蛋氨酸胆碱对染铅大鼠海马神经元影响

Effects of methioine choline on hippocampal neurons of lead-exposed rats

目的探讨蛋氨酸胆碱对刚断乳SD大鼠铅染毒后海马神经元形态及超微结构损伤的改善作用。方法 40只SPF级SD雄性大鼠随机分为5组:空白组、染铅组、蛋氨酸胆碱组、铅+低、高剂量蛋氨酸胆碱组,4和8周后分别麻醉动物,尾尖采血,原子吸收法测血铅含量;心脏灌注内固定,取海马做石蜡切片、硫堇染色观察海马神经元形态结构,戊二醛再固定,透射电镜观察超微结构。结果铅染毒4、8周后,染铅组大鼠血铅含量分别升高至(274.85±19.51)、(294.32±11.00)μg/L,与染铅组比较,铅+高剂量蛋氨酸胆碱组血铅含量(187.25±16.02,192.68±14.17)μg/L明显降低,差异有统计学意义(P<0.05);硫堇染色和透射电镜结果显示,4周时海马神经元无明显改变;8周时CA1区神经元有缺失、坏死,细胞数量由每3个视野(光镜400×)(306.00±43.05)个减少至(234.86±20.88)个,且超微结构发生改变,蛋氨酸胆碱干预后形态和结构均得到改善,且存在剂量-效应关系。结论铅对海马神经元形态和结构损伤出现较晚,蛋氨酸胆碱可改善铅染毒大鼠海马神经元的形态和结构损伤。

Objective To explore protective effects of methioine choline on morphology and structure of hippocampal neurons in rats exposed to lead.Methods Forty SPF weanling SD rats were randomly divided into five groups：blank,lead,methioine choline,and two lead plus different dose of methioine choline groups.After 4 and 8 weeks of treatment,the rats were anesthetized and blood sample was collected.Atomic absorption method was adopted to determine blood lead concentration.Cardiac perfusion fixation was conducted and hippocampus was removed for paraffin embedded sections.Thionin staining was adopted to observe morphology of hippocampal neurons.Transmission electron microscope（TEM） was used to observe ultramicrostructure of hippocampus after fixation with glutaraldelyde.Results After exposed to lead for 4 and 8 weeks,the blood lead concentration of the lead exposure group increased to 274.85±19.51,294.32±11.00 ug/L.Compared with that of the lead group,the blood lead concentration of high does methioine choline group（187.25±16.02,192.68±14.17 μg/L） reduced obviously with significant difference（P0.05）.Thionin staining and TEM showed that there was no significant change in hippocampal neurons after 4 weeks＇ treatment.But after 8 weeks,some nerve cell in CA1 disappeared and necrosed and the number of the neurons reduced from 306.00±43.05 to 234.86±20.88,with ultramicrostructure changes.After giving methioine choline,the morphology and structural of hippocampal neuronal were improved with dose-effect relationship.Conclusion The damages of hippocampal neuronal＇s morphology and structure caused by lead exposure is observed after longer exposure,and methionine choline palys an important role in the preventoin of the damages.