TITLE:
Electroacupuncture Attenuates Visceral Pain and Reverses Upregulation of TRPV1 Expression in Adult Rats with Neonatal Maternal Deprivation
AUTHORS:
Hongyan Zhu, Shufen Hu, Xiuhua Miao, Ying Xiao, Guangyin Xu
KEYWORDS:
Electroacupuncture, Irritable Bowel Syndrome, Chronic Visceral Pain, Dorsal Root Ganglion, TRPV1
JOURNAL NAME:
Chinese Medicine,
Vol.7 No.1,
March
9,
2016
ABSTRACT: Irritable bowel syndrome (IBS) is characterized by chronic visceral hypersensitivity that companied by altered bowel movement. However, the treatment options are very limited. The aim of this study was to investigate effects of electroacupuncture (EA) on visceral hypersensitivity in a rat model of IBS and to explore the underlying mechanisms of EA effects. Visceral hypersensitivity was established by neonatal maternal deprivation (NMD) in male rats on postnatal days 2 - 15. Behavioral experiments were conducted at the age of 7 weeks. Treatment with EA at Zusanli (stomach-36, ST-36) significantly reduced abdominal withdrawal reflex (AWR) scores in NMD rats but not in age-matched healthy control rats. In addition, EA treatment hyperpolarized resting membrane potentials, increased the rheobase and reduced the numbers of action potentials evoked by 2 and 3 times rheobase current stimulation of dorsal root ganglion (DRG) neurons innervating the colon. NMD markedly enhanced expression of TRPV1 in colon related DRGs while EA treatment drastically suppressed the expression of TRPV1 in DRGs of NMD rats. These data suggest that EA treatment produced an analgesic effect, which might be mediated at least in a part by suppression of TRPV1 expression and by inhibition of neuronal excitability of primary sensory neurons in rats with chronic visceral pain.