Effect of Electroacupuncture on Visceral Hyperalgesia, Serotonin and Fos Expression in an Animal Model of Irritable Bowel Syndrome

Abstract

Background/AimsWhile 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.MethodsSprague-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.ResultsRats 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.ConclusionsElectro acupuncture attenuates visceral hyperlagesia through down-regulation of central serotonergic activities in the brain-gut axis.

Serotonin enhances urinary bladder nociceptive processing via a 5-HT3 receptor mechanism

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Chronic electroacupuncture of the ST36 point improves baroreflex function and haemodynamic parameters in heart failure rats

“…For the EA protocol, acupuncture needles made of stainless steel, size 0.5 mm (Complementar Agulhas, Brazil), were inserted bilaterally in the stomach point 36, ST36 (ZuSanLi), which is located in the anterolateral portion of the hind limb, near the anterior tibial tuberosity, in the tibialis anterior muscle and is innervated by the deep fibular nerve (Tjen et al, 2004;Li et al, 2009). The needling was performed at a depth of 5 mm and confirmed by a slight muscle contraction (Wu et al, 2010) or by slight and repeated movement of the paw (Zhou et al, 2005). The NKL electro-stimulator (Model EL608) with eight channels was used.…”

Irritable bowel syndrome: The evolution of multi-dimensional looking and multidisciplinary treatments

“…Basically, it exhibits the physiological impacts on neural, humoral, opioid and serotonegic pathways with the effects of normalized motility, inhibited acid output, antinociceptive effect, reduced rectal hypersensitivity and altered 5-HT functions [170][171][172] . Acupuncture looks promising to treat FGIDs including IBS.…”