锰中毒对小鼠海马神经干细胞增殖的影响

目的探讨锰中毒对小鼠大脑海马区神经干细胞增殖状况的影响。方法将体重为8-10g的28只昆明种小鼠分为生理盐水对照组和低、中、高剂量3个染毒组每组7只，通过腹腔注射氯化锰染毒，染毒剂量分别为5、20、50mg／kg，用Morris水迷宫检测其学习记忆能力情况，以免疫组化方法检测其大脑海马结构的齿状回颗粒下区（SGZ）神经发生情况。结果（1）与对照组比较，各染毒组小鼠的学习和空间记忆能力明显降低，差异有统计学意义（P〈0．01），以高剂量组最为明显；同时，记忆能力与染毒剂量呈负相关（rs=-0．598，P〈0．01），而各组小鼠游泳速度的差异无统计学意义（P〉0．05）；（2）各染毒组小鼠的齿状回颗粒下区内5-溴代脱氧尿嘧啶核苷（BrdU）阳性细胞平均数目均比对照组明显降低，差异有统计学意义（P〈0．01），且随剂量加大而减少，与中毒剂量呈负相关（rs=-0．666，P〈0．01）；（3）空间记忆能力的减退和SGZ内BrdU阳性细胞平均数目减少之间呈正相关仉=0．734，P〈0．01）。结论幼年小鼠接触锰可影响其学习记忆能力，其机制可能与抑制海马结构的神经干细胞增殖有关。

Effects of manganismus on proliferation of neural stem cells in mice's hippocampys

OBJECTIVE: To explore the effects of manganese poisoning on the proliferation of neural stem cells (NSCs) in mice's hippocampus. METHODS: The mice (weight 8 approximately 10 g) were divided into control group(CG) low-dose group(LDG) middling-dose group(MDG) and high-dose group(HDG)by intraperitoneal injection of 0, 5, 20, 50 mg x kg(-1) x d(-1) of manganese chloride dissolved in physiological saline. The ability of learning and memory was detected by Morris Water Maze, and the proliferation of NSCs in subgranular zone (SGZ) in these mice's hippocampus was also detected by immunohistochemistry. RESULTS: 1) Compared with the CG, the ability of learning and memory in all manganism group decreased significantly (P < 0.01) and this phenomenon in HDG was most notable (P < 0.01). Meanwhile, the ability of memory was negatively correlated with the dose of manganese chloride (r(s) = -0.598, P < 0.01), but the difference of swimming speed in every group was of no statistic significance. (2) The numbers of NSCs in proliferation period in SGZ of all manganism groups was much lower than that of CG (P < 0.01) negatively correlated with the dose of manganese chloride (r(s) = -0.666, P < 0.01). (3) The reduction of NSCs had a postive correlation to the depression of learning and memory (r(s) = 0.734, P < 0.01). CONCLUSIONS: Manganismus can affect the ability of learning and memory, which is probably caused by the inhabition of manganese on NSCs in hippocampus.