Burke C R, Mussard M L, Gasser C L, Grum D E, Day M L
Department of Animal Science, The Ohio State University, Columbus, OH 43210, USA.
Theriogenology. 2003 Sep 1;60(4):647-58. doi: 10.1016/s0093-691x(03)00078-5.
Administration of estradiol benzoate (EB) induces atresia of the dominant follicle (DF) in the ovaries of cattle within 36 h but emergence of a new wave of follicular development is delayed by 3-5 days. The present study investigated the role of EB in determining timing of emergence of a new follicular wave after removing the influence of the DF. At 6.4+/-0.2 days after ovulation in Angus and Angus/Simmental cattle (n=26), aged 4.9+/-0.6 years and weighing 634+/-20 kg, all ovarian follicles > or =5mm in diameter were aspirated with a 17-gauge needle using an ultrasound-guided transvaginal approach (Day 0 or Hour 0) and animals immediately received 0 (0EB), 1 (1EB), 2 (2EB) or 4 (4EB) mg EB i.m./500 kg body weight (n=6 or 7 per treatment). Ovarian structures were monitored by ultrasonography on a daily basis until emergence of a new wave of follicular development. Concentrations of estradiol (E2) were different among all treatments between Hours 24 and 72, increasing (P<0.01) with greater doses of EB administered. Hour of peak follicle-stimulating hormone (FSH) was 29.3+/-4.0, 53.3+/-4.5, 81.1+/-15.5, and 91.4+/-8.2 for the 0EB, 1EB, 2EB, and 4EB treatments, respectively, and emergence of a new wave of follicular development occurred on Days 1.5+/-0.2, 3.3+/-0.3, 4.0+/-0.6 and 4.4+/-0.4, respectively. Timing of peak FSH and emergence of a new wave of follicular development was earliest (P<0.05) in the 0EB treatment, similar (P>0.1) among the 1EB and 2EB treatments, and most delayed (P<0.05) in the 4EB treatment when compared to the 0EB or 1EB treatments. The overall mean interval from peak FSH to emergence of a new wave of follicular development was 15.7+/-3.3 h and was not affected by treatment. Concentrations of E2 at 24 h before new emergence were not different among EB-treated animals (20.2+/-5.5 pg/ml), but lower (P<0.01) in the 0EB treatment (1.6+/-0.2 pg/ml). In a dose-dependent manner, EB delayed the pre-emergence surge in FSH that stimulates new follicular development after the DF has ceased to be functional. The importance of using an 'optimal' dose of EB in hormonal regimens using this agent to strategically regulate follicular development is emphasized by the outcomes of this study.
注射苯甲酸雌二醇（EB）可在36小时内诱导母牛卵巢中的优势卵泡（DF）闭锁，但新一波卵泡发育的出现会延迟3 - 5天。本研究探讨了在消除DF影响后，EB在确定新卵泡波出现时间方面的作用。在4.9±0.6岁、体重634±20千克的安格斯和安格斯/西门塔尔母牛（n = 26）排卵后6.4±0.2天，采用超声引导经阴道穿刺法，用17号针头抽吸所有直径≥5毫米的卵巢卵泡（第0天或第0小时），随后动物立即接受0（0EB）、1（1EB）、2（2EB）或4（4EB）毫克EB/500千克体重的肌肉注射（每种处理n = 6或7头）。每天通过超声监测卵巢结构，直至新一波卵泡发育出现。在24至72小时期间，所有处理组的雌二醇（E2）浓度不同，随着EB剂量增加而升高（P<0.01）。0EB、1EB、2EB和4EB处理组促卵泡激素（FSH）峰值出现时间分别为29.3±4.0、53.3±4.5、81.1±15.5和91.4±8.2小时，新一波卵泡发育分别在第1.5±0.2、3.3±0.3、4.0±0.6和4.4±0.4天出现。与0EB或1EB处理相比，0EB处理中FSH峰值和新一波卵泡发育出现时间最早（P<0.05），1EB和2EB处理组相似（P>0.1），4EB处理组最延迟（P<0.05）。从FSH峰值到新一波卵泡发育出现的总体平均间隔为15.7±3.3小时，不受处理影响。新卵泡出现前24小时，EB处理动物的E2浓度无差异（20.2±5.5皮克/毫升），但0EB处理组较低（P<0.01）（1.6±0.2皮克/毫升）。EB以剂量依赖方式延迟了DF不再发挥功能后刺激新卵泡发育的FSH出现前激增。本研究结果强调了在使用该药物的激素方案中使用“最佳”剂量EB以策略性调节卵泡发育的重要性。
