Effects of lead exposure during different gestation period to rat placenta and the expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1

Abstract

Objective To explore the pathogenesis of placenta toxicity of lead exposure during different gestation periods by testing the blood lead level and the expression of mairix metalloproteimrse-9(MMP-9)and tissue inhibitor of metalloproteinase-1(11MP-1)in rat placenta.Methods108 Wistar rats(72 female,36 male)were randomly divi(1ed into four groups.All rats were orally fed with 0.025%lead acetate during different gestation periods.Blood was obtained from the abdominal vena cava and the lead level in matemal blood was measured by means of atomic absorption speclremetrv at the end of the pregnancy.The expression of MMP-9 and TIMP-1 in rat placenta was tested by means of immunohistochemistry.Results(1)The blood lead level in the end of pregnancy was 0.04μmol/L ±0.01 in control group.while jn experimental groups the blood lead levels were all higher than 0.483μmol/L,among them the highest blood lead level was in experimental group C.(2)The expression of MMP-9 and TIMP-1 mostly distilhated in trophoblastic cells.(3)The expression of MMP-9 had significant difference in four groups(x2=28.381,P＜0.01).The expression of MMP-9 was significantly reduced in experimental group C(the highest blood lead level)compared with control group.(4)The expression of,TIMP-1 had significant difference in four groups(x2=18.177,P＜0.05).The expresion of TIMP-1 was signifieantly increased in experimental group A、C compared with control group.Conclusions The expression of MMP-9 and TIMp-1 in rat placenta mosfly distributed in trophoblastic cells.They would change when the deglee of lead poisoning was more serious.The inbalance of expression of MMp-9/TIMP1 may play an important role in pathogenesis of placenta toxicity of lead exposure. Key words: Iead; Models Animal; Piaeenta; Matrix Metalloproteinase-9; Tissue Inhibitor of Melalloproteinases