Wehrenberg W B
Neuroendocrinology. 1986;43(3):391-6. doi: 10.1159/000124554.
The effects of a continuous infusion of growth hormone-releasing factor (GRF) on pulsatile growth hormone (GH) secretion were studied in conscious, freely moving rats. Male Sprague-Dawley rats were prepared with 2 indwelling venous catheters and were then housed individually for 6-16 days in isolation chambers. After this period, normal saline, 1.5 microgram/h GRF or 15 micrograms/h GRF were continuously infused for 8 or 31 h via one of the catheters. Blood samples were drawn at approximately 20-min intervals via the other catheter during the last 6-7 h of the infusion. Plasma GH concentrations were determined by RIA. Saline-treated animals exhibited the typical pattern of spontaneous GH pulses. The frequency of GH pulses in animals infused with either dose of GRF was not different from that of the saline-infused rats. Likewise, trough GH concentrations were similar in all three treatment groups. However, peak GH concentrations in the rats receiving the 15-micrograms/h GRF infusion were remarkably higher than the concentrations observed in the other two groups, regardless of the duration of the infusion. This resulted in mean GH concentrations being significantly higher (p less than 0.01) in the 15-micrograms/h GRF-infused rats. These results demonstrate that pituitary episodic GH secretion continues even in the presence of a continuous GRF stimulation.
在清醒、自由活动的大鼠中研究了持续输注生长激素释放因子（GRF）对脉冲式生长激素（GH）分泌的影响。给雄性斯普拉格-道利大鼠植入2根留置静脉导管，然后将它们单独饲养在隔离室中6 - 16天。在此期间过后，通过其中一根导管持续输注生理盐水、1.5微克/小时GRF或15微克/小时GRF，持续8或31小时。在输注的最后6 - 7小时内，通过另一根导管每隔约20分钟采集一次血样。用放射免疫分析法测定血浆GH浓度。生理盐水处理的动物表现出典型的自发性GH脉冲模式。输注任一剂量GRF的动物中GH脉冲频率与输注生理盐水的大鼠无差异。同样，三个治疗组的GH谷浓度相似。然而，无论输注持续时间如何，接受15微克/小时GRF输注的大鼠的GH峰值浓度显著高于其他两组观察到的浓度。这导致接受15微克/小时GRF输注的大鼠的平均GH浓度显著更高（p < 0.01）。这些结果表明，即使存在持续的GRF刺激，垂体间歇性GH分泌仍会继续。
