Kotsuji F, Winters S J, Attardi B, Keeping H S, Oshima H, Troen P
Department of Medicine, Montefiore Hospital, Pittsburgh, Pennsylvania 15213.
Endocrinology. 1988 Dec;123(6):2683-9. doi: 10.1210/endo-123-6-2683.
The feedback effects of testosterone (T) and estradiol (E2) on FSH and LH secretion were compared in dispersed pituitary cells from adult male rats perifused with pulses of GnRH. Cells were stimulated with 10 nM GnRH for 2 min every 1 h. T (10 nM) pretreatment for 24 h reduced the amplitude of FSH and LH pulses to 77 +/- 4% (mean +/- SE) and 47 +/- 3% of control values, respectively (P less than 0.01), whereas 6-h T treatment was without effect. By contrast, interpulse secretion of FSH was increased after 24 h T to 184 +/- 7% of the control value (P less than 0.01), but interpulse LH release was unchanged (104 +/- 5%). E2 (0.075 nM) treatment of pituitary cells reduced GnRH-stimulated FSH and LH release within 2 h to 75 +/- 2% and 73 +/- 3% of control values, respectively (P less than 0.01). E2 pretreatment for 24 h stimulated (P less than 0.025) GnRH-induced FSH (136 +/- 10%) and LH (145 +/- 8%) release and also increased (P less than 0.01) interpulse FSH (127 +/- 5%) and LH (145 +/- 8%) secretion. These data indicate that the suppression of FSH and LH secretion by T in males is due in part to a direct effect on the pituitary. The findings that T suppresses GnRH-stimulated FSH less than LH, and that T stimulates interpulse FSH, but not LH, provide evidence for differential regulation of FSH and LH secretion by T. The dissimilar actions of T on GnRH-stimulated pulses and interpulse gonadotropin secretion suggest that interpulse secretion is unrelated to stimulation by GnRH, although its physiological significance is unknown. Since E2, in physiological levels for males, increased pituitary FSH and LH secretion, the suppression of gonadotropin secretion by E2 in vivo in males may result from an effect on the hypothalamic pulse generator; however, additional studies are needed before extending these conclusions to higher mammals and men.
在成年雄性大鼠的分散垂体细胞中，比较了睾酮（T）和雌二醇（E2）对促卵泡激素（FSH）和促黄体生成素（LH）分泌的反馈作用。这些细胞每隔1小时用10 nM促性腺激素释放激素（GnRH）刺激2分钟。预先用10 nM T处理24小时可使FSH和LH脉冲的幅度分别降至对照值的77±4%（平均值±标准误）和47±3%（P<0.01），而6小时的T处理则无效果。相比之下，24小时T处理后FSH的脉冲间期分泌增加至对照值的184±7%（P<0.01），但LH的脉冲间期释放未改变（104±5%）。用0.075 nM E2处理垂体细胞2小时内，GnRH刺激的FSH和LH释放分别降至对照值的75±2%和73±3%（P<0.01）。预先用E2处理24小时可刺激（P<0.025）GnRH诱导的FSH（136±10%）和LH（145±8%）释放，也增加（P<0.01）脉冲间期FSH（127±5%）和LH（145±8%）的分泌。这些数据表明，雄性中T对FSH和LH分泌的抑制部分归因于对垂体的直接作用。T对GnRH刺激的FSH的抑制作用小于对LH的抑制作用，以及T刺激脉冲间期FSH而非LH分泌的发现，为T对FSH和LH分泌的差异调节提供了证据。T对GnRH刺激的脉冲和脉冲间期促性腺激素分泌的不同作用表明，脉冲间期分泌与GnRH的刺激无关，尽管其生理意义尚不清楚。由于在雄性生理水平的E2增加了垂体FSH和LH的分泌，因此雄性体内E2对促性腺激素分泌的抑制可能是由于对下丘脑脉冲发生器的作用；然而，在将这些结论推广到高等哺乳动物和人类之前，还需要进一步的研究。
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