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Published Papers 【 display / non-display 】

• The early, long-term inhibition of brain-derived neurotrophic factor improves voiding, and storage dysfunctions in mice with spinal cord injury.

  Naoki Wada, Naoki Yoshimura, Masahiro Kurobe, Tetsuichi Saito, Pradeep Tyagi, Hidehiro Kakizaki

  Neurourology and urodynamics   39 ( 5 ) 1345 - 1354   2020.06 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  AIMS: We examined the time course of urodynamic changes and the effect of the short or long-term inhibition of brain-derived neurotrophic factor (BDNF) from the early phase after spinal cord injury (SCI) in mice. METHODS: The spinal cord of female C57BL/6N mice was completely transected. We examined filling cystometry and bladder BDNF levels at 10, 20, and 30 days after SCI, with an additional day-5 measurement of BDNF. In a separate group of mice, anti-BDNF antibody (Ab) (10 µg/kg/h) was subcutaneously administered using osmotic pumps from day 3 after SCI, and single-filling cystometry was performed at 10 and 30 days (7 and 27 days of treatment, respectively) after SCI. RESULTS: Compared to spinal intact mice, bladder mucosal BDNF was increased at each time point after SCI with the maximal level at day 5 after SCI. Voiding efficiency was lower at each time point after SCI than that of spinal intact mice. The number of non-voiding contractions (NVC) during bladder filling was gradually increased with time. In both 10- and 30-day SCI groups treated with anti-BDNF Ab, voiding efficiency was improved, and the duration of notch-like intravesical pressure reductions during voiding bladder contractions was prolonged. The number of NVC was significantly decreased only in 30-day SCI mice with 27-day anti-BDNF treatment. CONCLUSIONS: Overexpression of BDNF is associated with the deterioration of voiding efficiency after SCI. The early-started, long-term inhibition of BDNF improved voiding dysfunction and was also effective to reduce the later-phase development of detrusor overactivity after SCI.

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• Effects of a selective androgen receptor modulator (SARM), GSK2849466A, on stress urinary incontinence and bladder activity in rats with ovariectomy-induced oestrogen deficiency.

  Katsumi Kadekawa, Naoki Kawamorita, Takahiro Shimizu, Masahiro Kurobe, Philip S Turnbull, Sundeep Chandra, Takahito Kambara, Joanna C Barton, Alan J Russell, Naoki Yoshimura

  BJU international   125 ( 6 ) 911 - 919   2020.06 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  OBJECTIVES: To report the effect of a selective androgen receptor modulators (SARMs) on the urethral continence mechanisms in a rat model of stress urinary incontinence (SUI) induced by bilateral ovariectomy (OVX). MATERIALS AND METHODS: Female Sprague-Dawley rats with bilateral OVX were used. Rats were divided into five groups; sham operated, vehicle-treated OVX, low-dose SARM-treated OVX (GSK2849466A: 0.005 mg/kg/day, per os [p.o.]), high-dose SARM-treated OVX (GSK2849466A: 0.03 mg/kg/day, p.o.) and dihydrotestosterone (DHT)-treated OVX (1 mg/kg/day, subcutaneous) groups. After 4 weeks of SARM treatments or 3 weeks of DHT treatment (6 weeks after OVX), rats were subjected to evaluation of the sneeze-induced continence reflex using microtransducer-tipped catheter methods, sneeze-induced leak-point pressure, and continuous cystometry measurements, followed by histological analyses of urethral tissues. RESULTS: (i) OVX significantly impaired urethral continence function after 6 weeks to induce SUI during sneezing. (ii) Low-dose SARM treatment restored urethral baseline pressure (UBP) without affecting the amplitude of urethral response during sneezing (A-URS), partially reversing OVX-induced SUI during sneezing. (iii) High-dose SARM treatment reversed decreases in both UBP and A-URS, more effectively preventing SUI during sneezing. (iv) DHT treatment only restored A-URS without affecting UBP, partially preventing OVX-induced SUI during sneezing. (v) The high-dose SARM treatment induced hypertrophy of the striated and smooth muscle around the urethra. (vi) SARM treatment did not affect bladder function in sham or OVX rats. CONCLUSION: Treatment with SARMs could be a more effective modality for the treatment of SUI than DHT, without affecting bladder function, by enhancing smooth- and striated muscle-mediated urethral function under stress conditions such as sneezing.

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

  Nailong Cao, Eduardo C Alexandre, Daisuke Gotoh, Masahiro Kurobe, Shinsuke Mizoguchi, Baojun Gu, Naoki Yoshimura

  Life sciences   249   117537 - 117537   2020.05 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  AIMS: To 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 METHODS: Female 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 FINDINGS: UPP 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). SIGNIFICANCE: Low-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.

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• Urethral dysfunction in a rat model of chemically induced prostatic inflammation: potential involvement of the MRP5 pump.

  Eduardo C Alexandre, Nailong Cao, Shinsuke Mizoguchi, Tetsuichi Saito, Masahiro Kurobe, Daisuke Gotoh, Meri Okorie, Taro Igarashi, Edson Antunes, Naoki Yoshimura

  American journal of physiology. Renal physiology   318 ( 3 ) F754-F762   2020.03 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Prostate inflammation (PI) is a clinical condition associated with infection and/or inflammation of the prostate. It is a common disease frequently associated to lower urinary tract (LUT) symptoms. The urethra is an understudied structure in the LUT and plays a fundamental role in the urinary cycle. Here, we proposed to evaluate the effect of PI on the urethra tissue. Male Sprague-Dawley rats were used, and PI was induced by formalin injection into the ventral lobes of the prostate. The pelvic urethra at the prostatic level was harvested for histological analysis, contraction (electrical field stimulation and phenylephrine), and relaxation (sodium nitroprusside/MK-571) experiments. Various gene targets [cytochrome c oxidase subunit 2, transforming growth factor-β1, interleukin-1β, hypoxia-inducible factor-1α, α1A-adrenoceptor, inositol 1,4,5-trisphosphate receptor type 1, voltage-gated Ca2+ channel subunit-α1D, neuronal nitric oxide synthase, soluble guanylyl cyclase, phosphodiesterase 5A, protein kinase CGMP-dependent 1, and multidrug resistance-associated protein 5 (MRP5; ATP-binding cassette subfamily C member 5)] were quantified, and cGMP levels were measured. No histological changes were detected, and functional assays revealed decreased contraction and increased relaxation of urethras from the PI group. The addition of MK-571 to functional assays increased urethral relaxation. Genes associated with inflammation were upregulated in urethras from the PI group, such as cytochrome oxidase c subunit 2, transforming growth factor-β1, interleukin-1β, and hypoxia-inducible factor-1α. We also found increased expression of L-type Ca2+ channels and the neuronal nitric oxide synthase enzyme and decreased expression of the MRP5 pump. Finally, cGMP production was enhanced in urethral tissue of PI animals. The results indicate that PI is associated with proinflammatory gene expression in the urethra without histologically evident inflammation and that PI produces a dysfunctional urethra and MRP5 pump downregulation, which results in cGMP accumulation inside the cell. These findings would help to better understand LUT dysfunctions associated with PI and the role of MRP pumps in the control of LUT function.

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

  Ei-Ichiro Takaoka, Masahiro Kurobe, Takahisa Suzuki, Nobutaka Shimizu, Joonbeom Kwon, Hiroki Okada, Naoki Yoshimura, Christopher J Chermansky

  Neurourology and urodynamics   39 ( 3 ) 916 - 925   2020.03 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  AIMS: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

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