Mechanisms of Acupuncture Analgesia – Lina Englund, Physiotherapist
Acupuncture is widely used in physiotherapy practice for its pain relieving properties. The National Institutes of Health issued a statement in 1997 that supported the efficacy of acupuncture for specific conditions. The statement was based on well-designed, controlled clinical trials that showed especially good results in pain relief.
The Easy Explanation
The insertion of the needle into the human body generates an impulse that travels through the nervous system. Biomechanical interactions take place in these structures that involve release of neurotransmitters and feel-good hormones. All of which result in analgesia.
For The Science Nerd
The impulses reach several structures; peripheral nerves, spinal nerves, spinal cord, mid-brain, hypothalamus, thalamus and cerebral cortex. The peripheral nerves are depolarized which results in responses from other levels of the nervous centers.
Spinal Cord Level:
- Interacts with substantia gelatinosa cells (functions in the integration of sensory stimuli that give rise to the sensations of heat and pain)
- Endorphinergic cells release enkephalin or endorphins (pain relieving substances produced in the body with opiate qualities that reduce the sensation of pain)
- GABA, a neurotransmitter, potentiates acupuncture effects
- PAG cells release encephalin (see above)
- Raphe nucleus cells release serotonin and norepinephrine (neurotransmitters)
Hypothalamus Pituitary Complex:
- Beta-endorphine (an agonist of the opioid receptors) is released into cerebrospinal fluid and blood
- ACTH is released, increasing levels of cortisol (prevents the release of substances in the body that cause inflammation)
- Increases serotonin in the brain which mediates acupuncture analgesia
- Lowers the content of cerebro-norepinephrine (believed to be involved in chronic pain)
- Increases opiate-like substances in the blood and cerebrospinal fluid
- Central neurotransmitters exert descending control of the spinal cord
Take home message: Acupuncture releases feel-good hormones and neurotransmitters necessary to decrease the sensation of pain.
Written by Lina Englund