The Effects of Sacral Acupuncture on Acetic Acid-induced Bladder Irritation in Conscious Rats

ObjectivesTo investigate the effects of sacral acupuncture on acetic acid–induced bladder irritation using cystometry in conscious rats, with particular focus on effects on afferent fibers of the bladder.MethodsA total of 40 female Sprague-Dawley rats weighing 200-270 g were used. The animals were divided into 5 groups: (1) rats with bladder overactivity induced by acetic acid, without sacral acupuncture stimulation (irritated bladder group); (2) rats treated with sacral acupuncture stimulation after induction of bladder overactivity by acetic acid (acupuncture stimulation group); (3) rats treated with sacral acupuncture stimulation after capsaicin desensitization (capsaicin-desensitized group); (4) rats treated with atropine (atropine injection group); and (5) rats treated with sacral acupuncture stimulation after nonacetic acid infusion (nonirritated bladder group). Cystometry was carried out without anesthesia, and the following variables were measured in all animals: intercontraction interval (ICI), basal pressure, threshold pressure, and micturition pressure.ResultsIn the acupuncture stimulation group, sacral acupuncture stimulation resulted in a 140.1 ± 5.9% increase in ICI after acetic acid–induced irritation to an interval similar to baseline (P = .072). A significant difference in the percent of ICI increase was observed between the acupuncture stimulation and irritated bladder groups (P < .01). In the capsaicin-desensitized groups and acupuncture stimulation groups, no significant differences in ICI occurred, before and after acupuncture.ConclusionsSacral acupuncture could contribute to improve acetic acid–induced bladder irritation through inhibition of capsaicin-sensitive C-fiber activation.