Cavernosal Nerve Research Articles

A New Strategy, SuperEnzyme Gene Therapy in Penile Rehabilitation

Erectile dysfunction (ED) after radical prostatectomy (RP) is a very common condition. Prostacyclin (PGI(2)) is a prostaglandin with properties of vasodilation and anti-platelet aggregation. SuperEnzyme is a newly engineered protein with PGI(2) synthase activity that converts arachidonic acid directly to PGI(2). Transfection of SuperEnzyme into the penis to generate high levels of PGI(2) may increase penile blood inflow, alleviate hypoxia, and prevent apoptosis and fibrosis with potential use for ED after RP. The pathophysiology of ED after RP and the prostaglandin regulation was reviewed, and the possibly relevant mechanism of SuperEnzyme as a therapy for ED after RP was proposed. The rationale for SuperEnzyme as a possible therapy for ED after RP is analyzed. We reviewed the publications on the proposed pathophysiology of ED after RP, the molecular regulation of prostaglandin and methods of SuperEnzyme engineering and transfection. ED after RP is involved in hypoxia, apoptosis and fibrosis, mainly due to the cavernosal nerve injury. Transfection of SuperEnzyme into the penis of an animal model to produce PGI(2) is feasible. Animal studies with the use of SuperEnzyme gene therapy are needed to provide new insight into metabolic and signaling pathways of PGI(2) in the penis and the role of PGI(2) signaling in the recovery of erectile function after RP. SuperEnzyme may be a potential candidate as a gene therapy for ED after RP.

Reversal of Voltage‐Dependent Erectile Responses in the Zucker Obese‐Diabetic Rat by Rosuvastatin‐Altered RhoA/Rho‐kinase Signaling

The combination of independent risk factors for erectile dysfunction, obesity, hypertension, and diabetes are collectively manifested in a condition known as metabolic syndrome X (MSX). However, the regulatory mechanisms responsible for the erectile dysfunction (ED) are not fully understood. Clinical studies suggest that a pleiotropic effect of statin's ability to enhance vascular relaxation might be through an impact on nitric oxide signaling or through a regulation of RhoA activation. We hypothesized that regulatory aspects of short-term statin therapy involve the alteration of the RhoA/Rho-kinase signaling cascade and will reverse the ED seen in a rat model of MSX. The magnitude and sensitivity of the voltage-dependent maintenance of intracavernosal blood pressure and mean arterial blood pressure. These responses were correlated with tissue protein and mRNA expression levels of RhoA and Rho kinases. Erectile function was evaluated by assessing voltage-dependent stimulation of the cavernosal nerve in 16-20 weeks old lean and obese-diabetic Zucker rats treated with 5 mg/kg/day of rosuvastatin intraperitoneally for 3 days. Cavernosal tissue RhoA and Rho-kinases expression levels were evaluated by real-time reverse transcriptase-polymerase chain reaction, Western blot. The voltage-dependent erectile responses were suppressed by >30% in the obese-diabetic Zucker rat. The 3-day treatment with rosuvastatin partially restored the erectile response. The Rho-kinase inhibitor, H-1152, dose dependently increased the erectile responses and shifted the voltage sensitivity with statin treatment. Analysis of protein expression levels suggested elevation of RhoA and Rho kinases in obese-diabetics and statin treatment lowering Rho-kinase II. The RhoA and Rho-kinase II mRNA levels were significantly reduced in the rosuvastatin-treated obese-diabetic animals. These results support a hypothesis that short-term statin therapy may lower RhoA/Rho-kinase expression levels and improve cavernosal blood pressure response to Rho-kinase inhibition and voltage-stimulation, and reversing an augmented vasoconstricted state associated with diabetes and/or hypertension in MSX.

Androgens and Erectile Function: A Case for Early Androgen Use in Postprostatectomy Hypogonadal Men

Erectile dysfunction affects up to 80% of men following a radical prostatectomy (RP) and is a common concern for these patients. Currently, hypogonadal men are not treated with testosterone after a RP for fear of stimulating dormant prostate cancer cells even though there is little evidence to support this hesitancy. There is data, however, to support the use of testosterone to aid in faster and better recovery of erections following RP. The aim of this article is to explore the relationship between testosterone replacement therapy (TRT) and erectile preservation following RP. The results of findings in the literature on the association between testosterone and its role in preserving erectile function, particularly in men following RP. This article reviews and evaluates the literature that demonstrates the role of testosterone in obtaining erections and preserving erectile function. Additional articles were reviewed to assess the role of testosterone in erectile preservation following RP. This review demonstrates that testosterone does play a role in erectile function, particularly for men who have undergone a RP. Testosterone has been shown to have an effect on nitric oxide synthase release, phosphodiesterase type 5 expression and activity, and in cavernosal nerve function, and to contribute to venoocclusive disease in the penis. All of these effects are of particular importance to men attempting to preserve erectile function following RP. While the relationship between TRT and improvement in erectile function has been well established, the role of testosterone in men following RP may be of even greater significance. However, further studies are needed to assess the true safety of TRT following RP.

Fibrosis and Loss of Smooth Muscle in the Corpora Cavernosa Precede Corporal Veno-Occlusive Dysfunction (CVOD) Induced by Experimental Cavernosal Nerve Damage in the Rat

Corporal veno-occlusive dysfunction (CVOD), which usually is associated with a loss of smooth muscle cells (SMC) and an increase in fibrosis within the corpora cavernosa, can be induced by an injury to the cavernosal nerves. The corporal tissue expresses inducible nitric oxide synthase (iNOS), presumably as an antifibrotic and SMC-protective response. We studied the temporal relationship in the corpora between the expression of iNOS, other histological and biochemical changes, and the development of CVOD, after bilateral cavernosal nerve resection (BCNR) in the rat. Rats underwent either BCNR or sham operation. Cavernosometry was performed 1, 3, 7, 15, 30, and 45 days (N = 8/groups) after surgery. Penile tissue sections were subjected to Masson trichrome staining for SMC and collagen, and immunodetection for alpha smooth muscle actin, iNOS, neuronal NOS (nNOS), endothelial NOS (eNOS), proliferating cell nuclear antigen (PCNA), and terminal transferase dUTP nick end labeling (TUNEL). Quantitative western blot analysis was done in homogenates. Time course on the development of fibrosis and CVOD. Following BCNR, CVOD was detectable 30 days later, and it became more pronounced by 45 days. In contrast, the SMC/collagen ratio in the BCNR corpora was reduced at 7 days and bottomed at 30 and 45 days, due in part to the reduction of SMC, presumably caused by an increase in apoptosis peaking at 3 days. PCNA also peaked at 3 days, but then decayed. nNOS was reduced early (3-7 days) and disappeared at 30 days, whereas eNOS was not affected. iNOS was induced at day 3, and steadily increased peaking at 30 days. CVOD develops in the BCNR rat as a result of the early loss of corporal SMC by the neuropraxia-induced apoptosis, which the initial cell replication response cannot counteract, followed by fibrosis. The time course of iNOS induction supports the antifibrotic role of iNOS.

The Novel Antioxidant, AC3056 (2,6-di-t-butyl-4-((Dimethyl-4-Methoxyphenylsilyl)Methyloxy)Phenol), Reverses Erectile Dysfunction in Diabetic Rats and Improves NO-mediated Responses in Penile Tissue from Diabetic Men

Diabetes is associated with a high incidence of erectile dysfunction (ED) and poor response to standard treatments. Oxidative stress could be relevant in the pathophysiology of diabetic ED. To evaluate the effects of the antioxidant, AC3056 (2,6-di-t-butyl-4-((dimethyl-4-methoxyphenylsilyl)methyloxy)phenol), on diabetic ED. Erectile responses to cavernosal nerve electrical stimulation were determined in streptozotocin-induced diabetic rats. Relaxation of human corpus cavernosal (HCC) tissue and penile resistance arteries (HPRA) from human cavernosal specimens was evaluated in organ chambers and myographs, respectively. The influence of AC3056 on erectile responses, lipid peroxidation, and nitrite plus nitrate serum content, and nuclear factor-kappaB (NF-kappaB) expression in penile tissue, in diabetic rats, and on endothelium-dependent and neurogenic relaxation of HCC and HPRA from diabetic patients was determined. Eight weeks of diabetes caused ED in rats that was prevented by oral AC3056 (0.3% w/w in rat chow) when given from the induction of diabetes. AC3056 also prevented the diabetes-induced elevation of serum thiobarbituric acid-reactive substances (TBARS), the reduction of serum nitric oxide (NO) derivatives, and the increase of NF-kappaB expression. Acute oral administration of AC3056 (450 mg/kg) partially reversed ED in 8-week diabetic rats. Complete reversion of ED was achieved after 3 days of treatment with 0.3% AC3056. This effect remained after 5 weeks of treatment, but it disappeared after withdrawing for 1 week. Erectile function in diabetic rats was inversely related to serum TBARS. AC3056- (30 microM) reversed endothelial dysfunction in diabetic HCC and enhanced endothelium-dependent relaxation in diabetic HPRA and significantly potentiated neurogenic relaxation of both tissues. The reduced cGMP content in HCC from diabetic patients after exposure to acetylcholine (10 microM) was corrected by AC3056 (30 microM). These results suggest that oxidative stress has a relevant role in pathophysiology of diabetic ED and provide a rationale for the use of antioxidant therapy in the treatment of ED in diabetes.

Penile change following radical prostatectomy: Size, smooth muscle atrophy, and curve

Dr. Patrick Walsh's description of nerve-sparing prostatectomy was an important landmark in the surgical treatment of prostate cancer. Despite the dramatic improvement in postoperative potency rates, anecdotal reports of penile size loss were increasingly reported by patients. Experimental studies in animals revealed penile fibrosis and corporal cavernosal smooth muscle apoptosis after cavernosal nerve ablation. After an observational cross-sectional study demonstrated a time-dependent loss of penile length and circumference in men presenting with erectile dysfunction after nerve-sparing prostatectomy, several prospective studies supported the observational study. A prospective penile biopsy study before and after surgery demonstrated replacement of corporal smooth muscle with collagen and provided a possible explanation for loss of penile length. The mechanism has not yet been elucidated. This article reviews in detail the existing studies on loss of penile size after prostatectomy and possible etiologic mechanisms.

The Case for Postoperative PDE-5 Inhibitor Drug Treatment after Radical Prostatectomy

Journal of EndourologyVol. 22, No. 9 Prostate CancerThe Case for Postoperative PDE-5 Inhibitor Drug Treatment after Radical ProstatectomyAlberto Briganti, Andrea Gallina, Andrea Salonia, Guiseppe Zanni, Andrea Cestari, Giorgio Guazzoni, Patrizio Rigatti, and Francesco MontorsiAlberto BrigantiSearch for more papers by this author, Andrea GallinaSearch for more papers by this author, Andrea SaloniaSearch for more papers by this author, Guiseppe ZanniSearch for more papers by this author, Andrea CestariSearch for more papers by this author, Giorgio GuazzoniSearch for more papers by this author, Patrizio RigattiSearch for more papers by this author, and Francesco MontorsiSearch for more papers by this authorPublished Online:23 Sep 2008https://doi.org/10.1089/end.2008.9752AboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited byAlleviation of post-radical prostatectomy cavernosal fibrosis: future directions and potential utility for PDE5 inhibitors16 August 2011 | Expert Opinion on Investigational Drugs, Vol. 20, No. 10Sildenafil Promotes Smooth Muscle Preservation and Ameliorates Fibrosis Through Modulation of Extracellular Matrix and Tissue Growth Factor Gene Expression After Bilateral Cavernosal Nerve Resection in the RatThe Journal of Sexual Medicine, Vol. 8, No. 4REVIEW: Utilization of Pharmacotherapy for Erectile Dysfunction Following Treatment for Prostate Cancer1 March 2010 | The Journal of Sexual Medicine, Vol. 7, No. 3 Volume 22Issue 9Sep 2008 InformationMary Ann Liebert, Inc.To cite this article:Alberto Briganti, Andrea Gallina, Andrea Salonia, Guiseppe Zanni, Andrea Cestari, Giorgio Guazzoni, Patrizio Rigatti, and Francesco Montorsi.The Case for Postoperative PDE-5 Inhibitor Drug Treatment after Radical Prostatectomy.Journal of Endourology.Sep 2008.2025-2028.http://doi.org/10.1089/end.2008.9752Published in Volume: 22 Issue 9: September 23, 2008PDF download

Cavernous nerve regeneration using acellular nerve grafts

The restoration of erectile function following complete transection of nerve tissue during surgery remains challenging. Recently, graft procedures using sural nerve grafts during radical prostatectomy have had favorable outcomes, and this has rekindled interest in the applications of neural repair in a urologic setting. Although nerve repair using autologous donor graft is the gold standard of treatment currently, donor nerve availability and the associated donor site morbidity remain a problem. In this study, we investigated whether an "off-the-shelf" acellular nerve graft would serve as a viable substitute. We examined the capacity of acellular nerve scaffolds to facilitate the regeneration of cavernous nerve in a rodent model. Acellular nerve matrices, processed from donor rat corporal nerves, were interposed across nerve gaps. A total of 80 adult male Sprague-Dawley rats were divided into four groups. A 0.5-cm segment of cavernosal nerve was excised bilaterally in three of the four groups. In the first group, acellular nerve segments were inserted bilaterally at the defect site. The second group underwent autologous genitofemoral nerve grafts at the same site, and the third group had no repair. The fourth group underwent a sham procedure. Serial cavernosal nerve function assessment was performed using electromyography (EMG) at 1 and 3 months following initial surgery. Histological and immunocytochemical analyses were performed to identify the extent of nerve regeneration. Animals implanted with acellular nerve grafts demonstrated a significant recovery in erectile function when compared with the group that received no repair, both at 1 and 3 months. EMG of the acellular nerve grafts demonstrated adequate intracavernosal pressures by 3 months (87.6% of the normal non-injured nerves). Histologically, the retrieved regenerated nerve grafts demonstrated the presence of host cell infiltration within the nerve sheaths. Immunohistochemically, antibodies specific to axons and Schwann cells demonstrated an increase in nerve regeneration across the grafts over time. No organized nerve regeneration was observed when the cavernous nerve was not repaired. These findings show that the use of nerve guidance channel systems allow for accelerated and precise cavernosal nerve regeneration. Acellular nerve grafts represent a viable alternative to fresh autologous grafts in a rodent model of erectile dysfunction.

Current Literature Review

To assess whether intracavernosal injections of prostaglandin E1 (PGE1) can influence nitric oxide (NO) release in the corpora in a rat model of penile erection.The extracellular levels of NO were monitored at 100 seconds intervals in the corpus cavernosum of anesthetized rats by using differential normal pulse voltammetry with porphyrin-Nafion coated carbon fiber microelectrodes. The intracavernosal pressure (ICP) was simultaneously recorded. PGE1 was given either as a single dose (ranging from 0.2 to 15 μg.) or as repeated 2 μg. injections in alternate days for two weeks. The NO and ICP responses to electrostimulation of the cavernosal nerve (SCN) was studied in the animals in the repeated treatment schedule at 1, 7, 15 and 30 days after its termination. The levels of the three NO synthase (NOS) isoforms in the cavernous tissue were measured by immunoblotting.Acute PGE1 treatment dose-relatedly increased NO levels in the corpora, with a concomitant ICP increase with the highest dose. Repeated 2 μg. PGE1 injections increased the NO and ICP responses to SCN as compared with intact or vehicle-injected animals. This treatment also increased the penile content of the neuronal and endothelial NOS proteins. The inducible NOS isoform remained unchanged after either vehicle or PGE1 injections. The effects of the repeated PGE1 treatment were greater in the group studied 24 hours after the last injection and decreased progressively thereafter.Stimulation of NO release can contribute to the erectogenic effect of intracavernous PGE1 injections. The increased levels of constitutive NOS isoforms in the corpora could contribute to the improvement of the erectile function reported by some patients following repeated treatment with vasorelaxant agents.

Strain Differences in Susceptibility to In Vivo Erectile Dysfunction Following 6 weeks of Induced Hyperglycemia in the Mouse

With the large-scale availability of transgenic and knockout mouse models, the use of mice may greatly facilitate the examination of the mechanisms underlying diabetic erectile dysfunction (ED). Although in vitro studies of the mouse cavernosum show impairment of vasoreactivity, to date, no studies have demonstrated the in vivo impairment of erectile function in diabetic mice. To establish whether mouse models of type I diabetes exhibit in vivo ED. Hyperglycemia was induced by injection with streptozotocin (STZ, 125 mg/kg x 2 days) in two mouse strains, C57BLKS (BKS) and BALB/c. Six weeks after injection, the cavernosum was removed from some mice for the in vitro assessment of the endothelium and nerve-mediated dilatory responses of the cavernosal strips. The in vivo assessment of intracorporal pressure normalized to mean arterial pressure, in response to the electrical stimulation of the cavernosal nerve, was performed in the remaining mice. The main outcome measure of this study was the in vivo assessment of erectile function following diabetic induction in mice. Despite similar levels of sustained hyperglycemia following STZ injection, the phenotype of diabetic ED was observed only in BKS and not BALB/c mice. The cavernosum from diabetic BKS mice showed decreased endothelium-dependent dilation in response to acetylcholine (ACh), as well as impaired parasympathetic nerve-mediated relaxation. There was no change in ACh or nerve-mediated relaxation in the cavernousum from diabetic vs. control BALB/c mice. Further, in vivo physiologic assessment of erectile activity revealed a significant decrease in erectile function in diabetic BKS but not in BALB/c mice. Together these data first established in vivo ED in a mouse model of type I diabetes (BKS mouse) and importantly demonstrated that certain inbred strains may be protected from hyperglycemia-induced erectile impairment. Further study of the strain-dependent effects may offer important clues into the mechanisms of ED as it relates to type I diabetes.

Erectile dysfunction in the type II diabetic db/db mouse: impaired venoocclusion with altered cavernosal vasoreactivity and matrix

The number of men with type II diabetes-associated erectile dysfunction (ED) continues to grow rapidly; however, the majority of basic science studies has examined mechanisms of ED in animal models of type I diabetes. In this study, we first establish an in vivo mouse model of type II diabetic ED using the leptin receptor mutated db/db and wild-type control BKS mouse. Furthermore, we hypothesized that dual mechanistic impairments contribute to the impaired erectile function in the type II diabetic mouse, altered vasoreactivity, and venoocclusive disorder. In vivo erectile function was measured as intracavernosal pressure (ICP) normalized to mean arterial pressure (MAP) following electrical stimulation of the cavernosal nerve. Venoocclusion was assessed by the maintenance of elevated in vivo ICP following intracorporal saline infusion. Vasoreactivity of isolated cavernosum in response to contractile and dilatory stimulation was examined in vitro by myography. Collagen and elastin content were evaluated by quantification of hydroxyproline and desmosine, respectively, as well as by quantitative PCR and histological analysis of isolated cavernosum. Erectile function was significantly decreased in db/db vs. BKS mice in a manner consistent with impairments in venoocclusive ability and decreased inflow. Heightened vasoconstriction and attenuated dilation in cavernosum of db/db vs. BKS mice suggest an overall lowered relaxation ability and thus impaired filling of the cavernosal spaces. A decrease in desmosine and hydroxyproline as well as lowered mRNA levels for tropoelastin, fibrillin-1, and alpha1(I) collagen were detected. These vasoreactive and sinusoidal matrix alterations may alter tissue compliance dispensability, preventing the normal expansion necessary for erection.

Effect of muscle‐derived stem cells on the restoration of corpora cavernosa smooth muscle and erectile function in the aged rat

To determine whether skeletal muscle-derived stem cells (MDSCs) convert into smooth muscle cells (SMCs) both in vitro and in vivo, and in so doing ameliorate the erectile dysfunction (ED) of aged rats, and whether endogenous stem cells are present in the rat corpora cavernosa. MDSCs were obtained from mouse muscle, and shown by immunocytochemistry for alpha-smooth muscle actin (alpha SMA) to originate in vitro in myofibroblasts and SMCs, discriminating SMCs by calponin 1 expression. In vivo these MDSCs, labelled with 4',6-diamidino-2-phenylindole, were implanted into the corpora cavernosa of young adult (5-month old) and aged (20-month old) rats for 2 and 4 weeks. Histological changes were assessed by immunohistochemistry and quantitative Western blot. Functional changes were determined by electrical field stimulation (EFS) of the cavernosal nerve. The exogenous cells replicated and converted into SMCs, as shown in corporal tissue sections by confocal immunofluorescence microscopy for proliferating cell nuclear antigen (PCNA), alpha SMA, and smoothelin, and also by Western blot for alpha SMA and PCNA. MDSC differentiation was confirmed by the activation of the alpha SMA promoter-linked beta-galactosidase in transfected cells, both in vitro and after implantation in the corpora. Putative endogenous stem cells were shown in corporal tissue sections and Western blots by detecting CD34 and a possible Sca1 variant. EFS showed that implanted MDSCs raised in aged rats the maximal intracavernosal pressure/mean arterial pressure levels above (2 weeks) or up to (4 weeks) those of young adult rats. MDSCs implanted into the corpora cavernosa of aged rats converted into SMCs and corrected ED, and endogenous cells expressing stem cell markers were also found in untreated tissue. This suggests that exogenous stem cell implantation and/or endogenous stem cell modulation might be viable therapeutic approaches for ageing-related ED.

Chronic daily tadalafil prevents the corporal fibrosis and veno‐occlusive dysfunction that occurs after cavernosal nerve resection

To determine whether a long-term single daily oral dose of a longer half-life phosphodiesterase-5 (PDE5) inhibitor, tadalafil, has a similar effect to that of the shorter half-life PDE5 inhibitors sildenafil and vardenafil, and can prevent the fibrosis and resultant corporal veno-occlusive dysfunction (CVOD) occurring after cavernosal nerve (CN) injury. Male rats (10 per group) had either a sham operation, unilateral CN resection (CNR) or bilateral CNR, and were left untreated or given retrolingually 5 mg/kg per day of tadalafil. After 45 days, CVOD was assessed via cavernosometry, and the underlying corporal tissue changes were examined by immunohistochemistry and histochemistry (followed by quantitative image analysis), Western blots, and ad hoc methods. Tadalafil treatment normalized the low response to papaverine and high drop rate in the intracavernosal pressure measured by cavernosometry after CNR compared with sham-operated rats. Tadalafil also normalized the increase in penile shaft collagen content, and the reduction in corporal smooth muscle cell (SMC) content, SMC/collagen, and replication index, and improved the lower collagen III/I ratio and the increase in apoptotic index, caused by CNR, compared with sham operation. There were no effects of tadalafil on increased transforming growth factor beta1, inducible nitric oxide synthase and xanthine oxidoreductase levels. A long-term single daily dose of tadalafil prevented CVOD and the underlying corporal fibrosis in the rat caused by CN damage, as effectively as the previously reported continuous treatment with vardenafil or sildenafil, through a cGMP-related mechanism that appears to be independent of inducible nitric oxide synthase induction.

Long-term continuous sildenafil treatment ameliorates corporal veno-occlusive dysfunction (CVOD) induced by cavernosal nerve resection in rats

It was recently reported in the rat that vardenafil given in a continuous long-term manner was successful in preventing smooth muscle fibrosis in the penile corpora cavernosa and corporal veno-occlusive dysfunction (CVOD) that occur following bilateral cavernosal nerve resection (BCNR), a model for human erectile dysfunction after radical prostatectomy. To expand on this finding and to determine whether this effect was common to other PDE5 inhibitors, and occurred in part by stimulation of the spontaneous induction of inducible nitric oxide synthase (iNOS, also known as NOS2), male Fischer 344 rats (N=10/group) were subjected to either BCNR or unilateral cavernosal nerve resection (UCNR) and treated with sildenafil (20 mg kg(-1) day(-1)) in the drinking water daily for 45 days. Additional BCNR groups received L-NIL (6.7 mg kg(-1) day(-1)) as inhibitor of iNOS activity, with or without concurrent sildenafil administration. It was determined that sildenafil, like vardenafil, (1) prevented the 30% decrease in the smooth muscle cell/collagen ratio, and the 3-4-fold increase in apoptosis and reduction in cell proliferation, and partially counteracted the increase in collagen, seen with both UCNR and BCNR; and (2) normalized the CVOD, measured by dynamic infusion cavernosometry, induced by both BCNR and UCNR. The long-term inhibition of iNOS activity exacerbated corporal fibrosis and CVOD in the BCNR rats, but sildenafil functional effects were not affected by L-NIL. These data suggest that the salutary effects of continuous long-term PDE5 inhibitors on erectile function post-cavernosal nerve resection involve their ability to prevent the alterations in corporal histology induced by cavernosal nerve damage, in a process apparently independent from endogenous iNOS induction.

Preliminary Report of the Effect of High-Dose Adjuvant Intensity Modulated Radiation Therapy on the Sural Nerve Graft for Cavernosal Nerve Sacrifice After Radical Prostatectomy

A sural nerve graft may replace a killed cavernosal nerve. The effect of intensity-modulated radiation therapy (IMRT) on function of the graft has not been reported. Between 1998 and 2001, 8 patients (9 nerve grafts) were treated with postoperative IMRT (mean dose, 70 Gy). Two patients had neoadjuvant Lupron 30 mg 2 months prior to radiation. Potency was defined as ability to achieve spontaneous erection sufficient for vaginal penetration. Median follow-up was 31.6 months. Five patients (62.5%) who had erectile function after prostatectomy preserved spontaneous erectile function after radiation. Of these, 3 patients had both nerves resected (two receiving unilateral grafts and one receiving bilateral grafts) and 2 others had one graft and one nerve preserved. The impotent patients were impotent after surgery. High-dose postprostatectomy IMRT does not place sural nerve grafts at greater risk for failure. Larger numbers of patients are needed to confirm these encouraging, preliminary findings.

An animal model to study lower urinary tract symptoms and erectile dysfunction: the hyperlipidaemic rat

To present evidence that rats fed a high-fat diet could serve as a useful animal model to study both lower urinary tract symptoms (LUTS) and erectile dysfunction (ED), as recent epidemiological studies have shown a strong association between LUTS and ED but the physiological basis behind this relationship is unknown. In all, 24 male Sprague-Dawley rats were divided into two groups: nine controls were fed a 'normal' diet and 15 were fed a high-fat diet (hyperlipidaemic rats). After 6 months all the rats had bladder and erectile functions evaluated using awake cystometry and cavernosal nerve electrostimulation, respectively. After the functional studies were completed, the penis, prostate and bladder were collected for immunohistochemical analysis. The hyperlipidaemic rats had significantly higher serum cholesterol and low-density lipoprotein than the controls (P < 0.05). The hyperlipidaemic rats also had significantly worse erectile function (P = 0.004) and developed more bladder overactivity (P = 0.004) than the controls. In the hyperlipidaemic rats there was significant muscle hypertrophy in the peri-urethral lobe of the prostate (P < 0.001) and in the bladder (P < 0.05). There was also greater P2X(1) (purinoceptor) staining as well as other molecular changes in the bladder of the hyperlipidaemic rats. In this hyperlipidaemic rat model three abnormalities were consistently detected: prostatic enlargement, bladder overactivity, and ED. This rat model could be a useful research tool for understanding the common causes of LUTS and ED, as well as facilitating the development of preventive measures and better therapies to treat both conditions.

Gene transfer of the KATP channel restores age‐related erectile dysfunction in rats

To determine if gene transfer of the ATP-sensitive potassium (K(ATP)) channel can reverse age-related erectile dysfunction in the rat, as the K(ATP) channel is an important subtype of potassium channels regulating smooth muscle tone. In an in vitro study, gene were transferred using cDNA of the K(ATP) channel in cultured human corporal smooth muscle (CSM) cells and human embryonic kidney (HEK) cells. After gene transfer, the activities of transferred channels were assessed by the patch-clamp technique. In an in vivo study, 15 old rats were used for groups of gene therapy and nine young adult rats were used as normal controls. The old rats were divided into three groups, i.e. controls and two gene-transfer groups (Kir6.1 + SUR2B and Kir6.2 + SUR2B). The intracavernosal pressure (ICP) response to cavernosal nerve stimulation was assessed after intracorporal injection with naked cDNA of the K(ATP) channel. The transgene expression of the K(ATP) channel was examined by reverse transcription-polymerase chain reaction (RT-PCR) in rats transfected with cDNA of Kir 6.1 and 6.2. The transferred gene of the K(ATP) channel was functionally active and appropriate for gene transfer. The mean (sem) ratio of ICP to systemic blood pressure in the gene-transfer groups, at 79.4 (1)% and 76.5 (2.6)% (both eight rats) was significantly higher than that in age-matched control rats, at 59.4 (3.3)% (eight), and similar to that in the young control rats, at 77.1 (2.7)% (nine). The RT-PCR showed expression of Kir6.1 and 6.2 genes in the transfected groups. In vivo gene transfer of the K(ATP) channel can physiologically restore erectile function in aged rats, and might be applicable to the development of new forms of therapy for treating human erectile dysfunction.

Erectile function following unilateral cavernosal nerve graft

15642 Background: Over the past 20 years, radical prostatectomy has been a mainstay in the treatment of localized prostate cancer. With the adoption of nerve-sparing procedures, select patients may avoid the consequence of erectile dysfunction.Certain patients who are not candidates for nerve-sparing procedures may be eligible for nerve interposition grafts. While bilateral cavernosal nerve grafting after radical prostatectomy has shown efficacy, the effect of unilateral nerve grafting remains unclear. To further ascertain this outcome, we evaluated a large group of patients who underwent a unilateral cavernosal nerve replacement. Methods: Forty patients underwent unilateral nerve sparing surgery with concomitant contralateral cavernosal nerve replacement by a single surgeon from 2002 to 2006. Patient were selected based upon pre-op nomogram risk assessment, endorectal MRI evidence of extra capsular disease or intraop histology demonstrating margin positivity. Age, demographic data, Gleason score, clinical and pathologic stage and pre and post op IIEF data was collected and prospectively analyzed. An additional phone interview was conducted to assess outcomes and morbidity. Results: Full demographic and interview data was available for 28 of 40 patients (70%). Median follow-up was 19 months. The median age at RRP was 53 with a median pre-operative PSA of 6.5. Median pre- and post-op IIEF scores were 25 and 15 respectively. Median change in IIEF scores was 7.5. 22 of 28 patients (79%) men report being able to penetrate after surgery. 17 of those 22 (77%) continue to require PDE-5 inhibitors to facilitate penetration. 3 of the 6 patients (50%) who were unable to have intercourse following nerve replacement received adjuvant hormonal or radiation therapy. 27 patients (96%) reported numbness at the graft harvest site with three (10.7%) describing this as bothersome. One patient experienced a graft site infection and two of 28 (7.1%) patients reported pain at the harvest site. Conclusion: Unilateral sural nerve grafting is a feasible and well-tolerated approach for patients who must undergo wide resection of a neurovascular bundle. While men do show a sizable decrease in their IIEF score, 79% were able to achieve penetration following surgery. The majority of men require PDE-5 inhibitors to facilitate intercourse. No significant financial relationships to disclose.

고지혈증 흰쥐에서 발기부전에 대한 생약제제 KH-305의 효과

This study was designed to investigate effects of KH-305 on erectile dysfunction in hyperlipidemic rat. KH-305 has been evaluated for antihyperlipidemic and antierectile dysfunction effects on experimental hyperlipidemic rats induced by high cholesterol-diet. After oral administration of KH-305 water extract (50, 100, 200, 300 mg/kg) to hyperlipidemic rats for 8 weeks, the variables including body weight, total cholesterol, HDL-, and LDL-cholesterol levels in serum, the expression of eNOS and nNOS in penis were measured. Also, erectile function was determined by the measurements of intracavernosal pressure (ICP) and maximal arterial pressure (MAP) after electrical stimulation of the cavernosal nerve. Oral administration of KH-305 extracts significantly inhibited the increase of serum total cholesterol and LDL-cholesterol levels and the decrease of serum HDL-cholesterol level in hyperlipidemic rats induced by high fat diet. The penile expression level of the two enzymes (eNOS, nNOS) were increased significantly after oral administration of the KH-305 extracts. Erectile function after 10 volts stimulation was significantly decreased in the hyperlipidemic rat compared with the normal rat, but increased in KH-305 group compared with hyperlipidemic group. These results suggest that KH-305 is effective for erectile dysfunction in hyperipidemia.

Antisense and Short Hairpin RNA (shRNA) Constructs Targeting PIN (Protein Inhibitor of NOS) Ameliorate Aging-Related Erectile Dysfunction in the Rat

Over-expression of penile neuronal nitric oxide synthase (PnNOS) from a plasmid ameliorates aging-related erectile dysfunction (ED), whereas over-expression of the protein inhibitor of NOS (PIN), that binds to nNOS, increases ED. To improve this form of gene therapy for ED by comparing the electrical field response of short hairpin RNA (shRNA) for PIN with that of antisense PIN RNA. Both shRNA and antisense RNA gene therapy vectors increased intracavernosal pressure in aged rats. PIN small interfering RNA (siRNA), and plasmid constructs for cytomegalovirus promoter plasmid vector (pCMV-PIN), pCMV-PIN antisense RNA, pSilencer2.1-U6-PIN-shRNA; and pSilencer2.1-U6-randomer-shRNA were prepared and validated by transfection into HEK293 cells, determining the effects on PIN expression by Western blot. Plasmid constructs were then injected, followed by electroporation, into the penile corpora cavernosa of aged (20-month-old) Fisher 344 rats and, 1 month later, the erectile response was measured by intracavernosal pressure increase following electrical field stimulation (EFS) of the cavernosal nerve. PIN was estimated in penile tissue by Western blot and real-time reverse transcriptase-polymerase chain reaction. Cyclic guanosine monophosphate (cGMP) measurements were conducted by competitive enzyme immunoassay (EIA). Immunohistofluorescence detected PIN in corporal tissue sections. In cell culture, PIN siRNA and plasmid-expressed pU6-PIN-shRNA effectively reduced PIN expression from pCMV-PIN. pSilencer2.1-U6-PIN-shRNA corrected the impaired erectile response to EFS in aged rats and raised it above the value for young rats, more efficiently than pCMV-PIN antisense RNA. PIN mRNA expression in the penis was decreased by >70% by the shRNA but remained unaffected by the antisense RNA, whereas PIN protein expression was reduced in both cases, particularly in the dorsal nerve. PIN antisense increased cGMP concentration in treated tissue by twofold. pSilencer2.1-U6-PIN-shRNA gene therapy was more effective than the antisense PIN mRNA in ameliorating ED in the aged rat, thereby suggesting that PIN is indeed a physiological inhibitor of nNOS and nitrergic neurotransmission in the penis.