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目的观察发育期慢性低浓度铅暴露对大鼠脑海马代谢型谷氨酸受体5(mGluR5)表达和学习记忆能力影响。方法 30只孕鼠按体重随机分成3组,分别给予双蒸水、0.05%、0.20%醋酸铅饮水,断乳后仔鼠自行饮用含铅水,至出生后28、56 d用水迷宫方法测试仔鼠学习记忆行为改变;蛋白印迹(Western blot)方法检测脑海马mGluR5蛋白表达。结果发育期慢性低浓度铅暴露可导致仔鼠空间定位航行能力降低;与对照组比较,训练第3、5、7 d,0.05%、0.20%醋酸铅组大鼠寻找平台时间[分别为(40.13±9.20)、(32.82±6.45)、(26.83±7.12)和(61.50±13.84)、(54.51±9.65)、(19.81±4.92)s]明显延长,差异有统计学意义(P<0.05);生后第7、14、21、28 d,0.05%,0.20%醋酸铅组脑海马mGluR5蛋白表达量分别为[(0.607±0.027)、(0.845±0.010)、(0.713±0.004)、(0.587±0.011)]和[(0.540±0.025)、(0.573±0.014)、(0.551±0.014)、(0.492±0.017)],均明显低于对照组(P<0.05)。结论孕鼠低水平铅暴露可致仔鼠空间学习能力降低,其机制可能与脑海马mGluR5蛋白表达水平下降有关。
Objective To observe the effect of chronic low lead exposure during developmental period on the expression of hippocampal metabotropic glutamate receptor 5 (mGluR5) and learning and memory ability in rats. Methods Thirty pregnant rats were randomly divided into three groups according to their body weight. Rats were given double distilled water, 0.05% and 0.20% lead acetate respectively. After weaning, the pups themselves consumed lead-containing water. At 28 and 56 days after birth, The learning and memory behaviors were changed. The expression of mGluR5 protein in hippocampus was detected by Western blot. Results Chronic exposure to low concentrations of lead during developmental period led to the reduction of space navigation abilities in pups. Compared with the control group, rats in the lead, lead, and zinc groups at the 3rd, 5th, 7th d, 0.05% and 0.20% 9.20, 32.82 ± 6.45, 26.83 ± 7.12, and 61.50 ± 13.84, 54.51 ± 9.65, and 19.81 ± 4.92 s, respectively), the difference was statistically significant (P <0.05) The expression of mGluR5 protein in hippocampus of lead group at 7th, 14th, 21st, 28th day, 0.05% and 0.20% levels were (0.607 ± 0.027), (0.845 ± 0.010), (0.713 ± 0.004) and (0.587 ± 0.011) (0.540 ± 0.025), (0.573 ± 0.014), (0.551 ± 0.014) and (0.492 ± 0.017), respectively, were significantly lower than those in the control group (P <0.05). Conclusion Low level lead exposure in pregnant rats may decrease the spatial learning ability of offspring rats, which may be related to the decrease of mGluR5 protein expression in hippocampus.