title: Analgesic effects by electroacupuncture were decreased in inducible nitric oxide synthase knockout mice.
abstract: BACKGROUND
  This study was designed to investigate the involvement of inducible nitric oxide synthase (iNOS) in electroacupuncture (EA)-induced analgesia.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  The present findings suggested that iNOS may play a crucial role in both low- and high-frequency EA-induced analgesic effects.
authors.affiliation: Department of Acupoint and Meridian, College of Korean Medicine, Semyung University, Jechon 390-711, Korea.
authors.forename: Ee-Hwa
authors.initials: EH
authors.lastname: Kim
authors.forename: Hi-Joon
authors.initials: HJ
authors.lastname: Park
authors.forename: Hyangsook
authors.initials: H
authors.lastname: Lee
authors.forename: Jung-Chul
authors.initials: JC
authors.lastname: Seo
authors.forename: Meesuk
authors.initials: M
authors.lastname: Hong
authors.forename: Hun-Kuk
authors.initials: HK
authors.lastname: Park
authors.forename: Mi-Hyeon
authors.initials: MH
authors.lastname: Jang
authors.forename: Chang-Ju
authors.initials: CJ
authors.lastname: Kim
authors.forename: Eunyoung
authors.initials: E
authors.lastname: Ha
authors.forename: Hyejung
authors.initials: H
authors.lastname: Lee
authors.forename: Sungkeel
authors.initials: S
authors.lastname: Kang
authors.forename: Sunmi
authors.initials: S
authors.lastname: Choi
authors.forename: Yeonhee
authors.initials: Y
authors.lastname: Ryu
authors.forename: Joo-Ho
authors.initials: JH
authors.lastname: Chung
mesh_terms: D000698:Analgesia; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D015671:Electroacupuncture / Q000379:methods*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D052247:Nitric Oxide Synthase Type II / Q000172:deficiency*; D017288:Pain Threshold / Q000502:physiology / Q000528:radiation effects*; D011930:Reaction Time / Q000528:radiation effects; D013997:Time Factors
chemical_list: D052247:Nitric Oxide Synthase Type II