Musah A I, Schwabe C, Willham R L, Anderson L L
Endocrinology. 1986 Apr;118(4):1476-82. doi: 10.1210/endo-118-4-1476.
Purified porcine relaxin (3000 U/mg) was administered into the cervical os of primiparous beef heifers on day 278 of gestation (approximately 5 days before parturition normally occurs) to determine its effects on the induction of parturition, changes in progesterone, estrone (E1), 17 beta-estradiol (17 beta-E2), cervical dilation, and pelvic relaxation. Heifers were assigned randomly to 1 of 3 treatments: relaxin-double (two infusions of 3000 U, 12 h apart; n = 17), relaxin-single (3000 U; n = 14), and PBS-gel vehicle (n = 16). Relaxin induced marked earlier calving (P less than 0.002) than PBS-gel vehicle. The intervals between the administration of relaxin or the PBS-gel vehicle and calving were 2.0, 2.5, and 5.3 days for heifers given relaxin-double, relaxin-single, and PBS-gel vehicle, respectively. The duration of gestation was significantly reduced (P less than 0.002) in relaxin-treated heifers compared with that in control heifers. A precipitous decrease in progesterone (7.1 ng/ml) occurred in peripheral blood plasma within 24 h after relaxin treatment. Coincident with a decline in levels of progesterone, E1 and 17 beta-E2 increased by 1700 and 400 pg/ml, respectively, an increase of 35% compared with the 12% increase in these steroids in control heifers. Mean deviations of cervical dilation increased 643%, 526%, and 11% in heifers given relaxin-double, relaxin-single, and PBS-gel vehicle, respectively. Relaxin induced maximum pelvic opening between 12-36 h after treatment. Although relaxin induced significantly earlier calving, there was no incidence (0 of 31 heifers) of retained placenta. We conclude from this study that purified relaxin administered intracervically to primiparous beef heifers during late pregnancy induced premature parturition. Marked shifts of progesterone, E1, 17 beta-E2, pelvic canal expansion, and cervical relaxation reflect the premature parturition induced by relaxin.
在妊娠第278天（通常分娩前约5天），将纯化的猪松弛素（3000 U/mg）注入初产肉用小母牛的子宫颈内口，以确定其对诱导分娩、孕酮、雌酮（E1）、17β-雌二醇（17β-E2）变化、宫颈扩张和骨盆松弛的影响。小母牛被随机分配到3种处理中的1种：双倍剂量松弛素组（两次输注3000 U，间隔12小时；n = 17）、单剂量松弛素组（3000 U；n = 14）和PBS凝胶载体组（n = 16）。与PBS凝胶载体组相比，松弛素显著提前诱导产犊（P < 0.002）。给予双倍剂量松弛素、单剂量松弛素和PBS凝胶载体的小母牛，从给予松弛素或PBS凝胶载体到产犊的间隔时间分别为2.0、2.5和5.3天。与对照小母牛相比，松弛素处理的小母牛妊娠期显著缩短（P < 0.002）。松弛素处理后24小时内，外周血浆中的孕酮急剧下降（7.1 ng/ml）。与孕酮水平下降同时发生的是，E1和17β-E2分别增加了1700和400 pg/ml，与对照小母牛中这些类固醇增加12%相比，增加了35%。给予双倍剂量松弛素、单剂量松弛素和PBS凝胶载体的小母牛，宫颈扩张的平均偏差分别增加了643%、526%和11%。松弛素在治疗后12 - 36小时诱导最大骨盆开口。尽管松弛素显著提前诱导产犊，但没有发生胎盘滞留情况（31头小母牛中0头）。我们从这项研究得出结论，妊娠后期向初产肉用小母牛宫颈内给予纯化的松弛素可诱导早产。孕酮、E1、17β-E2、骨盆管扩张和宫颈松弛的显著变化反映了松弛素诱导的早产。
