Abstract
We have previously reported that acupuncture decreased the post-operative pain after abdominal surgery and significantly reduced the use of analgesic drugs, however, the mechanism of acupuncture analgesia is not completely elucidated. In this study, the effects of surgical invasion and acupuncture analgesia on serum β-endorphin, an endogenous opioid peptide that is involved in analgesic action, and adrenocorticotropic hormone (ACTH) levels were evaluated. Continuous electroacupuncture (EA; 3Hz) treatment was performed at Acupuncture point L14 (Hoku) and S36 (Tsusanli) for 3 hours from 3 hours after the operation in 11 patients (EA group). Another eleven patients not treated by EA served as controls. Peripheral blood (3ml) was collected before, during, immediately after surgery and at 3 hour intervals thereafter until 12 hours after operation, and serum β-endorphin and ACTH levels were measured by radioimmunoassay (RIA). During surgery, both β-endorphin and ACTH levels increased significantly. After operation, these levels tended to gradually decrease to preoperative values. The level of serum β-endorphin increased significantly again during the EA treatment but only in the EA group. Analgesic drugs for postoperative pain were used in 10 of the 11 cases in control group, but were used only in 1 of the 1 cases in the EA group. These results suggest that increased β-endorphin level induced by the EA reduced the postoperative pain, and even under the general anesthesia, the surgical invasions appear to be input into the central nervous system and activate stress-induced analgesia.
