Billestrup N, Swanson L W, Vale W
Proc Natl Acad Sci U S A. 1986 Sep;83(18):6854-7. doi: 10.1073/pnas.83.18.6854.
The mitogenic effect of the hypothalamic peptides growth hormone-releasing factor (GRF) and somatostatin on cultured growth hormone (GH)-producing cells (somatotrophs) was studied. Using autoradiographic detection of [3H]thymidine uptake and immunocytochemical identification of GH-producing cells, we show that 5 nM GRF causes a 20-fold increase in the percentage of somatotrophs labeled with [3H]thymidine. The total number of somatotrophs in GRF-treated cultures was increased by 60%. Somatostatin had no measurable effect on the labeling index by itself, but it partly inhibited the GRF-induced increase in both the labeling index and the total number of cells. Forskolin caused an increase in both the percentage of somatotrophs with a [3H]thymidine-labeled nucleus and the somatotroph number similar to that caused by GRF. GH secretion as well as cellular GH content in the GRF- or forskolin-treated cells increased with culture time over the entire period, whereas secretion and content of GH gradually decreased in control or somatostatin-treated cultures during the entire culture period. These data suggest that GRF and somatostatin regulate the mitotic activity of GH-producing cells and that the effect of GRF is possibly mediated by cyclic AMP.
研究了下丘脑肽生长激素释放因子（GRF）和生长抑素对培养的产生长激素（GH）细胞（生长激素细胞）的促有丝分裂作用。利用放射自显影检测[3H]胸腺嘧啶核苷摄取以及对产GH细胞进行免疫细胞化学鉴定，我们发现5 nM的GRF可使被[3H]胸腺嘧啶核苷标记的生长激素细胞百分比增加20倍。经GRF处理的培养物中生长激素细胞的总数增加了60%。生长抑素本身对标记指数没有可测量的影响，但它部分抑制了GRF诱导的标记指数和细胞总数的增加。福斯高林使具有[3H]胸腺嘧啶核苷标记细胞核的生长激素细胞百分比以及生长激素细胞数量增加，其增加程度与GRF引起的相似。在整个培养期间，经GRF或福斯高林处理的细胞中GH分泌以及细胞内GH含量随培养时间增加，而在整个培养期间，对照或生长抑素处理的培养物中GH分泌和含量逐渐下降。这些数据表明GRF和生长抑素调节产GH细胞的有丝分裂活性，并且GRF的作用可能由环磷酸腺苷介导。
