Inserting the needle at a specific point causes three different reactions:
Local reaction:
Local needle stimulation is investigated in relation to responses in cells, sensory receptors and nerve endings. A fixed electrical current, inflammatory radius or duration should not be attributed to every procedure. Measurements depend on the technique, tissue and experimental conditions, and require the particular research reference from which they were obtained. Local observations cannot be assumed identical across all people and applications.
These mechanisms cause a continuous peripheral sensory stimulus capable of activating endogenous mechanisms of analgesia and homeostasis.
The nervous system’s response thus depends on the therapist, as it is influenced by the point, the thickness of the needle used, the depth of acupuncture and the manipulation of the needle.
Regional reaction:
Insertion of the acupuncture needle stimulates a sensory receptor. The stimulus is then transmitted to the spinal cord, which produces a response affecting a larger area than the site of stimulation.
The knowledge gained from neurophysiology allows us to distinguish the presence of various reflex arcs involved both in the action of the acupuncture effect and in the selection of acupuncture points.
In addition to these reflex arcs, however, others contribute to the action of acupuncture to a greater or lesser extent. Some of these, such as the viscero-visceral reflexes, have been extensively investigated, while others continue to be discovered and studied.
Generalised reaction:
Research on endogenous opioids, including endorphins, has contributed to investigation of possible analgesic mechanisms. Observing such changes does not itself provide a complete explanation or establish clinical benefit for every application of acupuncture.
Endorphins are produced in the brain, spinal cord and other parts of the body as the body’s response to painful or stressful stimuli.
In addition to endogenous opioid peptides, neurotransmitters produced as the body’s response to skin stimulation after needle insertion also play an important role in acupuncture’s analgesic action.
Discussion of neurotransmitters in chronic pain research does not make acupuncture equivalent to medicines such as SSRIs, or justify replacing or altering prescribed medication. Each intervention requires its own clinical evaluation, including its indication, benefits and risks.
In addition to the endogenous analgesic substances secreted through acupuncture, increased levels of numerous other substances that contribute indirectly to the therapeutic effect, such as cortisol, ACTH and prostaglandins, have been observed.
Acupuncture: local and neural responses
A local response concerns what may occur at the stimulation site. A treatment outcome requires a different assessment.
For a description of the method, see Medical Acupuncture Methods. Related reading: Medical articles and health information.
Three scales of observation, different questions
Local, regional and generalised responses provide a way to organise a description of acupuncture. They do not mean every needle insertion produces an identical sequence with a fixed intensity and duration. Technique, the tissue stimulated and experimental conditions influence what is recorded. It helps to distinguish a theoretical model from a direct measurement, and a measurement from an outcome that matters to the person receiving care. These steps should remain visible when biological explanations are used in patient information.
At a local level, researchers may investigate the application site and communication involving cells and nerve endings. Detecting a change there does not by itself show that the cause of pain has been treated. Pressure, warmth or tenderness describes an experience during a session. None is a sufficient measure of success without considering what happens later to the symptoms and activities originally selected as goals. A noticeable sensation is not proof that a particular biological pathway has been activated successfully.
Neural processing and the experience of pain
Sensory information is processed at more than one level of the nervous system. Research explores possible neural and chemical mechanisms, while a complete explanation of how acupuncture works remains unresolved. The existence of the body’s own pain-modulating systems does not establish that a particular procedure is appropriate for every diagnosis. Clinical decisions need evidence from people with relevant problems, rather than biological plausibility alone. Findings from experimental conditions must be interpreted within the conditions under which they were obtained.
Pain experience is also influenced by context, expectations, sleep and the relationship with a practitioner. Recognising these factors does not suggest the pain is imaginary. It helps avoid an overly simple explanation in which every change is attributed to one chemical. Assessment can include pain intensity and ability to walk, work or rest, depending on the original difficulty. A useful account of progress describes these practical changes and their duration rather than relying exclusively on a general feeling immediately after treatment.
A shared chemical does not establish equivalence
When two interventions are discussed in relation to the same neurotransmitter, they do not thereby have the same action, dose or effectiveness. References to serotonin or endogenous opioids cannot justify replacing prescribed medication. Medicines are evaluated for particular indications and have their own risks. Acupuncture is evaluated as a distinct intervention. Any combination belongs in a discussion with the treating clinician, without transferring conclusions from one approach to the other merely because a biological term appears in both descriptions.
Likewise, a change in a hormonal or inflammatory marker should not automatically be called balancing the whole body. The report needs to identify which marker was measured, when and in what circumstances. The meaning of a change can differ according to the clinical situation. An impressive biological word does not offer a practical prediction of a symptom’s course or demonstrate that an underlying disease has resolved. Clinical outcomes and mechanistic observations are complementary forms of information, rather than interchangeable proof.
Agree goals and a review point
Before sessions, define a concrete functional goal and a time for reassessment. Recording the starting situation allows a clearer comparison than a general memory of wellbeing. Discuss diagnosis, existing medication, the proposed technique and financial commitment. Continuing should depend on actual progress, preferences and a review of the wider plan, rather than on a mechanism explanation alone. Clear review criteria also make it easier to reconsider an approach when expected changes are absent or concerns arise.
Sources for further information
Medical acupuncture and evidence
Is a local response the same as the duration of relief?
No. Cellular or neural recordings and experience over time are different measurements. One does not automatically determine the other.
Does recognition of a method establish an indication for every condition?
No. Training, regulation of instruments and evidence of effectiveness are different matters. Each application is considered for its particular purpose, medical history and relevant evidence.