ELECTROACUPUNCTURE DECREASES C-FOS EXPRESSION IN THE SPINAL-CORD INDUCED BY NOXIOUS-STIMULATION OF THE RAT BLADDER

Purpose: The present study investigated the effects of noxious stimula tion of the lower urinary tract on neuronal fos protein expression in the spinal micturition center of rats and also examined the effects of electroacupuncture (EA) on fos expression induced by noxious stimulat ion of the lower urinary tract. Materials and. Methods: Experiments we re conducted on 21 female Sprague-Dawley rats divided into four groups . Group 1 rats (n = 5) served as normal controls. Group 2 rats (n 5) r eceived EA at the Sanyinjiao acupoint. Group 3 animals (n = 6) were ca theterized through the urethra and instilled with 1% acetic acid, and group 4 (n = 5) animals received EA 1 hour before 1% acetic acid insti llation. All animals underwent arterial perfusion, laminectomy, and sp inal cord removal. Spinal cords were sectioned and processed for immun ohistochemical staining for fos protein. Results: No fos protein was d etected in any spinal neurons in normal control animals, and either no ne or few (0 to 4 cells/section) fos-immunoreactive (fos-IR) cells wer e seen in animals treated with EA. Noxious stimulation of the lower ur inary tract with 1% acetic acid drastically increased the number of fo s-IR neurons (39 to 127 cells/L-6 section, mean 76.17 +/- 13.98; 28 to 77, cells/S-1 section, mean 59 +/- 8.30; 7 to 35 cells/S-2 section, m ean 19.83 +/- 4.10). However, EA administered I hour before 1% acetic acid instillation significantly decreased the number of fos-IR neurons resulting from chemical irritation (0 to 50 cells/L-6 section, mean 1 9.8 +/- 9.33; 0 to 47 cells/S-1 section, mean 13.2 +/- 9.12; 0 to 37 c ells/S-2 section, mean 13.6 +/- 7.31). Conclusions: Our study demonstr ates that bladder instillation with 1% acetic acid induces fos protein expression in the spinal micturition center of the rat and that elect roacupuncture can reduce this expression. These results suggest a link between electroacupuncture and reduction in spinal neuronal cell acti vity.