Urethral Perfusion Pressure Research Articles

Time-dependent progress of lower urinary tract dysfunction in streptozotocin-induced diabetic rats with or without low-dose insulin treatment.

Objectives: To examine time-dependent functional and structural changes of the lower urinary tract in streptozotocin-induced diabetic rats with or without low-dose insulin treatment and explore the pathophysiological characteristics of insulin therapy on lower urinary tract dysfunction (LUTD) caused by diabetes mellitus (DM). Methods: Female Sprague-Dawley rats were divided into five groups: normal control (NC) group, 4 weeks insulin-treated DM (4-DI) group, 4 weeks DM (4-DM) group, 8 weeks insulin-treated DM (8-DI) group and 8 weeks DM (8-DM) group. DM was initially induced by i.p. injection of streptozotocin (65 mg/kg), and then the DI groups received subcutaneous implantation of insulin pellets under the mid dorsal skin. Voiding behavior was evaluated in metabolic cages. The function of bladder and urethra in vivo were evaluated by simultaneous recordings of the cystometrogram and urethral perfusion pressure (UPP) under urethane anesthesia. The function of bladder and urethra in vitro were tested by organ bath techniques. The morphologic changes of the bladder and urethra were investigated using Hematoxylin-Eosin and Masson's staining. Results: Both 4-and 8-weeks diabetic rats have altered micturition patterns, including increased 12-h urine volume, urinary frequency/12 hours and voided volume. In-vivo urodynamics showed the EUS bursting activity duration is longer in 4-DM group and shorter in 8-DM group compared to NC group. UPP change in 8-DM were significantly lower than NC group. While none of these changes were found between DI and NC groups. Organ bath showed the response to Carbachol and EFS in bladder smooth muscle per tissue weights was decreased significantly in 4- and 8-weeks DM groups compared with insulin-treated DM or NC groups. In contrast, the contraction of urethral muscle and maximum urethral muscle contraction per gram of the tissue to EFS stimulation were significantly increased in 4- and 8-weeks DM groups. The thickness of bladder smooth muscle was time-dependently increased, but the thickness of the urethral muscle had no difference. Conclusions: DM-induced LUTD is characterized by time-dependent functional and structural remodeling in the bladder and urethra, which shows the hypertrophy of the bladder smooth muscle, reduced urethral smooth muscle relaxation and EUS dysfunction. Low-dose insulin can protect against diuresis-induced bladder over-distention, preserve urethral relaxation and protect EUS bursting activity, which would be helpful to study the slow-onset, time-dependent progress of DM-induced LUTD.

Impaired nitric oxide mechanisms underlying lower urinary tract dysfunction in aging rats.

The study aimed to investigate the bladder and urethral activity and nitric oxide (NO)-related molecular changes in aging rats. Rats were divided into two groups: Group Y (young rats; 12 wk) and Group A (aging rats; 15 mo). A 24-h voiding assay was performed, and the urodynamic parameters were evaluated using awake cystometry (CMG) and urethral perfusion pressure (UPP) recordings under urethane anesthesia. The mRNA expression levels of NO-, ischemia-, and inflammation-related markers in urethra and bladder tissues and cGMP levels in the urethra were assessed. Body weight was significantly higher in Group A than in Group Y. Voiding assay results (24 h) were insignificant. In the CMG, the number of non-voiding contractions per voiding cycle and post-void residual volume were significantly higher in Group A than in Group Y; voiding efficiency was significantly lower in Group A than in Group Y. In the UPP recordings, the urethral pressure reduction and high-frequency oscillation (HFO) amplitude were significantly lower in Group A than in Group Y. The mRNA expression levels of Hif-1α, Vegf-a, and Tgf-β1 in the bladder were significantly higher in Group A than in Group Y. The mRNA expression levels of Nos1 and Prkg1 and the cGMP concentrations in the urethra were significantly lower in Group A than in Group Y. Aging rats can be useful models for studying the natural progression of age-related lower urinary tract dysfunctions, for which impaired NO-mediated transmitter function is likely to be an important mechanism.NEW & NOTEWORTHY Aging rats can be useful models for studying the natural progression of age-related lower urinary tract dysfunctions, for which impaired nitric oxide-mediated transmitter function is likely to be an important mechanism.

PD23-03 IMPAIRED NITRIC OXIDE MECHANISMS UNDERLYING LOWER URINARY TRACT DYSFUNCTION IN AGING RATS

You have accessJournal of UrologyCME1 Apr 2023PD23-03 IMPAIRED NITRIC OXIDE MECHANISMS UNDERLYING LOWER URINARY TRACT DYSFUNCTION IN AGING RATS Daisuke Gotoh, Kenta Onishi, Yosuke Morizawa, Shunta Hori, Yasushi Nakai, Makito Miyake, Kazumasa Torimoto, Fujimoto Kiyohide, and Naoki Yoshimura Daisuke GotohDaisuke Gotoh More articles by this author , Kenta OnishiKenta Onishi More articles by this author , Yosuke MorizawaYosuke Morizawa More articles by this author , Shunta HoriShunta Hori More articles by this author , Yasushi NakaiYasushi Nakai More articles by this author , Makito MiyakeMakito Miyake More articles by this author , Kazumasa TorimotoKazumasa Torimoto More articles by this author , Fujimoto KiyohideFujimoto Kiyohide More articles by this author , and Naoki YoshimuraNaoki Yoshimura More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003296.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Nitric oxide (NO) promotes the intracellular production of cyclic guanosine monophosphate (cGMP) in smooth muscles, reduces the intracellular calcium concentration, and enhances smooth muscle relaxation. However, it remains unknown whether changes in the expression of NO-related molecules are associated with the development of lower urinary tract dysfunction (LUTD) with age. Therefore, we examined changes in bladder and urethral activities, and in NO-related molecule expression using aging rats. METHODS: Fourteen Female Sprague–Dawley rats were divided into two age groups: (A) young rats (12 weeks old, n=8) and (B) aging rats (15 months old, n=6). In both groups, 24 h voiding assay was performed, and the urodynamic parameters were evaluated using cystometry (CMG) and urethral perfusion pressure (UPP) recordings. mRNA expression levels of NO-, ischemia-, and inflammation-related markers in bladder and urethra tissues were assessed, and the cGMP level in the urethra was measured. RESULTS: There was no significant difference in the 24-h voiding assay results between the groups. In CMG, the number of non-voiding contractions (NVCs) per voiding cycle and post-void residual (PVR) were significantly higher, and voiding efficiency (VE) was significantly lower in Group B than in Group A (Figure 1A, B). In the UPP recordings, urethral pressure (UP) reduction and high frequency oscillation (HFO) amplitudes were both significantly lower in Group B than in Group A (Figure 1C, D). In molecular studies, mRNA expression levels of HIF-1α, VEGF, and TGF-β1 in the bladder were significantly higher in Group B than in Group A (Figure 2A). mRNA expression levels of NOS1 and PKG were significantly lower in Group B than in Group A (Figure 2B). In addition, the concentration of cGMP in the urethra was significantly lower in Group B than in Group A (Figure 2C). CONCLUSIONS: Aging rats would be a useful model for the study of the natural progression of age-related LUTD, for which impaired NO-mediated transmitter function is likely to be an important mechanism. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e671 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Daisuke Gotoh More articles by this author Kenta Onishi More articles by this author Yosuke Morizawa More articles by this author Shunta Hori More articles by this author Yasushi Nakai More articles by this author Makito Miyake More articles by this author Kazumasa Torimoto More articles by this author Fujimoto Kiyohide More articles by this author Naoki Yoshimura More articles by this author Expand All Advertisement PDF downloadLoading ...

The potential involvement of MRP5 pump in urethral dysfunction in streptozotocin-induced diabetic rats.

To examine the effects of i.v. administration of MK-571, a MRP4/5 pump inhibitor, on urethral function in the urethane-anesthetized rat, and the changes of urethral multidrug resistance protein 5 (MRP5) pump in streptozotocin (STZ)-induced diabetes mellitus (DM) rats. Isovolumetric cystometry and urethral perfusion pressure (UPP) measurements were carried out in normal control (NC) group and 8week DM groups under urethane anesthesia. When stable rhythmic bladder contractions were showed, UPP parameters were recorded after successive administration of various dose of MK-571. Additionally, urethral cyclic guanosine monophosphate (cGMP) protein level was evaluated by ELISA, and changes of MRP5 pump and neurogenic nitric oxide synthase (nNOs) in the urethra were examined with immunohistochemical staining and Western blot analysis. In NC group, UPPnadir was significantly decreased but UPP change increased after administration of MK-571, while no significant differences in UPP parameters were observed in 8-week DM group. Furthermore, urethral MRP5 protein level was up-regulated, whereas urethral cGMP and nNOS protein levels were down-regulated in 8-week DM group. MK-571 could not restore NO-mediated urethral relaxation dysfunction in DM rats, which may be attributed to the up-regulation of urethral MRP5 pump, and thus decrease of intracellular cGMP concentration in the urethra. These novel results would be useful for a better understanding of DM-related lower urinary tract dysfunction LUT (LUTD). Also, they could be helpful to study the importance of MRP pumps in the control of urethral relaxation mechanisms under physiological and pathological states.

Influence of cerebral infarction on both bladder and urethral activities and changes after tramadol administration in rats.

We investigated the changes in bladder and urethral function after cerebral infarction (CI) and the influence of tramadol on these functions. Twenty-eight female Sprague Dawley rats were divided into normal and CI groups. In the awake condition, metabolic cage study and blood pressure were evaluated. Under urethane anesthesia, the intravenous effect of tramadol (0.01-1 mg/kg), which has both µ-opioid receptor stimulation and inhibition of norepinephrine and serotonin reuptake, on continuous cystometry, and simultaneous measurements of bladder and urethral perfusion pressure (UPP) were recorded. Infarcted lesions were examined by staining with triphenyltetrazolium chloride, a marker of mitochondrial enzyme activity. CI rats showed impaired sympathetic activity with Horner's syndrome and lower blood pressure. In metabolic cage study, urinary frequency during the dark phase was increased in CI rats. On bladder activity, in CI rats, the baseline pressure threshold for inducing bladder contractions was significantly lower (p < 0.01), and the intercontraction interval was prolonged after tramadol administration. On urethral activity, the baseline UPP was significantly lower in CI rats than in normal rats and it did not change after tramadol administration. Residual urine rate was significantly increased in normal rats, but not in CI rats. CI rats showed brain infarction including the cortex and hypothalamus, which is a center of the autonomic nervous system. CI-induced ischemic brain damage results in impairment of both bladder and urethral functions, in addition to decreased sympathetic activity. Bladder overactivity after CI can be improved by tramadol; however, urethral activity cannot be improved by it.

Improvement of urethral dysfunction by 5-HT1A receptor agonist NLX-112 in diabetic rats.

To examine the effects of the selective 5-HT1A receptor agonist, NLX-112, on urethral function in streptozotocin-induced diabetic rats. Female Sprague-Dawley rats (n = 32) were divided into two groups: rats with type 1 diabetes mellitus (T1DM) and age-matched normal control rats (NC). T1DM was induced by intraperitoneal injection of streptozotocin (65 mg/kg). Isovolumetric cystometry and urethral perfusion pressure (UPP) were evaluated 10 weeks postinjection in rats (n = 9 per group). The selective 5-HT1A receptor antagonist, WAY-100635 maleate salt, was administered after NLX-112 hydrochloride dose-response curve was generated (intravenously). The remaining rats were used for immunofluorescence and Western blot assays. Compared to controls, type 1 diabetic rats (T1D rats) had lower maximal intravesical pressure (IP max) and UPP changes. In T1D rats, NLX-112 hydrochloride (0.003-1.0 mg/kg) induced dose-dependent decreases in UPP nadir, IP max, high-frequency oscillations (HFOs) rate; and increases in UPP change and HFOs amplitude. WAY-100635 maleate salt (0.3 mg/kg) partially or completely reversed the NLX-112-induced changes. Immunofluorescence revealed that 5-HT1A receptors were found in the L6-S1 spinal cord dorsolateral nucleus, but the expression was significantly higher in the T1D rats. Additionally, Western blot showed there were significantly more 5-HT1A receptors in the ventral L6-S1 spinal cord of T1D rats. Urethral dysfunction in T1D rats was improved by NLX-112. 5-HT1A receptors were upregulated in the dorsolateral nucleus of L6-S1 spinal cord in T1D rats. These findings suggest that NLX-112 may constitute a novel therapeutic strategy to treat diabetic urethral dysfunction.

Age-associated bladder and urethral coordination impairment and changes in urethral oxidative stress in rats

AimsWe examined age-associated changes in bladder and urethral coordination involving the nitric oxide (NO)/soluble guanylyl cyclase (sGC) system, which induces urethral smooth muscle relaxation, and urethral ischemic/oxidative stress changes in rats. Main methodsSixteen female Sprague-Dawley rats were divided into young (3 months old) and middle-aged (12–15 months old) groups. Urethral activity was evaluated by simultaneously recording intravesical pressure under isovolumetric conditions and urethral perfusion pressure (UPP) under urethane anesthesia. Sodium nitroprusside (SNP, 0.1 mg/kg), an NO donor, and BAY 41-2272, a novel NO-independent stimulator of sGC (0.1 mg/kg), were administered intravenously to both groups. N-nitro-l-arginine methyl ester hydrochloride (l-NAME, 100 mg/kg) was also injected intravenously, to inhibit NO synthase activity in both groups. Staining for the ischemic marker, hypoxia-inducible factor-1α (HIF-1α), and the oxidative stress markers, 8-hydroxy-2′-deoxyguanosine (8-OHdG) and malondialdehyde (MDA), was performed on tissue sections of the urethra, in both groups. Key findingsBaseline UPP and UPP changes were significantly lower in middle-aged rats than in young rats. After administration of SNP and BAY 41-2272, baseline UPP and UPP nadir were significantly decreased in both groups. After administration of l-NAME, UPP change/bladder contraction amplitude in young rats was still lower than at baseline but was completely restored to control levels in middle-aged rats. Immunoreactivity of HIF-1α, 8-OHdG, and MDA was higher in middle-aged rats than in young rats. SignificanceAge-associated ischemic and oxidative stress in the urethra might be correlated with impairment of the NO/sGC system and with coordination of the bladder and urethra.

Changes in urethral smooth muscle and external urethral sphincter function with age in rats.

To confirm changes in urethral activity with age, both intravesical pressure and urethral perfusion pressure (UPP) were recorded and external urethral sphincter electromyography (EUS‐EMG) was performed. A total of 33 female Sprague Dawley rats aged 3 months (young rats), 12 months (middle‐aged rats), and 24 months (aged rats) were used. Bladder activity was evaluated using continuous cystometry. Urethral activity was evaluated by simultaneously recording intravesical pressure and UPP in isovolumetric conditions under urethane anesthesia in each group. Additionally, EUS‐EMG activity was monitored under the same conditions. In continuous cystometry, the amplitude of bladder contractions was not different among the three groups; nevertheless, residual urine volume was significantly increased in middle‐aged and aged rats, as compared in young rats. With respect to UPP, the change in UPP was significantly smaller in aged rats (60%) and middle‐aged rats (64%) than in young rats. Furthermore, the mean amplitude of high‐frequency oscillations of the EUS was significantly lower in aged (61%) and middle‐aged rats (70%) than in young rats. EUS‐EMG revealed EUS bursting activity during voiding with clear active and silent phases in young rats but unclear active and silent phases in aged rats. Masson's trichrome staining of the urethra showed EUS atrophy in aged rats compared to young and middle‐aged rats. The results indicate that aging induces two urethral dysfunctions in the urethral smooth muscle and EUS, which may lead to dyscoordination between the urinary bladder and urethra.

Effects of intravesical prostaglandin E2 on bladder function are preserved in capsaicin-desensitized rats.

Prostaglandin E2 (PGE2) instilled into the bladder generates symptoms of urinary urgency in healthy women and reduces bladder capacity and urethral pressure in both humans and female rats. Systemic capsaicin desensitization, which causes degeneration of C-fibers, prevented PGE2-mediated reductions in bladder capacity, suggesting that PGE2 acts as an irritant (Maggi CA, Giuliani S, Conte B, Furio M, Santicioli P, Meli P, Gragnani L, Meli A. Eur J Pharmacol 145: 105-112, 1988). In the present study, we instilled PGE2 in female rats after capsaicin desensitization but without the hypogastric nerve transection that was conducted in the Maggi et al. study. One week after capsaicin injection (125 mg/kg sc), rats underwent cystometric and urethral perfusion testing under urethane anesthesia with saline and 100 µM PGE2. Similar to naïve rats, capsaicin-desensitized rats exhibited a reduction in bladder capacity from 1.23 ± 0.08 mL to 0.70 ± 0.10 mL (P = 0.002, n = 9), a reduction in urethral perfusion pressure from 19.3 ± 2.1 cmH2O to 10.9 ± 1.2 cmH2O (P = 0.004, n = 9), and a reduction in bladder compliance from 0.13 ± 0.020 mL/cmH2O to 0.090 ± 0.014 mL/cmH2O (P = 0.011, n = 9). Thus, changes in bladder function following the instillation of PGE2 were not dependent on capsaicin-sensitive pathways. Further, these results suggest that urethral relaxation/weakness and/or increased detrusor pressure as a result of decreased compliance may contribute to urinary urgency and highlight potential targets for new therapies for overactive bladder.

PD24-05 OXIDATIVE STRESS INDUCES DETRUSOR UNDERACTIVITY AND URETHRAL DYSFUNCTION IN AGING RATS

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology II (PD24)1 Apr 2020PD24-05 OXIDATIVE STRESS INDUCES DETRUSOR UNDERACTIVITY AND URETHRAL DYSFUNCTION IN AGING RATS Asato Ohtsubo*, Takuma Oshiro, Ryu Kimura, Minoru Miyazato, Tomohiro Matsuo, Yasuyoshi Miyata, and Hideki Sakai Asato Ohtsubo*Asato Ohtsubo* More articles by this author , Takuma OshiroTakuma Oshiro More articles by this author , Ryu KimuraRyu Kimura More articles by this author , Minoru MiyazatoMinoru Miyazato More articles by this author , Tomohiro MatsuoTomohiro Matsuo More articles by this author , Yasuyoshi MiyataYasuyoshi Miyata More articles by this author , and Hideki SakaiHideki Sakai More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000881.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Age-related symptoms, such as urinary retention and a poor urinary stream have been attributed to detrusor underactivity. Our recent studies showed that by simultaneously recording intravesical pressure and urethral perfusion pressure (UPP), urethral relaxation during bladder contractions was diminished in aged rats. Nevertheless, L-arginine (a substrate of nitric oxide (NO) synthase) could not restore a diminished urethral relaxation. Thus, we hypothesized that age-associated oxidative stress would impair NO/soluble guanylyl cyclase (sGC) system which induces urethral relaxation. This hypothesis was tested by measuring an oxidative stress marker in the bladder and also by simultaneously recording intravesical pressure and UPP using BAY 41-2272 as a novel NO-independent stimulator of sGC. METHODS: Female Sprague Dawley rats (young rats aged 3 months and old rats aged 12–15 months) were used. 1) Oxidative stress marker staining for 8-hydroxy-2’-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) in the bladder was performed in both groups. 2) Urethral activity was evaluated by simultaneously recording the intravesical pressure under isovolumetric conditions and UPP under urethane anesthesia. 3) BAY 41-2272 (1 mg/kg) was administered intravenously in both groups under isovolumetric conditions. RESULTS: 1) Oxidative marker staining revealed that 8-OHdG and MDA levels were higher in aging rats than those in young rats. 2) UPP nadir during urethral relaxation was significantly higher (38%) in aging rats than in young rats (p < 0.05). The mean amplitude of high frequency oscillation (HFO) of the urethral striated muscle was also significantly lower (49%) in aging rats than in normal rats (p < 0.05). 3) BAY 41-2272 increased urethral relaxation in young rats while restoring impaired urethral relaxation in aged rats. CONCLUSIONS: These results indicate that aging induces a dysfunction in urethral relaxation during voiding, as evidenced by a decrease in HFO activity of the urethral striated muscle as well as NO mediated urethral relaxation of the urethral smooth muscle. Because NO-independent stimulator could restore impaired urethral relaxation in the aged bladder, age-associated oxidative stress in the NO/sGC system might be correlated with an age associated impairment in bladder and urethral coordination. This novel study coupled with physiological and morphological changes in the aged bladder would contribute to elucidating the process of aging in bladders. Source of Funding: This work was supported by a Grant-in-Aid for Scientific Research (18K17752, 18K10714 and 18K10749 ). © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e533-e534 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Asato Ohtsubo* More articles by this author Takuma Oshiro More articles by this author Ryu Kimura More articles by this author Minoru Miyazato More articles by this author Tomohiro Matsuo More articles by this author Yasuyoshi Miyata More articles by this author Hideki Sakai More articles by this author Expand All Advertisement PDF downloadLoading ...

MP48-03 THE EFFECTS OF L-ARGININE ON URETHRAL FUNCTION IN STREPTOZOTOCIN-INDUCED AND INSULIN-TREATED DIABETIC RATS

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Neurogenic Voiding Dysfunction (MP48)1 Apr 2020MP48-03 THE EFFECTS OF L-ARGININE ON URETHRAL FUNCTION IN STREPTOZOTOCIN-INDUCED AND INSULIN-TREATED DIABETIC RATS Nailong Cao, Baojun Gu*, Eduardo C Alexandre, Daisuke Gotoh, Masahiro Kurobe, Shinsuke Mizeguchi, and Naoki Yoshimura Nailong CaoNailong Cao More articles by this author , Baojun Gu*Baojun Gu* More articles by this author , Eduardo C AlexandreEduardo C Alexandre More articles by this author , Daisuke GotohDaisuke Gotoh More articles by this author , Masahiro KurobeMasahiro Kurobe More articles by this author , Shinsuke MizeguchiShinsuke Mizeguchi More articles by this author , and Naoki YoshimuraNaoki Yoshimura More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000903.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Normal lower urinary tract (LUT) function is dependent on the coordination between bladder and urethra, which is sensitive to a host of disorders, including diabetes mellitus (DM). Although STZ-induced diabetic rat model has been extensively used as a rodent model of the LUT dysfunction, it’s not a good physiological condition for diabetic patients. Our purpose is therefore to establish a physiological DM animal model with low dose insulin treatment, and examine the effects of L-arginine on urethral function in this animal model. METHODS: Thirty female Sprague-Dawley rats were divided into three groups. DM was initially induced by i. p. injection of STZ (65 mg/kg), and then received subcutaneous implantation of insulin under the mid dorsal skin. Isovolumetric cystometry and urethral perfusion pressure (UPP) measurements were performed under urethane anesthesia. L-arginine (100 mg/kg), was administered intravenously. Subsequently, N-nitro-L-arginine methyl ester hydrochloride (L-NAME) (50 mg/kg) was injected intravenously to inhibit NO synthase activity. The changes of urethral function among different groups in vitro were tested by organ bath. RESULTS: In vivo study, UPP nadir was only decreased by L-arginine both in Normal control (NC) and insulin-treated DM groups, but inhibited by L-NAME in all the groups (Fig.1). Furthermore, 5 out of 6 DM rats showed a similar detrusor-sphincter dyssynergia pattern after L-NAME (Fig.1). In vitro study, the ratio, namely urethral relaxation difference divided by relaxation before L-NAME administration, was significantly decreased in DM group (Fig.2). CONCLUSIONS: Low dose insulin can protest against diuresis-induced bladder overdistention and increase urethral relaxation, and this may be attributed to the protection of NO synthase and urethral NO sensitivity, but the longer effects should be further explored. Source of Funding: NIH (U54 DK112079 and R01 DK115476) © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e695-e695 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Nailong Cao More articles by this author Baojun Gu* More articles by this author Eduardo C Alexandre More articles by this author Daisuke Gotoh More articles by this author Masahiro Kurobe More articles by this author Shinsuke Mizeguchi More articles by this author Naoki Yoshimura More articles by this author Expand All Advertisement PDF downloadLoading ...

Urethral dysfunction and alterations of nitric oxide mechanisms in streptozotocin-induced diabetic rats with or without low-dose insulin treatment

AimsTo establish an animal model of diabetes mellitus (DM) with moderately elevated blood glucose levels, and to examine the nitric oxide (NO) mechanism controlling urethral function in streptozotocin (STZ)-induced DM rats. Main methodsFemale Sprague-Dawley rats were used. DM was induced by intraperitoneal injection of STZ (65 mg/kg) and some of them received subcutaneous implantation of a low-dose insulin pellet. Voiding behavior was evaluated in metabolic cages. Isovolumetric cystometry and urethral perfusion pressure (UPP) were then evaluated under urethane anesthesia, during which L-arginine (100 mg/kg) and N-nitro-L-arginine methyl ester hydrochloride (L-NAME) (50 mg/kg) were administered intravenously. In vitro urethral activity was also tested by organ bath muscle strip studies. Key findingsUPP changes and high-frequency oscillation (HFO) were significantly (P < 0.05) smaller in 8-weeks DM rats vs. normal control (NC) rats or insulin-treated DM rats, which showed reductions in urine overproduction and voided volume per micturition vs. untreated DM rats. UPP nadir was decreased by L-arginine in NC and insulin-treated DM groups, and decreased by L-NAME in all groups. Five of 6 untreated DM rats showed a detrusor-sphincter dyssynergia pattern after L-NAME. In in vitro studies, the relative ratio of L-NAME-induced reductions of urethral relaxation against pre-drug urethral relaxation was significantly smaller in DM vs. NC rats (P < 0.05). SignificanceLow-dose insulin-treated DM rats would be a useful model for studying natural progression of DM-induced lower urinary tract dysfunction. The impaired NO-mediated urethral relaxation mechanisms play an important role in DM-induced urethral dysfunction, which could contribute to DM-induced inefficient voiding.

Urethral dysfunction and therapeutic effects of a PDE 5 inhibitor (tadalafil) in a rat model of detrusor underactivity induced by pelvic nerve crush injury.

The urethral dysfunction produced by a rat model of peripheral neurogenic detrusor underactivity (DU) using pelvic nerve crush (PNC) injury was characterized and then tested with the administration of tadalafil, a phosphodiesterase type 5 (PDE 5) inhibitor. Ten days after producing PNC rats, awake cystometrograms (CMGs) and isovolumetric cystometrograms with urethral perfusion pressure (IC-UPP) measurements were performed. Also, in control rats, IC-UPP was recorded before and after intravenous atropine administration to determine if the reduction of bladder contraction pressure affects urethral relaxation during voiding. Then, CMG and IC-UPP measurements in PNC rats were recorded after intravenous administration of tadalafil. Lastly, real-time polymerase chain reaction was used to measure transcript levels of neuronal nitric oxide synthases (nNOS), endothelial nitric oxide synthases, and PDE 5 in urethral specimens from PNC and control rats. PNC rats demonstrated the characteristics of DU in CMG. Also, PNC rats exhibited significant decreases in isovolumetric bladder contraction amplitudes and urethral relaxation. Atropine attenuated the amplitude of isovolumetric bladder contractions; however, atropine did not affect urethral relaxation in control rats. Tadalafil decreased postvoid residual and increased voiding efficiency without changing bladder contraction amplitude in PNC rats. Also, tadalafil improved the amplitude of urethral relaxation during bladder contraction in PNC rats. Urethral nNOS transcript levels were upregulated in PNC rats compared to control rats. PNC rats revealed both DU and impaired urethral relaxation. PDE 5 inhibition in PNC rats enhanced urethral relaxation during voiding, resulting in improved voiding efficiency. Thus, urethral dysfunction could be a potential target for the treatment of inefficient voiding associated with neurogenic DU.

ASP6432, a type 1 lysophosphatidic acid receptor antagonist, reduces urethral function during urine voiding and improves voiding dysfunction

Current pharmacotherapies for voiding dysfunctions are in need of improvement. Lysophosphatidic acid (LPA) is a phospholipid that contracts the urethra by activating type 1 LPA receptors (LPA1). However, the role of LPA1 in regulating urethral tonus during urine voiding which primarily affects the voiding function has not been investigated. To elucidate the role of LPA1 in the regulation of urethral tonus during urine voiding, we investigated the effects of ASP6432, a novel LPA1 antagonist, and the α1-adrenoceptor antagonist tamsulosin on urethral perfusion pressure (UPP) at the filling phase (UPPbase) and the minimum UPP at the voiding phase (UPPnadir) in anesthetized rats under isovolumetric conditions. We further evaluated the effects of ASP6432 and tamsulosin on voiding dysfunction characterized by changes in post-void residual urine (PVR) and voiding efficiency (VE) induced by the nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) in conscious rats using single cystometry. ASP6432 dose-dependently decreased UPPbase and UPPnadir, while tamsulosin reduced UPPbase but did not change UPPnadir. ASP6432 dose-dependently suppressed the L-NAME-induced increase in PVR and decrease in VE, whereas tamsulosin did not affect either PVR or VE. We demonstrate that ASP6432 reduced UPPnadir and ameliorated L-NAME-induced voiding dysfunction, neither of which were affected by tamsulosin. Our study results suggest that LPA1 has a significant role in regulating urethral tonus during urine voiding, and highlight the potential of ASP6432 for improving voiding dysfunctions associated with various lower urinary tract diseases.

Effect of ASP6432, a Novel Type 1 Lysophosphatidic Acid Receptor Antagonist, on Urethral Function and Prostate Cell Proliferation.

Current pharmacotherapies for lower urinary tract symptoms associated with benign prostate hyperplasia (LUTS/BPH) are in need of improvement. Lysophosphatidic acid (LPA) is a phospholipid with various biologic functions. However, its exact role in the lower urinary tract and its target receptor subtype have not been fully elucidated. We investigated the role of LPA and the type 1 LPA receptor (LPA1) in urethral/prostatic contractile function and prostate cell proliferation by pharmacologically characterizing ASP6432 (potassium 1-(2-{[3,5-dimethoxy-4-methyl-N-(3-phenylpropyl)benzamido]methyl}-1,3-thiazole-4-carbonyl)-3-ethyl-2,2-dioxo-2λ6-diazathian-1-ide), a novel LPA1 antagonist. ASP6432 exhibited potent and selective antagonistic activity against LPA1 in cells expressing LPA receptor subtypes. In isolated rat tissue strips and anesthetized rats, ASP6432 concentration-/dose-dependently inhibited LPA-induced urethra and prostate contractions. In addition, in anesthetized rats, ASP6432 maximally decreased the urethral perfusion pressure (UPP) in the absence of exogenous LPA stimulation by 43% from baseline, whereas tamsulosin, an α1-adrenoceptor antagonist, reduced UPP by 22%. Further, in human prostate stromal cells, ASP6432 significantly and concentration-dependently suppressed LPA-induced bromodeoxyuridine incorporation. These results demonstrate a pivotal role for LPA and LPA1 in the regulation of urethral tonus and prostate cell proliferation. The potent urethral relaxation and inhibition of prostatic stromal cell growth indicate the potential of ASP6432 as a novel therapeutic agent for LUTS/BPH.

Age-associated urethral dysfunction in urethane-anesthetized rats.

We aimed to investigate the age-associated changes in movement coordination between the urinary bladder and the urethra in rats. A total of 17 female Sprague-Dawley rats were used. The rats were divided into young (3 months old) and middle-aged (12-15 months old) groups. In both groups, isovolumetric cystometry and urethral perfusion pressure (UPP) measurements were performed under urethane anesthesia. After the rhythmic bladder contractions stabilized, L-arginine, a nitric oxide (NO) substrate (100 mg/kg), was administered intravenously in both groups. Subsequently, N-nitro-L-arginine methyl ester hydrochloride (L-NAME) (50 mg/kg) was injected intravenously to inhibit NO synthase activity in both groups. UPP change, defined as UPP nadir minus baseline UPP, was significantly smaller in middle-aged rats (64%) than in young rats (P < 0.05). The mean amplitude of high-frequency oscillations (HFOs) of the external urethral sphincter was also significantly lower (62%) in middle-aged rats than that in young rats (P < 0.05). Urethral contraction during UPP change was also noted in middle-aged rats. This urethral contraction disappeared after L-arginine administration. UPP nadir during bladder contraction was inhibited by L-NAME in both groups. UPP change was greater in middle-aged rats than in young rats, and 3 out of 9 middle-aged rats showed a detrusor-sphincter dyssynergia pattern after L-NAME. The results indicated that aging induces dysfunction in movement coordination between the urinary bladder and the urethra. Thus, age-associated urethral dysfunctions may lead to inefficient voiding with increased post-void residual urine volume, which is often observed in elderly populations.

Urethral function and histopathology in aged female rats as a stress urinary incontinence model.

Stress urinary incontinence (SUI) is a common disease condition in elderly women, suggesting that its etiology may be linked to aging. To investigate the hypothesis that urethral dysfunction and histopathological changes are possible contributors to SUI in elderly women, several parameters of urethral function, as well as histological parameters, were compared between young and aged rats. Virgin female rats were examined at 3 different ages, namely 3, 12, and 24 months, corresponding to young, middle-aged, and aged rats, respectively. Urethral function was assessed by measuring the leak point pressure (LPP), pudendal nerve stimulation (PNS)-induced elevation in urethral pressure, and phenylephrine-induced increase in urethral perfusion pressure (UPP). Histopathological assessments were performed following hematoxylin and eosin (HE), Masson's trichrome, and immunofluorescence staining of urethral tissue. LPP of aged rats was significantly reduced compared to that of both young and middle-aged rats. PNS-induced elevation in urethral pressure in aged rats was also significantly lower than that in young rats. In contrast, there were no significant differences in the phenylephrine-induced increase in UPP between young and aged rats. Connective tissue area in the external urethral sphincter (EUS) layer was increased in aged rats, whereas the smooth muscle layer was histologically similar to that in young rats. The number of EUS fibers was significantly reduced in aged rats, whereas the cross-sectional area of EUS fibers increased from differed compared with young rats. We have demonstrated age-related changes in EUS function and morphology in the rat urethra, which are considered to be etiological risk factors for SUI in humans.

Grape seed proanthocyanidin extract alleviates urethral dysfunction in diabetic rats through modulating the NO-cGMP pathway.

Oxidative stress is closely associated with the onset of diabetes mellitus (DM). Diabetic urethropathy is one of the most common complications of DM, but few studies have been conducted to investigate the role of oxidative stress in diabetic urethropathy. Grape seed proanthocyanidin extract (GSPE) has been previously reported to reduce oxidative injury. The present study aimed to investigate the role of oxidative stress and the protective effects of GSPE on urethral dysfunction using a streptozotocin-induced DM rat model. Female Wistar rats were divided into a control group (n=36), a DM group (n=36) and a DM + GSPE group (n=36). Urodynamic testing was performed using a PowerLab data acquisition device. The expression of neuronal nitric oxide synthase (nNOS), 3-nitrotyrosine and nuclear factor erythroid 2-related factor 2 (Nrf2) was determined using western blot analysis. The expression of 3-nitrotyrosine was also determined using immunohistochemistry. Nitric oxide (NO), cyclic guanosine monophosphate (cGMP), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) were measured using commercial ELISA kits. A significant increase was observed in the intravesical pressure thresholds for inducing urethral relaxation and the urethral perfusion pressure nadir in DM rats compared with the control group. GSPE was observed to reverse the increase of these parameters compared with the DM group. In addition, GSPE could reverse the downregulation of nNOS, NO and cGMP expression, and the decreased activities of antioxidant enzymes (SOD and GSH-Px). GSPE reversed the upregulation of 3-nitrotyrosine and MDA in DM rats. GSPE also activated Nrf2, which is a key antioxidative transcription factor. The findings of the present study demonstrated that GSPE protects urethra function in DM rats through modulating the NO-cGMP signaling pathway. The protective roles of GSPE may be associated with activation of the Nrf2 defense pathway.

OAB without an overactive bladder in the acute prostaglandin E2 rat model.

Intravesical prostaglandin E2 (PGE2) was previously used to induce overactive bladder (OAB) symptoms, as it reduces bladder capacity in rats and causes a "strong urgency sensation" in healthy women. However, the mechanism by which this occurs is unclear. To clarify how PGE2 reduces bladder capacity, 100 µM PGE2 was administered intravesically during open, single-fill cystometry with simultaneous measurement of sphincter EMG in the urethane-anesthetized female Wistar rat. PGE2 was also applied to the urethra or bladder selectively by use of a ligature at the bladder neck before (urethra) or during (bladder) closed-outlet, single-fill cystometry. Additional tests of urethral perfusion with PGE2 were made. PGE2 decreased bladder capacity, increased voiding efficiency, and increased sphincter EMG during open cystometry compared with saline controls. The number of nonvoiding contractions did not change with PGE2; however, bladder compliance decreased. During closed-outlet cystometry, PGE2 applied only to the bladder or the urethra did not decrease bladder capacity. Urethral infusion of PGE2 decreased urethral perfusion pressure. Taken together, these results suggest that intravesical PGE2 may decrease bladder capacity by targeting afferents in the proximal urethra. This may occur through urethral relaxation and decreased bladder compliance, both of which may increase activation of proximal urethra afferents from distension of the proximal urethra. This hypothesis stands in contrast to many hypotheses of urgency that focus on bladder dysfunction as the primary cause of OAB symptoms. Targeting the urethra, particularly urethral smooth muscle, may be a promising avenue for the design of drugs and devices to treat OAB.

MP26-18 TIME-DEPENDENT BLADDER AND URETHRAL DYSFUNCTIONS IN AGING RATS

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Basic Research & Pathophysiology I1 Apr 2017MP26-18 TIME-DEPENDENT BLADDER AND URETHRAL DYSFUNCTIONS IN AGING RATS Takuma Oshiro, Minoru Miyazato, Asuka Ashikari, and Seiich Saito Takuma OshiroTakuma Oshiro More articles by this author , Minoru MiyazatoMinoru Miyazato More articles by this author , Asuka AshikariAsuka Ashikari More articles by this author , and Seiich SaitoSeiich Saito More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.789AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Age-related symptoms such as urinary retention, poor urine flow, and/or incontinence have been attributed to detrusor underactivity (DU). Our recent data showed that in continuous cystometry, bladder contractility did not diminish but post-void residual urine volume was higher in aging rats than in young rats. Thus, the assumption that bladder and urethral dysfunction occur simultaneously in aging rats seems reasonable. Therefore, we investigated this possibility by measuring time-dependent changes of bladder and urethral functions in rats. METHODS Female Sprague-Dawley rats (young rats aged 3 months and rats aged 12 and 24 months) were used. 1) Continuous cystometry was performed under awake condition in each group. 2) Urethral activity was evaluated by simultaneous recordings of intravesical pressure under isovolumetric conditions and urethral perfusion pressure (UPP) under urethane anesthesia in 3-month-old and 12-month-old rats. 3) Masson's trichrome staining in the bladder was performed in each group. RESULTS 1) Cystometric evaluations revealed that the intercontraction intervals in the 24-month-old rats were prolonged (p < 0.01) when compared with those in the 3-month-old or 12-month-old rats. In the 24-month-old rats, residual urine volume was significantly higher than in the 3-month-old or 12-month-old rats, and non-voiding contractions were prominent. However, the amplitude of bladder contraction did not differ among the three groups. 2) UPP relaxation (baseline UPP minus nadir UPP) was more significantly diminished (64%) in the 12-month-old rats than in the 3-month-old rats (p < 0.05). The mean rate and amplitude of high-frequency oscillation (HFO) of urethral striated muscle were also significantly lower (12% and 41%, respectively) in the 12-month-old rats than in the 3-month-old rats. 3) In the bladders of the 24-month-old rats, increases in smooth muscle cell hypertrophy and fibrous tissue were observed. CONCLUSIONS 1) Our aging model that focused on bladder function showed increased intercontraction intervals and non-voiding bladder contractions with increased residual urine volume, suggesting detrusor hyperactivity with impaired contractility bladder activity. 2) Our aging model that focused on urethral function indicates urethral dysfunction, as evident from the reduction in HFO activity of the urethral striated muscle and the urethral relaxation. Thus, age-associated bladder and urethral dysfunction seem likely to occur simultaneously, which leads to DU with a vicious cycle. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e326-e327 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Takuma Oshiro More articles by this author Minoru Miyazato More articles by this author Asuka Ashikari More articles by this author Seiich Saito More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...