亚慢性铅染毒大鼠学习记忆行为和大脑皮质、海马NOS、NO、SOD、MDA的影响

目的：研究亚慢性铅接触对大鼠学习记忆行为和大脑皮质、海马一氧化氮合成，脂质过氧化的影响，探讨其影响的可能性机理。方法：wistar大鼠分5组，每组分别以醋酸铅0、18．4、184．0mg／L剂量经口染毒，于染毒7、14、30、60、90d先测试学习记忆行为，再测定全血血铅及大脑皮质、海马中NOS、SOD活性、NO、MDA水平。用暗室电击试验测试学习记忆行为。用原子吸收法测全血血铅浓度。用左旋-精氨酸法测定NOS活性，用硝酸还原酶法测定NO水平，用亚硝酸盐显色法测定SOD活性，用硫代巴比妥法测定MDA水平。结果：1．低、高剂量染铅组血铅水平在各时点均显高于对照组，高剂量组亦高于低剂量组。2．暗室电击试验结果显示，染铅剂量越高，染铅时间越长，大鼠建立条件反射的时间越长。3．大脑皮质、海马NOS、NO、SOD、MDA测定结果显示，随着染铅剂量加大，NOS活性降低，同时NO水平下降，SOD活性显降低，MDA水平显升高。4．以学习记忆行为指标为应变量，血铅、海马和皮质NO、NOS、SOD、MDA为自变量的多因素分析，低剂量组血铅，海马NOS、皮质SOD进入回归方程；高剂量组血铅、海马NO、皮质SOD、MDA进入回归方程。结论：亚慢铅接触可能通过影响大鼠脑皮质、海马NOS、SOD酶活性及NO、MDA水平，干扰NO合成及脂质过氧化过程，进而影响大鼠的学习记忆行为。

The effect of sub-chronic lead exposure on learning and memory behavior and NOS、NO、SOD and MDA express in rat

Objective:To study the effects of sub chronic lead exposure on learning and memory behavior and nitric oxide synthesis and lipid peroxid of brain tissue in rat.Methods:The rats were divided into 7,14,30,60 and 90d groups.The drinking water containing 0,18 4 and 184 0 mg/L lead were provided to every group.The learning and memory behavior were by electric stroke test in darkroom and the express of nitric oxide synthase(NOS),nitric oxide(NO),super oxide dismutase(SOD) and malondialdehyde(MDA) in brain tissue were detected by different methods.Results:At the different time point,the blood concentration in high dose group was higher than lowdose group, P <0 05;The darkroom electric stroke test showed that the higher dose and longer time lead exposure need to the longer time to establish condition reflex;The detected results of NOS,NO,SOD and MDA in brain tissue showed high dose lead exposure made the NOS,SOD activity and express of NO decreased and MDA content markedly in creased, P <0 05;The multiple factor analysis that the learning and memory behavior was dependent variable and blood lead,NO,NOS,SOD,MDA of hippocampus and cerebral cortex were independent variable showed in low dose group,blood lead,NOS of hippocampus and SOD of cerebral cortex enter the regression equation and in high dose group,NO of hipppcampus and SOD,MDA of cerebral cortex enter the regression equation.Conclusion:The sub chronic lead exposure maybe can affect on learning and memory behavior through affecting on NOS and SOD activity the express of NO and MDA in brain tissue.