Baratta M, Grasselli F, Tamanini C
Istituto di Fisiologia Veterinaria, Universita' di Parma, Italy.
Biol Reprod. 1994 Jun;50(6):1320-7. doi: 10.1095/biolreprod50.6.1320.
The objective of this study was to investigate the direct effect of estradiol-17 beta (E2) and progesterone (P4) on LH release by pituitary cells of midluteal phase cows in vitro. Pituitaries were collected at the slaughterhouse; cells were dissociated with collagenase and hyaluronidase and maintained in a static culture system in Medium 199 (M199). Various concentrations of E2 (0.1-100 nM) and P4 (0.1 and 10 nM) were used to stimulate the cells for 2, 4, 6, 15, 24, 48, or 72 h. In addition, the synergistic action of E2 and P4 was investigated by exposure of the cells to a combination of the two hormones. At the end of each incubation, the cells were challenged with LHRH (1 nM) for 2 h. The medium was collected for LH analysis at the end of each incubation period and after the LHRH challenge; furthermore, intracellular LH content was quantified at the end of each experiment. The results indicate a positive action of E2 on basal release of LH beginning after 15 h of exposure (p < 0.01). LHRH-induced LH release was modulated by E2 in a time-dependent manner with an effect at first inhibitory, then stimulatory, and finally inhibitory again (p < 0.04). P4 alone did not affect LH release, but it negatively influenced LHRH-induced LH release. P4 also exerted a positive action on intracellular LH after 6 h of incubation. A substantial inhibitory effect (p < 0.001) on both tonic LH release and LHRH-induced LH release was observed in cells exposed for 16 h to P4 after a priming with E2 for 4 h.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究的目的是在体外研究17β-雌二醇（E2）和孕酮（P4）对黄体中期奶牛垂体细胞促黄体生成素（LH）释放的直接影响。垂体在屠宰场采集；细胞用胶原酶和透明质酸酶解离，并在199培养基（M199）的静态培养系统中培养。使用不同浓度的E2（0.1 - 100 nM）和P4（0.1和10 nM）刺激细胞2、4、6、15、24、48或72小时。此外，通过将细胞暴露于两种激素的组合来研究E2和P4的协同作用。在每次孵育结束时，用促性腺激素释放激素（LHRH，1 nM）刺激细胞2小时。在每个孵育期结束时以及LHRH刺激后收集培养基用于LH分析；此外，在每个实验结束时对细胞内LH含量进行定量。结果表明，暴露15小时后E2对LH的基础释放有正向作用（p < 0.01）。E2以时间依赖性方式调节LHRH诱导的LH释放，其作用先是抑制，然后是刺激，最后又是抑制（p < 0.04）。单独的P4不影响LH释放，但它对LHRH诱导的LH释放有负向影响。孵育6小时后P4对细胞内LH也有正向作用。在用E2预处理4小时后，将细胞暴露于P4 16小时，观察到对LH的持续性释放和LHRH诱导的LH释放均有显著抑制作用（p < 0.001）。（摘要截短至250字）
