Dickson S L, Leng G, Robinson I C
Department of Neurobiology, AFRC Babraham Institute, Cambridge, UK.
Brain Res. 1993 Sep 24;623(1):95-100. doi: 10.1016/0006-8993(93)90015-f.
Plasma growth hormone (GH) concentrations were measured following electrical stimulation of either the arcuate nucleus or the median eminence in urethane-anesthetized male rats. While electrical stimulation of the arcuate nucleus elicited a large pulse of GH secretion, stimulation of the median eminence was relatively ineffective. For stimulation of the arcuate nucleus, the frequency dependence of stimulus-secretion coupling for GH release was investigated by delivering 3 differing patterns of electrical stimulation, each of 2 min duration and containing 1,200 stimulus pulses: 10 Hz continuous; 20 Hz (10 s on/10 s off); and 50 Hz (2 s on/8 s off). To examine the effect of increasing the duration of the 50 Hz stimulus train on evoked GH release, a further three stimulation protocols were also tested: 50 Hz (2 s on/8 s off); 50 Hz (3 s on/7 s off) and 50 Hz (4 s on/6 s off). While evoked GH release (per stimulus pulse) was not significantly different for various frequencies of stimulation, it was greatly potentiated by increasing the duration of 50 Hz stimulus trains. These findings suggest that GH release is not linearly related to the activation of GRF neurons but is strongly facilitated with increases in burst duration.
在对经乌拉坦麻醉的雄性大鼠的弓状核或正中隆起进行电刺激后，测量其血浆生长激素（GH）浓度。虽然对弓状核的电刺激引发了大量的GH分泌脉冲，但对正中隆起的刺激相对无效。对于弓状核的刺激，通过给予3种不同模式的电刺激来研究刺激 - 分泌偶联对GH释放的频率依赖性，每种刺激持续2分钟，包含1200个刺激脉冲：10Hz连续刺激；20Hz（10秒开启/10秒关闭）；以及50Hz（2秒开启/8秒关闭）。为了研究增加50Hz刺激序列的持续时间对诱发的GH释放的影响，还测试了另外三种刺激方案：50Hz（2秒开启/8秒关闭）；50Hz（3秒开启/7秒关闭）和50Hz（4秒开启/6秒关闭）。虽然不同频率刺激诱发的GH释放（每个刺激脉冲）没有显著差异，但通过增加50Hz刺激序列的持续时间，GH释放得到了极大增强。这些发现表明，GH释放与生长激素释放因子（GRF）神经元的激活并非线性相关，而是随着爆发持续时间的增加而得到强烈促进。
