Physiological Mechanisms of Acupuncture

(NIH, 1997): “Many studies in animals and humans have demonstrated that acupuncture can cause multiple biological responses. These responses can occur locally, i.e., at or close to the site of application, or at a distance, mediated mainly by sensory neurons to many structures within the central nervous system. This can lead to activation of pathways affecting various physiological systems in the brain as well as in the periphery.” A focus of attention has been the role of endogenous opioids in acupuncture analgesia. Considerable evidence supports the claim that opioid peptides are released during acupuncture and that the analgesic effects of acupuncture are at least partially explained by their actions. That opioid antagonists such as naloxone reverse the analgesic effects of acupuncture further strengthens this hypothesis. Other physiological responses to acupuncture include:

    1. Group III & Group IV afferent neurons (via substance P)
    2. CNS activation via HPA axis, homeostatic effect
    3. Studied immune effects include stimulation of mast cell, bradykinin, cytokines
    4. Needle insertion at specific segmental level (and via dermatomal distribution) stimulating CNS descending control mediates some of the immune response to acupuncture
    5. Activate the hypothalamus and the pituitary gland, resulting in a broad spectrum of systemic effects
    6. Alter the secretion of neurotransmitters/neurohormones, regulate circulation & blood rheology, both centrally and peripherally,
    7. PET-Scans of the brain during acupuncture (Dold, 1998): University of California Irvine professor and physicist Zang-Hee Cho, a member of the National Academy of Science, inventor of an early version of the PET scanner and a pioneer of the MRI scanner, found that stimulation of the vision-related acupoint showed the same reaction in the brain as stimulation of the eye. As the acupuncture signal passes to the brain via nervous system, it possibly stimulates the hypothalamus, responsible for the production and release of hundreds of neurochemicals.
    8. Acupuncture: pain management coupled to immune stimulation (Gollub, 1999): “The phenomenon of acupuncture is both complex and dynamic. Recent information demonstrates that acupuncture may exert its actions on pain and immune processes. The coupling of these two systems occurs via common signaling molecules, i.e., opioid peptides. In this regard, we surmise that

• opioid activation leads to the processing of opioid peptides from their precursor, proenkephalin
• the simultaneous release of antibacterial peptides contained within the precursor as well.
• central nervous system pain circuits may be coupled to immune enhancement.
• Furthermore, acupuncture needle manipulation elicited signal increases bilaterally in the region of the primary and secondary somatosensory corticies in human brain as determined by magnetic resonance imaging.
• The maps reveal marked signal decreases bilaterally in multiple limbic and deep gray structures including the nucleus accumbens, amygdala, hypothalamus, hippocampus, and ventral tegmental area.
Taken together, we surmise a major central nervous system pathway as well as local pain and immune modulation during acupuncture.”
(Fu, 2000): “In recent years, more and more laboratory proof has accumulated that acupuncture can
• change the charge and potential of neurons,
• the concentrations of K(+), Na(+), Ca(++) and
• the content of neuro-transmitters such as aspartate, and taurine and
• the quantities of neuro-peptides such as beta-endorphin and leu-enkephalin.
• All these phenomena are directly related to nerve cells.”

Immune System effects of Acupuncture (Joos, 2002): “The following changes were found in the TCM group: within the lymphocyte subpopulations the CD3+ cells (p = 0.005) and CD4+ cells (p = 0.014) increased significantly. There were also significant changes in cytokine concentrations: interleukin (IL)-6 (p = 0.026) and IL-10 (p = 0.001) decreased whereas IL-8 (p = 0.050) rose significantly. Additionally, the in vitro lymphocyte proliferation rate increased significantly (p = 0.035) while the number of eosinophils decreased from 4.4% to 3.3% after acupuncture (p > 0.05). The control group, however, showed no significant changes apart from an increase in the CD4+ cells (p = 0.012).”

Difference between Manual and Electro Acupuncture (Kong, 2002): “Results showed that electroacupuncture mainly produced fMRI signal increases in precentral gyrus, postcentral gyrus/inferior parietal lobule, and putamen/insula; in contrast, manual needle manipulation produced prominent decreases of fMRI signals in posterior cingulate, superior temporal gyrus, putamen/insula. These results indicate that different brain networks are involved during manual and electroacupuncture stimulation. It suggests that different brain mechanisms may be recruited during manual and electroacupuncture.”

In Parkinson’s Disease (Wang L., 2002): “Under the auditory evoked brain stem potential (ABP) examination, the latent period of V wave and the intermittent periods of III-V peak and I-V peak were significantly shortened in Parkinson’s disease patients of the treatment group (N = 29) after acupuncture treatment. The difference of cumulative scores in Webster’s scale was also decreased in correlation analysis.”