Mulchahey J J, Di Blasio A M, Jaffe R B
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco 94143.
J Clin Endocrinol Metab. 1988 Feb;66(2):395-401. doi: 10.1210/jcem-66-2-395.
A reverse hemolytic plaque assay was used to measure the GH responses of fetal pituitary cells to GHRH, SRIH, T3 and glucocorticoids. Cells from eight human abortuses (18-22 weeks' gestation) showed accelerated plaque formation after treatment with 10(-7) mol/L GHRH-(1-44) [25.6 +/- 0.6% (+/- SE) of cells formed plaques (PFC); mean area, 14.5 +/- 2.7 X 10(4) micron2; all at 1 h], while 10(-7) mol/L SRIH-(1-28) slowed plaque formation (8.6 +/- 0.6% PFC; mean area, 4.2 +/- 0.8 X 10(4) micron2) vs. control (13.7 +/- 0.7% PFC; mean area, 5.3 +/- 0.8 X 10(4) micron2; all at 1 h). The proportion of PFC was equal in GHRH-treated and control groups by 4 h, suggesting that GHRH affects the amount of GH secreted per somatotroph rather than the number of cells that are preferentially responsive to GHRH. Qualitatively similar data were obtained using pituitary cells from four near-term rhesus fetuses. When cells were cultured in defined medium for 3 days, supplementation with T3 reduced basal GH secretion and attenuated the responses to GHRH. Culture with dexamethasone increased basal GH secretion and restored the responsiveness to GHRH. Dexamethasone also caused a shift in plaque area frequency distributions to patterns similar to those in serum-supplemented medium. We conclude that fetal somatotrophs are responsive to SRIH, GHRH, T3, and dexamethasone. Furthermore, glucocorticoids can maintain a subpopulation of fetal somatotrophs in the GHRH-responsive state.
采用反向溶血空斑试验来测定胎儿垂体细胞对生长激素释放激素（GHRH）、生长抑素（SRIH）、三碘甲状腺原氨酸（T3）和糖皮质激素的生长激素（GH）反应。来自8例人工流产胎儿（妊娠18 - 22周）的细胞，在用10⁻⁷mol/L GHRH - (1 - 44)处理后，空斑形成加速（形成空斑的细胞占25.6±0.6%（±标准误）；平均面积，14.5±2.7×10⁴μm²；均在1小时时），而10⁻⁷mol/L SRIH - (1 - 28)则减缓了空斑形成（形成空斑的细胞占8.6±0.6%；平均面积，4.2±0.8×10⁴μm²），与之相比，对照组（形成空斑的细胞占13.7±0.7%；平均面积，5.3±0.8×10⁴μm²；均在1小时时）。到4小时时，GHRH处理组和对照组形成空斑的细胞比例相等，这表明GHRH影响的是每个生长激素细胞分泌的GH量，而非优先对GHRH有反应的细胞数量。使用4例近足月恒河猴胎儿的垂体细胞获得了定性相似的数据。当细胞在限定培养基中培养3天时，添加T3可降低基础GH分泌并减弱对GHRH的反应。用地塞米松培养可增加基础GH分泌并恢复对GHRH的反应性。地塞米松还导致空斑面积频率分布向类似于血清补充培养基中的模式转变。我们得出结论，胎儿生长激素细胞对SRIH、GHRH、T3和地塞米松有反应。此外，糖皮质激素可使胎儿生长激素细胞的一个亚群维持在对GHRH有反应的状态。
