Abel R A, Ronca A E, Alberts J R
Department of Psychology, Indiana University, Bloomington 47405, USA.
Dev Psychobiol. 1998 Mar;32(2):91-9. doi: 10.1002/(sici)1098-2302(199803)32:2<91::aid-dev2>3.0.co;2-n.
The fetus' experience of birth derives from a sequence of stimulation provided by the mother's labor contractions, her licking and handling, and the contrasting environmental conditions of the uterus and outside world. In the present investigation, Day 21 fetal rats were externalized from the dam's body; subjects in one uterine horn were compressed by simulated uterine contractions while control subjects in the opposite horn were not compressed. All pups were Cesarean-delivered, stroked, and exposed to a thermal environment simulating either room (21 degrees C), nest (33 degrees C), or intrauterine (36 degrees C) temperature. After 1-hr exposure to the experimental temperature, all pups were maintained at 33 degrees C and tested for their suckling response to an anesthetized dam. When newborns were tested at 120 min postpartum, simulated contractions increased the probability of nipple attachment in pups exposed to 21 degrees C relative to noncompressed littermates maintained at the same temperature. Atypically warm postpartum conditions (nestlike or intrauterine) obviated the effects of compression by increasing suckling above the levels seen in noncompressed newborns exposed to the cool condition. Thus, compressions facilitate the achievement of suckling under thermal conditions resembling those typically encountered by the newborn rat.
胎儿的出生体验源于母亲分娩宫缩、舔舐和照料所带来的一系列刺激，以及子宫内与外界截然不同的环境条件。在本研究中，将妊娠21天的胎鼠从母鼠体内取出；一个子宫角内的实验对象受到模拟子宫收缩的挤压，而另一个子宫角内的对照对象则未受到挤压。所有幼崽均通过剖宫产取出，抚摸，并暴露于模拟室温（21摄氏度）、巢穴温度（33摄氏度）或子宫内温度（36摄氏度）的热环境中。在暴露于实验温度1小时后，所有幼崽均维持在33摄氏度，并测试它们对麻醉母鼠的哺乳反应。当在产后120分钟对新生幼崽进行测试时，相对于处于相同温度下未受挤压的同窝幼崽，模拟宫缩增加了暴露于21摄氏度的幼崽附着乳头的概率。产后异常温暖的条件（类似巢穴或子宫内的温度）通过使哺乳频率高于暴露于凉爽条件下的未受挤压新生幼崽，消除了挤压的影响。因此，在类似于新生大鼠通常遇到的热条件下，挤压有助于实现哺乳。
