Analgesic effects by electroacupuncture were decreased in inducible nitric oxide synthase knockout mice

• Published in: Neurological research (New York) Vol. 29 Suppl 1; p. S28
• Main Authors: Kim, Ee-Hwa, Park, Hi-Joon, Lee, Hyangsook, Seo, Jung-Chul, Hong, Meesuk, Park, Hun-Kuk, Jang, Mi-Hyeon, Kim, Chang-Ju, Ha, Eunyoung, Lee, Hyejung, Kang, Sungkeel, Choi, Sunmi, Ryu, Yeonhee, Chung, Joo-Ho
• Format: Journal Article
• Language: English
• Published: England 2007
• Subjects: Analgesia; Animals; Dose-Response Relationship, Radiation; Electroacupuncture - methods; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase Type II - deficiency; Pain Threshold - physiology; Pain Threshold - radiation effects; Reaction Time - radiation effects; Time Factors
• ISSN: 0161-6412
• DOI: 10.1179/016164107X172257

This study was designed to investigate the involvement of inducible nitric oxide synthase (iNOS) in electroacupuncture (EA)-induced analgesia. Two and 100 Hz EA stimulation were applied at acupoint ST 36 (Zusanli) in iNOS knockout mice (n = 28). Needles were inserted 5 mm in depth in ST36. After insertion, the needles were fixed in situ with adhesive tape. EA was applied after the basal threshold determination. The EA parameters were set as follows: constant square wave current output (pulse width: 0.6 ms at 2 Hz and 0.2 ms at 100 Hz) and 2 mA intensities. EA was performed for 30 minutes and tail-flick latencies (TFLs) were evaluated every 15 minutes for 1 hour. In 2 Hz EA stimulation, the tail-flick response (TFR) of wild-type mice for durations of 0, 15, 30, 45 and 60 minutes were 2.70 +/- 0.26, 4.19 +/- 0.37, 4.17 +/- 0.34, 3.57 +/- 0.27 and 3.39 +/- 0.32 seconds of TFLs. Meanwhile, iNOS -/- mice showed 4.10 +/- 0.33, 4.77 +/- 0.24, 5.26 +/- 0.30, 4.48 +/- 0.33 and 5.00 +/- 0.41 seconds of TFLs. In 100 Hz EA stimulation, the TFR of wild-type mice were 3.01 +/- 0.24, 4.67 +/- 0.31, 4.76 +/- 0.25, 4.04 +/- 0.45 and 4.26 +/- 0.30 seconds of TFLs. The iNOS -/- mice were 4.33 +/- 0.16, 5.29 +/- 0.28, 5.06 +/- 0.35, 4.52 +/- 0.17 and 4.80 +/- 0.28 seconds of TFLs. Wild-type mice exhibited 63.9% increase in TFL compared to the baseline after 2 Hz EA, whereas the iNOS knockout mice exhibited 32.9% increase in TFL. The TFL after 100 Hz EA showed similar trends: 66.5% increase in TFL in wildtype mice and 18.3% increase in the iNOS knockout mice. The present findings suggested that iNOS may play a crucial role in both low- and high-frequency EA-induced analgesic effects.