镧对大鼠大脑皮质兴奋性氨基酸和钙稳态的影响

目的 观察镧对大鼠学习记忆的影响,并从大脑皮质兴奋性氨基酸水平和钙稳态的角度探讨镧影响学习记忆的机制.方法 将40只雌性Wistar大鼠随机分为对照组和低、中、高剂量LaCl_3(0.25%,0.50%,1.0%)染毒组,每组10只.LaCl_3,染毒组仔鼠在出生至断乳后1个啁期间染镧,然后进行跳台测试,并测定大脑皮质中兴奋性氨基酸含量、细胞内钙离子浓度以及尼氏体表达水平.结果 跳台测试结果表明,LaCl_3,染毒组仔鼠的学习记忆能力明显低于对照水平,具有一定的剂量.效应关系;低、中剂量LaCl_3染毒组大脑皮质谷氨酸含量和细胞内Ca~(2+)浓度明显高于对照组,高剂量LaCl_3染毒组大脑皮质谷氨酸、天冬氨酸含量和细胞内Ca~(2+)浓度显著高于对照组和低、中剂量LaCl_3,染毒组.此外,低剂量LaCl_3染毒组大脑皮质神经细胞中尼氏体表达水平明显低于对照组,中和高剂量LaCl_3,染毒组大脑皮质神经细胞中尼氏体表达水平进一步降低.结论 本实验结果表明镧可能是通过使兴奋性氨基酸水平异常升高和钙稳态失衡的机制引起大脑皮质神经细胞损伤,造成学习记忆能力低下.

Effects of Lanthanum on Excitatory Amino Acids and Calcium Homeostasis of Cerebral Cortex in Rats

Objective To observe the effects of lanthanum on learning and memory,and explore the corresponding mechanism on the basis of the levels of excitatory amino acids and calcium homeostasis of cerebral cortex in rats.Methods Forty female Wistar rats were randomly divided into control,low-,moderate-and hish-dose lanthanum groups(ten rats in each group).The offspring of lanthanum exposure groups were administrated with lanthanum from weaning for one month.The capability of learning and memory was measured by neuroethology testing.The levels of excitatory amino acids,intracellular calcium ion and Nissl body expression of cerebral cortex were also detected.Results The capabilities of learning and memory in lanthanum exposure groups were significantly lower compared with the control,with a dose-dependent manner,The levels of glutumate and intracellular calcium ion of cerebral cortex in low-and moderate-dose group were significantly higher than those in controls,and the levels of glutamate,aspartate and intracellular calcium ion of cerebral cortex in high-dose group were increased significantly as compared with the control group,low dose group and moderate dose lanthanum group.Besides,Nissl body expression of cerebral cortex in low-dose group was lower than that in control group.and the levels of Nissl body expression of cerebral cortex in middle dose lanthanum group and high dose groups decreased further.Conclusion The increased levels of excitatory amino acids.caleium homeostasis unbalance and cellular iniuries in cerebral cortex may be involved in lower capacity of learning and memory in the rats exposed to lanthanum.