Liu T C, Jackson G L
Proc Soc Exp Biol Med. 1984 Nov;177(2):296-302. doi: 10.3181/00379727-177-41946.
In a series of four experiments, the temporal development of acute inhibitory and delayed stimulatory effects of 17 beta-estradiol (E) on luteinizing hormone (LH) release by superfused rat anterior pituitary cells pulsed with gonadotropin-releasing hormone (GnRH) was studied. Dispersed anterior pituitary cells from ovariectomized rats were cultured on Bio-Beads for 3 days and then placed in columns and superfused for up to 24 hr. During superfusion, the cells were exposed to GnRH pulses (3 X 10(-9) M, one 6-min pulse/hr). Cells treated with E (3 X 10(-10) M) either before (only 24 hr prior to superfusion) or before and during superfusion released significantly (P less than 0.05) more LH in response to the first few pulses of GnRH than cells treated with diluent. In contrast, cells treated with E only during superfusion initially released less GnRH-induced LH than cells treated with diluent. In a subsequent experiment, the inhibitory effect of E reached a maximum by 1.5 hr (P less than 0.01), and then gradually disappeared after 4.5 hr. Cells superfused simultaneously with E and fixed "low"-dose GnRH (5 X 10(-10) M) pulses did not exhibit enhanced LH responses with time to that dose of GnRH. However, E-superfused cells responded more than diluent-superfused cells to subsequent stimulation with a higher-dose GnRH pulse. Superfusion of cells with E for 16.5 hr in the absence of GnRH pulses also did not increase release of LH to low-dose (5 X 10(-10) M) pulses of GnRH, yet did cause a transitory increase to subsequent high-dose (10(-8) M) GnRH pulses. In conclusion, these results demonstrate the direct biphasic inhibitory then stimulatory effects of E on GnRH-induced LH release by superfused rat anterior pituitary cells. Expression of the stimulatory effect of E is related to the dose of GnRH.
在一系列四项实验中，研究了17β-雌二醇（E）对用促性腺激素释放激素（GnRH）脉冲刺激的大鼠垂体前叶细胞释放促黄体生成素（LH）的急性抑制作用和延迟刺激作用的时间发展过程。将来自去卵巢大鼠的分散垂体前叶细胞在生物珠上培养3天，然后置于柱中并进行长达24小时的灌流。在灌流期间，细胞暴露于GnRH脉冲（3×10⁻⁹ M，每小时一个6分钟的脉冲）。在灌流前（仅在灌流前24小时）或灌流前及灌流期间用E（3×10⁻¹⁰ M）处理的细胞，对GnRH的前几个脉冲产生的LH释放量显著（P＜0.05）高于用稀释剂处理的细胞。相反，仅在灌流期间用E处理的细胞最初释放的GnRH诱导的LH比用稀释剂处理的细胞少。在随后的实验中，E的抑制作用在1.5小时时达到最大值（P＜0.01），然后在4.5小时后逐渐消失。与E和固定的“低”剂量GnRH（5×10⁻¹⁰ M）脉冲同时灌流的细胞，对该剂量的GnRH的LH反应并未随时间增强。然而，用E灌流的细胞对随后更高剂量的GnRH脉冲刺激的反应比用稀释剂灌流的细胞更强。在无GnRH脉冲的情况下用E灌流细胞16.5小时，也未增加对低剂量（5×10⁻¹⁰ M）GnRH脉冲的LH释放，但确实导致对随后高剂量（10⁻⁸ M）GnRH脉冲的短暂增加。总之，这些结果证明了E对灌流的大鼠垂体前叶细胞GnRH诱导的LH释放具有直接的双相抑制作用，随后是刺激作用。E刺激作用的表达与GnRH的剂量有关。
