous pressure and karyometry demonstrates the protective effect of annexin‐A1 in an animal model of cavernous nerve injury. We found that annexin‐A1 effectively preserved erectile function, evidently through significantly protecting the corpus cavernosum tissue against fibrosis.

OBJECTIVE

• ? To evaluate the protective effect of annexin‐A1 against irreversible damage to cavernous tissue after cavernous nerve injury.

PATIENTS AND METHODS

• ? Thirty Sprague‐Dawley male rats were divided into 3 groups; sham‐operated rats (n= 10), bilateral cavernous nerve injury treated intravenously with 100 µg/kg annexin‐A1 (n= 10), and a crush group of rats submitted to bilateral cavernous nerve injury and vehicle (n= 10). Groups were compared in respect to intracavernous pressure and karyometric parameters.

RESULTS

• ? After annexin‐A1 treatment, the maximum changes in intracavernous pressure responses were significantly higher in the annexin‐A1 group compared to the vehicle‐only group on the 7^th postoperative day (p‐value <0.05). Hematoxylin‐eosin staining showed that the percentage of cavernosal smooth muscle was higher in the annexin‐A1 group. Karyometry showed that the nuclear volume was greater in the annexin‐A1 group, as was the major/minor smooth muscle cell diameter ratio compared to the vehicle‐only group on the 7^th postoperative day (p‐value <0.05).

CONCLUSION

• ? This is the first report that, by assessing changes in the intracavernous pressure and karyometry, demonstrates the protective effect of annexin‐A1 in an animal model of cavernous nerve injury. We found that annexin‐A1 effectively preserved erectile function, evidently through significantly protecting the corpus cavernosum tissue against fibrosis.

     

Intracavernosal vascular endothelial growth factor (VEGF) injection and adeno-associated virus-mediated VEGF gene therapy prevent and reverse venogenic erectile dysfunction in rats

Penile veno-occlusive dysfunction (venogenic erectile dysfunction) is a common cause of erectile dysfunction (ED). We investigated whether vascular endothelial growth factor (VEGF) can be used to prevent and reverse venogenic ED in a rat model. Pharmacological cavernosometry was developed and validated using adult male rats with either arteriogenic or venogenic ED. Castrated animals were treated with intracavernous VEGF as either a recombinant protein (C+VEGF) or adeno-associated virus (AAV)-mediated VEGF gene therapy (C+VEGF gene) in an attempt to prevent the development of venogenic ED. Other animal groups received testosterone replacement (C+testosterone) or intracavernous AAV-LacZ gene (C+LacZ). Animals with documented venogenic ED were treated with intracavernous VEGF in an attempt to reverse their ED. Functional analysis (pharmacological infusion cavernosometry) was performed following treatment. Penile specimens were harvested for immunohistochemistry and electron microscopic evaluation. Castrated rats showed a decrease in papaverine-induced intracavernous pressure and an increase in maintenance and drop rates during pharmacological cavernosometry. These changes were prevented by systemic testosterone and intracavernous VEGF or AAV-VEGF therapy. Moreover, intracavernous VEGF was able to reverse the venogenic ED produced by castration. The quantity of penile smooth muscle detected by alpha actin staining decreased after castration but not in the C+T, C+VEGF, or C+VEGF gene groups. Transmission electron microscopy revealed atrophy of penile smooth muscle cells and nerves in the castrated rats. In VEGF-treated rats, regeneration of smooth muscle and nerves as well as endothelial cell hypertrophy and hyperplasia were the prominent features. In our animal model, systemic testosterone replacement or intracavernous VEGF (protein and VEGF gene) prevented the veno-occlusive dysfunction in castrated animals. In rats with established venous leakage, VEGF treatment reversed the cavernosometric findings of leakage. Intracavernous injection of either VEGF protein or VEGF gene may be a preferred therapy to preserve erectile function in patients in whom testosterone therapy is contraindicated.     

Abnormal protein expression in the corpus cavernosum impairs erectile function in type 2 diabetes

Study Type – Aetiology (case control)
Level of Evidence 3b

OBJECTIVE

To investigate the changes in corporal relaxation, intracavernous pressure (ICP) and associated protein expression that control normal erectile function in rats with type 2 diabetes (T2D), as this disease is part of the ‘metabolic syndrome’ associated with a high rate of erectile dysfunction (ED) in men, resulting from failure of corpus cavernosum‐mediated processes.

MATERIALS AND METHODS

T2D was induced in rats by feeding them with a high‐fat diet (HFD) followed by an injection with low‐dose streptozotocin (STZ); they were then compared with rats that received a normal diet (ND).

RESULTS

Hyperglycaemia and dyslipidaemia were induced in HFD + STZ rats, suggesting that T2D was established. The rats with T2D had associated ED, as both nonadrenergic noncholinergic‐mediated corporal relaxation and increased ICP by cavernous nerve stimulation were significantly attenuated compared to the ND group. Western blot analysis revealed diabetes‐associated lower expression of endothelial and neuronal nitric oxide synthase (e and nNOS), and cGMP‐dependent protein kinase (PKG)‐1α/β expression in penile tissue than in the ND group. Contrary to the proteins that regulate corporal relaxation, there were relatively high levels of RhoA/Rho kinase receptor 1 (ROCK1) and ET‐A receptor (ETAR) in T2D rats. However, the expressed level of phosphodiesterase‐5 and insulin‐like growth factor binding protein 3 was not altered significantly in response to T2D.

CONCLUSION

Decreased expression of certain proteins that mediate the relaxant mechanism, associated with increased expression of certain proteins that mediate contractile mechanisms, might be important in the development of T2D‐associated ED. In particular, down‐regulated eNOS/nNOS/PKG1 as well as up‐regulated ETAR/RhoA/ROCK1 might participate in the aetiology of ED in T2D.     

The opiorphin gene (ProL1) and its homologues function in erectile physiology

OBJECTIVE

To determine if ProL1, a member of the opiorphin family of genes, can modulate erectile physiology, as it encodes a peptide which acts as a neutral endopeptidase inhibitor, other examples of which (Vcsa1, hSMR3A) modulate erectile physiology.

MATERIALS AND METHODS

We cloned members of the opiorphin family of genes into the same mammalian expression backbone (pVAX); 100 µg of these plasmids (pVAX‐Vcsa1, ‐hSMR3A, ‐hSMR3B and ‐ProL1) were injected intracorporally into retired breeder rats and the affect on erectile physiology assessed visually, by histology and by measuring the intracavernous pressure (ICP) and blood pressure (BP). As a positive control, rats were treated with pVAX‐hSlo (expressing the MaxiK potassium channel) and as a negative control the empty backbone plasmid was injected (pVAX). We also compared the level of expression of ProL1 in corporal tissue of patients not reporting erectile dysfunction (ED), ED associated with diabetes and ED not caused by diabetes.

RESULTS

Gene transfer of plasmids expressing all members of the opiorphin family had a similar and significant effect on erectile physiology. At the concentration used in these experiments (100 µg) they resulted in higher resting ICP, and histological and visual analysis showed evidence of a priapic‐like condition. After electrostimulation of the cavernous nerve, rats had significantly better ICP/BP than the negative control (pVAX). Gene transfer of pVAX‐hSlo increased the ICP/BP ratio to a similar extent to the opiorphin homologues, but with no evidence for a priapic‐like condition. Corpora cavernosa tissue samples obtained from men with ED, regardless of underlying causes, had significant down‐regulation of both hSMR3A and ProL1.

CONCLUSION

All members of the human opiorphin family of genes can potentially modulate erectile physiology. Both hSMR3 and ProL1 are down‐regulated in the corpora of men with ED, and therefore both genes can potentially act as markers of ED.     

Recombinant PAI‐1 therapy restores myoendothelial junctions and erectile function in PAI‐1‐deficient mice

Myoendothelial junctions are specialised projections of cell : cell contact through the internal elastic lamina between endothelial cells and vascular smooth muscle cells. These junctions allow for endothelial cells and vascular smooth muscle cells to make direct membrane apposition and are involved in cell : cell communication. In this study, we evaluated for the presence of myoendothelial junctions in murine corporal tissue and used plasminogen activator inhibitor (PAI)‐1‐deficient mice, which lack myoendothelial junctions, to determine whether myoendothelial junctions affect erectile function. Transmission electron microscopy demonstrated the presence of myoendothelial junctions in the corporal tissue of wild‐type mice and confirmed the decreased junction numbers in the tissue of PAI‐1^?/? mice. A potential role for myoendothelial junctions in tumescence was established; in that, PAI‐1^?/? mice demonstrated a significantly longer time to achieve maximal intracavernous pressure. Treatment of PAI‐1^?/? mice with recombinant PAI‐1 restored the number of myoendothelial junctions in the corporal tissue and also induced a significant decrease in time to maximal corporal pressures. Myoendothelial junctions were similarly identified in the human corporal tissue. These results suggest a critical role for myoendothelial junctions in erectile pathophysiology and therapies aimed at restoring myoendothelial junction numbers in the corporal tissue may provide a novel therapy for erectile dysfunction.     

Improvement in erectile function in a rat model of high cholesterol diet‐induced atherosclerosis by atorvastatin in a manner that is independent of its lipid‐lowering property

The purpose of the present study is to explore the effects of a lipid‐lowering drug atorvastatin, a three‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase inhibitor, in the treatment of erectile dysfunction (ED) in a rat model of atherosclerosis (AS) and the possible mechanisms underneath. A high‐cholesterol diet was administrated to Sprague‐Dawley rats in an attempt to induce an ASED model, which was later confirmed by abdominal aorta histopathology and erectile function evaluation. ASED rats were further assigned to non‐treatment group, atorvastatin low‐dose treatment group (5 mg kg^?1 day^?1), high‐dose group (10 mg kg^?1 day^?1) and sildenafil (1.5 mg kg^?1 day^?1) treatment group. Lipid profile, erectile function, oxidative stress biochemical markers, endothelial nitric oxide synthase (eNOS) and extracellular superoxide dismutase (SOD_EX) mRNA expression were evaluated after 8‐week treatment duration. Erectile function was impaired in AS rat model, which was preserved in atorvastatin and sildenafil intervention groups. The oxidative stress biochemical markers were attenuated, while eNOS and SOD_EX mRNA expression were restored in atorvastatin and sildenafil groups, which were found to be involved in ED pathogenesis. However, the lipid profile remained unaltered in the treatment group, and it was elevated in ASED rats. This kind of lipid‐lowering agent, or atorvastatin, has the utilisation potential in ASED treatment, even before lipid profiles altered. This effect on erectile function preservation of atorvastatin was attributed to its preservation of endothelial function, possibly through amelioration of oxidative stress and improvement in eNOS expression.     

Chronic partial bladder outlet obstruction does not impair erectile function in male rats

OBJECTIVE

To evaluate, in a well‐controlled study, the effect of surgically induced partial bladder outlet obstruction (PBOO) on male erectile function in a rat model.

MATERIALS AND METHODS

PBOO was created in 17 adult male Sprague‐Dawley rats by partial ligation of the proximal urethra. Sham‐operated and PBOO rats were evaluated for urodynamic and erectile function at 4–8 weeks after surgery. Erectile responses to electrical field stimulation (EFS) to the major pelvic ganglion, and to erectogenic agents (1,1‐diethyl‐2‐hydroxy‐2‐nitroso‐hydrazine, DEA‐NO, and Y‐27632) were evaluated and the area under the curve (AUC, a product of the intracavernous pressure and duration) was used to denote the erectile response.

RESULTS

Experimental PBOO in rats significantly increased the mean (sem ) bladder weight, to 256 (25) mg in PBOO rats vs 123 (24) mg in sham controls, and the voiding frequency to 1.01 (0.1) voids/min vs 0.72 (0.14) voids/min in sham controls (P < 0.05). There was no significant difference between the erectile response to EFS, with a mean AUC in sham control rats at 1.5, 3.0 and 4.5 V of 2603 (372), 3200 (332) and 3357 (166), respectively, vs 2273 (183), 3794 (211) and 4177 (306) in PBOO rats (P > 0.05); or to the erectogenic agents, the AUC for DEA‐NO being 9000 (975) in PBOO rats vs 13 201 (2756) in sham controls, and the AUC for Y‐27 632 being 44 915 (2462) and 45 907 (7408), respectively (P > 0.05). There was greater immunoreactivity to RhoA in bladder and penile tissues of PBOO than control rats.

CONCLUSION

PBOO does not affect erectile function in rats. Additional mechanisms or pathways might be involved in lower urinary tract symptom‐related erectile dysfunction in humans.