铅对仔鼠学习记忆及海马中CTGF表达影响

Lead(Pb^(2+)) impairs ability of learning and memory and effects expression of CTGF in hippocampus in mice

目的探讨母体铅染毒对其仔鼠学习记忆海马组织中结缔组织生长因子(CTGF)mRNA和蛋白表达的影响,为进一步研究铅的神经毒作用机制提供科学依据。方法采用自由饮水的方式于母鼠孕哺期染毒,染毒剂量为0.3,1,3g/L,每组10只,用石墨炉原子吸收光谱仪测定仔鼠出生后7,14,21d时血液和海马组织中铅含量。用RT-PCR和免疫组化方法分别测定21d不同剂量组仔鼠海马组织中CTGF mRNA和蛋白的表达。结果各剂量染铅组血染、海马组织中铅含量与对照组比较,明显升高(P均<0.05),血液和海马组织的铅含量随着日龄的变化有一定的规律性;迷宫实验中,对照组、0.3,1,3g/L组平均潜伏期分别为(39.13±6.12)(43.22±9.86),(50.85±12.35),(50.85±12.35)s,与对照组比较,0.3g/L组差异无统计学意义(P>0.05),与1,3g/L剂量组比较差异有统计学意义(P<0.05);在对照组、0.3,1,3g/L组仔鼠海马组织中,CTGF mRNA的相对表达量分别为(0.354±0.603),(0.945±0.522),(1.223±0.279),(1.612±0.136);CTGF蛋白表达的灰度值分别为(126.10±32.11),(186.31±36.17),(220.94±31.27),(286.21±31.24);与对照组比,0.3,1,3g/L组海马中(CTGF mRNA和蛋白表达明显升高(P均>0.05)。结论孕哺期母体铅暴露可使铅在仔鼠体内人蓄积,引起仔鼠学习记忆力功能损害;铅所引起的神经毒性可能通过铅诱导CTGF mRNA和蛋白的高表达,造成神经系统的损害。

Objective To fred the effect of lead on learning, memory and the expression of CTGF mRNA and protein in rats for further revealing neurotoxic mechanism of lead. Methods Pregnant mice（ 10 for ecah group） were exposed to low（0.3 g/L）,moderate（1 g/L） and high-level（3 g/L） Pb acetate in deionized drinking water from the first day of gestation to 21th postnatal day （PND）. The lead concentration in blood and hippocampus at the 7th, 14th, 21th day of neonatal mice pups was determined with graphite furnace atomic absorption spectrometry. The ability of learning and memory and the expression of connective tissue growth factor（CTGF） mRNA and protein in hippocampus of different pup groups at the 21th day were measured with Water Morris Maze,RT-PCR and immunohistochemistry assay. Results The lead concentration in lead exposure group was higher than that of control group（ P 〈 0.05 ）. The change of the lead level in blood and hippocampus showed a regular pattern. In Water Morris Maze test, the mean incubation period in control group, low,moderate, high lead exposure group were 39. 13 ± 6. 12,43.22 ± 9. 86,50. 85 ± 12. 35,50. 85 ± 12. 35 seconds, respectively. The relative expression level of CTGF mRNA in control group, low, moderate, and high lead exposure group were 0. 354 ± 0. 603,0. 945 ± 0. 522,1. 223 ± 0. 279,1. 612 ± 0. 136, and the gray scale of CTGF in hippocampus of pups were 126. 10 ±32. 11,186. 31 ±36. 17,220.94 ±31.27,286. 21 ±31.24,respectively. The low lead exposure group showed no statistically significance compared with the control group （ P 〉 0. 05 ）. However, there were statistical differences in moderate and high lead exposure groups（ P 〈 0.05, P 〈 0.01 ）. The expression of CTGF mRNA and protein was stronger in lead exposure groups than in control group （ P 〈 0. 05）. Conclusion Pb acetate exposure in pregnant mice results in lead accumulation in the body of rat pup, and affects study and memory function of pup mice. The neurotoxicity of Pb may result from the lead-induced high expression of CTGF mRNA and protein.