Acupuncture and endorphins

Acupuncture, a centuries-old practice of traditional Chinese medicine, has attracted growing interest from the international scientific community, particularly for the treatment of acute and chronic pain. Although it has been used for thousands of years, only in recent decades have investigators begun to understand the scientific mechanisms that explain its therapeutic effects. One of the most intriguing aspects of this technique is how the insertion of needles at specific body points can produce pain relief, leading scientists to investigate the neurobiological processes involved in depth. This understanding is fundamental not only for the scientific validation of acupuncture, but also for optimizing its treatment protocols and expanding its clinical applications in a responsible, evidence-based manner.

The study conducted by the renowned investigator Ji-Sheng Han, of the Neuroscience Institute of Peking University, aimed primarily to elucidate the mechanisms by which electroacupuncture produces analgesia, with particular focus on the role of endorphins and other natural opioid peptides of the organism. The research used a comprehensive methodological approach, combining experiments in laboratory animals with clinical studies in humans. Investigators employed different electrical stimulation frequencies applied through acupuncture needles, varying between 2 Hz, 15 Hz, and 100 Hz, to investigate how each frequency affects the release of different analgesic substances in the central nervous system. To measure the effects, they used pain threshold tests in animals, analysis of cerebrospinal fluid via radioimmunoassay techniques, and clinically assessed the reduction of analgesic consumption in patients undergoing surgery.

The results revealed surprising findings regarding how different frequencies of electrical stimulation activate distinct systems of natural pain relief. When electroacupuncture was applied at low frequency, specifically 2 Hz, a significant increase was observed in the release of enkephalins, beta-endorphins, and endomorphins, which are natural substances of the body with potent analgesic effects. By contrast, high-frequency stimulation at 100 Hz preferentially produced the release of dynorphins, another type of endogenous opioid peptide. The intermediate frequency of 15 Hz showed partial activation of both systems.

Even more striking was the discovery that the alternating combination of low and high frequencies, applied in cycles of 3 seconds each, resulted in the simultaneous release of all four types of endogenous opioid peptides, producing a maximum analgesic effect. This finding was subsequently confirmed in clinical studies, in which patients treated with the alternating-frequency protocol showed a 53% reduction in postoperative morphine requirements, compared with only 32-35% reduction when constant frequencies were used.

The clinical implications of these findings are profound for both patients and clinicians. For patients, especially those suffering from chronic pain such as low back pain or diabetic neuropathic pain, these results offer hope of more effective treatments with fewer side effects compared with conventional medications. The understanding that different frequencies activate different natural pain relief systems allows clinicians to tailor treatments to the specific type of pain of each patient. For clinicians, particularly those working in pain treatment centers, these findings provide a solid scientific basis for integrating electroacupuncture into conventional treatment protocols.

The possibility of significantly reducing the use of pharmaceutical opioids is particularly relevant in the current context of concern about dependence and adverse effects of these medications. In addition, the development of electroacupuncture devices that automatically alternate between different frequencies makes this technique more standardized and reproducible.

It is important to recognize some limitations of this study that should be considered when interpreting the results. First, much of the research was conducted in animal models, and although the clinical studies have confirmed the main findings, additional randomized clinical trials in diverse populations are needed to definitively establish the efficacy and safety of these protocols. In addition, the study focused primarily on mechanisms related to opioid peptides, but other neurotransmitters such as serotonin also play important roles in acupuncture analgesia, suggesting that the mechanisms are even more complex than initially described. The individual variability in treatment response was also not fully explored, and factors such as age, sex, pre-existing medical conditions, and medication use may influence the results.

Considering the overall picture, this research represents an important milestone in the scientific validation of acupuncture and paves the way for promising future developments. The discovery that the central nervous system can distinguish between different stimulation frequencies and respond by releasing different cocktails of natural analgesic substances not only scientifically explains a centuries-old practice but also suggests new therapeutic possibilities. For patients seeking alternatives to conventional pain treatments, especially those concerned about the risks of opioid medications, electroacupuncture emerges as a legitimate, scientifically grounded therapeutic option, offering hope of effective relief through activation of the body's own natural pain control systems.