锌对染铅大鼠海马一氧化氮合酶的保护作用

[目的]探讨铅对海马长时程增强(LTP)的影响与海马不同亚区一氧化氮合酶(NOS)变化的关系以及锌的拮抗作用.[方法]采用反映学习记忆功能的Y迷宫法测试大鼠神经行为的改变;用NADPH-黄递酶(NADPH-d)组化法和神经元型NOS(nNOS)的免疫组化法研究大鼠海马不同亚区NOS的活性及表达情况.[结果]染铅组大鼠的学习记忆能力比铅锌组和对照组明显下降(P＜0.05),铅锌组与对照组之间无差别;组化及免疫组化显示染铅组大鼠海马CA1区和齿状回的NOS和nNOS阳性神经元明显少于铅锌组和对照组(P＜0.05),在CA3区无差别,铅锌组与对照组各亚区均无差别.[结论]铅可损伤大鼠学习记忆能力,鉴于NOS参与LTP这一代表学习记忆的电生理指标的形成和维持,推测铅对学习记忆和海马LTP的影响可能与染铅后海马各区NOS的不同变化有关.锌对铅引起的学习记忆损伤和NOS的影响有拮抗作用.

Protection of zinc on hippocampal nitric oxide synthase in lead-exposed rats

To investigate the relationship between the effects of lead on long term potentiation(LTP) in hippocampus and changes of nitric oxide synthase(NOS) in subfields of hippocampus, and the antagonistic role of zinc.Y-maze test was applied to study the effects of lead on learning and memory ability in rats; NADPH-d histochemistry and nNOS immunohischemistry were used to investigate the activity and protein expression of NOS in different hippocampal subfields in lead-exposed rat.Compared with the control and lead-zinc group, the learning and memory ability of lead-exposed rats was significantly decreased(P<0.05); the number of NOS positive neurons and neuronal nitric oxide synthase(nNOS) positive neurons in CA_1 and dentate gyrus of lead-exposed rats were significantly decreased(P<0.05), but no significant changes in CA_3; no difference was found between the control and lead-zinc groups in CA_1, CA_3 and dentate gyrus.[Conclusion]Lead may damage the learning-memory ability of the rats; the effects of lead on LTP in hippocampus might be related to the changes of NOS in different subfields of hippocampus in lead-exposed rats; zinc might play an important role in preventing lead-induced damages.