Keith L D, Tam B, Ikeda H, Opsahl Z, Greer M A
Neuroendocrinology. 1986;43(4):445-52. doi: 10.1159/000124565.
We have examined the dynamics of thyrotropin-releasing hormone (TRH)-stimulated secretion of prolactin (PRL) and thyrotropin-stimulating hormone (TSH) using enzymatically dispersed rat adenohypophyseal cells suspended in a perfusion chamber with a volume of 0.2 ml to minimize mixing and dilution. One-min exposure to 3-300 nM TRH, the effective dose range, elicited immediate pulses of PRL and TSH secretion with dose-dependent amplitudes. At all TRH concentrations, following a brief burst of secretion lasting less than 1 min, release of both hormones declined precipitously. Increasing the duration of stimulation up to 30 min with half-maximal TRH concentrations did not alter the dynamics of the initial response and was ineffective in maintaining the initial amplitude of secretion. This phenomenon could not be attributed to exhaustion of readily releasable intracellular PRL and TSH, since an increment in TRH concentration elicited a second pulse of hormone secretion with temporal response characteristics identical to the first. The amplitude of the second pulse was dependent on both the initial concentration of TRH and the magnitude of the increment in TRH concentration. With a stepwise increase in TRH concentration during continuous perfusion, the sum of PRL or TSH secreted from all bursts of secretory activity approximated that achieved with a single exposure to the highest concentration of TRH employed. The high-amplitude secretory response to a given concentration of TRH was restored after an 8-min perfusion with medium alone.(ABSTRACT TRUNCATED AT 250 WORDS)
我们使用悬浮于容积为0.2 ml的灌注室中的酶分散大鼠腺垂体细胞，以尽量减少混合和稀释，研究了促甲状腺激素释放激素（TRH）刺激的催乳素（PRL）和促甲状腺激素（TSH）分泌的动力学。暴露于3 - 300 nM TRH（有效剂量范围）1分钟，会引发PRL和TSH分泌的即时脉冲，其幅度呈剂量依赖性。在所有TRH浓度下，在持续不到1分钟的短暂分泌爆发后，两种激素的释放急剧下降。用半数最大浓度的TRH将刺激持续时间延长至30分钟，并未改变初始反应的动力学，且无法维持初始分泌幅度。这种现象不能归因于易于释放的细胞内PRL和TSH耗竭，因为TRH浓度增加会引发第二个激素分泌脉冲，其时间反应特征与第一个相同。第二个脉冲的幅度取决于TRH的初始浓度和TRH浓度增加的幅度。在连续灌注过程中逐步增加TRH浓度时，所有分泌活动爆发分泌的PRL或TSH总和接近单次暴露于所用最高浓度TRH时所达到的水平。在用单独培养基灌注8分钟后，对给定浓度TRH的高幅度分泌反应得以恢复。（摘要截短于250字）
