高Gy所致豚鼠前庭功能障碍及其预适应防护的研究

目的 研究高G值作用后是否会造成脉鼠前庭功能紊乱，以及预先低G值暴露的预适应是否会对此有预防作用。方法 86只脉鼠随机分为空白对照组(10只)，10Gy组(28只)，2G组(20只)，预适应组(28只)，共4组。10Gy组直接给予10Gy5min暴露，2G组给予8d2G暴露(10Vd)，预适应组(28只)给予8d2G暴露后再给予10Gy5min暴露，对照组不给任何刺激。每组刺激后观察各脉鼠的行为学及前庭躯体和前庭眼动反射，包括有无头位震颤，头住偏斜，身体侧滚和转圈，有无自发眼震及眼住偏斜等前庭受损表现，并记录其持续时间。随后(刺激后约0．5h)每组各取8只用免疫组化方法观察前庭中枢核固ChAT活性并进行友度分析，其余用于其它指标研究。结果 10Gy5min的暴露( 10Gy组)可引起22／28(79％)脉鼠前庭行为学的异常，包括自发眼震、眼住偏斜、头位震颤、头位偏斜、身体转圈、侧滚转等；而在给予 10Gy5min的暴露前经过预适应(预适应组)的行为异常率只有14／28(50％)，两组之间具有显著差别(P＜0．05)。两组ChAT染色均明显高于对照组(P＜0．01)，不过两组之间未见明显差别。结论高G值作用可引起脉鼠前庭功能障碍，预适应具有一定的防护作用，中枢神经递质ChAT变化可能与此有一定关系。

High Gy Induced Vestibular Disorders in Guinea Pigs and Its Countermeasure by Preconditioning

Objective To explore if high G exposure can cause vestibular disorder in guinea pig and the possibility of preventing it by preconditioning with exposure to a low hypergravity environment before high G stimulus. Method A total of 86 guinea pigs were divided into 4 groups: 1)28 were treated with a stimulus of +10 Gy for 5 min (+10 Gy group);2)28 were preconditioned by exposure to 2 G environment for 8 d before the +10 Gy stimulus (preconditioning group); 3)20 were exposed to 2 G environment for 8 d, but without +10 Gy stimulus (2 G group); the rest 10 served as control. Their vestibular related behaviour, including vestibulo spinal reflex (VSR) and vestibulo ocular reflex (VOR) such as head tremble, head deviation, spontaneous nystagmus, eye deviation, body tilt or looping, were observed directly, the choline acetyltransferase(ChAT) activity in VNC (vestibular nucleon complex) in brain stem were investigated by immunohistochemistry technique, and the relative gamma in each group were analysed. Result The incidence of behavioral abnormalities (BA) in 10 Gy group(79%) is significantly higher than that in preconditioning group(50%).The relative gamma of staining showed that the content of ChAT in VNC of the +10 Gy group and preconditioning group were significantly higher than that in control group, but no difference was found between them in +10 Gy and preconditioning groups. Conclusion High G exposure of +10 Gy for 5 min could cause vestibular disorders in guinea pigs, and preconditioning with pre exposure to 2 G environment could alleviate it. ChAT activity changes in VNC may contribute to its mechanisms.