模拟航天失重病理特征的小鼠模型的制备

Preparation of a Novel Mouse Model Mimicking The Pathological Features of Space Weightlessness

目的航天员返回地球后常常出现共济失调、步态紊乱,是航天医学难题。急需制备一种符合航天失重导致运动失调病理特征的小鼠,为药物筛选提供新模型。方法将雄性C57BL/6J小鼠随机分成:a.对照组,野生健康成年小鼠;b.标准模型组-后肢悬吊组(hindlimb unloading,HU),按照常规方法建立后肢悬吊法模型;c.假手术组(顶核注射磷酸缓冲液组);d.模拟病理特征模型组(顶核注射甲醛组),该组利用立体定位向健康成年雄性小鼠的小脑顶核内微量注射病理浓度的甲醛(尾吊组脑部测得的浓度)。造模结束后用转棒、平衡木、步态分析来评估小鼠的运动能力、小脑切片尼氏染色检测顶核神经元死亡、试剂盒及荧光组化检测甲醛生成酶——氨基脲敏感胺氧化酶(semicarbazide-sensitive amine oxidase,SSAO)活性及表达。用甲醛荧光探针检测小脑顶核的甲醛浓度。结果后肢悬吊组相较对于对照组的小鼠运动平衡能力下降、步态紊乱,并伴随小脑内SSAO活性及表达增强、内源甲醛显著上升、顶核神经元死亡。其次,模拟病理特征组小鼠的顶核注射病理浓度甲醛注射后,也出现尾吊标准模型类似的生化及行为变化。结论模拟航天失重的后肢悬吊小鼠小脑内SSAO活性和表达增强导致顶核内源甲醛蓄积,而高浓度的甲醛诱发了小脑顶核神经元死亡而导致运动功能紊乱。特别是顶核注射甲醛制备的小鼠模型与标准组后肢悬吊模型的病理特征基本一致。这可能为航天失重诱发运动紊乱提供了一种潜在的药物筛选动物模型。

Objective To estabolish a new mouse animal model that mimics the pathological characteristics of space weightlessness.Methods Male C57BL/6J mice were randomly divided into 4 groups.(1)Standard model group:mice with hindlimb unloading(HU);(2)control group:wild-type mice;(3)Sham operation group:mice with phosphate buffer solution(PBS)-injected into fastigial nucleus(FN);(4)new model group:mice with excessive formaldehyde(FA)-injected into FN.All these mice were used to assessthe ability of move and balance by using accelerating rotarod,beam walking and gait analysis,respectively.After behaviors tests,cerebellar slices were used to examine the death of cerebellar neurons,biochemical detection of FA-generating enzyme:semicarbazide-sensitive amine oxidase(SSAO),and cerebellar FA concentration.Results Compared with control group,there were a marked elevation in activity and expression of SSAO,an increase in the levels of endogenous FA,and a massive death of cerebellar neurons associated with move disorders in HU model mice.More importantly,the new model mice with injectetion of FA into FN exhibited the similar pathological characteristics as to HU model,including motor disorders and biochemical indexes.Conclusion HU-enhanced activity and expression of SSAO in the cerebellum leads to endogenous FA accumulation in the cerebellar FN.Exssesive FA is the direct factor for cerebellar neuron death and motor disorders.Moreover,FA-injection into FN mimics the pathological characteristics of HU model.This may provide a novel experimental animal model for drug screening via space weightlessness-induced motor disorders.