Barrett David M W, Duggavathi Rajesha, Davies Kate L, Bartlewski Pawel M, Bagu Edward T, Rawlings Norman C
Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B4.
Biol Reprod. 2007 Aug;77(2):252-62. doi: 10.1095/biolreprod.106.058842. Epub 2007 Apr 11.
In a previous study, 10-day estradiol implant treatment truncated the FSH peaks that precede follicular waves in sheep, but subsequent ovine FSH (oFSH) injection reinitiated wave emergence. The present study's objectives were to examine the effects of a 20-day estradiol and progesterone treatment on FSH peaks, follicle waves, and responsiveness to oFSH injection. Also, different estradiol doses were given to see whether a model that differentially suppressed FSH peaks, LH pulses, or basal gonadotropin secretion could be produced in order to study effects of these changes on follicular dynamics. Mean estradiol concentrations were 11.8 +/- 0.4 pg/ml, FSH peaks were truncated, wave emergence was halted, and the number of small follicles (2-3 mm in diameter) was reduced (P < 0.05) in cyclic ewes given estradiol and progesterone implants (experiment 1). On Day 15 of treatment, oFSH injection failed to induce wave emergence. With three different estradiol implant sizes (experiment 2), estradiol concentrations were 5.2, 19.0, 27.5, and 34.8 (+/-4.6) pg/ml in control and treated ewes, respectively. All estradiol treatments truncated FSH peaks, except those that created the highest estradiol concentrations. Experiment 2-treated ewes had significantly reduced mean and basal FSH concentrations and LH pulse amplitude and frequency. We concluded that 20-day estradiol treatment truncated FSH peaks, blocking wave emergence, and reduced the small-follicle pool, rendering the ovary unresponsive to oFSH injection in terms of wave emergence. Varying the steroid treatment created differential FSH peak regulation compared with other gonadotropin secretory parameters. This provides a useful model for future studies of the endocrine regulation of ovine antral follicular dynamics.
在之前的一项研究中，为期10天的雌二醇植入治疗缩短了绵羊卵泡波之前的促卵泡素（FSH）峰值，但随后注射羊促卵泡素（oFSH）重新引发了卵泡波的出现。本研究的目的是检验为期20天的雌二醇和孕酮治疗对FSH峰值、卵泡波以及对oFSH注射反应性的影响。此外，给予不同剂量的雌二醇，以观察是否能建立一个对FSH峰值、促黄体生成素（LH）脉冲或基础促性腺激素分泌有不同抑制作用的模型，从而研究这些变化对卵泡动态的影响。在接受雌二醇和孕酮植入的周期性母羊中（实验1），平均雌二醇浓度为11.8±0.4 pg/ml，FSH峰值被截断，卵泡波出现停止，小卵泡（直径2 - 3毫米）数量减少（P<0.05）。在治疗的第15天，注射oFSH未能诱导卵泡波出现。使用三种不同大小的雌二醇植入物（实验2），对照母羊和处理母羊的雌二醇浓度分别为5.2、19.0、27.5和34.8（±4.6）pg/ml。除了产生最高雌二醇浓度的处理外，所有雌二醇处理均截断了FSH峰值。实验2处理的母羊平均FSH浓度、基础FSH浓度以及LH脉冲幅度和频率均显著降低。我们得出结论，为期20天的雌二醇治疗截断了FSH峰值，阻止了卵泡波出现，并减少了小卵泡池，使卵巢在卵泡波出现方面对oFSH注射无反应。与其他促性腺激素分泌参数相比，改变类固醇治疗可产生不同的FSH峰值调节。这为未来研究绵羊窦状卵泡动态的内分泌调节提供了一个有用的模型。
