Martínez M F, Kastelic J P, Colazo M G, Mapletoft R J
Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B4.
Domest Anim Endocrinol. 2007 Jul;33(1):77-90. doi: 10.1016/j.domaniend.2006.04.009. Epub 2006 May 15.
The effects of estradiol-17beta (E-17beta) or estradiol benzoate (EB) on gonadotrophin release, estrus and ovulation in beef cattle were evaluated in two experiments. In experiment 1, 16 ovariectomized cows received a previously used CIDR insert from days 0 to 7 and 1mg of EB on day 8; they also received 5mg of E-17beta on days 0 or 1, or 5mg of E-17beta+100mg of progesterone on day 0. There was only an effect of time (P<0.0001) on plasma concentrations of progesterone, estradiol, FSH, and LH. Following treatment with E-17beta, plasma FSH concentrations were suppressed for approximately 36 h, whereas plasma LH concentrations were reduced (P<0.05) for 6 h, but surged within 24 h. Injecting 1mg of EB 24 h after CIDR removal decreased (P<0.02) plasma LH concentrations for 6h, followed by an LH surge at 18 h. In experiment 2, ovary-intact heifers (n=40) received a used CIDR and 5mg of E-17beta+100mg of progesterone on day 0. On day 7, CIDR were removed, PGF given, and heifers received nothing (control) or 1mg of EB 12, 24, or 36 h later. In these groups, plasma LH peaked (mean+/-SEM) 78.0+/-23.0, 37.8+/-8.5, 44.4+/-10.3, and 51.0+/-5.1 h after CIDR removal (means, P<0.001; variances, P<0.001) and intervals from CIDR removal to ovulation were 102.0+/-6.7, 63.6+/-3.6, 81.6+/-3.5, and 78.0+/-4.1h (P<0.05). The interval from CIDR removal to ovulation was shorter and less variable in EB-treated groups; the interval from EB to ovulation was shortest (P<0.05) in the 12-h group. In summary, E-17beta or EB decreased both FSH and LH, but LH increased after 6h (despite elevated progesterone concentrations). Following CIDR removal, 1mg of EB effectively synchronized LH release, and ovulation (in intact cattle), but the interval from CIDR removal to EB treatment affected the time of ovulation.
在两项实验中评估了17β-雌二醇（E-17β）或苯甲酸雌二醇（EB）对肉牛促性腺激素释放、发情和排卵的影响。在实验1中，16头去卵巢母牛从第0天至第7天接受一个先前使用过的阴道孕酮释放环（CIDR），并在第8天接受1mg EB；它们还在第0天或第1天接受5mg E-17β，或在第0天接受5mg E-17β + 100mg孕酮。仅时间对孕酮、雌二醇、促卵泡素（FSH）和促黄体素（LH）的血浆浓度有影响（P<0.0001）。用E-17β处理后，血浆FSH浓度被抑制约36小时，而血浆LH浓度降低（P<0.05）6小时，但在24小时内激增。在取出CIDR后24小时注射1mg EB使血浆LH浓度降低（P<0.02）6小时，随后在18小时出现LH激增。在实验2中，40头未去卵巢的小母牛在第0天接受一个用过的CIDR和5mg E-17β + 100mg孕酮。在第7天，取出CIDR，给予前列腺素F2α（PGF），小母牛在取出CIDR后12、24或36小时分别不接受任何处理（对照）或接受1mg EB。在这些组中，血浆LH在取出CIDR后78.0±23.0、37.8±8.5、44.4±10.3和51.0±5.1小时达到峰值（平均值±标准误）（均值，P<0.001；方差，P<0.001），从取出CIDR到排卵的间隔分别为102.0±6.7、63.6±3.6、81.6±3.5和78.0±4.1小时（P<0.05）。在接受EB处理的组中，从取出CIDR到排卵的间隔更短且变异性更小；在12小时组中，从注射EB到排卵的间隔最短（P<0.05）。总之，E-17β或EB降低了FSH和LH两者，但6小时后LH升高（尽管孕酮浓度升高）。取出CIDR后，1mg EB有效地使LH释放同步化，并使（未去卵巢的牛）排卵同步化，但从取出CIDR到EB处理的间隔影响排卵时间。
