Restoration of LH output and 17β-oestradiol responsiveness in acutely ovariectomised Holstein dairy cows pre-treated with a GnRH agonist (deslorelin) for 10 days
Restoration of LH output and 17β-oestradiol responsiveness in acutely ovariectomised Holstein dairy cows pre-treated with a GnRH agonist (deslorelin) for 10 days
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DOI：
10.1016/s0378-4320(01)00192-0
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发表时间：
2002-03-15
影响因子：
2.2
通讯作者：
Macmillan, KL
中科院分区：
文献类型：
--
作者：
Padula, AM;Borman, JM;Macmillan, KL
这项研究的目的是首先确定卵巢在植入强有力的促性腺激素释放激素激动剂(地洛瑞林)治疗的奶牛中维持血浆促黄体生成素(LH)浓度的作用，其次描述同一动物在卵巢切除(OVX)后促黄体生成激素(LH)的变化。在成熟的荷斯坦奶牛中，发情是同步的，17天后，三分之二的奶牛植入了地洛瑞林。再过10天(第0天)，所有奶牛都进行了双侧卵巢切除。对照组(CON；n=4)不接受任何治疗，在OVX前一天(第1天)每隔15分钟采集一次血样，第4天和第10天同样采集血样。一组(DES_IN；n=4)在研究期间植入植入物，而另一组(DES_OUT；n=4)在OVX时拆除植入物。DES_IN奶牛在每个采样时段(-1天、+4天和+10天)每小时采样一次，而DES_OUT奶牛的采样方式与CON相似，但在每小时采样的第一天除外。术后平均促黄体生成素(0.61 ng/ml对1.79 ng/ml；P<；0.01)和促黄体生成素脉冲幅度(0.66 ng/ml对1.56 ng/ml；第一天)可预测的增加。与+10天相比；P<；0.01)发生在CON奶牛去卵巢后。与算术平均数相比，平滑的lh平均数显示出延迟的时间效应。CON奶牛OVX后脉搏频率无明显变化。从第一天开始，所有接受地洛瑞林治疗的奶牛的比较显示，与未治疗的奶牛相比，平滑平均促黄体生成素水平显著提高(0.80 ng/ml比0.34 ng/ml；DES_IN和DES_OUT比CON；P<；0.05)。DES-IN奶牛在OVX后第1天至+4天的平均促黄体生成素水平下降了54%(1.05 ng/ml对0.48 ng/ml；P<；0.01)，这表明卵巢可能参与了维持基础促黄体生成素升高的过程。在+11天肌肉注射500杯17β-雌二醇(E_2)后，黄体生成素的反应在不同治疗组之间有显著差异(P<；0.01)。CON奶牛表现出典型的黄体生成素高峰，在注射后17.3h达到最大浓度(10.3 ng/ml)。尽管DES_OUT奶牛在+4天时已恢复低幅度的黄体生成素搏动，但在+12天时对E_2的反应不一致。1头牛有明显的正常峰，其他牛仅表现出减弱的反应。+4天和+10天时，Desout奶牛的脉搏波幅低于CON(P<；0.05)。在E2后，DES_IN奶牛没有产生任何激增。注射500毫克雌二醇后，去卵巢前(第1天)的平均促黄体生成素水平保持不变(0.38 ng/mI对0.45 ng/mlE2前与1.05 ng/mlOVX前相比)。这项实验的结果表明，卵巢参与了长期使用促性腺激素释放激素激动剂治疗的奶牛基础促黄体生成素的升高。尽管黄体生成素脉冲的幅度和频率已经恢复，但每头奶牛对外源雌二醇组的黄体生成素峰值反应在12天后有所不同。(C)2002 Elsevier Science B.V.保留所有权利。
The objectives of the study were firstly to identify the role of the ovary in maintaining plasma luteinising hormone (LH) concentrations in cows treated with an implant of a potent GnRH agonist (deslorelin), and secondly to characterise the changes in LH following ovariectomy (OVX) in the same animals. Oestrus was synchronised in mature Holstein dairy cows and deslorelin implants were inserted 17 days later into two-third of the cows. A further 10 days later (day 0) all cows had bilateral OVX performed. A control group (CON; n = 4) received no treatment and had blood samples collected at 15-min intervals for 8 h on the day prior to OVX (day -1) and similarly on days 4 and 10. One group (DES_IN; n = 4) had implants in place for the duration of the study while another group had implants removed (DES_OUT; n = 4) at the time of OVX. DES_IN cows were sampled hourly at each sampling session (days -1, +4 and + 10), whereas DES_OUT cows were sampled similarly to CON except on day-1 when hourly samples were collected.Predictable post-operative increases in mean LH (0.61 ng/ml versus 1.79 ng/ml; P < 0.01) and LH pulse amplitude (0.66 ng/ml versus 1.56 ng/ml; day -1. versus day +10; P < 0.01) occurred after CON cows were ovariectomised. Smoothed LH means showed a delayed effect of time compared to arithmetic means. Pulse frequency was unchanged following OVX in CON cows. A comparison of all cows that had been treated with deslorelin from day -1 showed a significant elevation of smoothed mean LH compared to untreated cows (0.80 ng/ml versus 0.34 ng/ml; DES_IN and DES_OUT versus CON; P < 0.05). DES-IN cows had a 54% reduction in mean LH from day -1 to +4 following OVX (1.05 ng/ml versus 0.48 ng/ml; P < 0.01) indicating the probable involvement of the ovary in the maintenance of elevated basal LH. No further reduction was detected by day +10. The LH response to an intramuscular (IM) injection of 500 mug 17beta-oestradiol (E2) on day +11 varied significantly between treatment groups (P < 0.0 1). CON cows showed a typical LH surge, reaching maximum concentrations (10.3 ng/ml) at 17.3 h post-injection. Even though low amplitude LH pulsatility had been restored in DES_OUT cows by day +4, there was an inconsistent response to E2 on day +12. one cow had an apparently normal surge yet, others showed only attenuated responses. Pulse amplitude in DES-OUT cows was lower at days +4 and +10 compared to CON (P < 0.05). DES_IN cows did not produce any surge after E2. Mean LH prior to OVX (day -1) remained unchanged following the 500 mug oestradiol injection (0.38 ng/mI versus 0.45 ng/ml pre-E2 versus post-E2 compared to 1.05 ng/ml pre-OVX).The results of this experiment implicated ovarian involvement in maintaining elevated basal LH Output in cows that were chronically treated with a GnRH agonist. Individual cows varied in their LH surge response to exogenous E2 given 12 days after implant removal, even though LH pulse amplitude and frequency had been restored. (C) 2002 Elsevier Science B.V. All rights reserved.