Background and objective: Acupuncture has been claimed to be associated with activation of the endogenous antinociceptive system. The analgesic effects of acupuncture have been ascribed to beta-endorphin interacting with opioid receptors. However, firstly, the release of beta-endorphin into the blood has been proven to be induced by stress, i.e. under dysphoric conditions, and, secondly, if released under stress, beta-endorphin has been shown not to be analgesic. Our aim was to test whether beta-endorphin immunoreactive material is released into the cardiovascular compartment during acupuncture comparing the most frequently used types of acupuncture with standard pain treatment under apparently low stress conditions.
Methods: This prospective study included 15 male patients suffering from chronic low back pain. beta-Endorphin immunoreactive material and cortisol were measured in the plasma of patients who underwent, in random order, therapy according to a standard pain treatment, traditional Chinese acupuncture, sham acupuncture, electro acupuncture and electro acupuncture at non-acupuncture points before, at and after the treatment. Statistical analysis was performed using two-way ANOVA with repeated measures.
Results: A decrease in plasma cortisol concentration measured over the five treatment protocols was highly significant (P < 0.001). The beta-endorphin immunoreactive material concentrations in plasma were minimal at all times and in all treatment conditions. The influence of treatments by various acupuncture procedures on cortisol and beta-endorphin immunoreactive material plasma concentrations over the three time points was not significantly different.
Conclusions: beta-endorphin immunoreactive material in blood is not released by any type of acupuncture as tested under low stress conditions.