Nöthling Johan O, Gerber David, Gerstenberg Cornelia, Kaiser C, Döbeli M
Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, Republic of South Africa.
Theriogenology. 2003 May;59(9):1929-40. doi: 10.1016/s0093-691x(02)01292-x.
The purpose of this study was to investigate the abortifacient effects of high doses of metergoline when administered to pregnant beagle bitches during the second half of gestation and to define the endocrine effects of this treatment as represented by plasma progesterone and estradiol concentrations. Previously, metergoline had been shown to be incompletely luteolytic and induced abortion in only one of eight pregnant bitches when 0.4-0.5 mg/kg were administered twice daily for 5 days from Days 18 to 20 of diestrus. Nine pregnancies in six beagle bitches were used for the present study. Three bitches were treated in each of two consecutive pregnant cycles. Metergoline was administered at a dose of 0.6 mg/kg per os twice daily, starting on Day 28 after the cytological onset of diestrus. Abortion was induced in eight of the nine treated pregnancies and started after 3-23 days of treatment (mean 12.5 days, S.D. 6.4 days). The abortions were completed within 0.5-8 days (mean 2.2 days, S.D. 2.7 days). There were no side effects associated with metergoline treatment and none of the abortions was associated with complications that required intervention. In the single bitch that did not abort, an ovarian granulosa cell tumor was discovered when the single fetus had to be removed surgically at term. Plasma progesterone concentrations declined after the start of metergoline administration in all pregnancies but levels below 4.8 nmol/l were required for successful abortions. Plasma estradiol concentrations showed a tendency to decline and fluctuate concurrently with the plasma progesterone levels. However, suppression of plasma estradiol concentrations by metergoline was not as complete as the suppression of progesterone and did not seem a prerequisite for abortion. The hormone profiles and treatment period required for abortion tended to be similar for both cycles of the three bitches that were treated during two consecutive pregnancies. This suggests a bitch effect on the factors that determine the efficacy of metergoline to induce abortion. The large variation and length of the treatment period that was required until abortion commenced was probably related to the relatively early start of treatment compared to other studies. The results of this investigation suggest that, similar to other prolactin suppressing ergot derivatives, metergoline causes complete luteolysis and can be used to reliably induce abortion only during the last 3 weeks of gestation.
本研究的目的是调查在妊娠后半期给怀孕的比格犬母犬施用高剂量美替戈林的堕胎效果，并确定以血浆孕酮和雌二醇浓度为代表的这种治疗的内分泌效应。此前，已表明美替戈林溶黄体作用不完全，在发情后期第18至20天，每天两次施用0.4 - 0.5mg/kg，持续5天，八只怀孕母犬中只有一只发生流产。本研究使用了六只比格犬母犬的九次妊娠。在两个连续的怀孕周期中，每组三只母犬接受治疗。从发情期细胞学开始后的第28天起，每天两次口服美替戈林，剂量为0.6mg/kg。九次治疗的妊娠中有八次诱发了流产，流产在治疗3 - 23天后开始（平均12.5天，标准差6.4天）。流产在0.5 - 8天内完成（平均2.2天，标准差2.7天）。美替戈林治疗未出现副作用，且所有流产均未伴有需要干预的并发症。在未流产的那只母犬中，足月时因需手术取出单胎胎儿而发现了一个卵巢颗粒细胞瘤。所有妊娠在开始施用美替戈林后血浆孕酮浓度均下降，但成功流产需要孕酮水平低于4.8nmol/l。血浆雌二醇浓度呈现下降趋势，并与血浆孕酮水平同时波动。然而，美替戈林对血浆雌二醇浓度的抑制不如对孕酮的抑制完全，似乎也不是流产的先决条件。在两个连续妊娠期间接受治疗的三只母犬的两个周期中，流产所需的激素谱和治疗期往往相似。这表明母犬对决定美替戈林诱导流产效果的因素有影响。与其他研究相比，流产开始前所需治疗期的较大差异和长度可能与治疗开始相对较早有关。本研究结果表明，与其他抑制催乳素的麦角衍生物类似，美替戈林可导致完全溶黄体，并且仅在妊娠的最后3周可可靠地用于诱导流产。
