Intracavernous Pressure Response Research Articles

(018) Long Term Outcome of Tachosil Patching of the Penile Tunica Albuginea Defect in the Dog: Histological and Hemodynamic Results

Abstract Introduction The need for patching of the penile tunica albuginea (TA) might arise during surgery for Peyronie’s disease with or without a penile prosthesis. Clinically, TachoSil has evolved as an off-the-shelf hemostatic graft that does not need suturing. Results in patients are encouraging. However, its histopathological fate and its impact on the hemodynamics of erection are not known. Objective We evaluate the long-term histopathology and pharmacologically induced erection after Tachosil patching of the TA in dogs. Methods Under general anesthesia, the penis of two adult male beagle dogs was dissected through a midline incision, and TA was exposed. The femoral artery was cannulated and connected to an invasive pressure monitor to record BP. Intracavernous pressure (ICP) was measured on each cavernous side separately, as a complete septum isolates the two compartments of the penis. A 21-gauge butterfly needle was placed on either side proximally. Five minutes were allowed before taking baseline ICP. Ten mg of papaverine hydrochloride was injected intracavernosal. ICP was measured at 2 to10-min time points. On the left side, 2 cm proximal to the glans of the penis, a full-thickness defect was created in TA 1 cm long and 0.5 cm wide (Fig. 1. A, B &C). Four transverse incisions 1 cm long were made on the right side and placed 0.5 cm apart, exposing the corpus cavernosum (Fig. 1. D). A Tachosil patch (Takeda, Japan) was fashioned and applied to cover the defects. Proline 5/0 sutures were placed, marking the proximal and distal ends of the graft areas. The fascia, subcutaneous tissue, and skin were closed with absorbable sutures. Six months later, each dog was anesthetized, and the penis was dissected free from the covering fascia. Invasive BP and ICP measurements were repeated at baseline and after 10 mg papaverine injection. Silk and proline sutures were placed to identify the distal end and the left side of the penis. The penis was excised from the base of the glans penis distally to its root, at least 6 cm proximally and fixed in 10% formaldehyde solution. Transverse blocks of the penis were cut at 3 mm intervals and fixed in paraffin. Sections from each block were stained with H&E and trichrome and examined by a urology pathologist. Descriptive statistics are provided. Results Gross appearance showed a well-healed scar, and the subcutaneous tissue did not show significant adhesions. The graft site was impossible to distinguish, and the sutures were not visible. ICP measurement did not show a drop in pressure pre- and post-surgery (Fig. 2). Histologically, minimal foreign body reaction was seen, and the tunica albuginea was completely regenerated (Fig. 3). The underlying cavernous tissue did not show inflammation or necrosis. Conclusions Long-term histological results of Tachosil patching in the dog show complete tunica albuginea regeneration with minimal tissue reaction and no underlying cavernous tissue pathology. Hemodynamically the intracavernous pressure response to papaverine is maintained. Although only two animals are presented here, the results are striking. Further experimentation with more animals is warranted to support these findings. Disclosure No.

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

BackgroundDespite 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. AimThis study aimed to investigate the effects of PRP glue treatment on EF and CN preservation in rats after CNSP. MethodsAfter 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. ResultsThe 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. ConclusionsThese 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.

N‐acetylcysteine improves diabetic associated erectile dysfunction in streptozotocin‐induced diabetic mice by inhibiting oxidative stress

Oxidative stress appears to play a role in the pathogenesis of diabetes mellitus erectile dysfunction (DMED). This study aimed to investigate the effect of N‐acetylcysteine (NAC) on DMED in streptozotocin‐induced diabetic mice and to explore potential mechanisms. In the present study, we show that an erectile dysfunction is present in the streptozotocin‐induced mouse model of diabetes as indicated by decreases in intracavernous pressure responses to electro‐stimulation as well as from results of the apomorphine test of erectile function. After treatment of NAC, the intracavernous pressure was increased. In these DMED mice, oxidative stress and inflammatory responses were significantly reduced within the cavernous microenvironment, while activity of antioxidant enzymes in this cavernous tissue was enhanced after NAC treatment. These changes protected mitochondrial stress damage and a significant decreased in apoptosis within the cavernous tissue of DMED mice. This appears to involve activation of the nuclear factor erythroid 2‐like‐2 (Nrf2) signalling pathway, as well as suppression of the mitogen‐activated protein kinase (MAPK) p38/ NF‐κB pathway within cavernous tissue. In conclusion, NAC can improve erectile function through inhibiting oxidative stress via activating Nrf2 pathways and reducing apoptosis in streptozotocin‐induced diabetic mice. NAC might provide a promising therapeutic strategy for individuals with DMED.

Diabetes associated with hypertension exacerbated oxidative stress-mediated inflammation, apoptosis and autophagy leading to erectile dysfunction in rats.

Diabetes or hypertension contributes to erectile dysfunction (ED). We hypothesized that excess reactive oxygen species (ROS) production evoked by diabetes combined with hypertension may further suppress endothelial nitric oxide (NO) expression/activity and promote oxidative stress in the ED penis. Twenty-four adult male Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were divided into four groups: normal WKY, diabetic WKY, normal SHR and diabetic SHR. Intraperitoneal streptozotocin (65 mg/kg) was applied to induce type I diabetes. After 4-week diabetes and/or hypertension induction, we determined the intra-cavernous pressure (ICP) using electrical stimulation of cavernous nerves, intra-cavernosum NO amount using an electrochemical NO probe, and blood ROS using an ultrasensitive chemiluminescence-amplified analyzer. Western blot analysis and immunohistochemistry were used to explore the pathophysiologic mechanisms of inflammation, apoptosis and autophagy in the penis. A novel NO donor, CysaCysd Lu-5 (CCL5, (RCH2CH2S)(R'R"CHCH2S)Fe(NO)2, 1-4 µg), was intravenously administered to these ED rats for evaluating their ICP responses. In the baseline status, the lucigenin- and luminol-amplified blood ROS were significantly enhanced in the diabetic SHR rats vs normal WKY rats. Significantly decreased ICP, eNOS expression and NO amount were found in the normal SHR, diabetic WKY, and diabetic SHR vs normal WKY rats. Intravenous NO donor L-Arginine markedly increased ICP and NO amount, whereas eNOS inhibitor, Nω-Nitro-L-Arginine methyl ester hydrochloride depressed ICP in all four groups. Diabetes and/or hypertension alone increased fibrosis, proinflammatory NF-kB/ICAM-1 expression, mast cell numbers, CD68 expression and infiltration, Caspase 3-mediated apoptosis, Beclin-1/LC3-II-mediated autophagy and mild Nrf-2/HO-1 expression and depressed eNOS expression in the ED penis. The novel NO donor, CCL5, was more efficient than L-arginine to improve diabetes and/or hypertension-induced ED by the significant increase of ICP. Diabetes combined with hypertension synergistically exacerbated ED through enhanced oxidative stress, inflammation, apoptosis and autophagy and depressed eNOS activity and NO production.

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.

Testosterone replacement alters the cell size in visceral fat but not in subcutaneous fat in hypogonadal aged male rats as a late-onset hypogonadism animal model.

BackgroundPatients with late-onset hypogonadism (LOH) benefit from testosterone replacement by improvement in the parameters of the metabolic syndrome, but fat cell morphology in these patients is still unclear. This study aims to determine the effect of testosterone replacement on the morphology of fat cells in subcutaneous and visceral adipose tissue and on erectile function in hypogonadal aged male rats as a model of LOH.MethodsTen male Sprague-Dawley rats aged 20–22 months were randomly allocated to two groups, ie, aged male controls (control group, n=5) and aged males treated with testosterone replacement therapy (TRT group, n=5). Testosterone enanthate 25 mg was injected subcutaneously every 2 weeks for 6 weeks. At 6 weeks, the intracavernous pressure (ICP) and mean arterial blood pressure (MAP) ratio was assessed. Visceral and subcutaneous adipose tissue specimens were collected and analyzed using Image-J software.ResultsBody weight at 2, 4, and 6 weeks after TRT was 800.0±35.4 g, 767.5±46.3 g, and 780±40.4 g, respectively (not statistically significant). The ICP/MAP ratio was 0.341±0.015 in the TRT group and 0.274±0.049 in the control group (not statistically significant). The median subcutaneous fat cell size was 4.85×103 (range 0.85–12.53×103) μm2 in the control group and 4.93×103 (range 6.42–19.7×103) μm2 in the TRT group (not statistically significant). In contrast, median visceral fat cell size was significantly smaller in the TRT group (4.93×103 μm2 [range 0.51–14.88×103]) than in the control group (6.08×103 μm2 [0.77–19.97×103]; P<0.001, Mann-Whitney U test).ConclusionThis is the first study clearly indicating that TRT can decrease visceral fat cell size, which is a key modulator in the metabolic syndrome. However, a short course of TRT could not improve the ICP response in hypogonadal aged male rats. Further investigation is necessary to clarify the exact rationale of TRT on the visceral fat cell.

Short hairpin ribonucleic acid constructs targeting insulin-like growth factor binding protein-3 rehabilitated decreased testosterone concentrations in diabetic rats.

BackgroundThe aim of this study was to determine if shRNA constructs targeting insulin-like growth factor binding protein-3 can rehabilitate decreased serum testosterone concentrations in streptozotocin-induced diabetic rats.Material/MethodsAfter 12 weeks of intracavernous administration of IGFBP-3 shRNA, intracavernous pressure responses to electrical stimulation of cavernous nerves were evaluated. The expression of IGFBP-3 at mRNA and protein levels was detected by quantitative real-time PCR analysis and Western blot, respectively. The concentrations of serum testosterone and cavernous cyclic guanosine monophosphate were detected by enzyme-linked immunosorbent assay.ResultsAfter 12 weeks of intracavernous administration of IGFBP-3 shRNA, the cavernosal pressure was significantly increased in response to the cavernous nerves stimulation compared to the diabetic control group (p<0.01). Cavernous IGFBP-3 expression at both mRNA and protein levels was significantly inhibited. Both serum testosterone and cavernous cyclic guanosine monophosphate concentrations were significantly increased in the IGFBP-3 shRNA treatment group compared to the diabetic control group (p<0.01).ConclusionsThese results suggest that IGFBP-3 shRNA may rehabilitate erectile function via increases of concentrations of serum testosterone and cavernous cyclic guanosine monophosphate in streptozotocin-induced diabetic rats.

Novel Therapeutic Approach for Neurogenic Erectile Dysfunction: Effect of Neurotrophic Tyrosine Kinase Receptor Type 1 Monoclonal Antibody

BackgroundErectile dysfunction (ED) is a major health issue in aged populations, and neurogenic ED is particularly difficult to treat. Novel therapeutic approaches are needed for treatment of neurogenic ED of peripheral origin. ObjectiveTo investigate the therapeutic effects of a neurotrophic tyrosine kinase receptor type 1 monoclonal antibody (TrkA-mAb) on erectile function and sexual behavior in a rat model of cavernous nerve injury (CNI). Design, setting, and participantsIn one experiment, 84 male rats were randomly assigned to seven groups. The groups underwent either CNI or sham surgery, subsequent injection into the major pelvic ganglion (IMPG) of phosphate-buffered saline (PBS), an immunoglobulin G (IgG) control, or TrkA-mAb, and then intracavernosal (IC) injection of either PBS or varying TrkA-mAb concentrations immediately after surgery and then 1 wk later. Erectile function was assessed and histologic/molecular analyses were performed at 6 wk after surgery. In a second experiment, 36 male rats were randomly divided into three groups. The groups underwent CNI or sham surgery and then IC injection of PBS, IgG, or TrkA-mAb immediately after surgery and for 5 wk thereafter. At 6 wk after surgery, the performance of the rats in sexual behavior tests was videotaped. InterventionCNI or sham surgery; IMPG of PBS, IgG, or TrkA-mAb; IC injection of PBS or TrkA-mAb. Outcome measurements and statistical analysisThe intracavernous pressure response to cavernous nerve electrostimulation was measured and midpenile cross-sections were histologically examined. Western blotting (WB) of cavernous tissue protein was performed. Rats were assessed for chasing, mounting, intromission, and ejaculation behaviors during sexual behavior tests. The data were analyzed using one-way analysis of variance followed by the Tukey-Kramer t test. Results and limitationsRecovery of erectile function of varying degrees was observed in the TrkA-mAb groups. TrkA-mAb treatment significantly suppressed tyrosine hydroxylase–positive nerve fibers in the corpus cavernosum and enhanced neuronal nitric oxide synthase–positive fibers in the dorsal nerve. The ratio of smooth muscle to collagen in the corpus cavernosum was significantly improved in TrkA-mAb treatment groups compared to PBS vehicle and IgG control groups. WB confirmed these biological changes. There was a nonsignificant increase in the average number of intromissions and ejaculations in the TrkA-mAb group. The study limitations include small sample size, variability in sexual behavior, lack of data on the neuromuscular mechanism involved, and lack of information of the role of neurotrophins or cytokines in regeneration. ConclusionsTrkA-mAb successfully inhibits sympathetic nerve regeneration, leads to parasympathetic nerve regeneration, and has therapeutic effects on ED and sexual behavior disorder in a rat model of CNI. Patient summaryThis report provides strong evidence that a neurotrophic tyrosine kinase receptor type 1 monoclonal antibody (TrkA-mAb) inhibits sympathetic nerve regeneration, leads to parasympathetic nerve regeneration, and has therapeutic effects on erectile dysfunction and sexual behavior disorder in a rat model of cavernous nerve injury. The results raise the possibility that human patients with neurogenic erectile dysfunction may respond to TrkA-mAb in a manner that parallels the response seen in our rodent study.

Continuous-wave Infrared Subsurface Optical Stimulation of the Rat Prostate Cavernous Nerves Using a 1490-nm Diode Laser

To optimize the infrared laser wavelength and optical nerve stimulation (ONS) parameters for both deep and rapid subsurface cavernous nerve (CN) stimulation in a rat model, invivo. A 150-mW, 1490-nm diode laser providing an optical penetration depth (OPD) of 518 μm in water was operated in continuous-wave mode during stimulation of the CNs in 8 rats for 15 seconds irradiation time through a custom-built, single-mode fiber optic probe capable of producing a collimated, 1-mm diameter laser beam. Successful ONS was judged by an intracavernous pressure response in the rat penis. Subsurface ONS at 1490 nm was also compared with previous studies using 1455 nm and 1550 nm near-infrared diode laser wavelengths. Subsurface ONS of the rat CN was successful through fascia layers with a thickness up to 380 μm using an incident laser power of ∼50 mW. Intracavernous pressure response times as short as 4.6± 0.2 seconds were recorded using higher laser powers below the nerve damage threshold. The 1490-nm diode laser represents a compact, low cost, high power, and high quality infrared light source for use in ONS. This wavelength provides deeper penetration than 1455-nm diode laser and more rapid and efficient nerve stimulation than 1550-nm diode laser.

Temperature-controlled optical stimulation of the rat prostate cavernous nerves

Optical nerve stimulation (ONS) may be useful as a diagnostic tool for intraoperative identification and preservation of the prostate cavernous nerves (CN), responsible for erectile function, during prostate cancer surgery. Successful ONS requires elevating the nerve temperature to within a narrow range (~42 to 47°C) for nerve activation without thermal damage to the nerve. This preliminary study explores a prototype temperature-controlled optical nerve stimulation (TC-ONS) system for maintaining a constant (±1°C) nerve temperature during short-term ONS of the rat prostate CNs. A 150-mW, 1455-nm diode laser was operated in continuous-wave mode, with and without temperature control, during stimulation of the rat CNs for 15 to 30 s through a fiber optic probe with a 1-mm-diameter spot. A microcontroller opened and closed an in-line mechanical shutter in response to an infrared sensor, with a predetermined temperature set point. With TC-ONS, higher laser power settings were used to rapidly and safely elevate the CNs to a temperature necessary for a fast intracavernous pressure response, while also preventing excessive temperatures that would otherwise cause thermal damage to the nerve. With further development, TC-ONS may provide a rapid, stable, and safe method for intraoperative identification and preservation of the prostate CNs.

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

Both Immediate and Delayed Intracavernous Injection of Autologous Adipose-derived Stromal Vascular Fraction Enhances Recovery of Erectile Function in a Rat Model of Cavernous Nerve Injury

BackgroundIntracavernous injection of cultured adipose-derived stem cells (ADSCs) effectively restores erectile function in cavernous nerve (CN)–injured rats when administered at the time of injury. However, culturing exposes ADSCs to the risk of contamination and dedifferentiation. ObjectiveExplore the effect of uncultured autologous adipose-derived stromal vascular fraction (SVF) on improving erectile function in a rat model of CN injury when administered at the time of injury or 4 wk after injury. Design, setting, and participantsEighty-nine male Sprague Dawley rats were randomly divided into four groups. CN injury or sham surgery was performed at the start of the study, and rats were treated with either SVF or vehicle. Functional testing and histologic analysis were performed 12 wk after CN crush or sham surgery. InterventionWe used intracavernous injection of saline immediately after CN crush (n=23), intracavernous injection of SVF immediately after CN crush (n=17), intracavernous injection of SVF 4 wk after CN crush (n=23), or sham surgery (n=26). Outcome measurements and statistical analysisWe studied intracavernous pressure (ICP) response to CN electrostimulation and performed histologic examination of midpenile cross-sections. Data were analyzed using one-way analysis of variance followed by the Tukey-Kramer test. Results and limitationsBoth immediate and delayed treatment with SVF resulted in a significantly increased ICP-to-mean arterial pressure ratio compared with the vehicle-treated group. Both immediate and delayed treatment with SVF significantly increased expression of neuronal nitric oxide synthase and neurofilament in dorsal penile nerves compared to the vehicle group. Furthermore, the smooth muscle-to-collagen ratio within the corpus cavernosum was significantly improved in both of the SVF groups compared to vehicle-treated rats. The main limitation of the study is the lack of determination of the SVF components. ConclusionsUncultured autologous SVF injected immediately or 4 wk after CN crush improved erectile function, promoted nerve regeneration, and prevented fibrosis of the corpus cavernosum following CN injury.

Subsurface near‐infrared laser stimulation of the periprostatic cavernous nerves

Successful identification and preservation of the cavernous nerves (CN), which are responsible for sexual function and vulnerable to damage during prostate cancer surgery, will require subsurface detection of the CN's beneath a thin fascia layer. This study explores the feasibility of optical nerve stimulation (ONS) in the rat with a fascia layer placed over the CN. Two near-infrared diode lasers with wavelengths of 1455 and 1550 nm were operated in continuous-wave mode for stimulation of the CN in 8 rats, in vivo. Successful ONS was confirmed by an intracavernous pressure (ICP) response in the rat penis at 1455 nm through fascia with a thickness up to 110 μm and at 1550 nm through fascia with a thickness up to 450 μm. Higher incident laser power was required to produce an ICP response as fascia thickness was increased. Also, weaker and slower ICP responses were observed as fascia thickness was increased. Subsurface ONS of the rat CN at a depth of 450 μm using a 1550 nm laser is feasible as an intermediate step towards developing ONS as an intra-operative diagnostic tool for identification and preservation of the cavernous nerves during prostate cancer surgery.

Effects of Icariin on Improving Erectile Function in Streptozotocin‐Induced Diabetic Rats

Icariin has been shown to improve penile hemodynamics in animal models of erectile dysfunction from cavernous nerve injury and castration. The effects of icariin on penile hemodynamics in diabetic animals remain to be determined. Transforming growth factor β1 (TGFβ1) has been implicated in the pathogenesis of diabetes-related erectile dysfunction. The aim of this study was to investigate the effects of icariin in the penis of streptozotocin (STZ)-induced diabetic rat. Two-month-old Sprague-Dawley male rats received one-time intraperitoneal (IP) STZ (60 mg/kg) or vehicle injection after a 16-hour fast. Three days later, the STZ-induced diabetic rats were randomly divided into four groups and were treated with daily gavage feedings of a 50:50 mix of normal saline and dimethyl sulfoxide (DMSO) or icariin dissolved in DMSO at doses of 1, 5, and 10 mg/kg for 3 months. A positive control group underwent IP injection of saline followed by daily gavage of saline/DMSO solution. Treatment was stopped 1 week prior to functional assay and euthanasia. Penile hemodynamics was assessed by electrical stimulation of the cavernous nerves with real-time intracavernous pressure (ICP) measurement. After euthanasia, penile tissue was studied using immunohistochemistry, Western blot, and enzyme-linked immunosorbent assay (ELISA) to assess the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) and TGFβ1/Smad2 signaling pathway. Diabetes attenuated ICP response in control animals. Untreated diabetic animals had decreased smooth muscle/collagen ratio and endothelial cell content in the corpora cavernosa; treatment with icariin partially attenuating these effects. Icariin-treated animals also had a significantly greater expression of nicotinamide adenine dinucleotide phosphate-positive nerves and the endothelial cell markers, von Willebrand factor (vWF), and platelet endothelial cell adhesion molecule-1 (PECAM). TGFβ1/Smad2 signaling pathway was down-regulated in the penis from icariin-treated models relative to what was observed in negative control animals. Icariin treatment preserved penile hemodynamics, smooth muscle and endothelial integrity, and neuronal nitric oxide synthase expression in the penis of diabetic rats. Down-regulation of TGFβ1/Smad2 signaling pathway might mediate this effect.

Smooth muscle myosin expression, isoform composition, and functional activities in rat corpus cavernosum altered by the streptozotocin-induced type 1 diabetes

Diabetes mellitus (DM) is a quite common chronic disease, and the prevalence of erectile dysfunction (ED) is three times higher in this large population. Although diabetes-related ED has been studied extensively, the actin-myosin contractile apparatus was not examined. The mRNAs encoding smooth muscle myosin (SMM) heavy chains (MHC) and essential light chains (LC(17)) exist as several different alternatively spliced isoforms with distinct contractile properties. Recently, we provided novel data that blebbistatin (BLEB), a specific myosin II inhibitor, potently relaxed corpus cavernosum smooth muscle (CCSM). In this study, we examine whether diabetes alters SMM expression, alternative splicing, and/or functional activities, including sensitivity to BLEB. By using streptozotocin (STZ)-induced 2-mo diabetic rats, functional activities were tested in vivo by intracavernous pressure (ICP) recording during cavernous nerve stimulation and in vitro via organ bath contractility studies. SMM isoform composition was analyzed by competitive RT-PCR and total SMM, myocardin, and embryonic SMM (SMemb) expression by real-time RT-PCR. Results revealed that the blood glucose level of STZ rats was 407.0 vs. 129.5 mg/dl (control). STZ rats exhibited ED confirmed by significantly increased CCSM contractile response to phenylephrine and decreased ICP response. For STZ rats, SM-B, LC(17a) and SM2 isoforms, total SMM, and myocardin expression increased, whereas SM-A, LC(17b), and SM1 isoforms were decreased, with SMemb unchanged. BLEB was significantly more effective in relaxing STZ CCSM both in vitro and in vivo. Thus we demonstrated a novel diabetes-specific effect on alternative splicing of the SMM heavy chain and essential light chain genes to a SMM isoform composition favoring a heightened contractility and ED. A switch to a more contractile phenotype was supported further by total SMM expression increase. Moreover, the change in CCSM phenotype was associated with an increased sensitivity to BLEB, which may serve as a novel pharmacotherapy for ED.

Continuous-Wave Laser Stimulation of the Rat Prostate Cavernous Nerves Using a Compact and Inexpensive All Single Mode Optical Fiber System

Laser stimulation of the rat cavernous nerve (CN) recently has been demonstrated as an alternative to electrical stimulation for potential application in nerve mapping during nerve-sparing radical prostatectomy. Advantages include noncontact stimulation and improved spatial selectivity. Previous studies, however, have used large and/or expensive laser sources for stimulation. This study demonstrates the feasibility of optical stimulation of the rat CN, in vivo, using a compact, inexpensive all-single-mode fiberoptic system. A 1455-nm wavelength infrared diode laser beam was coupled into a 9-μm-core single-mode fiber for delivery through a 10F laparoscopic probe and used for laser stimulation of the CN in a total of eight rats, in vivo. Laser stimulation of the CN was observed at threshold temperatures of 41°C, with intracavernous pressure response times as short as 4 s, and magnitudes up to 50 mm Hg, compared with baselines of 10 mm Hg. This novel, all-single-mode-fiber laser nerve stimulation system introduces several advantages including: (1) lower cost laser; (2) more robust fiberoptic design, eliminating alignment and cleaning of bulk optical components; and (3) improved Gaussian spatial beam profile for simplified alignment of the laser beam with the nerve. With further development, laser nerve stimulation may be useful for identification and preservation of the CN during prostate cancer surgery.

Increased expression of insulin-like growth factor-binding protein-3 is implicated in erectile dysfunction in two-kidney one-clip hypertensive rats after propranolol treatment

This study aimed to investigate the role of insulin-like growth factor-binding protein-3 (IGFBP-3) in erectile dysfunction (ED) in two-kidney one-clip (2K-1C) hypertensive rats treated with the β-blocking agent propranolol. Adult male Wistar rats were randomly divided into three groups: a normal control group, a hypertensive control group and a propranolol treatment group (n=9). After 4 weeks of propranolol treatment, intracavernous pressure (ICP) responses to electrical stimulation of the cavernous nerves were evaluated. The expression of IGFBP-3 and insulin-like growth factor-1 (IGF-1) mRNA and protein in the rat cavernous tissue were detected by quantitative real-time PCR and Western blot, respectively. The concentration of cyclic guanosine monophosphate (cGMP) in the cavernous tissue was determined by enzyme-linked immunosorbent assay (ELISA). Cavernosal pressure in response to cavernous nerve stimulation was decreased 4 weeks after propranolol treatment (P<0.01, compared to the hypertensive control group). IGFBP-3 mRNA and protein expression was increased in the propranolol treatment group compared to the hypertensive control group (P<0.01), whereas IGF-1 expression was decreased in the propranolol treatment group compared to the hypertensive control group (P<0.01). In addition, cavernous cGMP concentration was decreased in the propranolol treatment group compared to the hypertensive control group (P<0.01). Taken together, these results suggest that the upregulation of IGFBP-3 may play a role in the development of ED in hypertensive rats.

1130 STREPTOZOTOCIN-INDUCED TYPE 1 DIABETES IN RAT ALTERS SMOOTH MUSCLE MYOSIN ISOFORM COMPOSITION TO A MORE CONTRACTILE PHENOTYPE AND INCREASES SENSITIVITY TO THE MYOSIN II SPECIFIC INHIBITOR BLEBBISTATIN

You have accessJournal of UrologySexual Function/Dysfunction/Andrology: Basic Research1 Apr 20111130 STREPTOZOTOCIN-INDUCED TYPE 1 DIABETES IN RAT ALTERS SMOOTH MUSCLE MYOSIN ISOFORM COMPOSITION TO A MORE CONTRACTILE PHENOTYPE AND INCREASES SENSITIVITY TO THE MYOSIN II SPECIFIC INHIBITOR BLEBBISTATIN Xinhua Zhang, Arnold Melman, and Michael DiSanto Xinhua ZhangXinhua Zhang Camden, NJ More articles by this author , Arnold MelmanArnold Melman Bronx, NY More articles by this author , and Michael DiSantoMichael DiSanto Camden, NJ More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.727AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The mRNAs encoding smooth muscle myosin (SMM) heavy chains (MHC) and the 17 kDa essential light chains (LC17) exist as several different isoforms with distinct contractile properties, produced via alternative splicing mechanisms. Recently, we provided novel data that blebbistatin (BLEB), a specific myosin II inhibitor, potently relaxed both rat and human corpus cavernosum smooth muscle (CCSM)(J Sexual Med, 2009). In this study, we determine if diabetes alters SMM expression, alternative splicing and/or functional activities including sensitivity to BLEB. METHODS Fisher 344 male streptozotocin (STZ)-induced diabetic rats were kept for 2 months. Functional activities were then tested in vivo by intracavernous pressure (ICP) recording and in vitro via organ bath contractility studies. SMM isoform composition was analyzed by competitive RT-PCR and total SMM, myocardin (a transcriptional regulator of SMM) and embryonic SMM (SMemb) expression by Real-time RT-PCR. RESULTS Average blood glucose levels of STZ rats were 407 vs 129.5 mg/dl in rats injected with saline (SHAM). STZ rats showed severe erectile dysfunction (ED) confirmed by decreased ICP response to electrical stimulation of cavernous nerve. For STZ rats, LC17a and SM-B isoforms (both associated with increased contractility and faster shortening velocity) and total SMM and myocardin expression increased while LC17b and SM-A isoforms (both associated with decreased contractility and slower shortening velocity) were decreased with SM1/2 SMM MHC isoforms and SMemb unchanged. Interestingly, BLEB was more effective in relaxing STZ CCSM both in vitro and in vivo. CONCLUSIONS We show for the first time to our knowledge a diabetes-specific effect on alternative splicing of the SMM heavy chain and essential light chain genes to a SMM isoform composition favoring a heightened contractility and ED. A switch to a more contractile phenotype is further supported by total SMM expression increase. Moreover, we provide novel data that the change in CCSM phenotype is associated with an increased sensitivity to BLEB, which may serve as a novel pharmacotherapy for ED with specificity to the faster type myosin isoforms found in the diabetic rat CCSM. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e454 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Xinhua Zhang Camden, NJ More articles by this author Arnold Melman Bronx, NY More articles by this author Michael DiSanto Camden, NJ More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...

Continuous-wave infrared optical nerve stimulation for potential diagnostic applications

Optical nerve stimulation using infrared laser radiation has recently been developed as a potential alternative to electrical nerve stimulation. However, recent studies have focused primarily on pulsed delivery of the laser radiation and at relatively low pulse rates. The objective of this study is to demonstrate faster optical stimulation of the prostate cavernous nerves using continuous-wave (cw) infrared laser radiation for potential diagnostic applications. A thulium fiber laser (λ=1870 nm) is used for noncontact optical stimulation of the rat prostate cavernous nerves in vivo. Optical nerve stimulation, as measured by an intracavernous pressure (ICP) response in the penis, is achieved with the laser operating in either cw mode, or with a 5-ms pulse duration at 10, 20, 30, 40, 50, and 100 Hz. Successful optical stimulation is observed to be primarily dependent on a threshold nerve temperature (42 to 45 °C), rather than an incident fluence, as previously reported. cw optical nerve stimulation provides a significantly faster ICP response time using a lower power (and also less expensive) laser than pulsed stimulation. cw optical nerve stimulation may therefore represent an alternative mode of stimulation for intraoperative diagnostic applications where a rapid response is critical, such as identification of the cavernous nerves during prostate cancer surgery.

Smooth-Muscle–Specific Gene Transfer with the Human Maxi-K Channel Improves Erectile Function and Enhances Sexual Behavior in Atherosclerotic Cynomolgus Monkeys

BackgroundDespite the advent of effective oral therapies for erectile dysfunction (ED), many patients are not successfully treated, and side effects have been documented. ObjectiveTo further evaluate the potential utility of naked DNA-based gene transfer as an attractive treatment option for ED. Design, setting and participantsThe effects of gene transfer on erectile function and sexual behavior were evaluated in eight male cynomolgus monkeys with ED secondary to moderately severe, diet-induced atherosclerosis. InterventionFollowing establishment of baseline characteristics, animals were subjected to intracavernous injection of a smooth-muscle–specific gene transfer vector (pSMAA-hSlo) encoding the pore-forming subunit of the human large-conductance, calcium-sensitive potassium channel (Maxi-K). MeasurementsFor the sexual behavior studies, 2 wk of baseline data were obtained, and then animals were placed in the presence of estrogen-implanted females (n=2) three times per week for 30min, and sexual behavior was recorded. The intracavernous pressure response to papaverine injection was also monitored. Results and limitationsDramatic changes in erectile function and sexual behavior were observed after intracorporal gene transfer. The frequency of partial (6±2 to 10±2) and full (2±1.5 to 5±1.4) erections were significantly increased, with a parallel 2–3-fold increase in the duration of the observed erections. The frequency and latency of ejaculation were increased and decreased, respectively. Frequency and duration of grooming by the female were increased, and the latency decreased. Increased latency and decreased frequency of body contact was also observed, and this is characteristic of the typical drop in consort intimacy that occurs after mating in most macaque species. In addition, an increased responsiveness to intracavernous papaverine injection was observed. ConclusionsThe data indicate that intracorporal Maxi-K–channel gene transfer enhances erectile capacity and sexual behavior; the data imply that increased erectile function per se may lead to increased sexual function.