Pau K Y, Orstead K M, Hess D L, Spies H G
Biol Reprod. 1986 Nov;35(4):1009-23. doi: 10.1095/biolreprod35.4.1009.
The feedback effects of two ovarian steroids, estradiol-17 beta (E2) and 20 alpha-hydroxypregn-4-en-3-one (20 alpha OH), were examined in both intact (INT) and ovariectomized (OVEX) does. We measured steroid-induced alterations in endogenous gonadotropin-releasing hormone (GnRH) from sequential 10-min samples of hypothalamic perfusates, simultaneous changes in peripheral plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the modification of pituitary responsiveness, i.e., increments in plasma LH (delta LH) and plasma FSH (delta FSH), after 50 ng, 250 ng, and 1 microgram of exogenous GnRH in individual does of 6 treatment groups. The groups were: INT does, OVEX does, OVEX does receiving either one (1 E2) or two (2 E2) E2-filled Silastic capsules, OVEX does receiving a 20 alpha OH-filled capsule (20 alpha OH), and OVEX does receiving both capsules of E2 and 20 alpha OH (1 E2 + 20 alpha OH). Ovariectomy enhanced the pulsatile release of hypothalamic GnRH and pituitary LH and FSH, and increased the LH response (delta LH) to exogenous GnRH (OVEX vs. INT, p less than 0.05). Replacement of E2 at the time of ovariectomy prevented the increased GnRH and gonadotropin secretion as well as the enhanced delta LH that were observed in untreated OVEX does. The release of hypothalamic GnRH in the 20 alpha OH group was lower (p less than 0.05) than that in the OVEX group and not different from that in the INT group. The release of pituitary LH and FSH and the delta LH in the 20 alpha OH group was not different from that in the OVEX group, but these parameters were greater (p less than 0.05) than those in the INT group. The hypothalamic GnRH pulse frequency in the 1 E2 + 20 alpha OH group was lower (p less than 0.05) than that in either the 1 E2 or the 20 alpha OH group, but the delta LH in the 1 E2 + 20 alpha OH group was not different from that in either the 1 E2 or the 20 alpha OH group. The highest dose (1 microgram) of exogenous GnRH stimulated a modest increase in FSH in the OVEX, 20 alpha OH, 1 E2 + 20 alpha OH, and 1 E2 groups; but a steroid effect on delta FSH among these 4 groups was not apparent.(ABSTRACT TRUNCATED AT 250 WORDS)
在完整（INT）和去卵巢（OVEX）的母羊中研究了两种卵巢甾体激素——雌二醇 - 17β（E2）和20α - 羟基孕 - 4 - 烯 - 3 - 酮（20α OH）的反馈作用。我们测量了甾体激素诱导的下丘脑灌流液连续10分钟样本中内源性促性腺激素释放激素（GnRH）的变化、外周血浆促黄体生成素（LH）和促卵泡生成素（FSH）的同步变化，以及6个治疗组中每只母羊在注射50 ng、250 ng和1 μg外源性GnRH后垂体反应性的改变，即血浆LH（ΔLH）和血浆FSH（ΔFSH）的增加。这些组分别为：INT母羊、OVEX母羊、接受一个（1 E2）或两个（2 E2）含E2的硅橡胶胶囊的OVEX母羊、接受一个含20α OH胶囊的OVEX母羊（20α OH），以及接受E2和20α OH两种胶囊的OVEX母羊（1 E2 + 20α OH）。去卵巢增强了下丘脑GnRH以及垂体LH和FSH的脉冲式释放，并增加了对外源性GnRH的LH反应（ΔLH）（OVEX与INT相比，p < 0.05）。去卵巢时补充E2可防止未治疗的OVEX母羊中观察到的GnRH和促性腺激素分泌增加以及ΔLH增强。20α OH组下丘脑GnRH的释放低于OVEX组（p < 0.05），与INT组无差异。20α OH组垂体LH和FSH的释放以及ΔLH与OVEX组无差异，但这些参数高于INT组（p < 0.05）。1 E2 + 20α OH组下丘脑GnRH脉冲频率低于1 E2组或20α OH组（p < 0.05），但1 E2 + 20α OH组的ΔLH与1 E2组或20α OH组无差异。最高剂量（1 μg）的外源性GnRH刺激OVEX、20α OH、1 E2 + 20α OH和1 E2组的FSH适度增加；但这4组中甾体激素对ΔFSH的影响不明显。（摘要截取自250字）
