Effect of electroacupuncture on visceral hyperalgesia, serotonin and fos expression in an animal model of irritable bowel syndrome.
OBJECTIVE
While it is well established that acupuncture relieves somatic pain, its therapeutic effect on visceral pain such as irritable bowel syndrome (IBS) is unclear. We evaluated the effect of acupuncture in treating visceral hyperalgesia in an animal model.


METHODS
Sprague-Dawley rats (n = 8 per group) with prior neonatal maternal separation stress were randomly allocated to receive 3-day treatment of either electroacupuncture (EA) or sham acupuncture at acupoint ST-36. Another group of rats without prior maternal separation was included as non-handled controls. Colorectal distension was performed on the day after acupuncture treatment. The 3 groups were compared for pain threshold as determined by abdominal withdrawal reflex and visceromotor response as measured by electromyogram. Colon, spinal cord, and brainstem were sampled for topographic distribution and quantitative assessment of serotonin and Fos expression by immunohistochemistry.


RESULTS
Rats in EA group had significantly higher pain threshold compared to those in sham acpuncture group (25.0 +/- 5.7 mmHg vs 18.7 +/- 5.2 mmHg, p = 0.01) and it was comparable with that of non-handled treatment naïve controls (29.4 +/- 9.3 mmHg, p = 0.28). They also had lower visceromotor response as measured by electromyogram compared to those received sham acupuncture at all colorectal distension pressures. EA significantly suppressed Fos expression in doral raphe nuclei of brainstem, superficial dorsal horn of spinal cord and colonic epithelium but suppressed 5-HT expression only in brainstem and spinal cord.


CONCLUSIONS
Electro acupuncture attenuates visceral hyperlagesia through down-regulation of central serotonergic activities in the brain-gut axis.
Wu
Justin Cy
JC
Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong.
Ziea
Eric Tc
ET
Lao
Lixing
L
Lam
Emma Fc
EF
Chan
Catherine Sm
CS
Liang
Angela Yq
AY
Chu
Sunny Lh
SL
Yew
David Tw
DT
Berman
Brian M
BM
Sung
Joseph Jy
JJ