SPECIFICITY OF MANUAL ACUPUNCTURE NEEDLING ON PAIN CONTROL:WHAT IS THE DIFFERENCE BETWEEN BL60, SP6 AND A NON-ACUPOINT?

Background: In the past three decades researchers have focused on studying the analgesia induced by various forms of electroacupuncture stimuli.However, physiological mechanisms of manual acupuncture remain unexplored.In this study, the mouse model of acetic acid-induced writhing was used to investigate the possible specificity of manual acupuncture needling in modulating different endogenous pain control systems.Methods: Swiss mice were treated with manual acupuncture before administration of intraperitoneal injection of acetic acid.Acupuncture needling was performed unilaterally in one acupoint of the mice lower limb(BL60-sural nerve or SP6-tibial nerve or non-acupoint-inferior gluteal nerve).To study the possible endogenous pain control systems involved in the antinociceptive effect induced by acupoint stimulation, animals were pre-treated with antagonists of opioid, serotonergic, adrenergic and dopaminergic systems.Results: We found that the non-acupoint point did not reduce the number of writhes of the mice compared to the control group(not treated).In other hand, acupuncture needling of BL60 and SP6 reduced the number of writhes in 70%±7% and 59%±7%, respectively.Antinociception induced by BL60 needling was abolished by pre-treating the animals with naloxone(nonselective opioid antagonist) and WAY100635(5HT1A serotonergic antagonist), but was not altered by ketanserin(5HT2A serotonergic antagonist), ondansetron(5HT3 serotonergic antagonist), yohimbine(α2-adrenergic antagonist) and sulpiride(D2-dopaminergic antagonist).Antinociception induced by SP6 needling was abolished by pre-treating the animals with sulpiride but was not altered by naloxone, yoimbine, WAY100635, ketanserin and ondansetron.Conclusion: These results indicate that the stimulus to acupoints analogous to BL60 and SP6 at the lower limb can reduce the pain-associated behavior in mice, while the non-acupoint point cannot.Moreover, our findings suggest that there is point specificity not only in reducing the pain behavior, but there isspecificity also in the endogenous pain control system modulated by each acupoint.