Dose-effect relationship between electroacupuncture with different parameters and the regulation of endogenous opioid peptide system

Endogenous opioid peptides (EOP) are the neurochemical basis of the anesthetic and analgesic effects of acupuncture, and the quantity of acupuncture stimulus can be controlled accurately by using electroacupuncture (EA). The present study explores the dose-effect relationship between EA with different parameters and the regulation of EOP system. In this paper, the intervention effects of EA on EOP system were specially discussed in terms of the single factor and the different combinations of the frequency, waveform and current intensity. This study shows that EOP system presents a frequency-response specificity. The low frequency of EA promotes the release of enkephalin, β-endorphin and endomorphin, the high one activates the dynorphin system selectively, and the intermediate frequency works on promoting the release of enkephalin and β-endorphin, as well as dynorphin. Sparse-dense wave of EA may induce the release of enkephalin, β-endorphin, endomorphin and dynorphin, presenting a synergistic effect. However, the waveform of EA should be selected flexibly in clinical practice. Sometimes the better therapeutic effect can also be obtained with the continuous wave of EA. EOP system is involved in mediating appropriate intensity of EA, while the acupuncture effect generated by an extra strong EA stimulation refers to a kind of stress response of non-opioid mechanism. The different combinations of EA parameters result in various effects. The combination of EA parameters should be optimized in accordance with different diseases, which is valuable for guiding clinical practice and the development of EA therapy.