目的探讨孕期亚硝酸盐暴露对海马损伤的作用。方法利用C57BL/6J小鼠建立孕期亚硝酸盐暴露模型,分为对照组(生理盐水)、低剂量亚硝酸盐组(60mg/kg)和高剂量亚硝酸盐组(120mg/kg)。收集出生当日(P0)、P7、P14及P30各年龄点仔鼠大脑,用于免疫荧光染色、彗星实验、Western blotting蛋白半定量分析,对海马损伤进行研究。结果不论是亚硝酸盐暴露组还是对照组,仔鼠齿状回增殖的神经干细胞数目均随着年龄的增长逐渐减少;在P0、P7、P14和P30年龄点,暴露组仔鼠增殖的神经干细胞的数量明显比对照组少,且具有剂量依赖性(P〈0.05,n=96)。为了鉴别这种抑制作用是否具有选择性,我们对P0仔鼠室管膜下区神经干细胞的增殖情况进行了观察。结果发现,亚硝酸盐暴露组室管膜下区的神经干细胞增殖较对照组也减少,同样具有剂量依赖性(P〈0.05);亚硝酸盐暴露组仔鼠门区炎症损伤细胞和凋亡细胞的数目比对照组多,具有剂量依赖性(P〈0.05);彗星实验结果显示,亚硝酸盐暴露组P0仔鼠海马细胞的彗尾比对照组长,具有剂量依赖性(P〈0.01);与对照组P0仔鼠相比,亚硝酸盐暴露组仔鼠海马组织内Caspase-8和核因子κB(NF-κB)蛋白的表达量较高(P〈0.05)。结论孕期亚硝酸盐暴露可通过抑制神经干细胞增殖,促进细胞损伤和凋亡而对仔鼠海马造成损伤。
Objective To investigate the effects on hippocampus after prenatal nitrite exposure. Methods C57BL/6J mice were used to establish the models of prenatal nitrite exposure with control group (physiological saline) , low dose nitrite exposure group (60 mg/kg) and high dose nitrite exposure group ( 120mg/kg). The pups of different groups at P0, P7, P14 and P30 were gathered for immunofluorescence, comet assay and Western blotting analysis to detect the hippocampal injury. Results In both nitrite exposure group and control group, the number of proliferative neuron in dentate gyrus gradually decreased with the growing age. At postnatal day 0 (P0) , P7, P14 and P30, after prenatal nitrite exposure, 5-bromo-2-deoxy Uridine (Brdg) positive cells decreased with dose dependency (P 〈 0.05, n = 96). In order to identify if the inhibtion was selective, we observed BrdU positive ceils in subventricular zone (SVZ) at P0 mouse. After nitrite exposure, BrdU positive cells in SVZ also decreased with dose dependency ( P 〈 0.05 ). The inflammatory injury and apoptosis cells in hilus increased with dose dependency after nitrite exposure (P 〈 0.05 ). The tail of hippocampus cells in nitrite exposure groups was longer than that in control groups with dose dependency (P 〈 0.01 ). The expressions of Caspase-8 and nuclear factor KB (NF-KB) protein in nitrite exposure groups in hippocampus were much higher than that in control groups ( P 〈 0.05 ). Conclusion Prenatal nitrite exposure can induce various hippoeampus injuries, such as neuroproliferative inhibition, oxidative stress and neuroapoptosis.