[Effects of electroacupuncture at "Futu"(LI 18), etc. on pain threshold and cervico-spinal mGlu receptor 5/cAmp/CREB signaling in rats with neck incision pain].Zhen Ci Yan Jiu. 2012 Jun; 37(3):191-6.ZC
To observe the effect of electroacupuncture (EA) at "Futu" (LI 18),etc. on the pain threshold and expression of metabotropic glutamate receptor subtype 5 (mGluR 5), cyclic adenosine monophosphate (cAMP), mitogen-activated protein kinase (MAPK), cAMP responsive element binding protein (CREB) genes in the cervico-spinal dorsal region in rats with neck incision pain so as to analyze its underlying analgesic mechanism in performing thyroid surgery.
Forty male Wistar rats were randomly divided into control, model, Futu (LI 18), Hegu (LI 4)-Neiguan (PC 6), Zusanli (ST 36)-Yanglingquan (GB 34) groups, with 8 cases in each group. Neck-incision pain model was established by making a longitudinal incision along the midline of the neck under anesthesia (isoflurane) except rats in the control group. EA(2 Hz/15 Hz, 1-2 mA) was applied to bilateral LI 18, LI 4-PC 6 and ST 36-GB 34 for 30 min, 4 h, 24 h and 48 h after modeling, respectively. The thermal pain threshold was detected before modeling, and before and after each treatment. After removing the ventral part, the spinal tissue of the cervical 1 -4 segments was collected for detecting the expression of mGluR 5, cAMP, MAPK, CREB genes by using quantitative real-time-PCR technique.
In comparison with the control group, the pain threshold of the model group was decreased obviously (P<0.05). Compared with the model group, the pain thresholds of the LI 18 and LI 4-PC 6 groups were upregulated markedly after treatment (P<0.05). No significant differences were found between the LI 18 and LI 4-PC 6 groups, and between the model and ST 36-GB 34 groups in pain thresholds (P>0.05). Compared with the control group, the expression le-vels of mGluR 5 mRNA, cAMP mRNA and CREB mRNA in the cervico-spinal cord were upregulated significantly in the model group (P<0.05). While in comparison with the model group, cervico-spinal cAMP mRNA, and CREB mRNA were down-regulated markedly (P<0.05) and mGluR 5 mRNA was down-regulated moderately (P>0.05) in the LI 18 group, rather than in the LI 4-PC 6 and ST 36-GB 34 groups (P>0.05).
EA-LI 18 can significantly suppress neck incision pain induced pain reaction, which may be closely associated with its functions in down-regulating expression levels of intracellular cAMP mRNA and CREB mRNA in the cervico-spinal cord.