Orpen B G, Furman N, Wong P Y, Fleming A S
Department of Psychology, Erindale College, University of Toronto, Ontario, Canada.
Physiol Behav. 1987;40(3):307-15. doi: 10.1016/0031-9384(87)90052-7.
These studies investigated the role of gestational hormones in controlling the duration of the postpartum period of elevated maternal responsiveness in rats. In the first study, females had pregnancies terminated by Caesarean section, and had ovaries removed on day 16 or 22 of pregnancy. Removal of the ovaries did not prevent the sustaining of an elevated maternal responsiveness for 7 days after pregnancy termination on either day. In the second study, changes in concentrations of estrogen and progesterone during pregnancy, and following parturition, were determined by radioimmunoassay. Levels of these hormones postpartum were found to decline to virgin levels by 7 days postpartum and could not therefore explain the elevated maternal behavior seen at this time. In the third study, ovariectomized virgins were given a pregnancy-mimicking schedule of estradiol and progesterone, with and without prolactin, and were tested for maternal behavior 2 and 7 days later. A 22-day estradiol-progesterone schedule induced rapid maternal behavior within 2 days, but did not sustain it for 7 days. Adding prolactin to the 22-day estradiol-progesterone schedule sustained some components of maternal behavior, notably nest-building and retrieval, but not maternal behavior as a whole.
这些研究调查了孕期激素在控制大鼠产后母体反应性增强阶段时长方面的作用。在第一项研究中，雌性大鼠通过剖腹产终止妊娠，并在妊娠第16天或第22天摘除卵巢。无论在哪一天终止妊娠，摘除卵巢均不能阻止产后7天内母体反应性持续增强。在第二项研究中，通过放射免疫分析法测定了孕期及分娩后雌激素和孕酮浓度的变化。发现这些激素在产后7天时降至未孕水平，因此无法解释此时观察到的母体行为增强现象。在第三项研究中，对摘除卵巢的未孕大鼠给予模拟妊娠的雌二醇和孕酮给药方案，同时添加或不添加催乳素，并在2天和7天后测试其母体行为。为期22天的雌二醇 - 孕酮给药方案在2天内诱导出快速的母体行为，但未能维持7天。在为期22天的雌二醇 - 孕酮给药方案中添加催乳素可维持母体行为的某些成分，特别是筑巢和找回行为，但不能维持整体的母体行为。
