Baer L A, Ronca A E, Wade C E
Lockheed Martin, NASA Ames Research Center, Moffett Field, CA, USA.
J Gravit Physiol. 2000 Dec;7(3):17-22.
We studied the effects of 2G hypergravity on the survival, body mass and growth of postnatal rats (Rattus norvegicus). Nursing litters comprised of either neonatal (Postnatal day [P]7) or pre-weanling (P14) rats and their mothers were exposed to 16 days of continuous centrifugation. All of the offspring survived and gained body mass, indicating that mothers nursed their young. Following the onset of centrifugation, neonatal and pre-weanling rats showed a reduction in growth relative to age-matched environmental controls (EC). At the completion of testing, body mass of the hypergravity (HG) groups was significantly less than that of controls (p<0.05). Over the course of the test, the HG-exposed P7 group showed an overall 55% gain in body mass as compared to a 71% increase in controls, while the HG-exposed P14 group showed a 62% increase relative to 75% in controls. Neonatal offspring (P7) gained body mass during centrifugation, but at significantly slower rates as compared to EC controls (p<0.05). In contrast, growth rates of pre-weanling (P14) rats were not reduced relative to controls, possibly related to the initiation of weaning, around P18 in the rat. These findings raise key issues relevant to studies of nursing mammals reared in altered gravity.
我们研究了2G超重力对新生大鼠（褐家鼠）存活、体重和生长的影响。哺乳窝仔由新生（出生后第[P]7天）或断奶前（P14）大鼠组成，它们及其母亲接受了16天的连续离心处理。所有后代均存活并增加了体重，表明母亲哺育了幼崽。离心开始后，新生和断奶前大鼠相对于年龄匹配的环境对照组（EC）生长减缓。测试结束时，超重力（HG）组的体重显著低于对照组（p<0.05）。在测试过程中，暴露于HG的P7组体重总体增加了55%，而对照组增加了71%，而暴露于HG的P14组体重增加了62%，对照组增加了75%。新生后代（P7）在离心过程中体重增加，但与EC对照组相比速度明显较慢（p<0.05）。相比之下，断奶前（P14）大鼠的生长速度相对于对照组并未降低，这可能与大鼠在P18左右开始断奶有关。这些发现提出了与在改变重力条件下饲养的哺乳类动物研究相关的关键问题。
