Physiological concentrations of L-leucine control the release of prolactin from cultured rat pituitary cells.
Physiological concentrations of L-leucine control the release of prolactin from cultured rat pituitary cells.
复制标题
L-亮氨酸的生理浓度控制培养的大鼠垂体细胞中催乳素的释放。
作者：
M. Cross;A. Walker
为了进一步确定PRL内分泌体外研究的最佳实验条件，评估了细胞外亮氨酸浓度对PRL分泌的影响。将维持在短期单层培养物中的大鼠垂体细胞洗涤至无血清，并置于补充有非必需氨基酸和0.1%明胶的最低必需培养基（MEM; 0.39 mM亮氨酸）中。在建立恒定的基础PRL释放速率后，将MEM替换为不含亮氨酸的MEM（如上所述补充），并跟踪PRL释放速率。PRL释放从细胞中的亮氨酸的培养基下降到15分钟内的30%，在控制中看到的速率。通过仅添加L-亮氨酸实现恢复到对照速率。D-异构体、异亮氨酸、缬氨酸、脯氨酸、亮氨酰-亮氨酸和亮氨酸-琼脂糖无效。在短期内，发现PRL合成的速率不依赖于细胞外亮氨酸，并且当在50微克/ml放线菌酮的存在下进行该实验时，还观察到在除去亮氨酸后观察到的释放抑制，以及随后的亮氨酸置换后的恢复。发现L-亮氨酸回收率是剂量依赖性的，亮氨酸浓度从20 mg/L增加到40 mg/L，导致PRL释放速率增加两倍。加入10（-7）M TRH表明亮氨酸对这种刺激物的反应是有限的，并允许识别对低至10 mg/L亮氨酸的反应。从这些实验中，可以得出结论，生理浓度的亮氨酸具体和深刻地影响PRL的释放的机制独立于蛋白质的合成。这种释放所需的亮氨酸以前没有报道过。
In an attempt to further define the optimum experimental conditions for the in vitro study of PRL endocrinology, the effect of extracellular leucine concentration on PRL secretion was assessed. Rat pituitary cells, maintained in short term monolayer culture, were washed free of serum and placed in Minimum Essential Medium (MEM; 0.39 mM leucine) supplemented with nonessential amino acids and 0.1% gelatin. After the establishment of a constant rate of basal PRL release, the MEM was replaced with leucine-free MEM (supplemented as above), and the rate of PRL release was followed. PRL release from the cells in the leucine-free medium fell within 15 min to a rate 30% of that seen in the controls. Return to the control rate was achieved by the addition of L-leucine only. The D-isomer, isoleucine, valine, proline, leucyl-leucine, and leucine-agarose were ineffective. In the short term, the rate of PRL synthesis was found to be independent of extracellular leucine and the inhibition of release seen upon removal of leucine, and the subsequent recovery upon replacement of leucine was also observed when this experiment was conducted in the presence of 50 micrograms/ml cycloheximide. The L-leucine recovery was found to be dose dependent, with an increase in leucine concentration from 20 to 40 mg/liter causing a tripling of the PRL release rate. The addition of 10(-7) M TRH showed that leucine can be limiting in the response to this stimulant and allowed a response to as little as 10 mg/liter leucine to be discerned. From these experiments, it is concluded that physiological concentrations of leucine specifically and profoundly affect the release of PRL by a mechanism independent of protein synthesis. This leucine requirement for release has not been previously reported.
新合成的催乳素颗粒的优先释放是促乳腺激素细胞功能异质性的结果。
影响因子：
4.8
作者：
Walker,AM;Farquhar,MG
通讯作者：
Farquhar,MG