title: Analgesic effects of intrathecal curcumin in the rat formalin test.
abstract: BACKGROUND
  Curcumin has been reported to have anti-inflammatory, antioxidant, antiviral, antifungal, antitumor, and antinociceptive activity when administered systemically. We investigated the analgesic efficacy of intrathecal curcumin in a rat model of inflammatory pain.
  
  
  METHODS
  Male Sprague Dawley rats were prepared for intrathecal catheterization. Pain was evoked by injection of formalin solution (5%, 50 µl) into the hind paw. Curcumin doses of 62.5, 125, 250, and 500 µg were delivered through an intrathecal catheter to examine the flinching responses. The ED(50) values (half-maximal effective dose) with 95% confidence intervals of curcumin for both phases of the formalin test were calculated from the dose-response lines fitted by least-squares linear regression on a log scale.
  
  
  RESULTS
  In rats with intrathecal administration of curcumin, the flinching responses were significantly decreased in both phases. The slope of the regression line was significantly different from zero only in phase 2, and the ED(50) value (95% confidence interval) of curcumin was 511.4 µg (23.5-1126.5). There was no apparent abnormal behavior following the administration of curcumin.
  
  
  CONCLUSIONS
  Intrathecal administration of curcumin decreased inflammatory pain in rats, and further investigation to elucidate the precise mechanism of spinal action of curcumin is warranted.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Hospital, Gwangju, Korea.
authors.forename: Yong Ku
authors.initials: YK
authors.lastname: Han
authors.forename: Seong Heon
authors.initials: SH
authors.lastname: Lee
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Jeong
authors.forename: Min Sun
authors.initials: MS
authors.lastname: Kim
authors.forename: Myung Ha
authors.initials: MH
authors.lastname: Yoon
authors.forename: Woong Mo
authors.initials: WM
authors.lastname: Kim