Increase In Intracavernous Pressure Research Articles

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.

Histologic and physiologic analysis of the relationship between the dorsal nerve of the penis and the corpus cavernosum on a rat model. A complementary pathway on the innervation of penile erection?

The dorsal nerve of the penis (DNP) is the terminal branch of the pudendal nerve which is responsible for the somatic innervation of the penis. This study aims to outline any direct role of the DNP in the hemodynamics of erection histologically and physiologically. Fifteen Wistar albino rats were sorted into the electrical activity (n = 6), intracavernous pressure (n = 4), and control (n = 5) groups. The dorsal nerve was electrostimulated and the simultaneous changes in intracavernous pressure and smooth muscle activity were recorded. Penile tissues were collected, fixed, and sectioned, the slides were stained with either hematoxylin-eosin for morphological evaluation or using the indirect immunoperoxidase technique to analyze the distributions of eNOS, iNOS, and nNOS. During electrostimulation, there was a simultaneous statistically significant decrease in the electrical activity inside the corpora in electromyography and an increase in intracavernous pressure. eNOS and iNOS immunoreactivities were higher in the study group than in the control group. nNOS immunoreactivity was moderate in both study and control groups. Some fibers in the dorsal nerve of penis continue into the corpora cavernosa through the tunica albuginea and have an active, direct role in the hemodynamic process of erection, which may be complementary to the main route of innervation.

Erectile Functional Restoration With Genital Branch of Genitofemoral Nerve to Pelvic Nerve Transfer After Spinal Root Transection in Rats

ObjectiveTo investigate the feasibility of erectile function restoration by the genitofemoral nerve to pelvic nerve transfer in rats. MethodsThirty-six male rats were included in this study. Rats in the nerve transfer group (n = 12) were subjected to pelvic nerve, sacral roots, and L6 roots transection and then bilateral genitofemoral nerve to pelvic nerve transfer, rats in the nerve resection group (n = 12) were subjected to pelvic nerve, sacral roots, and L6 roots transection without nerve transfer, and rats in the control group (n = 12) served as controls. After reinnervation, intracavernous pressure (ICP) assessment was performed. Fluoro-Gold was injected into the corpus cavernosum. Immediately before euthanasia, transferred nerves were stimulated to test penile intracavernous pressure. The L6, S1, and L1-2 spinal cord segments were used for retrogradely labeled neurons. Regenerative nerve morphologic examination assessment was performed. ResultsGenitofemoral nerve stimulation induced an increase in ICP in the nerve transfer group. The mean ICP in this group was (33.8 ± 9.4 mm Hg), which is higher than the mean value in the nerve resection group (3.9 ± 1.0 mm Hg) but lower than that in the control group (69.8 ± 12.2 mm Hg; P < .05). The formation of new neural pathways was confirmed by the appearance of Fluoro-Gold labeled neurons in the L-1 and L-2 spinal cord segments in the nerve transfer group. Regenerative nerve morphologic examination showed good axonal regeneration after genitofemoral nerve transfer. ConclusionNerve regeneration can be obtained by genitofemoral nerve to pelvic nerve transfer, and erectile function can be restored.

HP-01-005 Regulation of the relaxation of the corpus cavernosum by a near-infrared light-controlled NO donor in in vivo and in vitro studies

In our previous study, we developed some light-controlled NO donors. However, the low tissue permeability of those NO donors are problem. Thus, to improve tissue permeability, we developed a novel near-infrared light-controlled NO donor, NORD-1. In this study, we investigated whether NORD-1 and light irradiation could control the relaxation of the penile corpus cavernosum by conducting in vitro and in vivo studies using rats. [In vitro study] An isometric tension study was performed using the penises with tunica albuginea of intact Wistar-ST rats injected with NORD-1 or vehicle in the penis. The response to light irradiation was examined after precontraction with noradrenaline. [In vivo study] Intracavernous pressure (ICP) was measured to evaluate erectile function, under electrostimulation of the cavernous nerve (1, 2, 4, and 8 Hz) before and after injection of NORD-1 to the penile corpus cavernosum, with or without light irradiation. [In vitro study] a relaxing response to light irradiation was observed in the penises with tunica albuginea injected with NORD-1, but not in those injected with vehicle. The strength of the relaxation depended on the strength of the light irradiation. [In vivo study] The increased ICP by electrostimulation under light irradiation and NORD-1 treatment was obviously enhanced strength-dependently. Before the NORD-1 treatment, light irradiation did not change the increase in ICP.

Beneficial Effect of Berberis amurensis Rupr. on Penile Erection.

To investigate whether the methanol extract of Berberis amurensis Rupr. (BAR) augments penile erection using in vitro and in vivo experiments. The ex vivo study used corpus cavernosum strips prepared from adult male New Zealand White rabbits. In in vivo studies for intracavernous pressure (ICP), blood pressure, mean arterial pressure (MAP), and increase of peak ICP were continuously monitored during electrical stimulation of Sprague-Dawley rats. Preconstricted with phenylephrine (PE) in isolated endotheliumintact rabbit corus cavernosum, BAR relaxed penile smooth muscle in a dose-dependent manner, which was inhibited by pretreatment with NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, and 1H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one, a soluble guanylyl cclase inhibitor. BAR significantly relaxed penile smooth muscles dose-dependently in ex vivo, and this was inhibited by pretreatment with L-NAME 1H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one. BAR-induced relaxation was significantly attenuated by pretreatment with tetraethylammonium (TEA, P<0.01), a nonselective K+ channel blocker, 4-aminopyridine (4-AP, P<0.01), a voltage-dependent K+ channel blocker, and charybdotoxin (P<0.01), a large and intermediate conductance Ca2+ sensitive-K+ channel blocker, respectively. BAR induced an increase in peak ICP, ICP/MAP ratio and area under the curve dose dependently. BAR augments penile erection via the nitric oxide/cyclic guanosine monophosphate system and Ca2+ sensitive-K+ (BKCa and IKCa) channels in the corpus cavernosum.

The herbal formula KH-204 is protective against erectile dysfunction by minimizing oxidative stress and improving lipid profiles in a rat model of erectile dysfunction induced by hypercholesterolaemia

BackgroundHypercholesterolaemia (HC) is a major risk factor for ischemic heart disease and is also known to be a risk factor for erectile dysfunction (ED). ED caused by HC is thought to be related to HC-induced oxidative stress damage in the vascular endothelium and erectile tissue. KH-204 is an herbal formula with a strong antioxidant effect. We evaluated the effects of KH-204 on erectile function in a rat model of HC-induced ED.MethodsMale Sprague-Dawley rats (6 weeks old) were divided into normal control, high-fat and cholesterol diet (HFC), and HFC with KH-204 treatment (HFC + KH) groups (n = 12 each). Normal control group rats were fed normal chow diet. HFC and HFC + KH group rats were fed high-fat and cholesterol diets and treated with or without daily oral doses of KH-204 for 12 weeks. Subsequently, intracavernous pressure (ICP) and mean arterial pressure (MAP) were measured, and lipid profiles, expression of endothelial (eNOS) and neuronal (nNOS) nitric oxide synthase, oxidative stress (8-hydroxy-2-deoxyguanosine), and ratio of smooth muscle cells and collagen fibres were evaluated in the serum and corpora tissue.ResultsCompared to the HFC group, the HFC + KH group showed statistically significant increases in peak ICP and ICP/MAP ratio, expression of eNOS and nNOS, and ratio of smooth muscle cells and collagen fibres (p < 0.05). The HFC + KH group also showed statistically significant decreases in oxidative stress (p < 0.05). Further the lipid profiles of this group were ameliorated compared to those of the HFC group (p < 0.05).ConclusionsThe current study shows that the antioxidant and hypolipidemic effects of KH-204 are effective in ameliorating ED by restoring endothelial dysfunction and suggests that KH-204 may be a potential therapeutic agent for ED by correcting the fundamental cause of ED.

Anti-inflammatory and anti-fibrotic effects of annexin1 on erectile function after cavernous nerve injury in rats

The aim of this study was to investigate the effect of the anti-inflammatory and anti-fibrotic actions of ANX1 on erectile function (EF). Forty-eight male Wistar rats were randomly distributed into four equal groups: one group (sham operation-control) and three groups (bilateral cavernous nerve (CN) crush injury). Crush injury groups were treated prior to injury with an intravascular injection of either ANX1 (50 or 100 μg kg-1) or vehicle. EF was assessed by CN electrical stimulation at 2 and 7 days after CN injury with histomorphometric and immunohistochemical analysis. ANX1 demonstrated functional preservation as the increase in intracavernous pressure (ICP). A dose-response relationship regarding the effect on penile tissue was confirmed, and preservation of the penile dorsal nerves and anti-apoptotic effects in the corpus cavernosum (real P-value vs injured control). ANX1 treatment prevented collagen deposition and smooth muscle loss in the penis. ANX1 normalized the expression of vascular endothelial growth factor and decreased tumor necrosis factor-α in the lumen of the blood vessels of the organ. ANX1 proved effective in preserving EF in a rat model of neurogenic erectile dysfunction. ANX1 treatment before CN injury in rats improved erectile recovery, enhanced vascular regeneration and preserved the micro-architecture of the corpus cavernosum. The clinical availability of this compound merits application in penile rehabilitation studies following radical prostatectomy.

The effect of phosphodiesterase-5 inhibitor and extracorporeal shock wave on cavernous nerve stimulation-induced intracavernous pressure increase in the diabetic rat

The effect of phosphodiesterase-5 inhibitor and extracorporeal shock wave on cavernous nerve stimulation-induced intracavernous pressure increase in the diabetic rat

The effect of extracorporeal shock wave on cavernous nerve stimulation-induced intracavernous pressure increase in the diabetic rat

The effect of extracorporeal shock wave on cavernous nerve stimulation-induced intracavernous pressure increase in the diabetic rat

Erectile functional restoration with genital branch of genitofemoral nerve to cavernous nerve transfer after bilateral cavernous nerve resection in the rat.

To investigate the feasibility of erectile function restoration by genital branch of genitofemoral nerve (GN) to cavernous nerve (CN) transfer in rats. Thirty adult (3 months) male Sprague-Dawley rats were divided into 3 groups (n = 10 per group). Rats in sham group underwent sham operation, rats in nerve resection (NR) group underwent bilateral GN and CN resection to make a 2.5-mm gap, and rats in nerve transfer (NT) group underwent nerve anastomosis bilaterally between proximal stump of GN and distal stump of CN after nerve resection. Three months postoperatively, mating test observed 70% rats with intromission behaviors in NT group but only 10% rats in NR group. Electrostimulating the GN of NT group rats resulted in a significant increase in intracavernous pressure, and the ratio of intracavernous pressure increase to mean arterial pressure in NT group was significantly higher than that in NR group. Seven days after Fluoro-Gold injection into the penile crus, Fluoro-Gold-labeled neurons were found in ventral horn of L1 and L2 in NT group, indicating that a new erectile efferent pathway might be established. Axon counting and ultrastructure observation confirmed axonal regeneration in NT group. Furthermore, NT group had a higher expression of nitric oxide synthase in the dorsal penile nerve than that in NR group. The results have demonstrated that nerve regeneration can be obtained, and erectile function may be restored after GN to CN nerve transfer in bilateral CN resection rats, which provides an innovative and promising treatment for neurogenic erectile dysfunction.

Pelvic-floor muscle rehabilitation in erectile dysfunction and premature ejaculation.

In men, involuntary or voluntary ischiocavernosus muscle contractions after erection lead to intracavernous blood pressures far higher than the systolic pressure, which builds and maintains penile rigidity. Thus, erectile dysfunction may be partly due to ischiocavernosus muscle atrophy and may be treated by rehabilitation interventions. The purpose of this study was to determine whether pelvic-floor muscle strengthening interventions could be associated with increases in intracavernous pressure that would increase penile rigidity. An observational study was conducted. One hundred twenty-two men with isolated erectile dysfunction and 108 men with isolated premature ejaculation participated (no neuromuscular diseases or previous perineal rehabilitation). Thirty-minute sessions of voluntary contractions coupled with electrical stimulation were designed to increase ischiocavernosus muscle strength (monitored through intracavernous pressure increase). A linear mixed-effects model per group analyzed separately, then jointly, the maximum change in pressure (ΔP) and the maximum baseline (ie, respectively, the average contraction-generated difference in intracavernous pressure and the intracavernous pressure plateau at full erection, both measured during the highest moving average of the best 2 minutes of each session). Over 20 sessions, the maximum ΔP increased in erectile dysfunction as well as in premature ejaculation (87% and 88%, respectively, in men with positive trends). The maximum baseline also increased (99% and 72%, respectively, in men with positive trends). The joint modeling indicated that the mean expected progressions of the intracavernous pressure after 5 sessions in erectile dysfunction and premature ejaculation were 62.85 and 64.15 cm H2O, respectively. Indirect measurements were obtained of intracavernous pressure and ischiocavernosus muscle force. Pelvic-floor muscle rehabilitation was found to be beneficial in erectile dysfunction. However, its effects on symptoms of premature ejaculation, despite intracavernous pressure gains, were much more difficult to assess. The definitive proof of its benefits requires rather difficult-to-design clinical trials.

Effects and Mechanism of Action of aTribulus terrestrisExtract on Penile Erection

PurposeTribulus terrestris has been used as an aphrodisiac. However, little is known about the effects and mechanism of action of T. terrestris on penile erection. Therefore, the effect of a T. terrestris extract and the mechanism of action of the extract on relaxation of the corpus cavernosum (CC) were investigated. The erectogenic effects of an oral preparation of the extract were also assessed.Materials and MethodsThe relaxation effects and mechanism of action of the T. terrestris extract on rabbit CC were investigated in an organ bath. The intracavernous pressure (ICP) was calculated after oral administration of the extract for 1 month to evaluate whether the relaxation response of the CC shown in the organ bath occurred in vivo. Additionally, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were measured in the CC by immunoassay. Smooth muscle relaxation was expressed as the percentage decrease in precontraction induced by phenylephrine. The ICP was also assessed in rats after oral administration of the extract for 1 month, and changes in concentrations of cGMP and cAMP were monitored.ResultsConcentration-dependent relaxation effects of the extract on the CC were detected in the organ bath study. Relaxation of the CC by the T. terrestris extract was inhibited in both an endothelium-removed group and an L-arginen methyl ester pretreatment group. The ICP measured after oral administration of the T. terrestris extract for 1 month was higher than that measured in the control group, and a significant increase in cAMP was observed in the T. terrestris extract group.ConclusionsThe T. terrestris extract induced concentration-dependent relaxation of the CC in an organ bath. The mechanism included a reaction involving the nitric oxide/nitric oxide synthase pathway and endothelium of the CC. Moreover, in an in vivo study, the T. terrestris extract showed a significant concentration-dependent increase in ICP. Accordingly, the T. terrestris extract may improve erectile function.

Protective Effects of Hydrogen-Rich Saline Against Erectile Dysfunction in a Streptozotocin Induced Diabetic Rat Model

Hydrogen has antioxidative stress and anti-inflammatory effects. We investigated the effect of hydrogen on erectile dysfunction in streptozotocin induced diabetic rats. Diabetes was induced in Sprague-Dawley® rats by a single intravenous injection of streptozotocin. Diabetic rats were then randomized to a diabetes mellitus group and to a diabetic group that received hydrogen saline. The latter 8 rats were fed saturated hydrogen saline (5 ml/kg per day) by intragastric administration for 8 weeks. At the end of week 8 erectile function was assessed by measuring the increase in intracavernous pressure after cavernous nerve electrostimulation. We measured nitric oxide synthase activity, and malondialdehyde, 8-hydroxydeoxyguanosine, and nitrite and nitrate in the corpus cavernosum. eNOS protein immunolocalization in cavernous tissues was detected by immunohistochemistry. eNOS, Bcl-2 and Bax protein expression was determined by Western blot. We determined eNOS, Bcl-2 and Bax mRNA using real-time reverse transcriptase-polymerase chain reaction. Oxidative stress is involved in the pathophysiological mechanism of erectile dysfunction. Maximum intracavernous pressure in diabetic rats decreased significantly compared to controls and increased significantly compared to untreated diabetic rats after hydrogen-rich saline treatment. Decreased nitric oxide synthase activity, nitrite and nitrate, and eNOS expression as well as increased 8-hydroxydeoxyguanosine and malondialdehyde were found in the diabetic group compared to controls. Hydrogen-rich saline improved nitric oxide synthase activity, and malondialdehyde, nitrite and nitrate, and 8-hydroxydeoxyguanosine levels in the diabetic rat corpus cavernosum. Decreased eNOS in diabetic rats was ameliorated by hydrogen-rich saline. Also, apoptosis in the diabetic rat corpus cavernosum was significantly enhanced compared with controls. Hydrogen-rich saline therapy may decrease apoptosis in cavernous tissues and it ameliorated erectile dysfunction in diabetic rats by inhibiting oxidative stress and apoptosis. Hydrogen-rich saline effectively improved erectile function in a streptozotocin induced diabetic rat model of erectile dysfunction.

807 SPHINGOSINE-1-PHOSPHATE SIGNALING PATHWAY A NOVEL MOLECULAR TARGET FOR TREATING ERECTILE DYSFUNCTION

INTRODUCTION AND OBJECTIVES: The bioactive lipid sphingosine-1-phosphate (S1P) regulates smooth muscle (SM) contractility via three G protein-coupled receptors. The S1P1 receptor is associated with nitric oxide (NO)-mediated SM relaxation while S1P2 & S1P3 receptors are linked to SM contraction via activation of the Rho-kinase (ROK) pathway. Sphingosine kinase-1 (SphK1) is the main driver of S1P formation via phosphorylation of sphingosine. Here we determine the role the S1P signaling pathway plays in modulating corpus cavernosum (CC) SM (CCSM) tone in vitro and erectile function in vivo in both rats and humans emphasizing molecular signaling through S1P2 and S1P3 receptors. METHODS: Serum was obtained from normal adult male rats and male human donors from which S1P levels were assessed by high-performance liquid chromatography. CC from normal rats and men undergoing penile prosthesis surgery were used for molecular and physiological studies. Expression of S1P1-3 receptors and SphK1 was determined by Real-Time RT-PCR and Western blotting. In vitro organ bath contractility and in vivo cavernous nerve stimulated intracavernous pressure (ICP) increases were also measured. RESULTS: Circulating serum S1P levels were found to be 250 nM in adult male rats but only 100 nM in humans. Human and rat CC express mRNA and protein for SphK1 and all three S1P receptors with SphK1 expression increased significantly in men 60 years of age. Both exogenous S1P and the phosphorylated S1P1/S1P3 receptor agonist FTY720-P (1-10 M) contracted while the S1P2 selective antagonist JTE-013 and the S1P3 selective antagonist suramin relaxed CCSM in vitro in an NO-independent manner. Force produced by S1P and FTY720-P was similar to PE-induced contraction at low 1-5 M doses with both totally attenuated by 1 M ROK inhibitor H-1152. Intracavernous injection of FTY720-P to anesthetized rats severely inhibited cavernous nerve-induced ICP rise, while JTE-013 alone induced a strong dose-dependent increase in ICP reaching a partial-to-full erection at 500 nmoles. Finally, injection of SphK1 siRNA in vivo knocked down rat CC SphK1 by 80% and significantly potentiated ICP. CONCLUSIONS: This study provides the first clear evidences that the S1P pathway is another key component of the contractile machinery in CC and would be expected as a potential therapeutic target for priapism and erectile dysfunction (ED). Moreover, our recent publications demonstrating expression, function and obstruction-induced alteration of the S1P pathway in bladder may implicate this pathway in lower urinary tract symptoms (LUTS) associated ED.

1113 COMPARISON OF THE EFFECT ON INTRACAVERNOUS PRESSURE INCREASE AFTER ELECTRICAL STIMULATION OF CAVERNOUS NERVE BETWEEN DAILY AND WEEKLY ADMINISTRATION OF SILDENAFIL IN THE RAT

You have accessJournal of UrologySexual Function/Dysfunction/Andrology: Basic Research1 Apr 20111113 COMPARISON OF THE EFFECT ON INTRACAVERNOUS PRESSURE INCREASE AFTER ELECTRICAL STIMULATION OF CAVERNOUS NERVE BETWEEN DAILY AND WEEKLY ADMINISTRATION OF SILDENAFIL IN THE RAT Kuang-Kuo Chen Kuang-Kuo ChenKuang-Kuo Chen Taipei, Taiwan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.710AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Once daily or on-demand use of phosphodiesterase-5 inhibitors has been suggested to improve erectile function, especially for penile rehabilitation after radical prostatectomy. The objective of this study was to compare the effect of daily or weekly (on-demand) administration of sildenafil on intracavernous pressure (ICP) increase after electrical stimulation (ES) of cavernous nerve (CN) in the rat. METHODS Male adult Sprague-Dawley rats were used. Five groups of experiments were designed: 1) group 1: without administration of sildenafil, 2) group 2: daily oro-gastric administration (OGA) of sildenafil 0.13 mg for one week, 3) group 3: OGA of sildenafil 0.5 mg at the end of one week, 4) group 4: daily OGA of sildenafil 0.13 mg for 4 weeks, and 5) group 5: OGA of sildenafil 0.5 mg every week for 4 weeks. A 26-gauge needle was inserted into the corpus cavernosum to measure the ICP. The CN was electrically stimulated with parameters (5, 7.5, 10 V, 20 Hz, 2 ms, 1 minute) on the 7th day for the group 2 and group 3 rats, and on the 28th day for the group 4 and group 5 rats. The amount of ICP increase was calculated by subtracting resting ICP from peak ICP. RESULTS There was a significant increase of ICP from resting 12.5 ±1.4 mmHg to a peak 52.7 ±6.8 mmHg after ES of CN with parameter 10V in group 1 rats. A significant increase of ICP from resting 7.7 ±1.2 mmHg to a peak 75.3 ±3.5 mmHg after ES of CN with 10V was also noted in group 2 rats. There was a significant increase of ICP from resting 7.0 ±1.6 mmHg to a peak at 72.0 ±5.1 mmHg after ES of CN with 10V in group 3 rats. A significant increase of ICP from resting 8.7 ±2.6 mmHg to a peak at 67.2 ± 4.3 mmHg after ES of CN with 10V was also noted in group 4 rats. There was a significant increase of ICP from resting 8.8 ±2.5 mmHg to a peak at 66.3 ±5.3 mmHg after ES of CN in group 5 rats. The amount of ICP increase was 40.2 ±5.6 mmHg, 68.5 ±3.9 mmHg, 65.0 ±4.7 mmHg, 58.5 ±3.2 mmHg and 57.5 ±4.7 mmHg in group 1, 2, 3, 4, and 5, respectively. There was a significantly greater amount of ICP increase in groups 2, 3, 4, and 5 rats as compared with group 1 rats. No significant difference of amount of ICP increase was noted among group 2, 3, 4, and 5 rats. CONCLUSIONS The results suggest that there is a significant greater amount of ICP increase after ES of CN in the rats with daily or weekly oral administration of sildenafil than those without sildenafil administration. However, no significant difference of the ICP increase after ES of CN is noted among daily and weekly oral administration of sildenafil for up to 4 weeks in the rat. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e447 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Kuang-Kuo Chen Taipei, Taiwan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

1129 PROTEIN KINASE-A DEPENDENT PHOSPHORYLATION OF NEURONAL NITRIC OXIDE SYNTHASE: NOVEL MECHANISM FOR REGULATION OF NEURONAL NITRIC OXIDE SYNTHASE ACTIVATED PENILE ERECTION

INTRODUCTION AND OBJECTIVES: Penile erection is mediated by nitric oxide (NO) that is formed by both neuronal NO synthase (nNOS) and endothelial NOS (eNOS) in the penis. We have previously shown that eNOS is phosphorylated by protein kinase (PK)B/Akt in response to increased blood flow in the penis, leading to activation of eNOS and maintenance of erection. This study investigates the regulation and mechanism of nNOS activation by phosphorylation using rodent models of penile erection. METHODS: Male Sprague-Dawley rats (300–375g) or 8–10 weeks old C57BL6/J (wild type, wt) and nNOS knockout (ko) mice were used. Penile erection was monitored as intracavernous pressure (ICP) via a needle inserted to right corpus cavernosum. For electricallyinduced penile erection studies, cavernous nerve (CN) or major pelvic ganglion (MPG) was stimulated at various stimulation parameters and durations. Inhibition of nNOS phosphorylation was tested after perigangliar injection of Akt inhibitors [LY294002 (LY, 50 uM) and wortmannin (WT, 1uM)] and PKA inhibitors [H-89 (30 uM) and PKA inhibitor peptide (PKA-I, 60uM)]. For pharmacologically-induced erections, papaverine (1.5mg), forskolin (FSK, 0.25-5ug) or deoxy-FSK (dFSK, 0.25-5ug) were injected intracavernosally (ic) or directly beneath the MPG. Some mice were pretreated with L-NAME (100mg/kg, ip) 30 min prior to FSK injection. MPG and penis from various experiments were collected and processed for phospho(P)-protein analysis with western blot or for immunohistochemistry. RESULTS: P-specific antibody to nNOS-S1412 (homologous to S1177 in eNOS) revealed a 5–10 fold increase in P-nNOS-S1412 after CN electrical stimulation (ES) in rat MPG (p 0.05). nNOS-S1412 phosphorylation was voltageand time-dependent and sustained for 3–5 min after ES. Papaverine, a direct vasorelaxant, injected ic stimulated P-eNOS-S1177 in the rat penis, but did not increase P-nNOSS1412. Perigangliar injection of FSK, an activator of PKA, increased P-nNOS-S1412, while Akt inhibitors, WT and LY, had no effect. Furthermore, ic injection of FSK dose-dependently increased ICP in wt mice (p 0.05) while d-FSK, an inactive analog of FSK, had no effect. Pretreatment with L-NAME (100mg/kg, ip) abolished the effect of FSK in wt. In nNOS-ko mice, the ICP increase after FSK injection was 30–50% of the wt response. CONCLUSIONS: Our data suggests a novel mechanism of nNOS activation which involves PKA-dependent phosphorylation and reveals differentially regulated pools of NOS activity mediating penile erection.

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

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

Injections of Adipose Tissue-Derived Stem Cells and Stem Cell Lysate Improve Recovery of Erectile Function in a Rat Model of Cavernous Nerve Injury

Erectile dysfunction (ED) remains a major complication after radical prostatectomy. The use of adipose tissue-derived stem cells (ADSCs) has shown promising results for the treatment of ED. However, the mechanisms of action for stem cell therapy remain controversial, with increasing evidence pointing to paracrine pathways. To determine the effects and to identify the mechanism of action of ADSC and ADSC-derived lysate in a rat model of cavernous nerve (CN) crush injury. Thirty-two male Sprague-Dawley rats were randomly divided into four equal groups: one group underwent sham operation, while three groups underwent bilateral CN crush. Crush-injury groups were treated at the time of injury with intracavernous injection of ADSC, lysate, or vehicle only (injured controls). Erectile function was assessed by CN electrostimulation at 4 weeks. Penile tissue was collected for histology. Intracavernous pressure increase upon CN stimulation; neuronal nitric oxide synthase (nNOS) content in the dorsal penile nerve; smooth muscle content, collagen content, and number of apoptotic cells in the corpus cavernosum. Both ADSC and lysate treatments resulted in significant recovery of erectile function, as compared with vehicle treatment. nNOS content was preserved in both the ADSC and lysate group, with significantly higher expression compared with vehicle-treated animals. There was significantly less fibrosis and a significant preservation of smooth muscle content in the ADSC and lysate groups compared with injured controls. The observed functional improvement after lysate injection supports the hypothesis that ADSCs act through release of intracellular preformed substances or by active secretion of certain biomolecules. The underlying mechanism of recovery appears to involve neuron preservation and cytoprotection by inhibition of apoptosis. Penile injection of both ADSC and ADSC-derived lysate can improve recovery of erectile function in a rat model of neurogenic ED.

Activated RhoA/Rho Kinase Impairs Erectile Function After Cavernous Nerve Injury in Rats

RhoA and rho kinase serve as key regulators of penile vascular homeostasis. The role of RhoA/rho kinase signaling in the penis after cavernous nerve injury has not been fully investigated. We characterized the molecular expression profiles of RhoA/rho kinase signaling that occur in the penis after cavernous nerve injury. We hypothesized that erectile dysfunction after bilateral cavernous nerve injury is accompanied by up-regulation of RhoA/rho kinase activity in the rat penis. We used 2 groups, including sham operation and bilateral cavernous nerve injury. At 14 days after nerve injury each group underwent cavernous nerve stimulation to determine erectile function at baseline and after intracavernous injection of the rho kinase inhibitor Y-27632 (Tocris Bioscience, Ellisville, Missouri). Penes were assessed at baseline for protein expression of neuronal nitric oxide synthase, RhoA, and rho kinase 1 and 2 by Western blot, immunoreactivity of neuronal nitric oxide synthase, rho kinase 1 and 2, RhoA-guanosine triphosphatase and rho kinase activity. Erectile function was decreased in nerve injured rats. Neuronal nitric oxide synthase protein was significantly decreased while RhoA and rho kinase 2 protein levels were significantly increased in rat penes with nerve injury. Rho kinase 1 protein expression was equivalent. Rho kinase immunoreactivity was qualitatively increased in the corporeal smooth muscle of nerve injured rats. RhoA-guanosine triphosphatase and rho kinase activity was significantly increased in injured rat penes compared to that in sham operated penes. Intracavernous injection of Y-27632 caused a significantly greater increase in intracavernous pressure in nerve injured rats compared to that in sham operated rats, suggesting increased rho kinase activity. Data suggest that RhoA/rho kinase up-regulation in response to cavernous nerve injury contributes to penile vasculature dysfunction after cavernous nerve injury. Thus, the RhoA/rho kinase pathway may be a suitable target for treating post-radical prostatectomy erectile dysfunction.

Urotensin II: A Novel Target in Human Corpus Cavernosum

Urotensin II (U-II) is a cyclic peptide originally isolated from the teleost neurosecretory system and subsequently identified in other species, including man. U-II was identified as the natural ligand of an orphan G-protein coupled receptor (UT receptor). U-II and UT receptor are expressed in a variety of peripheral organs and especially in cardiovascular tissue. U-II caused both constrictor and vasodilator effect, depending by vascular bed. The in vivo functional consequences of U-II on the cardiovascular hemodynamics are not clearly understood. To investigate the presence of UT receptor and the effect of U-II in human corpus cavernosum (HCC) strips. To evaluate the effect of U-II in vivo in anesthetized rats. UT receptor expression as protein and as mRNA were assessed by Western blot and reverse transcriptase polymerase chain reaction. Next, the UT receptor localization was evaluated by immunohistochemical analysis. By using HCC strips, with or without endothelium, the effect of U-II (0.1 nM-10 microM) was evaluated. In order to asses the nitric oxide (NO) involvement, the strips were incubated with N (G)-nitro-L-arginine methyl ester (NO synthase inhibitor, 100 microM). U-II (0.1, 0.3, 1.0 nmol/rat) effect in vivo was studied in anesthetized rats by monitoring the intracavernous and systemic blood pressure. HCC expresses the UT receptor and its activation, by UII, causes an endothelium- and NO-dependent relaxation. UT receptor is expressed in human and rat corpus cavernosum. In HCC UT receptor is localized on endothelial cells. U-II significantly relaxed HCC strips in endothelium- and -NO-dependent fashion. The peptide caused a significant increase in intracavernous pressure in anesthetized rats. This study demonstrates that UT receptor is expressed on the endothelium of HCC. U-II/UT receptor system is involved in HCC function and it involves endothelium and NO pathway. Thus, U-II/UT receptor pathway could be involved in erectile function.