Abstract: OBJECTIVE:To study the effect of Lichong decoction(LD) on expression of matrix metalloproteinase-2(MMP-2) and metalloproteinase-2(TIMP-2) in a rat model of uterine leiomyoma(UL).METHODS:UL was induced in rats using exogenous estrogen and progesterone.LD was administered(p.o.) for 4 weeks,and mifepristone(RU-486)used as a control.To observe the effect of LD on the uterine coefficient and uterine transverse diameter,a radioimmunoassay method was used to detect serum levels of sex hormones.Light microscopic analyses of pathologic changes in the tissues of UL rats were evaluated.Expression of the proteins of matrix metalloproteinases(MMPs) and tissue inhibitors of metalloproteinases(TIMPs) in uterine tissues was assessed by immunohistochemical staining and western blotting.RESULTS:A UL model in rats was established successfully.LD reduced uterine weight,uterine coefficient,and uterine transverse diameter compared with untreated controls.LD reduced levels of estradiol,progesterone,follicle-stimulating hormone,and luteinizing hormone in our UL models.LD improved the pathologic condition of uterine muscle.Expression of MMP-2 protein decreased to varying extents in LD-treated groups,but TIMP-2 levels were enhanced.LD appears to reduce MMP-2 expression and increase TIMP-2 expression in UL tissue.CONCLUSION:These data suggest that the mechanism of action of LD on ULs may involve reduction of MMP-2 expression and increase in TIMP-2 expression in rats.

Key words: Leiomyoma, Matrix metalloproteinase 2, Tissue inhibitor of metalloproteinase-2, Lichong decoction