Western Mechanism of Action for Acupuncture

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Although acupuncture is just one component of traditional Chinese medicine, its precise effects on the human body remains an area on ongoing investigation. From a Western perspective acupuncture induces effects on neuropeptides, local circulation, inflammation, and the Central Nervous System (CNS).

NEUROTRANSMITTERS

Multiple neurotransmitters have been implicated in acupuncture’s mechanism of action from a Western perspective. The main neurotransmitters mechanisms for acupuncture include an increase in endogenous opioids and a decrease in substance P.

Endogenous Opioids

An increase in endogenous opioids in plasma or cerebrospinal fluid has been observedin humans who receive electro acupuncture [2]. Analgesic relief involves the activation of endogenous opioid systems and mu-opioid receptors (MOR) has also been shown in animal models[1,3,4]. Furthermore, part of the response to electro acupuncture is antagonized by the opioid receptor antagonist naloxone [5]. Han further deciphered that low-frequency (2 Hz) electro acupuncture induces the activation of mu- and delta- opioid receptors via the release of enkephalin, beta- endorphin, and endomorph in in supraspinal CNS regions, whereas the effects of high-frequency (100 Hz) electro acupuncture involve the actions of dynorphin on kappa opioid receptors in the spinal cord [6]. Studies performed by Harris et al, have shown that acupuncture therapy evoked not only short-term increases in MOR binding potential, but also long-term increases in multiple pain and sensory processing regions of the brain. These effects on MOR binding potentials were absent in the sham acupuncture group [9].

Substance P

Substance P (SP) exists in primary afferents that respond to painful stimuli and appears totransmit pain information into the central nervous system [7,8]. Immuno fluorescence studies of SP in the spinal cord, and dorsal root ganglion tissues in rats also suggest a possible involvement of the primary SP-positive sensory neurons in the transmission ofacupuncture stimulation signals [10].

Direct CNS Effects

Increases in both regional cerebral blood flow and glucose metabolism in the central nervoussystem have occurred following both manual acupuncture and electro acupuncture [11,12]. Studies performed within the last decade have shown that acupuncture induces different effects on the human brain as displayed through the use of a Functional Magnetic Resonance Imaging machine (FMRI) [13,14]. Acupuncture while utilizing FMRI, Single-Photon Emission ComputedTomography (SPECT), and Positron Emission Tomography (PET) showed acupuncture alteredbrain activity, increased cerebral blood flow, and increased glucose metabolism [15].

Increase in Local Blood Flow

Acupuncture has been shown to increase the nitric oxide levels in treated regions, resulting in increased local blood circulation [16-29]. In a RCT acupuncture increased nitric oxideactivity along meridians and the change in circulation was associated with reduced pain [17].The vasodilatory effects were not seen in noninvasive sham-acupuncture treatments [17].In another study, acupuncture stimulation was used on patients and showed increase in local blood flux through the use of laser Doppler flow before, during and after the acupuncture stimulation [20]. Indocyanine green perfusion imagining has also confirmed the vasoactive effect of acupuncture [21].

Anti-inflammatory Mechanism of Action

Acupuncture can reduce swelling and local inflammation [22,23]. In animal studies, electro acupuncture has been shown to reduce chronic inflammatory pain and is hypothesized to be related to up regulation of MrgprC gene expression which can modulate neurogenic inflammation [22]. Clinical evidence suggests that acupuncture improves allergic inflammation and symptoms of allergic rhinitis [24].

References

  1. Harris RE, Zubieta J-K, Scott DJ, Napadow V, Gracely RH, et al. Traditional Chinese Acupuncture and Placebo (Sham) Acupuncture Are Differentiated by Their Effects on μ-Opioid Receptors (MORs). NeuroImage. 2009; 47: 1077-1085.
  2. Sjolund B, Terenius L, Ericsson M. Increased cerebrospinal uid levels of endorphins after electro-acupuncture. ActaPhysiol Scand. 1977; 100: 382-384.
  3. 12. Jiang Y, He X, Yin X, Shen Y, Fang J. Anti-in ammatory and synovial-opioid system effects of electroacupuncture intervention on chronic pain in arthritic rats. Zhongguo Zhen Jiu. 201; 35: 917-921.</li
  4. Hsieh YL, Hong CZ, Liu SY, Chou LW, Yang CC. Acupuncture at distant myofascial trigger spots enhances endogenous opioids inrabbits: a possible mechanism for managing myofascial pain. Acupunct Med. 2016; 34: 302-309.
  5. Pomeranz B, Chiu D. Naloxone blockade of acupuncture analgesia: endorphin implicated. Life Sci. 1976; 19: 1757-1762.
  6. Han JS. Acupuncture: neuropeptide release produced by electrical stimulation of different frequencies. Trends Neurosci. 2003;26: 17-22.
  7. De Felipe C, Herrero JF, O’Brien JA, Palmer JA, Doyle CA, et al. Altered nociception, analgesia and aggression in mice lacking thereceptor for substance P. Nature. 1998; 392: 394-397.
  8. Donkin JJ, Turner RJ, Hassan I, Vink R. Substance P in traumatic brain injury. Prog Brain Res. 2007; 161: 97-109.
  9. National Center for Complementary and Integrative Health. Acupuncture. 2016.
  10. Zhang K, Xu DS, Cui JJ, Zhang ZY, Jing XH, et al. [The Expression of Substance P in Sensory Neurons and Nerve Fibers Associated with “Sanyinjiao” (SP 6) Region in the Rat]. Zhen Ci Yan Jiu. 2015; 40: 449-454.
  11. An YS, Moon SK, Min IK, Kim DY. Changes in regional cerebral blood ow and glucose metabolism following electro acupuncture at LI 4 and LI 11 in normal volunteers. J Altern Complement Med. 2009; 15: 1075-1081.
  12. Quirico PE, Allais G, Ferrando M, de Lorenzo C, Burzio C, et al. Effects of the acupoints PC 6 Neiguan and LR 3 Taichong on cerebral blood ow in normal subjects and in migraine patients. Neurol Sci. 2014; 35: 129-133.
  13. Ke Li, Baoci Shan, Jianyang Xu, Hua Liu, Wei Wang, et al. Changes in fMRI in the Human Brain Related to Different Durations ofManual Acupuncture Needling. The Journal of Alternative and Complementary Medicine. 2006; 12: 615-623.
  14. Liu H, Xu JY, Li L, Shan BC, Nie BB, et al. FMRI evidence of acupoints speci city in two adjacent acupoints. Evid BasedComplement Alternat Med. 2013.
  15. 26. Young-Sil An, Sang-Kwan Moon, In-Kyu Min, Deog-Yoon Kim. Changes in regional cerebral blood ow and glucose metabolismfollowing electroacupuncture at LI 4 and LI 11 in normal volunteers. The Journal of Alternative and Complementary Medicine. 2009;15: 1075-1081.
  16. Kusayanagi H, Ishikawa S, Tajika Y, Moue T, Sunagawa M, et al. In uence of Electroacupuncture Stimulation on Nitric Monoxide Production in Vascular Endothelial Cells in Rats. In Vivo. 2015; 29: 679-685.
  17. Tsuchiya M, Sato EF, Inoue M, Asada A. Acupuncture enhances generation of nitric oxide and increases local circulation. AnesthAnalg. 2007; 104: 301-307.
  18. Skorupska E, Rychlik M, Samborski W. Intensive vasodilatation in the sciatic pain area after dry needling. BMC Complement Altern Med. 2015; 15: 72.
  19. Wang SY, Zhang D, Tang LM, Li SY, Wen M, et al. Effects of Electroacupuncture Stimulation at “Zusanli” Acupoint on Hepatic NO Release and Blood Perfusion in Mice. Evid Based Complement Alternat Med. 2015.
  20. Blom M, Lundeberg T, Dawidson I, Angmar-Månsson B. Effects on local blood ux of acupuncture stimulation used to treat xerostomia in patients suffering from Sjögren’s Syndrome. J Oral Rehabil. 1993; 20: 541-548.
  21. An Y, Jeon JW, Kwon K, Choi C. Application of dynamic indocyanine green perfusion imaging for evaluation of vasoactive effect ofacupuncture: a preliminary follow-up study on normal healthy volunteers. Med Devices. 2014; 7: 17-21.
  22. Liu YJ, Fang F, Fang JQ, Zhang JR, Chi XL, et al. Analgesic Effect and Mechanism of Electroacupuncture on Rats with Chronic In ammatory Pain. Zhongguo Zhong Xi Yi Jie He Za Zhi. 2016; 36: 690-705.
  23. Lundeberg T. Peripheral effects of sensory nerve stimulation (acupuncture) in in ammation and ischemia. Scand J Rehabil Med Suppl. 1993; 29: 61-86.
  24. Wang Z, Chen T, Long M, Chen L, Wang L, et al. Electro- acupuncture at Acupoint ST36 Ameliorates In ammation and Regulates Th1/Th2 Balance in Delayed-Type Hypersensitivity. In ammation. 2016.

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