Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B4.
Anim Reprod Sci. 2010 Jul;120(1-4):56-64. doi: 10.1016/j.anireprosci.2010.03.002. Epub 2010 Mar 6.
In ewes, immunization against GnRH blocks LH pulses but mean serum FSH concentrations are only partly reduced; the fate of the FSH peaks that precede ovarian follicular waves has not been studied. In this study, we used immunization against GnRH to examine the need for pulsed GnRH secretion in the genesis of FSH peaks in the anestrous ewe. Six anestrous ewes were given a GnRH immunogen on Day 0 and a booster injection on Day 28. Control ewes (n=6) received adjuvant only. Transrectal ultrasonography was performed daily for 2 days prior to and 10 days following both the primary (Days -2 to 10) and booster (Days 26-38) injections and for a 13-day period beginning 26 days after booster injection (Days 54-66). Blood samples were collected daily. Intensive bleeding (every 12min for 7h) was performed on Days 9, 37, and 65 of the experimental period to characterize the pulsatile pattern of LH secretion. GnRH antibody titers were increased and LH pulses were abolished immediately after booster immunization (P<0.05). The number of FSH peaks, FSH peak concentration and amplitude and basal FSH concentrations were only decreased in immunized ewes in the period of observations starting 26 days after booster immunization (P<0.05); however, some peaks were still seen. The number of follicular waves was decreased in the period around booster immunization and no follicular waves were seen during the period starting 26 days after booster immunization in immunized ewes (P<0.05). In summary, in anestrous ewes, when pulsed LH secretion was abolished by immunization against GnRH, the peaks in serum concentrations of FSH that trigger ovarian follicular waves continued for a period of time. We concluded that although blocking the effects of GnRH gradually causes a diminution of FSH secretion, there is no acute requirement for GnRH in the regulation of FSH peaks. The existence of FSH peaks in the absence of follicular waves, and pulsed LH secretion, suggests that some endogenous rhythm may drive the occurrence of FSH peaks, independent of both changes in negative feedback by secretory products from ovarian antral follicles and GnRH.
在母羊中，针对 GnRH 的免疫会阻止 LH 脉冲，但血清 FSH 浓度的平均值仅部分降低；在卵巢卵泡波之前发生的 FSH 峰的命运尚未研究。在这项研究中，我们使用针对 GnRH 的免疫来检查在 anestrous 母羊中产生 FSH 峰是否需要脉冲 GnRH 分泌。六只 anestrous 母羊在第 0 天接受 GnRH 免疫原，并在第 28 天接受加强注射。对照母羊（n=6）仅接受佐剂。在初次（第-2 天至 10 天）和加强（第 26 天至 38 天）注射之前和之后的 2 天以及加强注射后 26 天（第 54-66 天）开始的 13 天内每天进行经直肠超声检查。每天采集血液样本。在实验期间的第 9、37 和 65 天，进行密集出血（每 12 分钟 7 小时），以描述 LH 分泌的脉冲模式。加强免疫后，立即增加 GnRH 抗体滴度并消除 LH 脉冲（P<0.05）。在加强免疫后 26 天开始的观察期间，免疫母羊的 FSH 峰数、FSH 峰浓度和幅度以及基础 FSH 浓度仅降低（P<0.05）；然而，仍可见一些峰。在加强免疫周围的时期，卵泡波的数量减少，并且在加强免疫后 26 天开始的时期，免疫母羊中未见卵泡波（P<0.05）。总之，在 anestrous 母羊中，当针对 GnRH 的免疫消除脉冲 LH 分泌时，触发卵巢卵泡波的血清 FSH 浓度的峰持续了一段时间。我们得出的结论是，尽管逐渐阻断 GnRH 的作用会导致 FSH 分泌减少，但在调节 FSH 峰时，并不需要 GnRH 的急性作用。在没有卵泡波和脉冲 LH 分泌的情况下存在 FSH 峰表明，某些内源性节律可能独立于来自卵巢窦卵泡的分泌产物的负反馈和 GnRH 驱动 FSH 峰的发生。
