JAXA/Institute of Space and Astronautical Science, Sagamihara 252-5210, Japan.
Graduate Program in Health Sciences and Technology, University of Brasilia, Brasilia 72220-140, DF, Brazil.
Life (Basel). 2014 Apr 24;4(2):174-88. doi: 10.3390/life4020174.
The ability to maintain the body relative to the external environment is important for adaptation to altered gravity. However, the physiological limits for adaptation or the disruption of body orientation are not known. In this study, we analyzed postural changes in mice upon exposure to various low gravities. Male C57BL6/J mice (n = 6) were exposed to various gravity-deceleration conditions by customized parabolic flight-maneuvers targeting the partial-gravity levels of 0.60, 0.30, 0.15 and μ g (<0.001 g). Video recordings of postural responses were analyzed frame-by-frame by high-definition cineradiography and with exact instantaneous values of gravity and jerk. As a result, the coordinated extension of the neck, spine and hindlimbs was observed during the initial phase of gravity deceleration. Joint angles widened to 120%-200% of the reference g level, and the magnitude of the thoracic-curvature stretching was correlated with gravity and jerk, i.e., the gravity deceleration rate. A certain range of jerk facilitated mouse skeletal stretching efficiently, and a jerk of -0.3~-0.4 j (g/s) induced the maximum extension of the thoracic-curvature. The postural response of animals to low gravity may undergo differential regulation by gravity and jerk.
维持身体相对于外部环境的能力对于适应改变的重力非常重要。然而，适应的生理极限或身体方向的破坏尚不清楚。在这项研究中，我们分析了小鼠在暴露于各种低重力下的姿势变化。通过针对 0.60、0.30、0.15 和 μ g（<0.001 g）的部分重力水平的定制抛物线飞行操作，将雄性 C57BL6/J 小鼠（n=6）暴露于各种重力减速条件下。通过高清运动射线照相术和精确的重力和急动度的瞬时值逐帧分析姿势反应的视频记录。结果，在重力减速的初始阶段观察到颈部、脊柱和后肢的协调伸展。关节角度扩大到参考 g 水平的 120%-200%，并且胸椎伸展的幅度与重力和急动度相关，即重力减速率。一定范围的急动度有效地促进了小鼠骨骼的伸展，并且急动度为-0.3~-0.4 j（g/s）诱导了胸椎伸展的最大幅度。动物对低重力的姿势反应可能通过重力和急动度进行差异调节。
