Goldsmith L T, Grob H S, Scherer K J, Surve A, Steinetz B G, Weiss G
Endocrinology. 1981 Aug;109(2):548-52. doi: 10.1210/endo-109-2-548.
To investigate the control mechanisms for the secretion of relaxin in pregnant rats, the effects of the fetus, placenta, and uterus were studied. Plasma immunoreactive relaxin and progesterone were measured in pregnant rats, from days 8--1 post partum. On day 16 of pregnancy, groups of animals were subjected to removal of the fetuses, conceptuses (fetuses and placentae), or uteri. To determine whether there are extraovarian sources of circulating relaxin, a group of pregnant rats was ovariectomized on day 16. Immunoreactive relaxin was undetectable in the plasma of pregnant rats before day 10, and increased to a mean concentration of 0.52 +/- 0.01 (SEM) ng/ml on day 13. In control animals, immunoreactive relaxin levels remained at about this concentration throughout the remainder of pregnancy and declined rapidly post partum. The pattern of secretion of relaxin in fetectomized animals was similar to that in controls. In contrast, a significant decline in immunoreactive relaxin was seen, within 24 h after surgery, in those animals in which removal of the conceptuses or hysterectomy was performed. In these animals, immunoreactive relaxin was undetectable within 48 h after surgery and remained undetectable throughout the experimental period. In animals that were ovariectomized, immunoreactive relaxin was undetectable 24 h after surgery. Progesterone secretion in animals that had fetectomy or removal of the conceptuses performed was similar to that in controls. These groups showed a significant decline in progesterone on day 17 of pregnancy, and progesterone continued to decline until day 1 post partum. Progesterone in hysterectomized animals declined more abruptly than in either controls or other experimental groups. Ovariectomy resulted in a prompt fall in plasma progesterone. These results indicate that in the rat, the fetus is not needed for the maintenance of relaxin secretion throughout pregnancy, the placenta controls the ovarian secretion of relaxin. The uterus does not exert a tropic effect upon relaxin secretion, no extraovarian sources of circulating relaxin exist in the rat, and there is a divergence between progesterone and relaxin secretion during rat pregnancy.
为研究妊娠大鼠中松弛素分泌的调控机制，对胎儿、胎盘和子宫的作用进行了研究。在妊娠第8天至产后第1天期间，测定妊娠大鼠血浆中的免疫反应性松弛素和孕酮。在妊娠第16天，将动物分组进行胎儿、孕体（胎儿和胎盘）或子宫切除。为确定循环松弛素是否存在卵巢外来源，一组妊娠大鼠在第16天进行卵巢切除术。妊娠第10天前的妊娠大鼠血浆中未检测到免疫反应性松弛素，在第13天增加到平均浓度0.52±0.01（SEM）ng/ml。在对照动物中，免疫反应性松弛素水平在妊娠剩余时间内保持在该浓度左右，并在产后迅速下降。切除胎儿的动物中松弛素的分泌模式与对照相似。相反，在进行孕体切除或子宫切除的动物中，术后24小时内免疫反应性松弛素显著下降。在这些动物中，术后48小时内免疫反应性松弛素检测不到，并在整个实验期间保持未检测到状态。在进行卵巢切除的动物中，术后24小时免疫反应性松弛素检测不到。进行胎儿切除或孕体切除的动物中孕酮分泌与对照相似。这些组在妊娠第17天孕酮显著下降，孕酮持续下降直至产后第1天。子宫切除动物的孕酮下降比对照或其他实验组更突然。卵巢切除导致血浆孕酮迅速下降。这些结果表明，在大鼠中，整个妊娠期维持松弛素分泌不需要胎儿，胎盘控制卵巢分泌松弛素。子宫对松弛素分泌没有促生长作用，大鼠中不存在循环松弛素的卵巢外来源，并且大鼠妊娠期间孕酮和松弛素分泌存在差异。
