BACKGROUND:The Chinese herbal compound realgar exerts detoxification effects as an adjuvant. It is suggested that realgar exerts detoxification via the following pathways: in the pathological state, realgar corrects the oxidative stress state by increasing stress levels, activating some endogenous protective factors and antagonizing the excessive release of inflammatory factors, as well as inhibiting complement activation. OBJECTIVE: To observe the changes in stress proteins, inflammatory mediators, and complement in the brain tissue and serum of rats with inflammatory brain injury, which have been treated with the Chinese herbal compound Angong Niuhuang, and to compare the efficacy of Angong Niuhuang with that of realgar, to verify the mechanism of action of realgar. DESIGN, TIME AND SETTING: Randomized, controlled, cytological experiment, performed in the Institute of Clinical Pharmacology, Guangzhou University of Traditional Chinese Medicine in March 2006. MATERIALS: Thirty-six healthy, male, Sprague Dawley rats received 250 U/kg Bordetella pertussis via the common carotid artery within 15 seconds to induce inflammatory brain injury. Reagents and kits were as follows: Realgar and Angong Niuhuang powder (Foshan Second Pharmaceutical Factory, China), Bordetella pertussis diagnostic antigen (National Institute for the Control of Pharmaceutical and Biological Products, China), heat shock protein 70 (HSP70) enzyme-labeled immunosorbent assay (ELISA) kit (Stressgen, USA), tumor necrosis factor-α (TNF-α) ELISA kit (Biosource, USA), nitric oxide synthase (NOS) kit, Coomassie brilliant blue protein kit (Nanjing Jiancheng Bioengineering Co.,Ltd., China), and complements C3 and C4 (Shanghai Kehua Dongling Diagnositic Products Co.,Ltd., China). METHODS: Thirty-six rats were randomly and evenly divided into the following six groups: normal control, model, high-, middle-, and low-dose realgar-treated, and Angong Niuhuang-treated groups. At one hour prior to establishing the model, rats in the high-, middle-, and low-dose realgar-treated groups were administered 300, 150, and 75 mg/kg realgar, respectively; while rats in the Angong Niuhuang group received 1.5 g/kg Angong Niuhuang powder; In the model group, rats were administered Bordetalla pertussis only. MAIN OUTCOME MEASURES: Two hours after the administration of Bordetalla pertussis, the HSP70 level in the brain tissue and serum levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and TNF-α were determined by ELISA tests, hemooxygenase-1 (HO-1) activity in the brain tissue and serum was determined by dual-wavelength spectrophotometry, NOS and inducible nitric oxide synthase (iNOS) activities in the brain tissue were measured by the Bradford assay method, and serum levels of complement C3 and C4 were determined by immunoturbidimetry. RESULTS: In the high-dose realgar and Angong Niuhuang groups, the HSP70 level in the brain tissue of rats with inflammatory brain injury was increased significantly (P < 0.01). In the realgar-treated groups, HO-1 activity in the brain tissue and serum was dose-dependently enhanced with increasing realgar doses. However, no significant difference existed between the realgar groups and the model group (P > 0.05). In the Angong Niuhuang group, HO-1 activity in the brain tissue and serum was increased (P < 0.05). In the realgar and Angong Niuhuang groups, serum levels of IL-1β, IL-6, and TNF-α were significantly decreased; the serum IL-1β level recovered to the normal level and serum levels of IL-6 and TNF-α dose-dependently decreased in the realgar groups. NOS activity in the brain tissue was lower in the high-dose realgar group than in the model group (P < 0.05). iNOS activity was significantly lower in the middle- and high-dose realgar groups than in the model group (P < 0.01). NOS and iNOS activities were significantly lower in the Angong Niuhuang group than in the model group (P < 0.01). The serum C3 level was significantly decreased in the middle-dose realgar and Angong Niuhuang groups (P < 0.01). CONCLUSION: At certain doses, realgar is able to correct the oxidative stress state, by inducing and activating endogenous protective factors, such as HSP70, and inhibiting the excessive release of inflammatory mediators, such as IL-1β, IL-6, and TNF-α. However, it remains unclear whether realgarinhibits the activation of C3 and C4. BACKGROUND: The Chinese herbal compound realgar exerts detoxification effects as an adjuvant. It is suggested that realgar exerts detoxification via the following pathways: in the pathological state, realgar corrects the oxidative stress state by increasing stress levels, activating some endogenous protective factors and antagonizing the excessive release of inflammatory factors, as well as inhibiting complement activation. OBJECTIVE: To observe the changes in stress proteins, inflammatory mediators, and complement in the brain tissue and serum of rats with inflammatory brain injury, which have been treated with the Chinese herbal compound Angong Niuhuang, and to compare the efficacy of Angong Niuhuang with that of realgar, to verify the mechanism of action of realgar. DESIGN, TIME AND SETTING: Randomized, controlled, cytological experiment, performed in the Institute of Clinical Pharmacology, Guangzhou University of Traditional Chinese Medicine in March 2006. MATERIALS: Thirty-six heal thy, male, Sprague Dawley rats received 250 U / kg Bordetella pertussis via the common carotid artery within 15 seconds to induce inflammatory brain injury. Reagents and kits were as follows: Realgar and Angong Niuhuang powder (Foshan Second Pharmaceutical Factory, China), Bordetella pertussis diagnostic antigen (National Institute for the Control of Pharmaceutical and Biological Products, China), heat shock protein 70 (HSP70) enzyme-labeled immunosorbent assay (ELISA) kit (Stressgen, USA) ELISA kit (Biosource, USA), nitric oxide synthase (NOS) kit, Coomassie brilliant blue protein kit (Nanjing Jiancheng Bioengineering Co., Ltd.), and complements C3 and C4 (Shanghai Kehua Dongling Diagnostic Products Co., , China). METHODS: Thirty-six rats were randomly and equally divided into the following six groups: normal control, model, high-, middle-, and low-dose realgar-treated, and Angong Niuhuang-treated groups. At one hour prior to establishing the model, rats in the high, middle-, and low-dose realgar-treated groups were administered 300, 150, and 75 mg / kg realgar, respectively; while rats in the Angong Niuhuang group received 1.5 g / kg Angong Niuhuang powder; MAIN OUTCOME MEASURES: Two hours after the administration of Bordetalla pertussis, the HSP70 level in the brain tissue and serum levels of interleukin-1β (IL-1β), interleukin-6 (IL -6), and TNF-α were determined by ELISA tests of hemooxygenase-1 (HO-1) activity in the brain tissue and serum was determined by dual-wavelength spectrophotometry, NOS and inducible nitric oxide synthase (iNOS) activities in the brain tissue were measured by the Bradford assay method, and serum levels of complement C3 and C4 were determined by immunoturbidimetry. RESULTS: In the high-dose realgar and Angong Niuhuang groups, the HSP70 level in the brain tissue of rats with inflammatory brain injury increased significantly (P <0.01). In the realgar-treated groups, HO-1 activity in the brain tissue and serum was dose-dependently enhanced with increasing realgar doses. However, no significant difference existed between the realgar groups and the model group (P> 0.05) In the Angong Niuhuang group, HO-1 activity in the brain tissue and serum was increased (P <0.05). In the realgar and Angong Niuhuang groups, serum levels of IL-1β, IL-6 and TNF-α were significantly decreased; the serum IL-1 β level recovered to the normal level and serum levels of IL-6 and TNF-α dose-dependently decreased in the realgar groups. NOS activity in the brain tissue was lower in the high-dose realgar group than in the model group (P <0.05). iNOS activity was significantly lower in the middle- and high-dose realgar groups than in the model group (P <0.01) .NOS and iNOS activities were significantly lower in the Angong Niuhuang group than in the model group (P <0.01). The serum C3 level was significantly decreased in the midd le-doseRealgar and Angong Niuhuang groups (P <0.01). CONCLUSION: At certain doses, realgar is able to correct the oxidative stress state, by inducing and activating endogenous protective factors, such as HSP70, and inhibiting the excessive release of inflammatory mediators, such as IL-1β, IL-6, and TNF-α. However, it remains unclear whether realgar inhibits the activation of C3 and C4.