Explore : the journal of science and healing
-
The involvement of the peripheral opioid system in modulating inflammatory pain has been well documented. This study aimed to investigate the possibility of electroacupuncture (EA)-mediated peripheral opioid release. Rats were injected with complete Freund's adjuvant in one of the hind paws to induce localized inflammatory pain. ⋯ Intraplantar but not intraperitoneal injection of naloxone methiodide, a peripherally acting opioid receptor antagonist, eliminated the analgesic effect at 30 minutes after EA treatment. Intraplantar injection of an antibody against beta-endorphin and a corticotropin-releasing factor antagonist also produced a reduction in PWL in rats receiving EA. These data strongly suggest that peripheral opioids are released by EA at the inflammatory site.