Sp8阳性细胞在健康及放射性脑损伤豚鼠 SGZ 区的表达

摘要

Objective ① To observe the expression of Sp8 positive cells(Sp8+)around the subgranular zone(SGZ)in normal adult guinea pig and to explore the correlation between the expression of Sp8+ and age; ② To observe the changes of Sp8 and DCX expression in the ipsilateral(irradiated)sides and further evaluate the effect of X-ray on neural stem cells(NSCs)in dentate gyrus of hippocampus. Methods ① Brain tissue sections were stained by immunohistochemical staining and immunofluorescence technique. 6-month-old adult guinea pigs were selected randomly for observing Sp8+ cells expression around the SGZ; ② Sp8 was double-labeled by immunofluorescence with CB, GFAP, PSA-NCAM, Sox2, Ki67 respectively; ③ Newborn, 6-month-old, 2-year-old and 3.5-year-old guinea pigs(4 in each group)were applied to observe the expression of sp8+ cells in the SGZ; ④ Twenty healthy adult guinea pigs were employed to accept X-ray irradiation of the left brain on the 1st, 3rd, 7th day respectively. Each animal received two times of irradiation(3 days apart), each with 5 Gy applied, and were broken end on the 14th day to observe the changes of Sp8, and DCX expression in the ipsilateral sides compared with the contralateral sides by immunohistochemistry technique(ABC)method. Results ① Sp8+ cells in healthy adult guinea pigs SGZ were widely expressed; ② Sp8+ cells at the SGZ co-expressed neural stem cell markers Sox2; ③ The expression of Sp8+ cells were gradually decreased with age(P<0.05); ④ DCX positive cells in the ipsilateral side were significantly downregulated compared with the contralateral side in the SGZ(P<0.05), and the amount of Sp8+cells around the SGZ appeared comparable between the two sides(P>0.05). Conclusion widely expressed in neurogenic regions of hippocampus; ② Sp8+ which labeled neural progenitor-like cells in adult guinea pigs were in quiescent; ③ Loss of neural progenitor population with age in the hippocampal dentate gyrus; ④ Sp8+ cells around the SGZ were resistant to X-ray irradiation.① Sp8+ were widely expressed in neurogenic regions of hippocampus; ② Sp8+ which labeled neural progenitor-like cells in adult guinea pigs were in quiescent; ③ Loss of neural progenitor population with age in the hippocampal dentate gyrus; ④ Sp8+ cells around the SGZ were resistant to X-ray irradiation.%目的：①观察 Sp8阳性细胞（Sp8+）在健康成年豚鼠海马齿状回颗粒细胞下区（SGZ 区）的表达，并探讨其表达与年龄的相关性；②观察放射性脑损伤豚鼠放射侧 SGZ 区 Sp8及 DCX 的表达变化，进一步探讨 X 线对海马齿状回神经干细胞群的影响。方法①运用免疫组化染色及免疫荧光技术对脑组织切片进行染色。随机选取6个月龄健康成年豚鼠4只用于形态学观察，观察正常成年豚鼠 SGZ 区的 Sp8表达；② Sp8分别与 Neun、CB、GFAP、PSA-NCAM、Sox2、Ki67抗体进行免疫双标；③新生、6个月龄、2岁以及3.5岁豚鼠各4只，用于观察Sp8在不同年龄组豚鼠SGZ区表达的差别；④建立单侧颅脑放射性脑损伤模型：6个月龄健康成年豚鼠20只分别在第1、3、7天接受左侧颅脑 X 线照射，每天照射2次，单次照射剂量为5Gy，于第14天进行断头处理。选取海马部位清晰完整的冠状位组织切片，分别进行 Sp8及 DCX 的免疫组化染色，观察两者在放射侧 SGZ 区的表达变化。结果① Sp8+细胞在健康成年豚鼠 SGZ 区广泛表达；② Sp8+细胞与神经干细胞标记物 Sox2共存；③豚鼠 SGZ 区 Sp8+细胞的表达随着年龄的增长呈逐渐下降趋势（P<0.05）；④放射侧 SGZ 区 DCX 阳性细胞数量较对照侧显著减少（P<0.05），而两侧 Sp8+细胞数量差异不明显（P>0.05）。结论① Sp8+细胞在豚鼠海马齿状回神经发生区广泛表达；② Sp8可能是海马齿状回神经发生区静息状态神经干细胞的一种标记物；③豚鼠 SGZ 区神经干/祖细胞的减少与年龄呈负相关性；④ X 线抑制 SGZ 区新生神经元的生成，而 Sp8+细胞可抵抗 X 线损伤。