Education and practice

To fi nd appropriate and effective treatment options for chronic pain syndromes is a challenging task. Multimodal treatment approach has been gaining acceptance for chronic pain. However, combining treatments, such as acupuncture, with rational pharmacology is still in its infancy. Acupuncture infl uences the opioid and cannabinoid system through releasing endogenous receptor ligands. Low dose naltrexone also acts on both these systems, and upregulates the opioid and cannabinoid receptors. The authors hypothesise that low dose naltrexone could enhance the pain-relieving effect of acupuncture. Jan M Keppel Hesselink, David J Kopsky picomolar) of naltrexone, an opioid antagonist. Furthermore, there is signifi cant crosstalk between the opioid and the cannabinoid systems, and low dose naltrexone (LDN) might facilitate this crosstalk. In addition, LDN also enhances cannabinoid-induced analgesia. Based on these facts we will discuss a theoretical framework of boosting acupuncture analgesic effects by adding LDN in order to modulate further the endogenous cannabinoid and opioid systems. THE ENDOGENOUS OPIOID AND CANNABINOID SYSTEMS, AND THEIR CROSS TALK Opioid and cannabinoid receptors are expressed in our brain and our peripheral nervous system, as well as in other tissues, such as cells of the immune system. These receptors can be activated by endogenous ligands, and for the opioid system alone around 30 opioid peptides have already been identifi ed. All these ligands are synthesised on the base of three opioid peptide precursors: proenkephalin, prodynorphin and proopiomelanocortin. Many endogenous opioid peptides and fatty acids are produced by the body as biological relevant answers to infl ammation and pain. Moreover, infl ammation and pain increase the synthesis of opioid receptors. The four classical opioid receptors—μ opioid receptor (MOR), δ opioid receptor (DOR), 11_acupmed3566.indd 127 5/19/2011 3:13:33 PM group.bmj.com on May 30, 2011 Published by aim.bmj.com Downloaded from