甲基汞染毒对小鼠海马超微结构及mGluR2、3、5mRNA表达的影响

Effects of perinatal exposure to methylmercury on changes of hippocampal ultrastructure and expression of metabotropic glutamate receptor 2,3,5mRNAs in offspring's mice

目的观察围产期甲基汞染毒对幼鼠海马的超微结构及mGlu2、3、5mRNA表达的影响。方法将BALB/c孕鼠随机分为四组,分别给予0、1、2、4mg/(kg·d)氯化甲基汞饮水染毒至仔鼠出生后18d,于21、42、60天进行电镜超微结构观察及实时荧光定量PCR检测。结果各组海马组织损伤随染毒剂量的增加而加剧,且损伤随去除染毒时间的增加而减轻。荧光定量PCR显示Ⅰ、Ⅱ、Ⅲ组mGluR3、mGluR5的mRNA表达随染毒剂量增加而下降,而Ⅳ组的表达略高于Ⅲ组;mGluR2基因Ⅱ组的mRNA表达最低,Ⅲ、Ⅳ组的表达随染毒剂量增加而升高。仔鼠生后21、42、60天各染毒组的mGluR2、mGluR3、mGluR5基因mRNA表达量均低于相应对照组,且随仔鼠的增龄而增加。结论围产期海马组织损伤随甲基汞染毒剂量增加而加剧;mGluR2、mGluR3、mGluR5基因mRNA表达量随染毒剂量改变而改变,但两者之间不存在剂量效应关系。

Objectives To observe the effects of perinatal exposure to methylmercury on the changes of hippocampal uhrastructure and the expression of metabotropic glutamate receptor （mGluR） 2, 3, 5 mRNAs in offspring＇s mice. Methods Pregnant mice were randomly divided into four groups consisting of control group and low-dose, moderate-dose and high-dose groups. The mice in four groups were respectively fed with methylmercury chloride at the doses of 0, 1, 2 and 4 mg/kg·d from the gestation day 1 to the postnatal day 18. The offspring＇ s mice were respectively killed on 18, 21, 42 and 60 d after birth for the observation of the hippocampal ultrastructure with electron microscope and the detection of mGluR2, 3, 5 mRNAs expression with fluoresce quantified PCR, respectively. Results The hippocampal injury was aggravated or ameliorated significantly with the increase of exposure to methylmercury dose or with the increase of unexposure time, respectively. The expression of mGluR3 and mGluR5 mRNAs in the control group, low-dose group and moderate- dose group decreased with the increase of exposure to methylmercury dose, while there was a higher expression of mGluR3 and mGluR5 mRNAs in high-dose group comparing to those in moderate-dose group. The expression of mGluR2 in low-dose group was lowest among all four groups, and intensified in moderate-dose and high-dose groups with the in- crease of exposure to methylmercury dose. The all expressions of mGluR2, 3, 5 mRNAs in the low-, moderate-and high-dose groups were lower than those in the control group on postnatal day 21, 42 and 60, although the expressions in three groups tended to intensify with the increase of the day age. Conclusions The hippocampal injury may be aggravated with the increase of perinatal exposure to methylmercury dose. The expression of mGluR2, 3, 5 mRNAs may be changed with the increase of exposure to methylmercury dose, however, there is no significant dose-effect relationship to be confirmed between them.