ALTERATIONS IN THE CONTROL OF LUTEINIZING-HORMONE PULSE FREQUENCY UNDERLIE THE SEASONAL-VARIATION IN ESTRADIOL NEGATIVE FEEDBACK IN THE EWE
ALTERATIONS IN THE CONTROL OF LUTEINIZING-HORMONE PULSE FREQUENCY UNDERLIE THE SEASONAL-VARIATION IN ESTRADIOL NEGATIVE FEEDBACK IN THE EWE
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DOI：
10.1095/biolreprod27.3.580
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发表时间：
1982-01-01
影响因子：
3.6
通讯作者：
KARSCH, FJ
中科院分区：
文献类型：
--
作者：
GOODMAN, RL;BITTMAN, EL;KARSCH, FJ
研究了在完整的无情母羊中观察到的脉动性黄体生成素（LH）分泌频率低的因素。由于雌二醇是一种强效的黄体生成素抑制剂，因此我们首先研究了它对黄体生成素脉冲的影响。在去势母羊中植入产生生理雌二醇浓度为1 - 3pg /ml的植入物，可以显著降低黄体生成素脉冲频率或完全消除黄体生成素脉冲。这与繁殖季节的反应形成对比，在繁殖季节，雌二醇通过降低LH脉冲的幅度而不是频率对LH产生微弱的抑制作用。这些数据，再加上观察到雌二醇治疗并没有抑制垂体对促性腺激素释放激素（GnRH）的反应，导致雌二醇是一种更有效的黄体生成素分泌抑制剂，因为它获得了抑制下丘脑GnRH释放频率的能力。不依赖于类固醇反馈的脉动性黄体生成素分泌的季节性变化也可能是导致未发情母羊黄体生成素脉冲频率较低的原因，因为未经治疗的去势母羊的黄体生成素脉冲在发情期间的频率比在繁殖季节低40%。有趣的是，在去卵巢的失情母羊中，脉冲振幅也相应增加，因此在一年中的两个时间里，LH的平均水平是相同的。最后，由于黄体酮抑制黄体生成素脉冲频率的能力也在每年的这个时候增强，因此在发情期间产生黄体生成素脉冲的系统对所有抑制性类固醇的敏感性可能普遍增加。这一系列实验的结果与雌二醇作用于脉冲产生系统的结论是一致的，该脉冲产生系统的频率部分受到环境影响的抑制，是造成季节性停经期间LH脉冲频率较低的原因。
The factors responsible for the low frequency of pulsatile luteinizing hormone (LH) secretion observed in intact anestrous ewes were examined. Because estradiol is a potent inhibitor of LH in anestrus, its effect was first examined on LH pulses. Treatment of ovariectomized ewes with implants that produced physiological estradiol concentrations ranging from 1 to 3 pg/ml either drastically decreased LH pulse frequency or completely abolished LH pulses in anestrus. This contrasts with the response in the breeding season, when estradiol exerts a weak inhibition of LH by decreasing the amplitude, but not the frequency, of LH pulses. These data, together with the observation that this estradiol treatment did not suppress the pituitary response to gonadotropin releasing hormone (GnRH) in anestrus, lead to the hypothesis that estradiol is a more potent inhibitor of LH secretion in anestrus because it gains the capacity to suppress the frequency of hypothalamic GnRH discharges. Seasonal changes in pulsatile LH secretion that are independent of steroid feedback may also contribute to the low LH pulse frequency of anestrus ewes, because LH pulses in untreated ovariectomized ewes were 40% less frequent in anestrus than in the breeding season. Interestingly, there was a corresponding increase in pulse amplitude in ovariectomized anestrous ewes, so that mean LH levels were identical at both times of the year. Finally, there may be a general increase in the sensitivity of the system that generates LH pulses to all inhibitory steroids in anestrus since the ability of progesterone to suppress LH pulse frequency was also enhanced at this time of year. The results of this series of experiments are consistent with the conclusion that estradiol, acting on a pulse generating system whose frequency is partially damped by environmental effects, is responsible for the low frequency of LH pulses during seasonal anestrus.