Wallace J M, Martin G B, McNeilly A S
Centre for Reproductive Biology, University of Edinburgh.
J Endocrinol. 1988 Jan;116(1):123-35. doi: 10.1677/joe.0.1160123.
It has previously been shown that treatment of ewes with bovine follicular fluid (bFF) throughout the luteal phase of the oestrous cycle lowers plasma levels of FSH but increases the frequency and amplitude of the pulses of LH. Under these conditions, ovarian follicles grow to a maximum diameter of 2.7 mm and have a reduced capacity to release oestradiol. We have examined the nature of the gonadotrophin signals controlling follicular development in the normally cycling ewe and have investigated the effects of previous exposure to bFF on these signals and the follicular responses to them. Control ewes (n = 7) were injected i.v. with 9 ml bovine serum and treated ewes were injected with 9 ml bFF, twice daily from days 1 to 10 of the luteal phase (day 0 = oestrus). The ewes were injected with prostaglandin analogue on day 11 of the cycle to induce luteolysis and the gonadotrophin patterns were studied in blood sampled from these animals every 10 min for up to 72 h during the subsequent follicular phase. Following luteolysis (and the end of bFF treatment), LH pulse frequency increased rapidly in both groups and reached 1 pulse/h within 6 h. Thereafter, pulse frequency increased marginally and reached 1 pulse/50 min by the onset of the LH surge. This pattern was not affected by previous treatment with bFF. In the control ewes, the amplitude of the LH pulses did not change significantly following luteolysis or at any time during the follicular phase, while the levels of FSH declined slowly until the onset of the surge. In the treated ewes, on the other hand, there was an immediate increase in both LH pulse amplitude and the concentration of FSH immediately after the end of bFF treatment at luteolysis, and they remained above control levels for 24 and 16 h respectively. Plasma prolactin levels did not appear to change around the time of luteolysis but showed a marked and significant diurnal rhythm (nadir around noon and peak around midnight) in both groups. The concentrations of prolactin were significantly (P less than 0.001) lower and the preovulatory peak was delayed and reduced in the bFF-treated ewes relative to controls. The onset of oestrus was also significantly (P less than 0.01) delayed by bFF treatment, but the ovulation rates did not differ between the groups. Furthermore, comparisons within or between groups revealed no significant relationships between any of the variables of plasma LH secretion during the follicular phase and the subsequent ovulation rate.(ABSTRACT TRUNCATED AT 400 WORDS)
先前的研究表明，在发情周期的黄体期，用牛卵泡液（bFF）处理母羊会降低血浆促卵泡素（FSH）水平，但会增加促黄体素（LH）脉冲的频率和幅度。在这些条件下，卵巢卵泡生长到最大直径2.7毫米，释放雌二醇的能力降低。我们研究了正常发情周期母羊中控制卵泡发育的促性腺激素信号的性质，并研究了先前暴露于bFF对这些信号以及卵泡对它们的反应的影响。对照母羊（n = 7）静脉注射9毫升牛血清，处理组母羊在黄体期第1天至第10天每天两次注射9毫升bFF（第0天 = 发情期）。在周期的第11天给母羊注射前列腺素类似物以诱导黄体溶解，并在随后的卵泡期对这些动物每10分钟采集一次血液，研究促性腺激素模式，持续72小时。黄体溶解后（以及bFF处理结束后），两组的LH脉冲频率均迅速增加，6小时内达到1次脉冲/小时。此后，脉冲频率略有增加，在LH峰出现时达到1次脉冲/50分钟。这种模式不受先前bFF处理的影响。在对照母羊中，黄体溶解后或卵泡期的任何时候，LH脉冲的幅度均无明显变化，而FSH水平则缓慢下降，直到峰出现。另一方面，在处理组母羊中，黄体溶解时bFF处理结束后，LH脉冲幅度和FSH浓度立即立即增加，并且它们分别在24小时和16小时内保持高于对照水平。血浆催乳素水平在黄体溶解时似乎没有变化，但两组均显示出明显且显著的昼夜节律（中午左右最低，午夜左右最高）。与对照组相比，bFF处理的母羊催乳素浓度显著降低（P < 0.001），排卵前峰值延迟且降低。bFF处理也使发情开始显著延迟（P < 0.01），但两组的排卵率没有差异。此外，组内或组间比较显示，卵泡期血浆LH分泌的任何变量与随后的排卵率之间均无显著关系。（摘要截短至400字）
