Martin T F, Kowalchyk J A
Endocrinology. 1984 Oct;115(4):1527-36. doi: 10.1210/endo-115-4-1527.
The studies reported here were directed toward establishing the mechanism by which TRH acutely stimulates PRL secretion in GH3 pituitary cells. Studies of TRH stimulation of PRL secretion were conducted on a time scale which enables comparison with other reported rapid effects of TRH on GH3 cells. TRH stimulation of secretion was found to be extremely rapid in onset (less than or equal to 10 sec) and biphasic (phase I, 0-2 min; phase II, 5-60 min). The earliest (phase I) secretory response was observed to be independent of medium Ca+2 concentration or Ca+2 influx, but to be dependent on an intracellular Ca+2 pool. The phase II response to TRH was found to depend, in part, on medium Ca+2. The phase I response to TRH could be mimicked only by agents known to influence Ca+2 translocation in GH3 cells (60 mM K+, A23187, ionomycin, carbonyl cyanide p-trifluoromethoxyphenylhydrazone, and carbonyl cyanide m-chlorophenylhydrazone). These agents failed to promote sustained PRL release characteristic of phase II. It is concluded that the ability of TRH to rapidly stimulate PRL secretion (phase I) is correlated with its ability to rapidly promote a transient cytoplasmic Ca+2 concentration rise from an intracellular Ca+2 pool.
本文报道的研究旨在确定促甲状腺激素释放激素（TRH）急性刺激GH3垂体细胞中催乳素（PRL）分泌的机制。对TRH刺激PRL分泌的研究是在一个时间尺度上进行的，以便能够与其他报道的TRH对GH3细胞的快速作用进行比较。发现TRH刺激分泌的起效极其迅速（小于或等于10秒）且呈双相性（第一阶段，0 - 2分钟；第二阶段，5 - 60分钟）。观察到最早的（第一阶段）分泌反应与培养基中Ca²⁺浓度或Ca²⁺内流无关，但依赖于细胞内Ca²⁺池。发现TRH的第二阶段反应部分依赖于培养基中的Ca²⁺。只有已知能影响GH3细胞中Ca²⁺转运的试剂（60 mM K⁺、A23187、离子霉素、羰基氰对三氟甲氧基苯腙和羰基氰间氯苯腙）才能模拟TRH的第一阶段反应。这些试剂未能促进第二阶段特有的持续PRL释放。得出的结论是，TRH快速刺激PRL分泌（第一阶段）的能力与其快速促进细胞内Ca²⁺池导致细胞质Ca²⁺浓度短暂升高的能力相关。
