| Baicalin, a flavonoid compound derived from the root of Scutellaria baicalensisi Georgi,is one of the most effective ingredient of Scutellaria, which has sugnificant effect on pyretolysis. Baicalin is also valid on bacteriostatic action , such as decreasing the con-dosage of antibiotics, reducing toxico and adverse reaction and changing some drug-resistance bacteria into sensitive bacteria. Therefore, baicalin has been noticed and has distinctive advantages compared to western antipyretic medicine. Pyretogenesis is the common symptom in many clinic diseases, which has a complicated process of multiple links and factors. So, the body temperature may decrease to nomal if one of these links was refrained. Howerer, the mechanism of the antipyresis of baicalin is not clear now , and whether it can prevent the production of endogenous pyrogen(EP) or not has not been reported.The purpose of the essay was attempted to explor the relationship between the antipyretic effect of baicalin and EP by assessing the changes in core temperature(Tco), in serum, hypothalamus and cerebral spinal fluid(CSF) levers of IL-6, IL-1βand TNF-αconcentrations during yeast-induced fever in rats with or without systemic treatment of baicalin. Moreover, in order to approach whether baicilin exert its antipyresis by inhibiting the transcription of IL-1β, the RT-PCR assay was used to determine IL-1βmRNA of hypothalamu in rats.1. The antipyretic effect of baicanlin on rats of yeast-induced feverDose of sterile saline or 20% yeast(2 g·kg -1)was subcutaneously(sc) adminstered in rats, then baiclin(160,80,40mg·kg-1) were intragastric administered to rats, and their effects on Tco were measured every 2 hours ,.Temperature response was assessed as changes from pre-injection values(△T℃), the curve produce for 14 hours after the injection, in term of degrees centigrade were calculated. Subcutaneous administration of yeast caused fever at 6 hour, with Tco maximal at 8 hour and maintaining fever of 14 hours. The△T were dose dependently reduced by pretreatment with baiclin(160,80,40mg·kg-1,ig)after yeast injection. The results demonstrate that baicalin may exert its antipyresis during yeast-fever.2. The effects of baicalin on EP and the studies of correlation between its antipyretic effect and EPAfter sc injection of dose of sterile saline or yeast in rats, baicalin (160mg·kg-1,80mg·kg-1,40mg·kg-1) were intragastrically(ig) administered in rats and their effects on Tco were measured. Dual antibody ELISA assay was used to detemine the levers of EP in serum , hypothalamus and CSF 8 hours after administration. Then the antipyresis for regression equation of EP were calculated. The temperature elevation was significantly reduced as well as the IL-6, IL-1βand TNF-αconcentrations in serum , hypothalamus and CSF after systemic adminstration of baicalin(160mg·kg-1). The correlation analysis suggested the variation ratio of temperature induded by baicalin had direct correlation with that of IL-1β(r=0.8726,P <0. 05), as well as the TNF-α(r=0.8624,P <0. 01), but it had no correlation with IL-6(r=0.3794,P > 0. 05). Moreover, it also demenstrated that there were direct correlation between the reduction of rats'temperature and the decrease of cytokine contents in serum(r=0.8838,P < 0. 01),hypothalamus (r=0.6734,P < 0. 05) respectivly,in CSF(r= 0.3521,P > 0. 05). The results suggested that baicalin may exert its antipyresis by decreasing the contents of IL-1βand TNF-αin serum and hypothalamus.3. The effect of baicalin on EPmRNA expressionThe IL-1βmRNA of hypothalamu was assessed by RT-PCR assay 8 hours after ig administration of baicalin(160mg·kg-1)in rats. It showed that the expression of IL-1β mRNA in the rats'hypothalamus was significantly reduced accompaning with the temperature decrase after pretreatment with baicalin. The results suggested that the antipyretic effect of baicalin may be revelent to decreasing the transcription of IL-1β, and hence the reduction of its contents in rats'hypothalamus. |
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