超重状态出生大鼠转入正常重力状态后行为和Fos表达的改变

Altered behaviour and expression of Fos in rats born in hypergravity and their re adaptation to the normal gravity

本工作观察了在超重 (2G)环境中出生、生存 4个月后返回正常 (1G)环境的Long Evans大鼠运动行为的改变和恢复 ,以及相关脑区Fos表达水平的变化 ,并与旋转刺激 (重力变化的对照组 )和去前庭传入大鼠相比较。结果表明 :重力的变化导致实验大鼠静态和运动行为模式改变 ,伸肌张力增加 ,运动平衡、游泳定向和空中翻正的能力降低 ;对 1G环境再适应的时程因行为的不同而异 ,其中游泳定向能力的恢复时间最长 ,长于 1个月。旋转刺激只对运动行为有短暂的影响。Fos表达被认为是揭示参与应答感觉刺激而功能活跃脑区的有用工具。结果显示 ,正常和毁迷路的对照大鼠的Fos呈低水平表达 ,减重刺激使上、下丘脑和围导水管灰质、中缝背核及孤束核的水平显著上调 ,相反 ,下橄榄、蓝斑和前庭核团的Fos水平没有明显改变 。

Changes in behaviour relevant to the vestibular system were studied in Long Evans rats which were fertilized, born and housed in 2 acceleration of gravity for 4 months and thereafter exposed to 1 acceleration of gravity, and expression of Fos protein in the brain stem was examined. Data from the hypergravity rats were compared respectively with those from the rotation group and the labyrinthectomized group. Static and locomotion modes of the hypergravity rats were changed, tension of extensor was enhanced and the abilities in locomotion equalization and orientation in swimming and air righting response were reduced. The adaptation process varied with different behaviours. The time for recovery of the ability of orientating in swimming was the longest, taking more than 1 month. The Fos protein expression provides a useful tool for mapping brain functional activities after sensory stimulation, showing a low basal level in normal and labyrinthectomized groups. The hypergravity rats, on the other hand, exhibited more Fos positive cells in the superior colliculus, inferior colliculus, periaqueductal gray, raphe dorsal nucleus and solitary nucleus. In contrast, the inferior olivary nuclei, locus coeruleus and vestibular nuclei were not strongly labeled. These spatial patterns of Fos expression suggest that a decrease in gravity inertial force may activate a neural pathway different from the vestibulo olivar pathways activated by an increase in gravity inertial force.