Kita Sayaka, Shibata Shigeki, Kim Hyeteok, Otsubo Akira, Ito Masao, Iwasaki Ken-ichi
Department of Hygiene and Space Medicine, Nihon University School of Medicine, Tokyo, Japan.
Aviat Space Environ Med. 2006 Aug;77(8):842-5.
Previous reports have shown that exposure to hypergravity decreases rat body mass during the initial phase, with this decrease and level of gravity showing a dose-response relationship. The present study examined whether rate of body mass gain after the initial phase of exposure is attenuated by hypergravity in a dose-dependent manner and sought to identify any threshold.
Male 10-wk-old rats (n = 64) were used, with 16 rats serving as 1.0-G controls, and 48 rats exposed to hypergravity for 14 d in 4 groups (1.5, 2.0, 2.5, and 3.5 G; n = 12 each). Body mass gain was evaluated according to slope of change in body mass from day 7 of exposure to hypergravity, as both absolute and relative values.
Slopes of body mass gain did not differ between the 1.0- and 1.5-G groups (6.09 and 5.75 g x d(-1), respectively), but were significantly less for the 2.0-, 2.5-, and 3.5-G groups (4.91, 3.03 and 1.99 g x d(-1), respectively) than for the 1.0- and 1.5-G groups. Body mass gain as a relative value did not differ between the 1.0-, 1.5-, and 2.0-G groups (1.5 +/- 0.2, 1.6 +/- 0.6 and 1.4 +/- 0.3 g x d(-1) x 100 g(-1) body mass, respectively), but was significantly less for the 2.5- and 3.5-G groups (1.1 +/- 0.6 and 0.8 +/- 0.3 g x d(-1) x 100 g(-1) body mass, respectively) than for the 1.0-, 1.5-, and 2.0-G groups. Absolute values and rate of body mass gain were reduced with increases in gravity.
Exposure to hypergravity attenuates body mass gain in a dose-dependent manner, with a threshold possibly existing between 1.5- and 2.5-G for 10-wk-old male rats.
先前的报告表明，在初始阶段暴露于超重力环境会使大鼠体重下降，且这种下降与重力水平呈剂量反应关系。本研究旨在探讨在初始暴露阶段之后，超重力是否会以剂量依赖的方式减弱体重增加速率，并试图确定是否存在任何阈值。
使用10周龄雄性大鼠（n = 64），其中16只大鼠作为1.0-G对照组，48只大鼠分为4组（1.5、2.0、2.5和3.5 G；每组n = 12），暴露于超重力环境14天。根据从暴露于超重力第7天起体重变化的斜率评估体重增加情况，包括绝对值和相对值。
1.0-G组和1.5-G组的体重增加斜率无差异（分别为6.09和5.75 g x d(-1)），但2.0-G、2.5-G和3.5-G组的体重增加斜率显著低于1.0-G组和1.5-G组（分别为4.91、3.03和1.99 g x d(-1)）。1.0-G、1.5-G和2.0-G组的体重增加相对值无差异（分别为1.5 +/- 0.2、1.6 +/- 0.6和1.4 +/- 0.3 g x d(-1) x 100 g(-1)体重），但2.5-G和3.5-G组的体重增加相对值显著低于1.0-G、1.5-G和2.0-G组（分别为1.1 +/- 0.6和0.8 +/- 0.3 g x d(-1) x 100 g(-1)体重）。体重增加的绝对值和速率随重力增加而降低。
暴露于超重力环境会以剂量依赖的方式减弱体重增加，对于10周龄雄性大鼠，阈值可能存在于1.5-G和2.5-G之间。
