Acute Intravesical Capsaicin for the Study of TRPV1 in the Lower Urinary Tract: Clinical Relevance and Potential for Innovation.

Capsaicin acts on sensory nerves via vanilloid receptors. TRPV1 has been extensively studied with respect to functional lower urinary tract (LUT) conditions in rodents and humans. We aimed to (1) provide background information on capsaicin and TRPV1 and its mechanisms of action and basis for clinical use, (2) review the use of acute intravesical capsaicin instillation (AICI) in rodents to mimic various LUT disorders in which capsaicin sensitive C-fibers are involved and (3) discuss future innovative treatments. A comprehensive search of the major literature databases until June 2022 was conducted. Both capsaicin-sensitive and resistant unmyelinated bladder afferent C-fibers are involved in non-neurogenic overactive bladder/detrusor overactivity (OAB/DO). AICI is a suitable model to study afferent hyperactivity mimicking human OAB. Capsaicin-sensitive C-fibers are also involved in neurogenic DO (NDO) and potential targets for NDO treatment. AICI has been successfully tested for NDO treatment in humans. Capsaicin-sensitive bladder afferents are targets for NDO treatment. TRPV1-immunoreactive nerve fibers are involved in the pathogenesis of interstitial cystitis/painful bladder syndrome (IC/PBS). The AICI experimental model appears relevant for the preclinical study of treatments targeting bladder afferents for refractory IC/BPS. The activity of capsaicin-sensitive bladder afferents is increased in experimental bladder outlet obstruction (BOO). The AICI model may also be relevant for bladder disorders resulting from C-fiber hyperexcitabilities related to BOO. In conclusion, there is a rationale for the selective blockade of TRPV1 channels for various bladder disorders. The AICI model is clinically relevant for the investigation of pathophysiological conditions in which bladder C-fiber afferents are overexcited and for assessing innovative treatments for bladder disorders based on their pathophysiology.

Intracavernosal OnabotulinumtoxinA Exerts a Synergistic Pro-Erectile Effect When Combined With Sildenafil in Spontaneously Hypertensive Rats.

BACKGROUND: Botulinum toxin A (BTX-A) has a variety of uses in medicine. Some evidence suggests that intracavernosal (ic) BTX-A injection administered in addition to phosphodiesterase type 5 inhibitors (PDE5-Is) could effectively treat erectile dysfunction (ED) in insufficient responders to PDE5-Is. AIM: To provide experimental pharmacological evidence for the use of onabotulinumtoxinA ic alone or in combination with PDE5-Is for difficult-to-treat ED. We thus compared the effects of BTX-A ic alone and BTX-A ic combined with PDE5-I iv, and a placebo treatment ic or iv. METHODS: Erectile function was evaluated following cavernous nerve electrical stimulation (6 V, 1-millisecond pulse, 45-second duration) at different frequencies (0, 2, 3, 4, 5, 7.5, and 10 Hz) in 4 groups (n = 8 / group) of anesthetized, spontaneously hypertensive rats, a robust animal model of ED of vascular origin. Rats were treated by onabotulinumtoxinA 10U or saline ic 1 week prior to erectile function testing and sildenafil (0.3 mg/kg) or saline iv 4 minutes prior to testing. Frequency-response curves were compared with a 2 way ANOVA. OUTCOMES: Both onabotulinumtoxinA ic, and sildenafil iv significantly improved erectile responses in spontaneously hypertensive rats, however the effect was greatly amplified when the treatments were combined. RESULTS: Intracavernosal pressure and/or mean arterial pressure ratios were significantly increased by sildenafil and onabotulinumtoxinA ic versus the control condition. OnabotulinumtoxinA 10U ic combined with sildenafil iv significantly potentiated erectile responses. Area under the curve and/or mean arterial pressure ratio increased by 19% with sildenafil iv, by 15% with onabotulinumtoxinA ic and by 58% with the combined treatment following cavernous nerve electrical stimulation at 6V, 1 ms, 10 Hz: these stimulation parameters elicited the maximal erectile response. CLINICAL TRANSLATION: These data provide a pharmacological rationale for the combined administration of onabotulinumtoxinA ic and sildenafil iv since the effects of both treatments were potentiated when their administration was combined. STRENGTHS & LIMITATIONS: First evidence of a synergistic pro-erectile effect of BTX-A combined with PDE5-I, however the mechanism behind the pro-erectile effect of BTX-A ic remains hypothetical. CONCLUSIONS: These results support further studies into the mechanisms behind the pro-erectile effect of BTX-A ic, as well as multicenter randomized control trials to evaluate the safety and efficacy of BTX-A ic combined with sildenafil for difficult-to-treat ED. Giuliano F., Joussain C., Denys P., et al. Intracavernosal OnabotulinumtoxinA Exerts a Synergistic Pro-Erectile Effect When Combined With Sildenafil in Spontaneously Hypertensive Rats. J Sex Med 2022;19:899-906.

Silodosin improves functional consequences of lower urinary tract obstruction secondary to benign prostate hypertrophy, a proof of concept study in the spontaneously hypertensive rat supplemented with testosterone.

BACKGROUND: The main purpose of this study is to investigate the effect of silodosin on the urodynamic consequences in a previously established model of lower urinary tract symptoms associated with benign prostate hyperplasia, the spontaneously hypertensive rats (SHR) supplemented with testosterone. METHODS: Three groups of animals (8-week-old; n = 10/group) were considered: Wistar Kyoto (control) rats (WKY), SHR supplemented with testosterone at 3 mg/kg/day and treated with either vehicle (SHR-T, n = 10) or silodosin at 0.1 mg/kg/day (SHR-T + silodosin, n = 10) by oral gavage for 6 weeks. Cystometry experiments were performed. The bladder was harvested, weighed and paraffin-embedded for morphometric analysis. The prostate was also harvested and weighed. RESULTS: The number of animals included in the analysis were n = 10/10 for WKY and n = 7-8/10 for each SHR rats supplemented with testosterone group. SHR-T displayed a significant decrease in the intercontraction interval, infused volume and mean flow rate whereas the frequency of non-voiding contractions was increased. Silodosin improved the voiding behavior of SHR-T by significantly increasing the intercontraction interval, the infused volume and the mean flow rate and decreasing the number of non-voiding contractions. SHR-T displayed a significant increase in prostate and bladder weights and a 15% increase in the detrusor wall area compared to WKY. CONCLUSIONS: Chronic silodosin treatment relieved storage symptoms in SHR supplemented with testosterone and decreased the frequency of non-voiding detrusor contractions during the filling phase.

Enteric Nervous System Remodeling in a Rat Model of Spinal Cord Injury: A Pilot Study.

The physiopathology of digestive disorders in patients with spinal cord injury (SCI) remains largely unknown, particularly the involvement of the enteric nervous system (ENS). We aimed in a rat model of chronic thoracic SCI to characterize (1) changes in the neurochemical coding of enteric neurons and their putative consequences upon neuromuscular response, and (2) the inflammatory response of the colon. Ex vivo motility of proximal and distal colon segments of SCI and control (CT) rats were studied in an organ chamber in response to electrical field stimulation (EFS) and bethanechol. Immunohistochemical analysis of proximal and distal segments was performed using antibodies again Hu, neuronal nitric oxide synthase, (nNOS), and choline acetyltransferase. Colonic content of acetylcholine and acetylcholinesterase was measured; messenger RNA (mRNA) expression of inflammatory cytokines was measured using reverse transcription quantitative polymerase chain reaction (RT-qPCR) approaches. Compared with the CT rats, the contractile response to bethanechol was significantly decreased in the proximal colon of SCI rats but not in the distal colon. The proportion of nNOS immunoreactive (IR) neurons was significantly reduced in the proximal but not distal colon of SCI rats. No change in proportion of choline acetyltransferase (ChAT)-IR was reported; the tissue concentration of acetylcholine was significantly decreased in the proximal colon of SCI rats. The expression of tumor necrosis factor alpha (TNF-α) and intercellular adhesion molecule-1 (ICAM-1) was significantly reduced in the proximal and distal colon of SCI rats. This study demonstrates that functional motor and enteric neuroplastic changes affect preferentially the proximal colon compared with the distal colon. The underlying mechanisms and factors responsible for these changes remain to be discovered.

Extracorporeal Shock Waves Therapy Delivered by Aries Improves Erectile Dysfunction in Spontaneously Hypertensive Rats Through Penile Tissue Remodeling and Neovascularization.

BACKGROUND: Low-intensity extracorporeal shock wave therapy (Li-ESWT) has been reported to improve erectile function in patients with moderate-to-severe erectile dysfunction (ED) or even convert phosphodiesterase type 5 inhibitors nonresponders to responders. ED is highly prevalent in hypertensive patients. The effect of Li-ESWT on an animal model of hypertension-associated ED has not been reported. AIM: To investigate the effect of Li-ESWT on hypertension-associated ED and provide plausible mechanisms of action of Li-ESWT on local mechanisms of penile erection. METHODS: Spontaneously hypertensive rats (SHRs) in the active group (n = 13) received Li-ESWT at energy flux density 0.06 mJ/mm2 (Aries; Dornier MedTech, Wessling, Germany) twice weekly for 6 weeks. The emitter was set to zero for SHRs in the sham group (n = 12). Erectile function was assessed 4 weeks post-treatment by monitoring intracavernosal pressure (ICP) in response to electrical stimulation of cavernous nerve before and after single dose of 0.3 mg/kg intravenous sildenafil. Cavernosal tissue was then evaluated for collagen/smooth muscle content, neuronal nitric oxide synthase (nNOS), and vascular endothelial factor (CD31) expression. OUTCOMES: Erectile function was assessed with ICP, erectile tissue remodeling was studied by smooth muscle/collagen ratio, nNOS and CD31 were semiquantitatively evaluated on cavernosal sections. RESULTS: The improvement of ICP parameters was greater in Li-ESWT-treated rats compared with controls with and without sildenafil. Sildenafil led to 20% increase in area under the intracavernosal pressure curve measured during the entire response/mean arterial pressure at 10 Hz in ESWT_SHR + sildenafil compared with ESWT_SHR. The smooth muscle/collagen ratio increased 2.5-fold in Li-ESWT compared with sham. Expression of CD31 tended to be increased whereas nNOS was unchanged. CONCLUSIONS: Li-ESWT by Aries may represent an effective noninvasive therapeutic alternative and a relevant add-on therapy to phosphodiesterase type 5 inhibitors for ED in hypertensive patients, and it is suggested that it acts via remodeling of the penile tissue and promoting cavernosal vascularization. Assaly R, Giuliano F, Clement P, et al. Extracorporeal Shock Waves Therapy Delivered by Aries Improves Erectile Dysfunction in Spontaneously Hypertensive Rats Through Penile Tissue Remodeling and Neovascularization. Sex Med 2019;7:441-450.

The Favorable Effect of Empagliflozin on Erectile Function in an Experimental Model of Type 2 Diabetes.

INTRODUCTION: Following the results of the EMPA-REG Outcome trial, we hypothesized that empagliflozin, a highly potent and specific sodium/glucose cotransporteur 2 inhibitor, could improve type 2 diabetes mellitus (T2DM)-associated erectile dysfunction (ED), a highly prevalent complication of T2DM, very often coexisting with cardiovascular complications and considered as a prognostic factor of cardiovascular disease in men with diabetes. AIM: To investigate the effects of chronic treatment with empagliflozin on ED in a T2DM rat model in the presence or absence of sildenafil. METHODS: Male Goto-Kakizaki (GK), a model of T2DM, and age-matched Wistar rats received placebo or empagliflozin treatment at 25.3 ± 0.9 mg/kg/d for 4 weeks. Then, the in vivo effect of empagliflozin on erectile function was assessed by electrical stimulation of the cavernous nerve at different frequencies under anesthesia in the presence or absence of acute intravenous injection of sildenafil. Endothelium-dependent, -independent, and nitrergic relaxations of cavernosal strips from the rats were studied. MAIN OUTCOME MEASURES: Body weight, food consumption, metabolic parameters, plasma inflammation biomarkers, and in vivo erectile responses elicited by electrical stimulation of the cavernous nerve in empagliflozin-treated and untreated GK rats and control Wistar rats were assessed and followed by concentration or frequency response curves to endothelium-dependent, -independent, and nitrergic relaxations of cavernosal strips from these rats. RESULTS: Chronic empagliflozin followed by acute sildenafil significantly improved erectile responses in adult GK rats (n = 12-15/group). Ratios of intracavernous pressure and area under the curve/mean arterial pressure during the electrical stimulation were significantly increased in empagliflozin-treated vs untreated GK rats. Nitrergic relaxations of cavernosal strips from GK rats were significantly increased with empagliflozin compared with placebo. Moreover, the effect of sildenafil on erectile function was not altered by empagliflozin treatment. CLINICAL IMPLICATIONS: Empagliflozin may benefit T2DM patient with ED. STRENGTHS & LIMITATIONS: The mechanism(s) by which empagliflozin shows favorable effect on erectile function in GK rats needs to be further elucidated. CONCLUSION: Empagliflozin shows favorable effect on erectile function in diabetic GK rats mediated by an improvement of nitrergic relaxation of erectile tissue. Whether this favorable effect on ED in the experimental context of T2DM is due to better glycemic control or to another effect of empagliflozin deserves further investigation. Assaly R, Gorny D, Compagnie S, et al. The Favorable Effect of Empagliflozin on Erectile Function in an Experimental Model of Type 2 Diabetes. J Sex Med 2018;15:1224-1234.

Low Intensity Extracorporeal Shock Wave Therapy Improves Erectile Function in a Model of Type II Diabetes Independently of NO/cGMP Pathway.

PURPOSE: Erectile dysfunction is highly prevalent in type II diabetes mellitus. Low intensity extracorporeal shock wave therapy improves erectile function in patients with erectile dysfunction of vasculogenic origin, including diabetes. However, its mode of action remains unknown. We investigated the effects of low intensity extracorporeal shock wave therapy compared to or combined with sildenafil on erectile dysfunction in a type II diabetes mellitus model. Our purpose was to test our hypothesis of a mode of action targeting the cavernous nitric oxide/cyclic guanosine monophosphate pathway. MATERIALS AND METHODS: GK rats, a validated model of type II diabetes mellitus, and age matched Wistar rats were treated with low intensity extracorporeal shock wave therapy twice weekly for 3 weeks. Treatment was repeated after a 3-week no-treatment interval. The penis was stretched and dipped in a specifically designed water-filled cage. Shock waves were delivered by a calibrated probe yielding a controlled energy flux density (0.09 mJ/mm(2)). The probe was attached to an electrohydraulic unit with a focused shock wave source, allowing for accurate extrapolation to humans. Following a 4-week washout period erectile function was assessed as well as endothelium dependent and independent, and nitrergic relaxations of the corpus cavernosum of GK rats. RESULTS: Low intensity extracorporeal shock wave therapy significantly improved erectile function in GK rats to the same extent as sildenafil. Treatment effects were potentiated when combined with sildenafil. Shock wave effects were not associated with improved cavernous endothelium dependent or independent, or nitrergic reactivity. CONCLUSIONS: Low intensity extracorporeal shock wave therapy improved erectile function in GK rats. Unexpectedly, this was not mediated by a nitric oxide/cyclic guanosine monophosphate dependent mechanism. Sildenafil increased shock wave efficacy. This preclinical paradigm to deliver low intensity extracorporeal shock wave therapy to the rat penis should help further exploration of the mode of action of this therapy on erectile tissue.

Does Reduction of Number of Intradetrusor Injection Sites of aboBoNTA (Dysport®) Impact Efficacy and Safety in a Rat Model of Neurogenic Detrusor Overactivity?

Intradetrusor injections of Botulinum toxin A-currently onabotulinumtoxinA-is registered as a second-line treatment to treat neurogenic detrusor overactivity (NDO). The common clinical practice is 30 × 1 mL injections in the detrusor; however, protocols remain variable and standardization is warranted. The effect of reducing the number of injection sites of Dysport(®) abobotulinumtoxinA (aboBoNTA) was assessed in the spinal cord-injured rat (SCI). Nineteen days post-spinalization, female rats received intradetrusor injections of saline or aboBoNTA 22.5 U distributed among four or eight sites. Two days after injection, continuous cystometry was performed in conscious rats. Efficacy of aboBoNTA 22.5 U was assessed versus aggregated saline groups on clinically-relevant parameters: maximal pressure, bladder capacity, compliance, voiding efficiency, as well as amplitude, frequency, and volume threshold for nonvoiding contractions (NVC). AboBoNTA 22.5 U significantly decreased maximal pressure, without affecting voiding efficiency. Injected in four sites, aboBoNTA significantly increased bladder capacity and compliance while only the latter when in eight sites. AboBoNTA significantly reduced NVC frequency and amplitude. This preclinical investigation showed similar inhibiting effects of aboBoNTA despite the number of sites reduction. Further studies are warranted to optimize dosing schemes to improve the risk-benefit ratio of BoNTA-based treatment modalities for NDO and further idiopathic overactive bladder.

Bladder and erectile dysfunctions in the Type 2 diabetic Goto-Kakizaki rat.

Despite the fact that urogenito-sexual complications significantly impact the quality of life of diabetic patients, a robust in vivo experimental model is lacking. Bladder and erectile function in the Type 2 diabetic Goto-Kakizaki (GK) rat and responses to standard-of-care treatments for each disorder have been assessed. GK rats (n = 25, 18-wk-old, GK/Par colony) and age-matched Wistar rats (n = 23), characterized for their metabolic parameters, were used. Bladder function was assessed by cystometry in conscious rats treated by intravenous solifenacin (1 mg/kg). Subsequently, erectile function was assessed under anesthesia following electrical stimulation of the cavernous nerve in presence of intravenous sildenafil (0.3 mg/kg). GK rats displayed detrusor overactivity with a significant increase in frequency/amplitude of nonvoiding contractions during the filling phase, together with an increase in bladder capacity, intercontraction interval, voided volume, and maximal pressure of voiding contraction. Solifenacin significantly decreased parameters characterizing voiding contractions without modifying voiding efficiency. Erectile function in GK rats was markedly impaired and remained so after sildenafil treatment despite a significant improvement. GK rats display both bladder and erectile dysfunctions and respond at least partially to standard-of-care treatments for each disorder, thus representing a suitable model to investigate the pathophysiology and assess the efficacy of new therapeutic agents for Type 2 diabetes-associated bladder and erectile complications.

Involvement of connexins 43 and 45 in functional mechanism of human detrusor overactivity in neurogenic bladder.

OBJECTIVE: To assess the involvement of connexins (Cxs) 43 and 45 in the selective inhibition of detrusor contractions in patients with neurogenic detrusor overactivity (NDO). MATERIALS AND METHODS: Detrusor strips with and without mucosa were obtained from patients undergoing cystectomy for either neurogenic bladder with NDO refractory to pharmacologic treatment or bladder cancer with no overactive bladder symptoms (ie, control group). The strips were isometrically mounted in organ baths. The effects of the selective inhibitors Cxs 43 and 45 on carbachol-induced contractions of bladder strips were assessed. RESULTS: Overall, 47 patients with a median age of 61 years (range 19-83) were included. The female-to-male ratio was 0.42. Selective inhibitors of Cxs 43 and 45 significantly inhibited carbachol-induced contractions of bladder strips from patient with NDO (P <.01) but had no effect in the control group. When tested without mucosa, the effect of the Cx 43 inhibitor in the NDO patient strips was abolished, but it remained unchanged with the Cx 45 inhibitor (P <.05). CONCLUSION: The pharmacologic modulation of Cx-mediated intercellular communication, targeting Cxs 43 and 45, is directly involved in the functional mechanism of NDO and might represent a future target for the treatment of NDO.

Evaluation of the effects of a new intravaginal gel, containing purified bovine colostrum, on vaginal blood flow and vaginal atrophy in ovariectomized rat.

INTRODUCTION: Vaginal dryness due to vaginal atrophy is a common complaint of postmenopausal women, interfering with sexual function and quality of life. Hormone replacement therapy is the only effective therapy but with known risks that leave unmet medical needs. A new product, ZP-025 vaginal gel, containing purified (dialyzed lyophilized) bovine colostrum, has been developed for the treatment of vaginal dryness secondary to vaginal atrophy. AIM: The study aims to investigate the effects of intravaginal application of ZP-025 on vaginal atrophy using an animal model. METHODS: Ovariectomized female Sprague-Dawley rats were used. Three weeks after surgery, rats were divided into four groups and treated for 4 weeks (twice a day) with placebo or ZP-025 at low (0.5%) or high (2.3%) concentrations of colostrum; in the control group, rats did not receive any treatment. Changes in vaginal blood flow due to pelvic nerve stimulation were assessed by laser Doppler flowmetry and vaginal tissue was collected for histological assay. MAIN OUTCOME MEASURES: The main outcome measures were vaginal blood flow before and after pelvic nerve stimulation and histology of vaginal epithelium. RESULTS: Treatment with ZP-025 to ovariectomized rats induced an increase of vaginal blood flow parameters (vascular capacitance, amplitude and area under the curve of the response) in response to pelvic nerve stimulation compared with control group, statistically significant at 2.3%. Vaginal epithelium showed a physiological estrous cycle aspect in treated animals, with at least five cell layers vs. one or two cell layers in control rats. As expected from a topical formulation, systemic effects on body weights and uterine wet weights were not observed with application of ZP-025. CONCLUSIONS: In this study, the new product ZP-025, containing purified colostrum, was shown to have beneficial effects on vaginal atrophy in ovariectomized rats, improving vaginal hemodynamics and thickness of vaginal epithelium. Vailati S, Melloni E, Riscassi E, Behr Roussel D, and Sardina M. Evaluation of the effects of a new intravaginal gel, containing purified bovine colostrum, on vaginal blood flow and vaginal atrophy in ovariectomized rat. Sex Med 2013;1:35-43.

An aryloxypropanolamine hß3-adrenoceptor agonist as bladder smooth muscle relaxant.

The relaxant effect of an aryloxypropanolamine ß3-adrenoceptor agonist on carbachol pre-contracted human detrusor muscle strips was evaluated and compared with literature results from reference compounds of similar mode of action, including mirabegron. A significant relaxation was observed for rac-4-{2-hydroxy-3-[1-(5-phenylthieno[2,3-d]pyrimidin-4-yl)piperidin-4-ylamino]propoxy}-2-(hydroxymethyl)phenol which was similar to that exerted by mirabegron. In order to allow for a thorough discussion of results in comparison to reference compounds, their affinity, selectivity and efficacy as hß3-AR agonists have been evaluated and discussed thoroughly. A ranking of hß3-AR agonists by relative efficacy resulted in the closest analogy to the order of relaxation potential, with only the relaxant effect of mirabegron not reflecting its excellent relative efficacy as such.

A new experimental rat model of erectile dysfunction and lower urinary tract symptoms associated with benign prostatic hyperplasia: the testosterone-supplemented spontaneously hypertensive rat.

UNLABELLED: What's known on the subject? and What does the study add? Lower urinary tract symptoms (LUTS) resulting from benign prostatic hyperplasia (BPH) and erectile dysfunction (ED) are common problems in the aging male population. Moreover, several recent studies have shown that ED is closely associated with the presence and severity of LUTS independently of co-morbidities. However, the pathophysiological mechanisms linking LUTS/BPH and ED remain largely unexplored. The major difficulty in studying such relationships between ED and LUTS/BPH, and of exploring the impact of new therapeutic approaches for both LUTS/BPH and ED, is the lack of experimental model combining ED, prostate enlargement and bladder dysfunction all at once. The present study describes a new model of BPH, the SHR supplemented with testosterone which is the first animal model which displays all at once the key features of BPH: prostate enlargement and an increased sympathetic tone of bladder outlet mimicking the static and the dynamic components of voiding symptoms of BPH, a significant impairment of bladder function which reflects the storage symptoms of BPH and finally, ED. This model could be very relevant to better characterize the close relationship that exists between BPH/LUTS and ED, and to evaluate new therapeutic strategies for BPH together with their side effect profile on sexual function on the same animal, thus allowing a reduction of the number of animals to be used in such studies. Study Type - Aetiology (case control) Level of Evidence 3b. OBJECTIVE: • To design a new experimental model combining erectile dysfunction, prostate enlargement and urodynamic impairment characteristic of lower urinary tract symptoms (LUTS) associated with benign prostate hyperplasia (BPH). MATERIALS AND METHODS: • Three groups of animals (12-week-old; n= 7/group) were considered: Wistar Kyoto (control) rats (WKY), untreated spontaneously hypertensive rats (SHR) and SHR treated with testosterone (SHR-T, 3 mg/kg/day) for 3 weeks. • Cystometry experiments and evaluation of erectile function were performed. Prostate enlargement was evaluated. RESULTS: • SHR displayed a significant decrease in the intercontraction interval (ICI) and in the voided volume (VV) whereas non-voiding contractions (NVC) were increased. SHR-T exhibited a further decreased ICI and VV and an increased frequency of NVC. • Erectile responses to electrical stimulation of the cavernous nerve were significantly impaired in both SHR (-66%) and SHR-T (-58%). • The prostate weight was similar in WKY and SHR, but significantly increased in SHR-T. CONCLUSIONS: • The testosterone-supplemented SHR represents an experimental model for urodynamic impairment combining both static and dynamic components of voiding symptoms with erectile dysfunction and prostate enlargement. • This model is suitable for the assessment of sexual side effects of LUTS/BPH treatments and efficacy of new therapeutic agents in LUTS/BPH and associated erectile dysfunction.

Minimal effective dose of dysport and botox in a rat model of neurogenic detrusor overactivity.

BACKGROUND: Two botulinum toxins A have been evaluated for the treatment of refractory neurogenic detrusor overactivity (NDO) in humans: Dysport (abobotulinumtoxinA) and Botox (onabotulinumtoxinA). However, these two distinct commercialized products have different potency units and are not interchangeable. OBJECTIVE: Assessment of the dose response and determination of minimal effective dose (MED) for Dysport and Botox in spinal cord-injured (SCI) rats with NDO. DESIGN, SETTING, AND PARTICIPANTS: Female, adult, Sprague-Dawley rats (n=98) underwent T8-T9 spinal cord transection. Nineteen days after spinal cord injury, rats received intradetrusor injections (25µl injected, eight sites) of vehicle (V); Dysport 2, 5, 7.5, 10, and 12.5 U; and Botox 0.8, 2, 5, 7.5, and 10 U. Two days after injection, continuous cystometry was performed in conscious rats. MEASUREMENTS: Voiding contractions (VC) were assessed by duration of VC, intercontraction interval, voided volume, maximal pressure, pressure threshold change, and intravesical baseline pressure (BP), while nonvoiding contractions (NVC) were evaluated by amplitude, frequency, and volume threshold to elicit NVC. MEDs for Dysport and Botox were determined by analysis of variance step-down trend test. RESULTS AND LIMITATIONS: MEDs for Dysport and Botox were 10 U and 7.5 U, respectively. Regarding VC, only BP significantly decreased after 10 U Dysport and 7.5 U Botox compared to V (from 3.7±0.6 to 1.5±0.1 and 1.4±0.3mm Hg, respectively; p<0.01 and p<0.001, respectively). Dysport (10 U) and Botox (7.5 U) significantly inhibited NVC by decreasing their amplitude (from 7.4±1.1 to 5.8±0.5 and 5.4±0.6mm Hg, respectively; p<0.05); frequency (from 2.2±0.4 to 1.5±0.2 and 1.3±0.3 NVC per minute, respectively; p<0.01); and increasing volume threshold to elicit NVC (from 29.8±3.7 to 47.6±6.9 and 47.7±6.3%, respectively; p<0.05 and p<0.001, respectively). CONCLUSIONS: This is the first preclinical dose-ranging study with Dysport and Botox under standardized conditions showing similar inhibiting effects on NDO, albeit at different MEDs. It highlights the importance of distinguishing each preparation for predicted outcomes and doses to be used. Further studies in patients with NDO are warranted to confirm these experimental results.

Combination of BAY 60-4552 and vardenafil exerts proerectile facilitator effects in rats with cavernous nerve injury: a proof of concept study for the treatment of phosphodiesterase type 5 inhibitor failure.

BACKGROUND: Radical prostatectomy (RP) is frequently responsible for erectile dysfunction (ED). Post-RP patients often show a failure to respond to phosphodiesterase type 5 (PDE5) inhibitors. OBJECTIVE: The acute effect of BAY 60-4552, the soluble guanylate cyclase (sGC) stimulator, and vardenafil were evaluated alone or in combination on erectile responses to electrical stimulation of the cavernous nerve (ES CN) in rats with cavernous nerve (CN) crush injury-induced ED. DESIGN, SETTING, AND PARTICIPANTS: Male adult Sprague-Dawley rats underwent laparotomy (sham, n=10) or bilateral CN crush injury (n=56). After 3 wk of recovery, erectile function was evaluated under urethane anaesthesia following ES CN at different frequencies. MEASUREMENTS: The acute effects of intravenous (IV) injection of vehicle, vardenafil 0.03 mg/kg, BAY 60-4552 0.03 mg/kg or 0.3 mg/kg, or a BAY 60-4552 0.03 mg/kg plus vardenafil 0.03 mg/kg combination were evaluated in CN-crushed rats. RESULTS AND LIMITATIONS: Bilateral CN crush injury followed by a 3-wk recovery period decreased erectile responses to ES CN by about 50%. In CN-crushed rats, IV vardenafil 0.03 mg/kg and BAY 60-4552 (0.03 or 0.3 mg/kg) increased erectile responses to ES CN to the same extent: Δ intracavernosal pressure/mean arterial pressure (ICP/MAP) at 10 Hz ES CN was 21±1% after vehicle, 25±3% (p<0.001) after vardenafil, and 26±5% and 27±5% after BAY 60-4552 0.03 mg/kg (p<0.01) and 0.3 mg/kg (p<0.001), respectively. The combination of vardenafil with BAY 60-4552 in CN-crushed rats totally restored erectile responses to ES CN equivalent to sham rats (ΔICP/MAP at 10 Hz ES CN: 34±4% after BAY 60-4552/vardenafil combination vs 39±4% in sham rats; not significant). CONCLUSIONS: The present study supports the concept that the combined administration of a sGC stimulator, BAY 60-4552, and vardenafil provides synergistic beneficial effects and might therefore salvage patients who experience treatment failures with PDE5 inhibitors after RP.

Vardenafil decreases bladder afferent nerve activity in unanesthetized, decerebrate, spinal cord-injured rats.

BACKGROUND: Phosphodiesterase type 5 inhibitors (PDE5-Is) improve storage symptoms in benign prostatic hyperplasia patients, despite a lack of effect on peak urinary flow rate. Moreover, vardenafil improves urodynamic parameters in spinal cord-injured (SCI) patients with neurogenic detrusor overactivity (NDO). SCI rats also display NDO characterized by nonvoiding contractions (NVCs) during bladder filling, resulting in an increased bladder afferent nerve firing (BANF). OBJECTIVE: We postulated that vardenafil could improve urodynamic parameters by reducing BANF. The effect of vardenafil has been investigated on intravesical pressure by cystometry experiments while recording BANF in response to bladder filling. DESIGN, SETTING, AND PARTICIPANTS: Complete T7-T8 spinalization was performed in 15 female adult Sprague-Dawley rats (250-275 g). MEASUREMENTS: At 21-29 d postspinalization, fine filaments were dissected from the L6 dorsal roots and placed across a bipolar electrode. Bladder afferent nerve fibers were identified by electrical stimulation of the pelvic nerve and bladder distension. SCI rats were decerebrated before cystometry experiments. Bladders were filled to determine the maximal bladder filling volume (BFV) for each rat. Then, after bladder stabilization at 75% of maximal BFV, saline (n=7) or vardenafil 1 mg/kg (n=8) was delivered intravenously. NVCs and BANF were recorded for 45 min. RESULTS AND LIMITATIONS: In all SCI rats, BANF was already present and regular at resting conditions (26.2±4.1 spikes per second). During bladder filling, intravesical pressure (IVP) slowly increased with transient NVCs superimposed. Concomitantly, BANF progressively increased up to 2.4-fold at maximal BFV (2.08±0.24 ml). After stabilization at submaximal BFV, BANF was increased by 186±37%. Vardenafil injection induced an immediate decrease in NVCs compared to saline (p<0.001) and BANF (52% decrease vs 28% in saline after 45 min; p<0.001). CONCLUSIONS: Systemic vardenafil reduced both NVCs and BANF in unanesthetized, decerebrate, SCI rats. These findings provide new insights into the mechanism of action by which PDE5-Is improve storage symptoms in SCI patients.

Effects of potassium channel modulators on myogenic spontaneous phasic contractile activity in human detrusor from neurogenic patients.

OBJECTIVE: To characterize the spontaneous contractile activity (SCA) developed by detrusor from patients with neurogenic detrusor overactivity (NDO) because the alteration of detrusor properties plays a critical role in the pathogenesis of detrusor overactivity, as well as to evaluate the role of K(ATP) and K(Ca) channels on this SCA because these channels regulate detrusor SCA in many species, including humans without overactive bladder (OAB). PATIENTS AND METHODS: Human bladder samples were obtained from 44 patients undergoing cystectomy for bladder cancer with no known OAB symptoms and from 38 patients suffering from urodynamically diagnosed NDO. Detrusor strips with or without urothelium/suburothelium were mounted isometrically in organ baths filled with Krebs-HEPES (37 °C; 95% O(2) /5% CO(2) ). Strips were incubated with 10 µm pinacidil (K(ATP) opener) followed by 10 µm glibenclamide (K(ATP) blocker). In another set of experiments, strips were incubated with 30 µm NS-1619 (BK(Ca) opener) followed by 100 nm iberiotoxin (BK(Ca) blocker) or with 100 nm apamin (SK(Ca) blocker). RESULTS: SCA occurred more frequently with larger amplitude and area under the curve in detrusor strips from NDO patients compared to control patients. The presence of urothelium/suburothelium did not significantly modify SCA in either patient population. Pinacidil markedly inhibited SCA of detrusor strips from control and NDO patients. This effect was reversed by glibenclamide. By contrast, NS-1619 followed by iberiotoxin did not elicit any significant changes in SCA from NDO patients, contrary to control patients. CONCLUSIONS: K(ATP) and SK(Ca) channels regulate SCA of NDO patients' detrusor strips. By contrast, BK(Ca) channels are not involved in the regulation of detrusor SCA in NDO patients, whereas they regulate SCA in control patients. These results should be considered in the development of K(+) channels openers for the treatment of NDO. Moreover, SCA observed in vitro should be regarded as an in vitro modelling of human NDO.

Nitric oxide/cyclic guanosine monophosphate signalling mediates an inhibitory action on sensory pathways of the micturition reflex in the rat.

BACKGROUND: Overactive bladder can be associated with a hyperexcitability of bladder afferent C-fibres. Several studies have suggested that nitric oxide (NO) or its downstream signalling could modulate the micturition reflex (MR) by reducing the excitability of bladder afferents. OBJECTIVES: To evaluate the role of the NO/cyclic guanosine monophosphate (cGMP) signalling pathway on the MR in a model of bladder hyperactivity (BHA) associated with C-fibre activation in the rat. DESIGN, SETTING, AND PARTICIPANTS: Adult female Sprague Dawley rats were used. MEASUREMENTS: Cystometry was performed in anaesthetised rats. The effects of 0.1 mg/kg of sodium nitroprusside (SNP), an NO donor; 10 mg/kg of 8Br-cGMP, a cGMP analogue; 3 mg/kg of sildenafil and 1 mg/kg of vardenafil, two phosphodiesterase type 5 inhibitors (PDE5-I); 10 mg/ml of L-N(G)-nitroarginine methyl ester (L-NAME), an NO synthase inhibitor; and 1 mg/kg of LY-83583, a guanylate cyclase inhibitor, were investigated on BHA during intravesical capsaicin (30 micromol/l) instillation. All drugs were delivered intravenously except for L-NAME, which was intravesically administered. RESULTS AND LIMITATIONS: SNP, 8Br-cGMP, and PDE5-I increased the intercontraction interval (ICI), while SNP and PDE5-I increased the micturition pressure threshold (MPT). L-NAME and LY-83583 decreased MPT, and L-NAME decreased ICI. 8Br-cGMP decreased the maximum intravesical pressure (MP), contrary to L-NAME and LY-83583. SNP and PDE5-I had no effect on MP. SNP increased the voided volume (VV). PDE5-I and 8Br-cGMP also increased VV, although not significantly. In contrast, L-NAME tended to decrease VV. Although 8Br-cGMP decreased the baseline intravesical pressure, LY-83583 increased it. Neither SNP nor PDE5-I nor L-NAME had any effect on baseline pressure. CONCLUSIONS: Compounds activating the NO/cGMP pathway inhibited BHA, whereas compounds inhibiting the NO/cGMP pathway increased it. These results indicate that the NO/cGMP signalling pathway is involved in the regulation of the MR, with an action that seems more predominant on the sensory rather on the motor component of the MR in a rat model of BHA associated with C-fibre afferent activation.