Acupuncture produces therapeutic effects by inserting metal needles at specific acupoints and applying manual manipulation (lifting-thrusting, rotating) or electrical stimulation (electroacupuncture). The body has approximately 361 meridian points distributed across 14 meridians; theory holds that manipulating “Qi” flow improves health.
## Indications with Strong Clinical Evidence
**Chronic pain**: RCT evidence is most solid for acupuncture treating chronic low back pain, neck pain, osteoarthritis, and migraine. A large 2012 meta-analysis in Archives of Internal Medicine (~18,000 patients, 29 RCTs) showed acupuncture outperformed sham acupuncture and usual care for chronic pain — effect sizes modest but statistically and clinically significant.
**Chemotherapy-induced nausea and vomiting (CINV)**: PC6 (Neiguan) point stimulation is rated effective by Cochrane systematic reviews; multiple high-quality RCTs confirm acupuncture/acupressure at PC6 reduces post-chemotherapy nausea — now recommended in multiple cancer supportive care guidelines.
**Tension headache and migraine prevention**: a 2022 Cochrane review (22 RCTs) found acupuncture comparable to preventive medications (topiramate, valproate) for migraine prevention, with fewer adverse effects.
## Neural Mechanisms: Hypotheses and Debates
Modern neuroscience attempts to establish biological mechanisms for acupuncture:
**Endogenous opioid release hypothesis**: electroacupuncture can trigger release of endogenous opioids (endorphins, enkephalins); naloxone (opioid receptor antagonist) partially reverses acupuncture analgesia, supporting this hypothesis.
**Connective tissue mechanism (Langevin hypothesis)**: Harvard Medical School researcher Helene Langevin’s team found that acupuncture points overlap extensively with connective tissue planes (fascia); the lifting-thrusting-rotating movements wind connective tissue around the needle, generating mechanical signal transduction.
**Local adenosine release**: mouse experiments (Nanna Goldman team, 2010, Nature Neuroscience) showed analgesic effects from needling Zusanli (ST36) are partly mediated through adenosine receptors (A1R); adenosine enzyme inhibitors can enhance acupuncture effects.
**Anatomical basis of meridians**: no dedicated anatomical structures corresponding to the traditional meridian system have been found, but evidence suggests meridian pathways overlap with subcutaneous connective tissue planes and neurovascular bundle distributions.
See [TCM Modernization Overview](https://sunqi.org/tcm-modernization-overview-en/) and [Cochrane acupuncture reviews](https://www.cochranelibrary.com/).
