Low-frequency electro-acupuncture reduces the nociceptive response and the pain mediator enhancement induced by nerve growth factor

A number of studies have shown that the potential clinical benefits of nerve growth factor (NGF) administration are limited by its undesirable side effects, which include hyperalgesia and pain. The ancient therapeutic technique of acupuncture and its modern derivate electro-acupuncture (EA) have been proven effective in reducing hyperalgesia as well as nociceptive and neuropathic pain in several pathological conditions. The present study addresses the question of whether EA can suppress the hyperalgesia induced by NGF administration. We treated adult healthy rats with repeated injections of murine NGF and/or low-frequency electro-acupuncture. We found that EA was able to counteract the NGF-induced hyperalgesic response when assessed by a hot plate test. Moreover, EA counteracted the NGF-driven variation of substance P (SP) and transient receptor potential vanilloid type 1 (TRPV1) response in both hind-paw skin as well as the corresponding dorsal root ganglia (DRG). Our findings indicate that low-frequency EA could be useful as a supportive therapy to reduce NGF-induced side effects, such as hypersensitivity, hyperalgesia, and pain, when clinical treatment with NGF is necessary.