Ronca A E, Alberts J R
Life Sciences Division, National Aeronautics and Space Administration Ames Research Center, Moffett Field, California 94035, USA.
J Appl Physiol (1985). 2000 Dec;89(6):2318-24. doi: 10.1152/jappl.2000.89.6.2318.
Ten pregnant Norway rats (Rattus norvegicus) were flown for 11 days on board the NASA space shuttle from gestational day 9 (launch) until gestational day 20 (landing) of the rats' 22-day pregnancy. After the birth of the pups, vestibular responses were analyzed from postnatal day (P) 0 until P5. In the first test, P0 neonates were supported on a platform in a side-lying position. Skyward head movements (i.e., movements performed against the gravity vector) were more frequent than head movements toward Earth in both flight and control neonates. In the second test, the contact-righting reflex, composed of stereotyped movements that rotate the body from supine to prone on a solid surface, was analyzed in P0 neonates. The frequency and latency of contact-righting responses did not differ in flight and control neonates. In the third test, vestibular head righting, with tactile and proprioceptive cues removed, was tested in neonates on P1, P3, and P5 by using a water-immersion test. Righting responses were observed less frequently in P1 and P3 flight neonates compared with controls. However, this deficit was transient, as evidenced by complete response recovery on P5. Collectively, these findings provide evidence for a selective disruption of vestibular-mediated responses after prenatal exposure to spaceflight.
十只怀孕的挪威大鼠（褐家鼠）搭乘美国国家航空航天局的航天飞机飞行了11天，从大鼠22天孕期的第9天（发射）到第20天（着陆）。幼崽出生后，对出生后第（P）0天到第P5天的前庭反应进行了分析。在第一次测试中，将P0期的新生儿支撑在一个平台上，使其侧卧。在飞行组和对照组的新生儿中，头部向上的运动（即逆重力矢量进行的运动）比头部朝向地面的运动更频繁。在第二次测试中，对P0期的新生儿分析了接触翻正反射，该反射由一系列刻板运动组成，可使身体在固体表面上从仰卧转为俯卧。飞行组和对照组新生儿的接触翻正反应的频率和潜伏期没有差异。在第三次测试中，通过水浸试验对P1、P3和P5期的新生儿进行了去除触觉和本体感觉线索的前庭头部翻正测试。与对照组相比，P1和P3期飞行组新生儿的翻正反应观察到的频率较低。然而，这种缺陷是短暂的，P5期反应完全恢复证明了这一点。总的来说，这些发现为产前暴露于太空飞行后前庭介导反应的选择性破坏提供了证据。
