Ice Water Testing Reveals Hypersensitivity In Adult Rats That Experienced Neonatal Bladder Inflammation
October 19, 2017
UroToday - Animal Models Show Long-Term Effects of Neonatal Inflammation, implications for painful bladder syndrome/interstitial cystitis
The majority of female patients with BPS report pain during urodynamics when ice-cold saline in instilled after the routine testing. This is not the case with patients with detrusor overactivity or normal controls.(1) Dr. Alan Randich and co-workers from Birmingham, Alabama sought to look at an animal model with female rat pups to determine whether rats that underwent neonatal bladder inflammation would show enhanced electromyogram (EMG) responses during ice water testing as adults. Intravesical zymosan was used to cause bladder inflammation in the neonates. The researchers found that neonatal bladder inflammation produced bladder hypersensitivity to the infusion of ice-cold saline, but did not produce uninhibited detrusor contractions.
This is believed to be the first demonstration of an increase in cold sensitivity produced by neonatal bladder manipulation in a preclinical model. Similar hypersensitivity has been shown in BPS patients, while ice water testing in patients with overactive bladder by history provoked uninhibited detrusor contractions. Thus, the authors believe their model may be useful as a translational model of BPS. None of the rats had an identifiable bladder cooling reflex, but those that had undergone bladder inflammation as neonates demonstrated nociceptive reflex responses to ice water testing in the bladder.
This group has previously observed that neonatal exposure to bladder inflammation increases micturition frequency in adult rats, decreases the micturition reflex threshold and enhances EMG responses to graded bladder distention. The bladder cold hypersensitivity noted in the current study did not require adult re-exposure to bladder inflammation. They conclude that it is possible neonatal inflammation treatments altered TRPA1 expressing neurons or other cold temperature sensing channels that remain to be identified.
Randich A, Mebane H, Ness TJ
Reference:
1. Mukerji G, Waters J, Chessell IP, Bountra C, Agarwal SK, Anand P. Pain during ice water test distinguishes clinical bladder hypersensitivity from overactivity disorders. BMC Urol. 2006 Dec 27;6:31.
J Urol. 2009 Jul;182(1):337-42
10.1016/j.juro.2009.02.107
UroToday Contributing Editor Philip M. Hanno, MD, MPH
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