Cavernosal Nerve Injury Research Articles

The effects of trimetazidine and sildenafil on bilateral cavernosal nerve injury induced oxidative damage and cavernosal fibrosis in rats.

Aim. The aim of this study was to compare the effects of sildenafil and trimetazidine on bilateral cavernosal nerve injury-induced oxidative damage and fibrotic changes in cavernosal tissue in rat model. Material and Methods. A total of 32 male Sprague-Dawley rats were randomly divided into 4 groups; each group consist 8 rats (control, BCI, BCI + TMZ, and BCI + sildenafil groups). Tissue superoxide dismutase (SOD), malondialdehyde (MDA), and protein carbonyl (PC) levels were determined biochemically and distribution of cavernosal fibrosis density among groups was performed histopathologically. Results. Tissue SOD levels in BCI group were significantly lower than the control group (P < 0.05). Tissue MDA and PC levels in BCI group were significantly higher than the control group (P < 0.05). TMZ and sildenafil administration significantly increased tissue SOD levels (P < 0.05) and reduced tissue MDA and PC levels (P < 0.05). Histologically, the degree of cavernosal fibrosis and collagen density was higher in BCI group in comparison to control, TMZ-treated, and sildenafil-treated groups. Conclusion. BCI caused oxidative damage and increased cavernosal fibrosis in rat penis. TMZ and sildenafil treatment decreased oxidative damage and reduced the degree of fibrosis in penile tissue due to BCI.

Penile rehabilitation should not be the norm for patients post-radical prostatectomy.

Penile rehabilitation should not be the norm for patients post-radical prostatectomy.

The sGC activator BAY 60-2770 has potent erectile activity in the rat

Nitric oxide (NO) is the principal mediator of penile erection, and soluble guanylate cyclase (sGC) is the receptor for NO. In pathophysiological conditions when sGC is inactivated and not responsive to NO or sGC stimulators a new class of agents called sGC activators increase the activity of NO-insensitive sGC and produce erection. The aim of this study was to investigate erectile responses to BAY 60-2770, a sGC activator, under physiological and pathophysiological conditions. In the present study increases in intracavernosal pressure (ICP) in response to intracavernosal (ic) injections of BAY 60-2770 were investigated under baseline conditions, when sGC was inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), when nitric oxide synthase (NOS) was inhibited by N-nitro-L-arginine methyl ester (L-NAME), and after cavernosal nerve crush injury. Under baseline conditions ic injections of BAY 60-2770 increase ICP, ICP/mean arterial pressure (MAP), and area under the ICP curve (AUC) and produce small decreases in MAP at the highest doses studied. BAY 60-2770 was very potent in its ability to induce erection and responses to BAY 60-2770 were enhanced by ODQ which attenuates erectile responses to sodium nitroprusside (SNP), diethylamine NONOate (DEA/NO), and cavernosal nerve stimulation. Responses to BAY 60-2770 were not altered by L-NAME or cavernosal nerve crush injury. These data indicate that BAY 60-2770 has potent erectile activity that is enhanced by ODQ and show that responses to BAY 60-2770 are not attenuated by NOS inhibition or cavernosal nerve injury. These results suggest that BAY 60-2770 would be effective in the treatment of erectile dysfunction when NO bioavailability is reduced, after pelvic nerve injury, and when sGC is oxidized.

Analysis of Erectile Responses to BAY 41-8543 and Muscarinic Receptor Stimulation in the Rat

Soluble guanylate cyclase (sGC) is the receptor for nitric oxide (NO) and in pathophysiologic conditions where NO formation or bioavailability is impaired, erectile dysfunction (ED) occurs. The aim of this study was to investigate erectile responses to the sGC stimulator BAY 41-8543 in physiologic and pathophysiologic conditions. Increases in intracavernosal pressure (ICP) in response to intracavernosal (ic) injections of BAY 41-8543 were investigated in the anesthetized rat. Increases in ICP/MAP in response to ic injections of BAY 41-8543 and the interaction of BAY 41-8543 with exogenous and endogenously released NO were investigated and the effect of the sGC stimulator on cavernosal nerve injury was assessed. The mechanism of the increase in ICP/MAP in response to ic injection of acetylcholine was investigated. The ic injections of BAY 41-8543 increased ICP/MAP and the duration of the response. BAY 41-8543 was less potent than sodium nitroprusside (SNP) and ic injections of BAY 41-8543 and SNP produced a larger response than the algebraic sum of responses to either agent alone. Simultaneous ic injection of BAY 41-8543 and cavernosal nerve stimulation produced a greater response than either intervention alone. Atropine and cavernosal nerve crush injury decreased the response to nerve stimulation and ic injection of BAY 41-8543 restored the response. These data show that BAY 41-8543 has significant erectile activity and can synergize with exogenous and endogenously released NO. This study shows that atropine and nerve crush attenuate the response to cavernosal nerve stimulation and that BAY 41-8543 can restore the response. The results with atropine, L-NAME and hexamethonium indicate that the response to ic injection of acetylcholine is mediated by muscarinic receptors and the release of NO with no significant role for nicotinic receptors. These results suggest that BAY 41-8543 would be useful in the treatment of ED.

The effect of mirodenafil on the penile erection and corpus cavernosum in the rat model of cavernosal nerve injury

Impotence is one of the common complications after the radical prostatectomy. One of the main reasons of this complication is due to the dysfunction of the veins in corpus cavernosum. Recent studies have shown that the erectile function is improved after the long-term therapy of phosphodiesterase type 5 inhibitor among patients with post-prostatectomy erectile dysfunction. In this study, we evaluated the effects of mirodenafil on the penile erection and corpus cavernosum tissues in the rat model of cavernosal nerve injury. Rats were divided into four groups: (1) control group, (2) bilateral cavernosal nerve injury group, (3) mirodenafil 10 mg therapy group after the nerve injury and (4) mirodenafil 20 mg therapy group after the nerve injury. After we identified the nerve from the pelvic nerve complex on the lateral side of the prostate, the rats in the control group were sutured without causing any nerve injury and in other groups we damaged the nerve by compressing it with a vessel clamp. Then, 10 and 20 mg kg−1 of mirodenafil were orally administered to two experimental groups. After 8 weeks, the intracavernosal pressure (ICP) was recorded. The immunohistochemical staining and western blot were performed, and the effect of mirodenafil on the expression of cyclic guanosine monophosphate (cGMP) was evaluated through enzyme-linked immunosorbent assay. The ICP of nerve-injured group was decreased compared with the control group; however, the ICP of the mirodenafil-administered groups was improved compared with the nerve-injured group. The Masson's trichrome staining confirmed that the smooth muscle (SM) component was increased in the mirodenafil-administered groups. The nitric oxide synthase expression and cGMP of mirodenafil-administered groups was increased compared with the nerve-injured group. Long-term therapy of mirodenafil may improve the erectile function after the radical prostatectomy by preserving the SM content and inhibiting the fibrosis of the corpus cavernosum.

Outcome of preemptive penile rehabilitation before bilateral cavernosal nerve injury in rats

In this study, prophylactic penile rehabilitation (PR) with sildenafil before and after a cavernosal nerve (CN) injury was analyzed in an animal model. Thirty-six animals were divided into six groups as follows: (1) those with no CN injury (i.e., sham), (2) those with a bilateral CN injury (i.e., control), (3, 4) those with a bilateral CN injury treated with 10-20 mg/kg of sildenafil subcutaneously (SC) on a daily basis commencing 1 month prior to and after nerve injuries, respectively, (5, 6) those with a bilateral CN injury treated daily with 10-20 mg/kg of sildenafil SC after the nerve injuries, respectively. Mean arterial pressure (MAP) and intracavernosal pressure (ICP) were measured in response to CN stimulation to assess erectile function (EF). Neuronal nitric oxide synthase (nNOS) immunohistochemical analysis and real-time polymerase chain reaction (RT-PCR) were performed. The maximal ICP/MAP ratio was 60 ± 18% in the sham, 22 ± 5% in the control, 28 ± 9% in Group III, 45 ± 16% in Group IV, 45 ± 17% in Group V, and 49 ± 21% in Group VI. Although EF was improved with sildenafil treatment in a dose-dependent fashion, no statistically significant difference was observed between the preemptive and standard rehabilitation groups. Again, nNOS immunoreactivity and RT-PCR results showed the beneficial effect of sildenafil, but the study did not support the efficacy of preemptive rehabilitation when compared to the standard rehabilitation group. Although, a dose-response relationship was observed for PR treatment with sildenafil; i.e., outcomes improved at higher doses of sildenafil for PR, preemptive PR should not be pursued as an alternative rehabilitation modality.

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.

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.

The effect of intracavernosal growth differentiation factor‐5 therapy in a rat model of cavernosal nerve injury

To determine whether the intracavernosal application of growth differentiation factor-5 (GDF-5) influences nerve regeneration and erectile function after cavernosal nerve injury in a rat model. Thirty-two male Sprague-Dawley rats were randomly divided into four equal groups: eight had a sham operation (uninjured controls), while 24 had bilateral cavernosal nerve crush. The crush-injury groups were treated at the time of injury with an impregnated collagen sponge implanted into the right corpus cavernosum. The sponge contained no GDF-5 (injured controls), 2 microg (low concentration), or 20 microg GDF-5 (high concentration). Erectile function was assessed by cavernosal nerve electrostimulation at 8 weeks. Midshaft penile tissue samples were histochemically evaluated for neuronal nitric oxide synthase (nNOS)-containing fibres in the dorsal penile nerve. There was no erectile dysfunction in the uninjured control group, as shown by a mean (sem) maximal increase in intracavernosal pressure (ICP) of 149.5 (17.0) cmH(2)O on stimulation. By comparison, the ICP decreased in the injured control group, by 21.3 (6.7) cmH(2)O. After cavernosal nerve injury, the recovery of erectile function was greatest in the low-concentration GDF-5 group; the maximum ICP increase was 40.8 (13.3) cmH(2)O, vs 24.3 (5.9) cmH(2)O for 20 microg GDF-5. Histologically, the low-concentration group had significantly more nNOS-containing nerve fibres, at 163 (24.7), than the high-concentration group, at 76 (17.3), or injured controls, at 67 (23.8). By contrast, the uninjured controls had a mean of 538 (40.6) nerve fibres in the dorsal nerve. Bilateral cavernosal nerve crush resulted in erectile dysfunction with accompanying neurological changes in the rat. The intracavernosal application of GDF-5 enhanced the recovery of erectile function and n-NOS nerve preservation, with a 2-microg dose giving the most promising results.

The Effect of Neural Embryonic Stem Cell Therapy in a Rat Model of Cavernosal Nerve Injury

No AccessJournal of UrologyUrological Survey: Male and Female Sexual Function and Dysfunction; Andrology1 Sep 2005The Effect of Neural Embryonic Stem Cell Therapy in a Rat Model of Cavernosal Nerve Injury Allen D. SeftelM.D. Allen D. SeftelAllen D. Seftel More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(01)68507-0AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "The Effect of Neural Embryonic Stem Cell Therapy in a Rat Model of Cavernosal Nerve Injury." The Journal of Urology, 174(3), p. 1045 © 2005 by American Urological Association, Inc.FiguresReferencesRelatedDetails Volume 174Issue 3September 2005Page: 1045 Advertisement Copyright & Permissions© 2005 by American Urological Association, Inc.MetricsAuthor Information Allen D. Seftel More articles by this author Expand All Advertisement PDF downloadLoading ...

The additive erectile recovery effect of brain‐derived neurotrophic factor combined with vascular endothelial growth factor in a rat model of neurogenic impotence

To test the hypothesis that combined intracavernosal injection with vascular endothelial growth factor (VEGF) with adeno-associated virus-mediated brain-derived neurotrophic factor (AAV-BDNF) synergistically facilitates the neural regeneration and erectile function after cavernosal nerve injury. Forty Sprague-Dawley male rats were randomly divided into five equal groups: eight had a sham operation while 32 had bilateral cavernosal nerve freezing followed by an immediate intracavernosal injection with either phosphate-buffered saline (PBS), VEGF, AAV-BDNF, or AAV-BDNF + VEGF. Erectile function was assessed by cavernosal nerve electrostimulation at 3 months, and samples of the major pelvic ganglia and penile tissue were evaluated histologically. In this animal model of impotence from nerve injury, the recovery of erectile function was greatest in those receiving AAV-BDNF + VEGF; the mean (sd) maximal intracavernosal pressure in this group was 87.2 (20.78) cmH2O, compared with 37.3 (11.39) for VEGF alone and 49.8 (29.58) for AAV-BDNF alone. No erectile dysfunction was identified in the sham group, with a pressure of 100.7 (22.70) cmH2O, while all treatment groups significantly outperformed the PBS (control) group, at 29.3 (13.52) cmH2O. Furthermore, all animals receiving monotherapy or combined treatment had more NADPH-diaphorase-positive nerve fibres than controls but less than in the sham group. Bilateral cavernosal nerve freezing causes erectile dysfunction with accompanying neurological changes. Intracavernosal injection with either VEGF or AAV-BDNF alone enhances nerve regeneration, with combined therapy (VEGF and AAV-BDNF) promoting neural and erectile recovery additively.

ORIGINAL RESEARCH—BASIC SCIENCE: A Nitric Oxide‐Releasing PDE5 Inhibitor Relaxes Human Corpus Cavernosum in the Absence of Endogenous Nitric Oxide

ABSTRACT Introduction In conditions with severe deficiency of endogenous nitric oxide (NO), such as long-term diabetes and cavernosal nerve injury, phosphodiesterase type 5 (PDE5) inhibitors have reduced efficacy in the treatment of erectile dysfunction. NO-releasing PDE5 inhibitors could be an alternative therapeutic approach in such cases. Aim We therefore aimed to compare sildenafil and NO-releasing sildenafil (NCX-911) in relaxing human corpus cavernosum in the absence or presence of endogenous NO. Methods The two compounds were compared in reducing the phenylephrine-induced tone of human corpus cavernosum in the presence or absence of an inhibitor of NO synthase (L-NAME; 500 µM) or an inhibitor of soluble guanylate cyclase (ODQ, 10 µM). Results NCX-911 was as potent as sildenafil in control conditions (EC50 = 733.1 ± 94.4 nM and 800.7 ± 155.8 nM, respectively). The potency of NCX-911 was not altered but that of sildenafil decreased significantly in the presence of L-NAME (EC50 = 980.4 ± 106.7 nM and 2446.7 ± 256.8 nM, respectively; P &amp;lt; 0.001 for sildenafil vs. control). Both compounds below 1 µM failed to induce relaxation in the presence of ODQ (EC50 = 6578 ± 1150 nM and 6488 ± 938 nM for NCX-911 and sildenafil, respectively). Conclusion These results show that the potency of NCX-911 was maintained unlike sildenafil in the absence of endogenous NO confirming the potential use of NO-releasing PDE5 inhibitors in NO-deficient conditions.

The effect of neural embryonic stem cell therapy in a rat model of cavernosal nerve injury.

To isolate embryonic stem cells that have differentiated along the neuronal cell line, and to assess whether injecting these neural stem cells into the corpus cavernosum influences cavernosal nerve regeneration and functional status. Embryonic neural stem cells were obtained; 26 male Sprague-Dawley rats were divided into four groups: five had a sham operation; eight (controls) had a bilateral cavernosal nerve crush and injection of culture medium into the corpora cavernosa; four had an injection of neural embryonic stem (NES) cells into the major pelvic ganglion (MPG); and nine had bilateral cavernosal nerve crush and injection of NES cells into the corpora cavernosa. Erectile response was assessed by cavernosal nerve electrostimulation at 3 months, and penile tissue samples were evaluated histochemically for nitric oxide synthase (NOS)-containing fibres, tyrosine hydroxylase and neurofilament staining. The groups injected with NES cells into the MPG and corpora cavernosa had significantly higher intracavernosal pressures than the control group. Immunohistochemical staining also revealed differences in the quality of the NOS-containing nerve fibres. Neurofilament staining was significantly better in the experimental groups injected with NES cells. We were able to isolate embryonic stem cells that had differentiated along the neural cell line and, using these NES cells intracavernosally, showed improved erectile function in a rat model of neurogenic impotence.

The effect of vascular endothelial growth factor and brain-derived neurotrophic factor on cavernosal nerve regeneration in a nerve-crush rat model.

To test the hypothesis that an intracavernosal injection with brain-derived neurotrophin factor (BDNF) and vascular endothelial growth factor (VEGF) can facilitate nerve regeneration and recovery of erectile function after cavernosal nerve injury. The study included 25 Sprague-Dawley rats; four had a sham operation, seven bilateral nerve crushing with no further intervention, and 14 bilateral nerve crushing with either an immediate (seven) or delayed for 1 month (seven) intracavernosal injection with BDNF+VEGF. Erectile function was assessed by cavernosal nerve electrostimulation at 3 months, and neural regeneration by NADPH-diaphorase staining and tyrosine hydroxylase (TH) staining of penile tissue and major pelvic ganglia (MPG). After nerve crushing, the functional evaluation at 3 months showed a lower mean (SD) intracavernosal pressure (ICP) with cavernosal nerve stimulation, at 33.9 (15.3) cmH2O, than in the sham group, at 107.8 (18.1) cmH2O. With an immediate injection with BDNF+VEGF the ICP was significantly higher than in the controls, at 67.8 (38.5) cmH2O. Even delayed injection with BDNF+VEGF improved the ICP, to 78.0 (21.8) cmH2O. Histological analysis of specimens stained for NADPH and TH showed a significant change in the morphology of terminal branches of the cavernosal and dorsal nerves, and the staining quality of the neurones in the MPG. The number of positively stained nerve fibres tended to revert to normal after treatment with BDNF+VEGF. An intracavernosal injection with BDNF+VEGF appears to both prevent degeneration and facilitate regeneration of neurones containing neuronal nitric oxide synthase in the MPG, dorsal nerve and intracavernosal tissue. Therefore it might have therapeutic potential for enhancing the recovery of erectile function after radical pelvic surgery.

Possible molecular mechanisms of cryoablation-induced impotence in a rat model

Objectives. Cryoablation of the prostate has been reported to induce impotence as a consequence of cavernosal nerve injury. This study is designed to investigate the early and late effects of cavernosal nerve cryoablation on growth factor expression and erectile function in a rat model. Methods. Forty male rats were divided into two groups (n = 20 each). The first group underwent unilateral cavernosal nerve freezing (experimental group). Before their euthanization at 1 and 3 months (10 rats each), erectile function was assessed by electrostimulation of the cavernous nerves. The second group served as the control and was killed at the same time points. Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) techniques were used to identify protein and gene expression of nerve growth factor (NGF), transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), and insulin-like growth factor-1 (IGF-1) in the rat penis and pelvic ganglia. Results. Electrostimulation of the frozen nerve after 3 months revealed a significantly higher maximal intracavernosal pressure and a shorter latency period than in the 1-month group. At 3 months, immunoblot showed upregulation of NGF, TGF-alpha, and the precursor form of IGF-1 protein expression in the penile tissue; RT-PCR showed downregulation of NGF gene expression in the pelvic ganglia of the frozen side. Conclusions. The results show that erectile function decreased at 1 month and then partially recovered 3 months after cavernosal nerve freezing. This alteration in erectile function was associated with differential gene and protein expression of the growth factors (NGF, TGF-alpha, EGF, and IGF-1). Further studies are required to elucidate the potential role of these growth factors in the prevention and treatment of cryoablation-induced impotence.