模拟失重14d大鼠中脑导水管周围灰质Fos蛋白表达的改变

Alteration of Fos Expression in Periaqueductal Gray of Rat after 2 Weeks Simulated Weightlessness.

目的观察大鼠模拟失重后中脑导水管周围灰质(periaqueductafgray,PAG)神经元Fos蛋白表达的改变。方法采用雌性大鼠尾部悬吊法建立模拟失重模型,按体重配对原则随机将大鼠分为2组,即模拟失重14d(SW-14d)组和正常对照(Con)组;根据实验干预措施的不同,每组又分为3个亚组,即电刺激(electrical stimulation,ES)亚组,琥珀胆碱(succinylcholine,Sch)预处理(pretreatment ofSch,PS)亚组和单纯琥珀胆碱注射(Sch injection,SI)亚组,每个亚组4只大鼠。采用免疫组织化学ABC法对大鼠中脑冰冻切片进行染色,显微镜下进行观察并拍照,对Fos免疫阳性细胞进行形态与计数分析。结果两组大鼠PAG腹外侧区均观察到Fos样蛋白的表达。与正常对照组相比,模拟失重组Fos免疫阳性细胞,核着色较淡,边界较为模糊;Fos免疫阳性细胞数明显减少。不同亚组大鼠Fos免疫阳性细胞计数分析表现为:Sch预处理亚组>伤害性电刺激亚组>单纯琥珀胆碱注射亚组,正常对照组大鼠阳性细胞计数结果分别为71.06±8.96、46.94±3.38和35.04±4.62;模拟失重2周组分别为32.91±2.99,27.77±3.27和11.75±1.00。结论伤害性电刺激可诱发大鼠PAG腹外侧区神经元Fos样蛋白的表达,而琥珀胆碱可使其表达增加;模拟失重后伤害性电刺激诱发的Fos样蛋白在PAG的表达减少。

Objective To investigate effects of simulated weightlessness on expression of Fos in rat periaqueductal gray （PAG）. Methods The model of weightlessness was simulated by tail-suspended female rats, and all rats were randomly divided into 14 d tail-suspension （SW-14 d） group and con- trol （Con） group. Each group was further divided into 3 subsets of 4 rats according to experimental intervention： electrical stimulation subset （ES）,pretreatment with succinylcholine subset （PS） and succinylcholine injection subset （SI）. The quantity and appearance of Fos-like immuno-positive （FLI） neurons in ventrolateral part of PAG were investigated by immunocytochemical staining method. Results FLI neurons in ventrolateral part of PAG were observed in both groups. As compared with control group, FLI neurons in SW-14 d group were stained lightly, cellular integrity were impaired and celluar verge were unclear. Analysis of countings showed number of FLI neurons was the largest in PS , medium in ES and small in SI subset. In control group they are 71.06 ± 8.96, 46.94 ± 3.38 and 35.04 ± 4.62 respectively and in 14 d simulated weightlessness group, they are 32.91 22.99, 27.77 ±3.27 and 11.75 ± 1.00 respectively. As compared with control groups, number of FLI neurons in all subsets of 14 d tail-suspension group decreased obviously. Conclusion Nociceptive stimulus can induce expression of Fos in neurons of ventrolateral part in PAG, introvenous injection of succinylcholine （SCH） can result in increase of FLI neurons in ventrolateral part of PAG. Number of FLI neurons in ventrolateral part of PAG decreased obviously after 2 weeks simulated weightlessness.