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- Aizawa, Naoki, et al.
(author)
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Inhibition of Peripheral FAAH Depresses Activities of Bladder Mechanosensitive Nerve Fibers of the Rat
- 2014
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In: Journal of Urology. - : Elsevier. - 0022-5347 .- 1527-3792. ; 192:3, s. 956-963
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Journal article (peer-reviewed)abstract
- Purpose: FAAH degrades endocannabinoids and fatty acid amides. FAAH inhibition reduces micturition frequency and counteracts bladder overactivity in rats. We studied the effects of the peripherally active selective FAAH inhibitor URB937, and the CB1 and CB2 receptor antagonists rimonabant and SR144528, respectively, on single unit afferent activity of primary bladder afferents in rats. Materials and Methods: Female Sprague Dawley (R) rats were anesthetized. Single unit afferent activity of A delta or C-fibers from the L6 dorsal roots was recorded during bladder filling before and after URB937 administration with or without rimonabant or SR144528. Drugs (1 mg/kg) were given intravenously. FAAH, CB1 and CB2 expression, and expression of the sensory marker CGRP in the L6 dorsal root ganglion were compared by immunofluorescence. Results: A total of 102 single afferent fibers (48 A delta and 54 C-fibers) were isolated from 57 rats. URB937 decreased single unit afferent activity of C-fibers to a mean +/- SEM of 78% +/- 9% and of A delta-fibers to a mean of 67% +/- 7% while increasing bladder compliance to a mean of 116% +/- 3%. The effects of URB937 on single unit afferent activity and bladder compliance were counteracted by rimonabant or SR144528. Rimonabant increased single unit afferent activity of each fiber type but SR144528 affected only A delta-fiber activity. CGRP positive L6 dorsal root ganglion neurons showed strong FAAH, CB1 and CB2 staining. Conclusions: To our knowledge we report for the first time that inhibiting peripheral FAAH depresses the Ad and C-fiber activity of primary bladder afferents via CB1 and CB2 receptors. CB antagonists alone exerted facilitatory effects on single unit afferent activity during bladder filling in rats. The endocannabinoid system may be involved in physiological control of micturition as regulators of afferent signals.
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| 3. |
- Aizawa, Naoki, et al.
(author)
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URB937, a peripherally restricted inhibitor for fatty acid amide hydrolase, reduces prostaglandin E-2-induced bladder overactivity and hyperactivity of bladder mechano-afferent nerve fibres in rats
- 2016
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In: BJU International. - : WILEY-BLACKWELL. - 1464-4096 .- 1464-410X. ; 117:5, s. 821-828
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Journal article (peer-reviewed)abstract
- Objective To determine if inhibition of the endocannabinoid-degrading enzyme fatty acid amide hydrolase (FAAH) can counteract the changes in urodynamic variables and bladder afferent activities induced by intravesical prostaglandin E-2 (PGE(2)) instillation in rats. Materials and methods In female Sprague-Dawley rats we studied the effects of URB937, a peripherally restricted FAAH inhibitor, on single-unit afferent activity (SAA) during PGE(2)-induced bladder overactivity (BO). SAA measurements were made in urethane-anaesthetised rats and Ad-and C-fibres were identified by electrical stimulation of the pelvic nerve and by bladder distention. Cystometry (CMG) in conscious animals and during SAA measurements was performed during intravesical instillation of PGE(2) (50 or 100 mu M) after intravenous administration of URB937 (0.1 and 1 mg/kg) or vehicle. In separate experiments, the comparative expressions of FAAH and cannabinoid receptors, CB1 and CB2, in microsurgically removed L6 dorsal root ganglion (DRG) were studied by immunofluorescence. Results During CMG, 1 mg/kg URB937, but not vehicle or 0.1 mg/kg URB937, counteracted the PGE(2)-induced changes in urodynamic variables. PGE(2) increased the SAAs of C-fibres, but not Ad-fibres. URB937 (1 mg/kg) depressed Ad-fibre SAA and abolished the facilitated C-fibre SAA induced by PGE(2). The DRG nerve cells showed strong staining for FAAH, CB1 and CB2, with a mean (SEM) of 77 (2)% and 87 (3)% of FAAH-positive nerve cell bodies co-expressing CB1 or CB2 immunofluorescence, respectively. Conclusion The present results show that URB937, a peripherally restricted FAAH inhibitor, reduces BO and C-fibre hyperactivity in the rat bladder provoked by PGE(2), suggesting an important role of the peripheral endocannabinoid system in BO and hypersensitivity.
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