Estradiol-17β stimulates basal and thyrotropin releasing hormone induced prolactin secretion by bovine pituitary cells in primary culture
Estradiol-17β stimulates basal and thyrotropin releasing hormone induced prolactin secretion by bovine pituitary cells in primary culture
复制标题
雌二醇-17β刺激原代培养物中牛垂体细胞的基础和促甲状腺素释放激素诱导的催乳素分泌
DOI：
10.1016/0303-7207(79)90098-4
复制
发表时间：
1979
影响因子：
4.1
通讯作者：
E. Convey
中科院分区：
文献类型：
--
作者：
V. Padmanabhan;E. Convey
进行了一系列实验，证明雌二醇-17 β直接影响原代培养的牛垂体细胞，导致基础和促甲状腺激素释放激素（TRH）诱导的催乳素分泌增加。促乳素释放垂体细胞与TRH在0.001，0.01，0.1和1 ng/ml的浓度孵育线性增加对数浓度。垂体细胞暴露于5，50或500 ng/ml雌二醇4小时不影响基础或TRH诱导的催乳素释放。然而，当暴露于雌二醇的时间延长到6，12，或24小时，0.5，5或50纳克雌二醇/毫升培养基引起垂体细胞释放更多的催乳素，并有更多的总催乳素的系统（媒体+细胞内容）比可比的控制。这些增加与所用雌二醇的对数浓度增加呈线性相关。为了确定雌二醇对催乳素分泌的长期影响，将垂体细胞与雌二醇-17 β孵育11天，在此期间，从第3天开始以24小时的间隔收集培养基。在第3天，对照培养物培养基中的催乳素积累平均为2.5 ng/ml，并逐渐下降，到第11天达到相对较低的水平（100 ng/ml）。虽然催乳素分泌减少，在文化期间，雌二醇的刺激作用是显而易见的。此外，在第11天，这些细胞仍然释放催乳素以响应TRH（1 ng/ml），并且TRH诱导的催乳素释放的幅度随着雌二醇-17 β浓度的增加而增加。我们的结论是，雌二醇将增加基础和TRH诱导的催乳素释放的牛催乳细胞。这些结果与以下观点一致：牛妊娠结束时发生的雌二醇增加可能参与该种属分娩时发生的催乳素激增。
A series of experiments were conducted which demonstrate that estradiol-17β directly affects bovine pituitary cells in primary culture causing an increase in basal and thyrotropin releasing hormone (TRH)-induced prolactin secretion. Prolactin release by pituitary cells incubated with TRH at concentrations of 0.001, 0.01, 0.1 and 1 ng/ml increased linearly with increasing log concentrations. Exposure of pituitary cells to 5, 50 or 500 ng/ml estradiol for 4 h did not affect basal or TRH-induced prolactin release. However, when the period of exposure to estradiol was prolonged to 6, 12, or 24 h, 0.5, 5 or 50 ng estradiol/ml medium caused pituitary cells to release more prolactin and there was more total prolactin in the system (medium +cell content) than for comparable controls. These increases were linearly related to increasing log concentrations of estradiol used. To determine the chronic effect of estradiol on prolactin secretion, pituitary cells were incubated with estradiol-17β for 11 days during which medium was collected at 24 h intervals beginning on day 3. On day 3, prolactin accumulation in medium of control cultures averaged 2.5 ng/ml, and decreased gradually reaching relatively low levels by day 11 (100 ng/ml). Although prolactin secretion decreased during the culture period, stimulatory effects of estradiol were evident throughout. In addition, these cells still released prolactin in response to TRH (1 ng/ml) on day 11 and magnitude of TRH-induced prolactin release increased with increasing concentrations of estradiol-17β. We conclude that estradiol will increase basal and TRH-induced prolactin release by bovine lactotrophs. These results are consistent with the view that the increase in estradiol that occurs at the end of pregnancy in cattle, may participate in the prolactin surge that occurs at parturition in this species.