Long-term functional change of cryoinjury-induced detrusor underactivity and effects of extracorporeal shock wave therapy in a rat model
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To investigate the long-term functional change of cryoinjury-induced detrusor underactivity (DU) and the therapeutic potential of repeated low-energy shock wave therapy (LESW).
Fifty-six female Sprague–Dawley rats were assigned into sham and cryoinjury of bladder with or without LESW (0.05 or 0.12 mJ/mm2; 200 pulses; twice a week for 2 weeks after cryoinjury). Under halothane anesthesia, an incision was made in lower abdomen, and cryoinjury was provoked by bilateral placement of a chilled aluminum rod on the bladder filled with 1 ml saline. Measurement of contractile responses to KCl and carbachol in vitro, conscious voiding, and histological and protein changes were performed on week 1, 2, and 4 after cryoinjury.
Cryoinjury of bladder induced a significant decrease in the detrusor contraction amplitude at week 1 (55.0%) and week 2 (57.2%), but the decrease in the contractile response to KCl and carbachol was only noted at week 1. At week 1, significantly increased COX-2 and TGF-β1 expression accompanied a decrease of VEGF and CGRP expression. At week 4, there was a partial recovery of voiding function and a significant increase in the Ki-67 staining. LESW treatment at higher energy level further amplified the Ki-67 staining and improved the recovery of contraction amplitude and the expression of TGF-β1 and VEGF.
Cryoinjury of detrusor induces DU/UAB with functional impairment lasting for up to 4 weeks, but the associated molecular changes are restored by 2 weeks. LESW improved bladder wall composition, and hastened functional recovery from cryoinjury.
KeywordsDetrusor underactivity Shock wave Cryoinjury
We appreciate the Biostatistics Center, Kaohsiung Chang Gung Memorial Hospital for statistics work.
The study was supported by Kaohsiung Chang Gung Memorial Hospital CRRPG8F0472 and Ministry of Science and Technology, Taiwan, under Grant Nos. 104-2314-B-182A-064-MY3 and 106-2314-B-182A-122-MY3.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Experimental protocols were approved by the Institutional Animal Care and Use Committee of the Kaohsiung Chang Gung Memorial Hospital. The work was performed at Kaohsiung Chang Gung Memorial Hospital.
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