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, or, an herbal medicine derived from the gum resin ofBirdw. (BC) of the family Burseraceae, has been used traditionally in China to alleviate pain and reduceinflammation. The present study is an investigation of the effects of a BC extract on persistent hyperalgesiaand edema in rats with peripheral inflammation.In this randomized, blinded study, the antihyperalgesic and antiedema effects of 3 dosages of BCwere compared to a vehicle control. Inflammation was induced in rats by injecting complete Freund's adjuvant(CFA) into one hind paw. A single oral dose of the BC extract was administered daily for 7 days, beginningone day before CFA. Hyperalgesia was assessed using a paw withdrawal latency (PWL) test pre-CFA and 2hours, 5 hours, 1 day, and 5 days post-CFA. Edema was determined by measuring paw thickness at the sametime points. Spinal Fos protein expression was analyzed 2 hours post-CFA. Adverse effects of the extract weremonitored by observing the animals closely for unusual behavioral changes.Compared to control, a dosage of 0.45 g/kg BC significantly lengthened PWL and reduced pawedema on day 5 post-CFA. At 0.90 g/kg, BC significantly lengthened PWL at 5 hours, 1 day, and 5 days, andreduced paw edema at 2 hours, 5 hours, 1 day, and 5 days. This dosage also significantly suppressed spinalFos expression in the medial half of laminae I–II. At 1.80 g/kg, BC significantly lengthened PWL and reducedpaw edema at all time points.No noticeable adverse effects were observed in animals given the lower dosages of BC, but adverse effectsin some animals were observed at 1.80 g/kg per day. In the acute toxicity study, the maximal single dose of2.50 g/kg produced no adverse effects in the treated rats during the 14 days of observation.The data suggest that BC produces significant antihyperalgesia and anti-inflammation effectsand that the antihyperalgesia may be mediated by suppressed inflammation-induced Fos expression in the spinaldorsal horn neurons. [ABSTRACT FROM AUTHOR]