Augmentation of Immunity Theory:
This theory states that Acupuncture raises levels of triglycerides, specific hormones, prostaglandins, white blood counts, gamma globulins, opsonins, and overall anti-body levels.
This theory states that Acupuncture stimulates the secretions of endorphins in the body, specifically Enkaphalins. Enkaphalins are pentapeptides that have opiate qualities and are found in the brain, spinal cord, and other body parts.
This theory holds that neurotransmitter levels are altered by acupuncture.
Gate Control Theory:
According to this theory, the perception of pain is controlled by a part of the nervous system that regulates the impulse, which will later be interpreted as pain. This part of the nervous system is called the "Gate." If the gate is hit with too many impulses, it becomes overwhelmed, and it closes. This prevents some of the impulses from getting through. The first gates to close would be the ones that are the smallest. The nerve fibers that carry the impulses of pain are rather small nerve fibers called "C" fibers. These are the gates that close during Acupuncture.
This states that Acupuncture has the effect of constricting or dilating blood vessels. This may be caused by the body's release of Vasodilaters (such as Histamine), in response to Acupuncture.