Nett T M, Flores J A, Carnevali F, Kile J P
Department of Physiology, Colorado State University, Fort Collins 80523.
Biol Reprod. 1990 Oct;43(4):554-8. doi: 10.1095/biolreprod43.4.554.
The purpose of this experiment was to determine if pituitary stores of LH could be replenished by administration of GnRH when circulating concentrations of both progesterone and estradiol-17 beta (estradiol) were present at levels observed during late gestation. Ten ovariectomized (OVX) ewes were administered estradiol and progesterone via Silastic implants for 69 days. One group of 5 steroid-treated OVX ewes was given GnRH for an additional 42 days (250 ng once every 4 h). Steroid treatment alone reduced (p less than 0.01) the amount of LH in the anterior pituitary gland by 77%. Pulsatile administration of GnRH to steroid-treated ewes resulted in a further decrease (p less than 0.01) in pituitary content of LH. Compared to the OVX ewes, concentrations of mRNAs for alpha- and LH beta-subunits were depressed (p less than 0.01) in all steroid-treated ewes, whether or not they received GnRH. The ability of the dosage of GnRH used to induce release of LH was examined by collecting blood samples for analysis of LH at 15 days and 42 days after GnRH treatment was initiated. Two of 5 and 3 of 5 steroid-treated ewes that received pulses of GnRH responded with increased serum concentrations of LH after GnRH administration during the first and second bleedings, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
本实验的目的是确定当孕酮和雌二醇 - 17β（雌二醇）的循环浓度处于妊娠后期观察到的水平时，给予促性腺激素释放激素（GnRH）是否能补充垂体中促黄体生成素（LH）的储存量。十只去卵巢（OVX）母羊通过硅胶植入物给予雌二醇和孕酮，持续69天。一组5只接受类固醇治疗的OVX母羊额外给予GnRH 42天（每4小时一次，每次250纳克）。单独的类固醇治疗使垂体前叶中LH的含量降低了77%（p < 0.01）。对接受类固醇治疗的母羊进行GnRH脉冲给药导致垂体中LH含量进一步下降（p < 0.01）。与OVX母羊相比，无论是否接受GnRH，所有接受类固醇治疗的母羊中α亚基和LHβ亚基的mRNA浓度均降低（p < 0.01）。通过在开始GnRH治疗后的第15天和第42天采集血样分析LH，来检测所使用的GnRH剂量诱导LH释放的能力。5只接受GnRH脉冲治疗的类固醇处理母羊中，分别有2只和3只在首次和第二次采血时GnRH给药后血清LH浓度升高。（摘要截选至250字）
