Bourdage R J, Fitz T A, Niswender G D
Proc Soc Exp Biol Med. 1984 Apr;175(4):483-6. doi: 10.3181/00379727-175-41824.
Experiments were conducted in vitro on ovine small luteal cells to evaluate their steroidogenic response to ovine luteinizing hormone (oLH) and human chorionic gonadotropin (hCG) administered continuously throughout the experimental period or as a 15-min pulse. Both oLH and hCG stimulated a significant increase in progesterone secretion (P less than 0.001) by small luteal cells. Human chorionic gonadotropin administered continuously or as a pulse maintained progesterone secretion at 40-55% of experimental maximum at least 6 hr while oLH-stimulated progesterone secretion declined to basal levels by 4 hr after a 15-min pulse or declined to 25% of the experimental maximum within 6 hr under constant stimulation. The responses of small luteal cells to oLH and hCG were found to differ (P less than 0.001). The sustained progesterone secretion of luteal cells in response to a pulse of hCG may be due to longer residence of occupied receptor complex on the cell membrane. In contrast, the decline in oLH stimulated progesterone secretion, even when hormone is continuously present in the medium, may be related to a rapid internalization of receptor-hormone complexes and down-regulation of receptors.
在体外对绵羊小黄体细胞进行实验，以评估它们在整个实验期间持续给予或作为15分钟脉冲给予绵羊促黄体激素（oLH）和人绒毛膜促性腺激素（hCG）时的类固醇生成反应。oLH和hCG均刺激小黄体细胞孕酮分泌显著增加（P<0.001）。持续给予或作为脉冲给予的hCG使孕酮分泌维持在实验最大值的40 - 55%至少6小时，而oLH刺激的孕酮分泌在15分钟脉冲后4小时降至基础水平，或在持续刺激下6小时内降至实验最大值的25%。发现小黄体细胞对oLH和hCG的反应不同（P<0.001）。黄体细胞对hCG脉冲的持续孕酮分泌可能是由于占据的受体复合物在细胞膜上停留时间更长。相比之下，即使培养基中持续存在激素，oLH刺激的孕酮分泌下降可能与受体 - 激素复合物的快速内化和受体下调有关。
