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- Aronsson, Patrik, 1983, et al.
(författare)
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A novel in situ urinary bladder model for studying afferent and efferent mechanisms in the micturition reflex in the rat.
- 2014
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Ingår i: Neurourology and urodynamics. - : Wiley. - 1520-6777 .- 0733-2467. ; 33:5, s. 550-557
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: The search for new animal models to investigate both efferent and afferent levels of the micturition reflex, to better understand urinary dysfunctions, is of great importance. Therefore in this study we developed and characterized, by comparisons with a conventional whole bladder model, a novel in situ model. METHODS: The urinary bladder was carefully prepared and separated, via a midline incision, into two halves all the way to the urethra in pentobarbitone and medetomidine anesthetized male rats. The separated bladder halves (with no direct connection) were immobilized with ligatures to the underlying tissue. The tension could thereafter be recorded at one side, while the other half was occasionally stretched in order to evoke an afferent signal. Also, injections of ATP and methacholine and electric nerve stimulation were employed. RESULTS: Ipsilateral stretch of 30 and 50mN induced a force-dependent contractile response on the contralateral side. Moreover, electrical stimulation of efferent pelvic nerve fibers, and intravenous injections of methacholine and ATP, evoked dose-dependent contractions, resembling responses observed in the whole bladder model. Here, the threshold frequency at electrical stimulation of the efferent fibers was <2Hz and the maximum response appeared at 10-20Hz, while afferent stimulation had a threshold of 5-10Hz with the maximum response at 40Hz. CONCLUSIONS: In the current study we show that stimulation of afferents at one side of the bladder induces, via impulses from the central nervous system, contractions from the other side. This novel model enables quantitative comparisons of changes occurring within the micturition reflex arc in bladder disorders.
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| 2. |
- Aronsson, Patrik, 1983, et al.
(författare)
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Cyclophosphamide-induced alterations of the micturition reflex in a novel in situ urinary bladder model in the anesthetized rat
- 2015
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Ingår i: Neurourology and Urodynamics. - : Wiley. - 0733-2467. ; 34:4, s. 375-380
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Cyclophosphamide-induced cystitis alterations have been reported to occur both at efferent and afferent level in the micturition reflex arc. In particular, the stretching of the bladder wall causing urothelial release of ATP has been proposed as one of the pivotal mechanisms causing these alterations. To evaluate functional changes at efferent and afferent levels of the micturition reflex following cyclophosphamide treatment we have applied a novel in situ half bladder rat model. Methods: Male Sprague-Dawley rats were treated with either saline or cyclophosphamide (100mg/kg), and stretch-, electric-, methacholine-, and ATP-induced responses were thereafter measured at 60-72hr postinjection under pentobarbitone anesthesia. In the novel in situ half bladder model, the urinary bladder was prepared via a midline incision, where the two halves were separated all the way to the urethra as previously described. Results: Following bladder stretch of 30-80mN, of the half that was not used for tension measurement, the cyclophosphamide-treated animals evoked significant two- to threefold larger contractile responses as compared to saline-treated control animals. A sensitization of the afferent arm was shown in cyclophosphamide-treated animals, since afferent stimulation evoked similar responses as in control animals despite that the efferent pelvic nerve stimulation displayed a lower contraction-frequency relationship in cyclophosphamide-treated animals. Atropine reduced the stretch(reflex)-evoked contraction by up to 50% in control and 75-80% in cyclophosphamide-treated rats. Subsequent addition of PPADS further reduced the contractions. Conclusion: The micturition reflex response is increased following cyclophosphamide-induced cystitis, as compared to control. The likely cause is sensitization at mechanosensor level in the micturition arc, which overrides the decrement of the efferent cholinergic effects. © 2014 Wiley Periodicals, Inc.
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