The Antiinflammatory and Analgesic Effects of Baicalin in... : Anesthesia & Analgesia (original) (raw)

TECHNOLOGY, COMPUTING, AND SIMULATION: Research Report

The Antiinflammatory and Analgesic Effects of Baicalin in Carrageenan-Evoked Thermal Hyperalgesia

Chou, Tz-Chong PhD*; Chang, Li-Ping MD, PhD†; Li, Chi-Yuan MD‡; Wong, Chih-Shung MD, PhD‡; Yang, Shih-Ping MD, PhD§

*Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, Republic of China; and

†Department of Radiation Oncology,

‡Department of Anesthesiology, and

§Division of Cardiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China

Supported in part by a research grant from the National Science Council of Taiwan (NSC 88-2314-B016-072) and a grant from Tri-Service General Hospital (TSGH-C91-15), Republic of China.

Accepted for publication June 27, 2003.

Address correspondence and reprint requests to Tz-Chong Chou, PhD, Department of Physiology and Biophysics, National Defense Medical Center, No. 161, Min-Chuan E. Rd., Sec. 6, Taipei, Taiwan, ROC. Address e-mail to [email protected].

We tested baicalin for its antiinflammatory and analgesic effects (and the mechanisms) in a rat model of carrageenan-evoked thermal hyperalgesia. Pre- or posttreatment with baicalin (10, 30, or 100 mg/kg intraperitoneally) caused a significant analgesic effect with a similar effect of dose-matched ibuprofen. Furthermore, baicalin dose-dependently attenuated tumor necrosis factor-α (from 3510 ± 150 pg/mL to 2860 ± 148 pg/mL to 1480 ± 210 pg/mL), interleukin (IL)-1β (from 3210 ± 210 pg/mL to 2200 ± 140 pg/mL to 750 ± 95 pg/mL), and IL-6 (from 58.5 ± 9.8 pg/mL to 38.5 ± 9.0 to 21.0 ± 8.1 ng/mL) formation but enhanced IL-10 (from 18.1 ± 2.5 pg/mL to 36.1 ± 5.5 pg/mL to 71.2 ± 9.5 pg/mL) production in paw exudates at 4 h after carrageenan injection. Prostaglandin E2 (PGE2) and nitrate formation in the carrageenan-injected paws were dose-dependently inhibited by baicalin (10–100 mg/kg intraperitoneally) (PGE2: from 15.9 ± 2.1 ng/mL to 12.1 ± 1.6 ng/mL to 6.2 ± 1.8 ng/mL; nitrate: from 39.8 ± 4.8 μM to 27.5 ± 3.0 μM to 17.2 ± 1.6 μM) at 4 h but not at 1.5 h after carrageenan injection. Increased myeloperoxidase activity in carrageenan-injected paws was also dose-dependently reduced by baicalin. These findings suggest that the antiinflammatory and analgesic mechanisms of baicalin may be associated with the inhibition of critical inflammatory mediators, including nitric oxide, PGE2, and proinflammatory cytokines, accompanied by an increase in IL-10 production, as well as neutrophil infiltration at sites of inflammation.