Molecular mechanisms underlying the effects of acupuncture on neuropathic pain

Protective Mechanism of Electroacupuncture on Peripheral Neurotoxicity Induced by Oxaliplatin in Rats

OBJECTIVE

To study the effect of electroacupuncture (EA) on oxaliplatin-induced peripheral neuropathy (OIPN) in rats.

METHODS

Male Sprague-Dawley rats were equally divided into 3 groups using a random number table: the control group, the OIPN group, and the EA (OIPN + EA) group, with 10 rats in each. The time courses of mechanical, cold sensitivity, and microcirculation blood flow intensity were determined. The morphology of the dorsal root ganglion (DRG) was observed by electron microscopic examination. The protein levels of nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and the transient receptor potential (TRP) protein family in DRGs were assayed by Western blot.

RESULTS

EA treatment significantly reduced mechanical allodynia and cold allodynia in OIPN rats (P<0.01). Notably, oxaliplatin treatment resulted in impaired microcirculatory blood flow and pathomorphological defects in DRGs (P<0.01). EA treatment increased the microcirculation blood flow and attenuated the pathological changes induced by oxaliplatin (P<0.01). In addition, the expression levels of Nrf2 and HO-1 were down-regulated, and the TRP protein family was over-expressed in the DRGs of OIPN rats (P<0.01). EA increased the expression levels of Nrf2 and HO-1 and decreased the level of TRP protein family in DRG (P<0.05 or P<0.01).

CONCLUSION

EA may be a potential alternative therapy for OIPN, and its mechanism may be mainly mediated by restoring the Nrf2/HO-1 signaling pathway.

Remodeling Effects of the Combination of GGT Scaffolds, Percutaneous Electrical Stimulation, and Acupuncture on Large Bone Defects in Rats

The regeneration defect of bone is a long-term physiological process after bone injuries. To accelerate the bone remodeling process, the combination of chemical and physical stimulations provides an efficient strategy to allow maturation and to functionalize osteoclasts and osteoblasts. This study aims to investigate the dual effects of a tricalcium phosphate (TCP)-based gelatin scaffold (GGT) in combination with electroacupuncture stimulation on the activation of osteoclasts and osteoblasts, as well as new bone regrowth in vitro and in vivo. We demonstrated that electrical stimulation changes the pH of a culture medium and activates osteoblasts and osteoclasts in an in vitro co-culture system. Furthermore, we showed that electroacupuncture stimulation can enhance osteogenesis and new bone regrowth in vivo and can upregulate the mechanism among parathyroid hormone intact (PTH-i), calcium, osteoclasts, and osteoblasts in the bone-defected rats. Those results showed the potential interest to combine the electroacupuncture technique with GGT scaffolds to improve bone remodeling after injury.

Acupuncture Therapies for Addressing Post Odontectomy Neuropathy

Background: Third-molar extraction is a common oral surgical procedure that can cause complications. Although rare, nerve injuries that result in permanent neuropathy can occur and include a variety of complaints such as sensory disorders, taste-sensation disorders, speech articulation disorders, etc. Acupuncture is one of several nonpharmacologic therapies that has played a role in managing neuropathic lesions and has been proven to produce good results. Case: A 44-year-old woman with postodontectomy neuropathy developed paresthesia, dysarthria, xerostomia, dysgeusia, pain in the gums and lower right jaw, a chewing disorder, and cephalgia. Her numerical rating scale (NRS) results were: lower right gum pain, 3/10; numbness of the tongue, 4/10; and headache, 1/10. A physical examination revealed dysarthria, a decreased sense of sharpness and dullness in the right mandibular nerve branches, decreased right masseter muscle contractions, and tenderness on the right GB 20 point. Electromyography revealed partial functional lesions in the postganglion at the right fifth cranial nerve. She had body acupuncture therapy at GV 20, GB 20, ST 5, ST 6, ST 7, CV 23, LI 4, HT 5, ST 36, LU 7, and KI 6; ear acupuncture at the Parotid and Shenmen points; and treatment with the Tan Balance Method. Results: After 3 consecutive sessions of acupuncture therapy, this patient's symptoms were reduced. Conclusions: Acupuncture was helpful for reducing paresthesia, dysarthria, xerostomia, dysgeusia, gum and lower right jaw pain, a chewing disorder, and cephalgia in this patient with postodontectomy neuropathy. Clinical trials are needed to support the findings in this case.

Electroacupuncture Attenuates Neuropathic Pain and Comorbid Negative Behavior: The Involvement of the Dopamine System in the Amygdala

Neuropathic pain (NeuP) is an important clinical problem accompanying negative mood symptoms. Neuroinflammation in the amygdala is critically involved in NeuP, and the dopamine (DA) system acts as an important endogenous anti-inflammatory pathway. Electroacupuncture (EA) can improve the clinical outcomes in NeuP, but the underlying mechanisms have not been fully elucidated. This study was designed to assess the effectiveness of EA on pain and pain-related depressive-like and anxiety-like behaviors and explore the role of the DA system in the effects of EA. Male Sprague-Dawley rats were subjected to the chronic constrictive injury (CCI) model to induce NeuP. EA treatment was carried out for 30 min once every other day for 3 weeks. The results showed that CCI caused mechanical hyperalgesia and depressive and anxiety-like behaviors in rats and neuroinflammation in the amygdala, such as an increased protein level of TNFα and IL-1β and activation of astrocytes. EA treatment significantly improved mechanical allodynia and the emotional dysfunction induced by CCI. The effects of EA were accompanied by markedly decreased expression of TNFα, IL-1β, and glial fibrillary acid protein (GFAP) in the amygdala. Moreover, EA treatment reversed CCI-induced down-regulation of DA concentration, tyrosine hydroxylase (TH) expression, and DRD1 and DRD2 receptors. These results suggest that EA-ameliorated NeuP may possibly be associated with the DA system to inhibit the neuroinflammation in the amygdala.

Cellular Reorganization Plays a Vital Role in Acupuncture Analgesia

Background: Acupuncture has a long history of relieving many forms of pain. However, many of acupuncture's mechanisms are still unknown and/or misunderstood. Objective: This review looks at past research on many different methods and targets of study related to acupuncture. The main focus is upon the importance of connective-tissue planes in and around acupuncture points. Method: Relevant articles from journals as well as books on the topic were searched manually for information related to the topic. Results: Various studies offered different (and sometimes interrelated) mechanisms for how acupuncture needling results in analgesia among other effects. Emerging evidence, however, has shown the increasing importance of extracellular matrix rearrangements that result in lower mechanical stress states of surrounding tissues. This leads to lower constant stimulation of regional mechanoreceptors, in turn, reducing chronic pain and discomfort. Conclusions: The extracellular matrix has emerged as an important area of study on the effects of acupuncture needling.

Electroacupuncture Treatment Improves Learning-Memory Ability and Brain Glucose Metabolism in a Mouse Model of Alzheimer's Disease: Using Morris Water Maze and Micro-PET

Introduction. Alzheimer's disease (AD) causes progressive hippocampus dysfunctions leading to the impairment of learning and memory ability and low level of uptake rate of glucose in hippocampus. What is more, there is no effective treatment for AD. In this study, we evaluated the beneficial and protective effects of electroacupuncture in senescence-accelerated mouse prone 8 (SAMP8). Method. In the electroacupuncture paradigm, electroacupuncture treatment was performed once a day for 15 days on 7.5-month-old SAMP8 male mice. In the normal control paradigm and AD control group, 7.5-month-old SAMR1 male mice and SAMP8 male mice were grabbed and bandaged while electroacupuncture group therapy, in order to ensure the same treatment conditions, once a day, 15 days. Results. From the Morris water maze (MWM) test, we found that the treatment of electroacupuncture can improve the spatial learning and memory ability of SAMP8 mouse, and from the micro-PET test, we proved that after the electroacupuncture treatment the level of uptake rate of glucose in hippocampus was higher than normal control group. Conclusion. These results suggest that the treatment of electroacupuncture may provide a viable treatment option for AD.