STEROID FEEDBACK INHIBITION OF PULSATILE SECRETION OF GONADOTROPIN-RELEASING-HORMONE IN THE EWE
STEROID FEEDBACK INHIBITION OF PULSATILE SECRETION OF GONADOTROPIN-RELEASING-HORMONE IN THE EWE
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DOI：
10.1095/biolreprod36.5.1207
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发表时间：
1987-06-01
影响因子：
3.6
通讯作者：
CLARKE, IJ
中科院分区：
文献类型：
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作者：
KARSCH, FJ;CUMMINS, JT;CLARKE, IJ
在发情中后期和繁殖初期，卵巢切除后的母羊中，评估了循环雌二醇和黄体酮持续升高对促性腺激素释放激素（GnRH）和黄体生成素（LH）脉冲式分泌的长期负反馈效应。在垂体门脉血的系列样本中监测 GnRH 分泌。从卵巢切除术开始，皮下注射类固醇。硅橡胶植入物，将雌二醇和黄体酮的血浆浓度维持在与动情周期黄体中期的循环水平相似的水平；对照母羊没有接受类固醇替代。对卵巢切除后第 8-10 天 6 小时内连续样品中激素脉冲模式的分析揭示了未经治疗的卵巢切除母羊下丘脑-垂体门静脉血中 GnRH 和外周血中 LH 的离散、并发脉冲。这些脉冲平均每 97 分钟发生一次。 用雌二醇或黄体酮治疗大大减少或消除了可检测到的 GnRH 和 LH 的脉冲式分泌，在 19 只接受类固醇治疗的母羊中，只有 3 只出现不频繁的脉冲。在任何一组母羊中，GnRH 或 LH 脉冲模式均未观察到重大季节性差异。我们在卵巢切除母羊中的发现直接支持了这样的结论：雌二醇和黄体酮对母羊促性腺激素分泌的负反馈作用包括对大脑的作用以及随后对脉动性 GnRH 分泌的抑制。
The long-term negative feedback effects of sustained elevations in circulating estradiol and progesterone on the pulsatile secretion of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) were evaluated in the ewe following ovariectomy during the mid-late anestrous and early breeding seasons. GnRH secretion was monitored in serial samples of hypophyseal portal blood. Steroids were administered from the time of ovariectomy by s.c. Silastic implants, which maintained plasma concentrations of estradiol and progesterone at levels resembling those that circulate during the mid-luteal phase of the estrous cycle; control ewes did not receive steroidal replacement. Analysis of hormonal pulse patterns in serial samples during 6-h periods on Days 8-10 after ovariectomy disclosed discrete, concurrent pulses of GnRH in hypothalamo-hypophyseal portal blood and LH in peripheral blood of untreated ovariectomized ewes. These pulses occurred every 97 min on the average. Treatment with either estradiol or progesterone greatly diminished or abolished detectable pulsatile secretion of GnRH and LH, infrequent pulses being evident in only 3 of 19 steroid-treated ewes. No major seasonal difference was observed in GnRH or LH pulse patterns in any group of ewes. Our finding in the ovariectomized ewe provide direct support for the conclusion that the negative-feedback effects of estradiol and progesterone on gondadotropin secretion in the ewe include an action on the brain and a consequent inhibition of pulsatile GnRH secretion.