The effects of sacral acupuncture on acetic acid-induced bladder irritation in conscious rats

To 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.

A 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.

In 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.

Sacral acupuncture could contribute to improve acetic acid-induced bladder irritation through inhibition of capsaicin-sensitive C-fiber activation.