低剂量电离辐射对大鼠海马新生神经元树突生长发育的抑制作用

目的 观察电离辐射对幼年大鼠海马齿状回新生神经元树突生长发育的影响。方法 SD大鼠按随机数字表法分为照射组(20只)和健康对照组(20只),照射组给予单次2 Gy全脑照射。所有大鼠均予海马区立体定向注射反转录病毒标记新生神经元,免疫荧光染色观察照射后不同时间新生神经元树突形态的变化。结果 与健康对照组相比,照射组在照射后2周和4周新生神经元树突总长度、最长树突的长度均显著减少(t=3.10、2.07、2.94、4.02,P<0.05),神经元分支数在照射后2周显著减少(t=2.23,P<0.05)。照射后4周,海马区新生神经元数量显著降低(t=8.43,P<0.05)。结论 低剂量电离辐射可抑制幼年大鼠海马齿状回新生神经元的生长发育,这可能是射线致海马依赖的认知功能障碍发生的机制之一。

The inhibiting effects of low dose radiation on dendritic growth of newborn neurons in rat hippocampus

Objective To investigate the effects of low dose radiation on dendritic growth of newborn neurons in the hippocampus of young rat. Methods One month-old male rats were randomized into radiation group and sham control group. Radiation group received whole brain irradiation at a single dose of 2 Gy. Retrovirus expressing green fluorescent protein (GFP) was used to label newborn neurons in the hippocampus through stereotaxic intracranial infusion. Immunofluorescence assays were performed to detect dendritic architecture alterations induced by irradiation at different time points. Results Compared with control group, the lengths of total dendrite and the longest dendrite significantly decreased at 2 and 4 weeks after irradiation(t=3.10, 2.07, 2.94, 4.02, P<0.05). The branching points of new born neurons were also decreased significantly at 2 weeks post irradiation(t=2.23, P<0.05).The number of new born neurons reduced at 4 weeks post irradiation(t=8.43,P<0.05). Conclusions Low dose radiation could inhibit newborn neuron growth in the hippocampus of young rat, which may be one of the most important mechanisms involved in radiation-induced cognitive impairment.