[Mechanisms of liver-soothing and mind-regulating acupuncture mediating opioid receptor participated in the treatment of migraine].

OBJECTIVE

To observe the effect of "Shugan Tiaoshen"(liver-soothing and mind-regulating) acupuncture on behavior reactions, opioid receptor expressions in the anterior cingulate cortex tissue and inflammatory factors in the serum in migraine rats, in order to explore its mechanism underlying improvement of migraine.

METHODS

In the first part of this study, forty male Wistar rats were randomized into control, model, routine acupuncture and "Shugan Tiaoshen" acupuncture groups (=10/group), and in the second part, other 40 more male Wistar rats were randomized into low, medium and high dosage of blocker of μopioid receptor (OPRM）CTOP5 and PBS groups (=10/group, for validating the involvement of opioid receptor in the effect of "Shugan Tiaoshen"). The migraine model was established by subcutaneous injection of glyceryl trinitrate. Routine acupuncture was applied to "Baihui" (GV20) and bilateral"Fengchi" (GB20), and "Shugan Tiaoshen" acupuncture applied to GV20, and bila-teral GB20, "Neiguan" (PC6) and "Taichong" (LR3), with the needles retained for 30 min. Behavior responses (head scratching, tail biting, cage climbing and number of going there and back) were scaled. Serum IL-1β, IL-6 and TNF-α were detected by ELISA, and the expression levels of opioid receptor μ, δ and κ (OPRM, OPRD, OPRK) mRNAs and proteins in the anterior cingulate cortex were detected by fluorescence quantitative PCR and Western blot separately. In the second part of this study, CTOP solution (5μL at concentrations of 20μg/μL,10μg/μL and 5μg/μL) or PBS was injected into the bilateral rostral portions of anterior cingulate cortex 30 min before every "Shugan Tiaoshen" acupuncture intervention, followed by observing the behavioral changes and assaying the contents of serum IL-1β, IL-6 and TNF-α.

RESULTS

After modeling, the behavioral score, serum IL-1β, IL-6 and TNF-α contents were significantly increased in the model group relevant to the control group (<0.05), and the beha-vioral score had no significant difference among the model and two acupuncture groups before intervention (>0.05). Whereas the expression levels of OPRM, OPRD and OPRK mRNAs and proteins had a slight increase in the model group (>0.05). After the intervention, the behavioral score, serum IL-1β, IL-6 and TNF-α contents were significantly decreased and the expression levels of OPRM, OPRD and OPRK mRNAs (2.150, 1.066 and 0.805 folds in the "Shugan Tiaoshen" group) and proteins (2.273, 0.901 and 0.893 folds in the "Shugan Tiaoshen" group) notably up-regulated in both "Shugan Tiaoshen" and routine acupuncture groups relevant to the model group (<0.01, <0.05), showing that the biggest up-regulation of mRNA expression was OPRM. Comparison between two acupuncture groups showed that the behavioral score, and serum IL-1β, IL-6 and TNF-α contents were significantly lower, and the expression levels of OPRM, OPRD and OPRK mRNAs and proteins obviously higher in the "Shugan Tiaoshen" group than those in the routine acupuncture group (<0.01,<0.05). Results of the second part of this study showed that after injection of antagonist CTOP of OPRM, the therapeutic effect of "Shugan Tiaoshen" acupuncture was weakened in the reduction of behavioral score and serum IL-1β, IL-6 and TNF-α contents, being minimal, moderate and maximum in the high, medium and low dose of antagonist relevant to PBS in sequence (<0.05, <0.01).

CONCLUSION

"Shugan Tiaoshen" acupuncture can mitigate pain in migraine rats, which may be associated with its function in up-regulating the expressions of opioid receptors (especially OPRM), and in inhibiting inflammatory reaction in the anterior cingulate cortex.