Hwang J J, Shanks R D, Sherwood O D
Department of Physiology and Biophysics, University of Illinois, Urbana-Champaign 61801.
Endocrinology. 1989 Jul;125(1):260-6. doi: 10.1210/endo-125-1-260.
The purpose of this investigation was to use an approach targeted specifically on endogenous relaxin to determine the influence of antepartum (days 20-22) relaxin on cervical modifications and birth in the rat. To that end, a monoclonal antibody specific for rat relaxin, designated MCA1, was used to neutralize endogenous relaxin in intact pregnant rats. MCA1 or PBS vehicle was administered iv to intact rats daily from days 20-22 of pregnancy. Cervices were removed at 1200 h on day 22. Cervices obtained from MCA1-treated rats were less extensible than cervices obtained from PBS-treated control rats. Furthermore, wet weight, dry weight, water content, and uronate content were lower in cervices obtained from MCA1-treated rats than in cervices from PBS-treated controls. Birth and maternal behavior of MCA1-treated and PBS-treated control rats were observed continuously from 2100 h on day 22 until day 2 postpartum (d2PP). MCA1-treated rats exhibited significantly prolonged durations of litter delivery as well as reduced incidences of live pups on d2PP compared with controls. There were lower incidences of normal maternal behavior observed at birth and on d1PP with MCA1-treated rats than with control rats. In addition, little or no milk was observed in the abdomen of most live pups of MCA1-treated rats on d2PP, whereas abundant milk was observed in the abdomen of all live pups of control rats. The mean live pup weight on d2PP was lower in the litters of MCA1-treated rats than in control litters. The present study indicates that in the rat endogenous relaxin is needed during the antepartum period for normal cervical growth and extensibility, normal litter delivery, and high postpartum pup survival. This work supports the hypothesis that the influence of endogenous relaxin on birth is attributable, at least in part, to its effects on the cervix.
本研究的目的是采用一种专门针对内源性松弛素的方法，以确定产前（第20 - 22天）松弛素对大鼠宫颈变化和分娩的影响。为此，使用一种对大鼠松弛素具有特异性的单克隆抗体，命名为MCA1，来中和完整妊娠大鼠体内的内源性松弛素。从妊娠第20 - 22天起，每天给完整大鼠静脉注射MCA1或PBS载体。在第22天12:00时取出宫颈。与PBS处理的对照大鼠获得的宫颈相比，MCA1处理的大鼠获得的宫颈伸展性较差。此外，MCA1处理的大鼠获得的宫颈的湿重、干重、含水量和糖醛酸含量均低于PBS处理的对照大鼠。从第22天21:00开始持续观察MCA1处理组和PBS处理对照组大鼠的分娩及母性行为，直至产后第2天（d2PP）。与对照组相比，MCA1处理的大鼠分娩持续时间显著延长，且d2PP时活仔出生率降低。与对照大鼠相比，MCA1处理的大鼠在出生时和产后第1天（d1PP）观察到的正常母性行为发生率较低。此外，在d2PP时，大多数MCA1处理的大鼠的活仔腹部几乎没有或没有观察到乳汁，而对照大鼠的所有活仔腹部都有大量乳汁。MCA1处理的大鼠窝中d2PP时的平均活仔体重低于对照窝。本研究表明，在大鼠产前期间，内源性松弛素是正常宫颈生长和伸展性、正常分娩以及高产后幼仔存活率所必需的。这项工作支持了这样一种假设，即内源性松弛素对分娩的影响至少部分归因于其对宫颈的作用。
