Dymshitz J, Ben-Jonathan N
Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis 46223.
Endocrinology. 1991 May;128(5):2469-75. doi: 10.1210/endo-128-5-2469.
There is extensive evidence that the posterior pituitary (PP) participates in the regulation of PRL secretion. We recently reported that a putative PRL-releasing factor is localized, and possibly produced, in the intermediate lobe of the PP. The aim of the present investigation was to determine whether cultured PP cells affect anterior pituitary (AP) function in terms of cell content and cumulative release of PRL. Anterior and posterior pituitaries from adult male rats were dispersed with trypsin and cultured either alone or together for 4 and 8 days in serum-free medium. The concentrations of PRL, GH, and LH in cell extracts and culture media were measured by RIA. Coculturing of AP and PP cells at different plating densities resulted in a 2-fold rise in PRL cell content after 4 days. The cumulative release of PRL in the cocultures was significantly increased only after 8 days. LH and GH were affected slightly, or not at all. Medium conditioned by PP cells mimicked the effects of coculture on the cumulative release of PRL, but not on the cell content. Short-term incubation with TRH induced a much larger release of PRL from AP + PP cocultures than from AP cells cultured alone. In conclusion, these data suggest that 1) PP cells stimulate the production and release of PRL in a hormone-specific manner, and 2) coculturing of AP + PP cells augments the responsiveness of lactotrophs to secretagogues such as TRH. We propose that at least two factors, one of which might be PRL-releasing factor, are involved in these effects.
有大量证据表明，垂体后叶（PP）参与催乳素（PRL）分泌的调节。我们最近报道，一种假定的PRL释放因子定位于PP的中间叶，并且可能在其中产生。本研究的目的是确定培养的PP细胞在PRL的细胞含量和累积释放方面是否会影响垂体前叶（AP）的功能。将成年雄性大鼠的垂体前叶和垂体后叶用胰蛋白酶分散，在无血清培养基中单独或共同培养4天和8天。通过放射免疫分析（RIA）测定细胞提取物和培养基中PRL、生长激素（GH）和促黄体生成素（LH）的浓度。以不同接种密度将AP和PP细胞共培养4天后，PRL细胞含量增加了2倍。共培养物中PRL的累积释放仅在8天后显著增加。LH和GH受到的影响较小或根本没有受到影响。PP细胞条件培养基模拟了共培养对PRL累积释放的影响，但对细胞含量没有影响。与促甲状腺激素释放激素（TRH）短期孵育后，AP + PP共培养物中PRL的释放量比单独培养的AP细胞大得多。总之，这些数据表明：1）PP细胞以激素特异性方式刺激PRL的产生和释放；2）AP + PP细胞共培养增强了催乳细胞对TRH等促分泌素的反应性。我们提出，至少有两个因素参与了这些作用，其中一个因素可能是PRL释放因子。
