Terry L C, Martin J B
Endocrinology. 1981 May;108(5):1869-73. doi: 10.1210/endo-108-5-1869.
The present experiments were designed to study the effect of the centrally active alpha-adrenergic receptor agonist, clonidine, on episodic GH and PRL secretion in male rats after selective blockade of norepinephrine (NE) and epinephrine (EP) synthesis with the dopamine-beta-hydroxylase inhibitor, FLA-63. Freely behaving, chronically cannulated rats were maintained on a constant light-dark cycle in isolation test chambers. Beginning at 1000 h, blood samples were removed every 20 min for 5-h periods without disturbing the animal. FLA-63 was administered (10 or 20 mg/kg ip) at 0845 h. Clonidine (15 or 150 microgram/kg iv) was given at times that coincided with the spontaneous occurrence of episodic GH peaks or troughs observed in control animals. Results of the present study are summarized as follows: 1) selective blockade of NE and EP synthesis with FLA-63 (20 mg/kg) caused complete suppression of episodic GH but had no significant effect on PRL release; 2) clonidine (150 microgram/kg) restored the pulsatile pattern of GH secretion in FLA-63-treated rats, and 3) clonidine (15 and 150 microgram/kg) stimulated PRL release in a dose-dependent manner. These findings suggest a major stimulatory role of alpha-adrenergic receptors in episodic GH and PRL secretion.
本实验旨在研究中枢活性α-肾上腺素能受体激动剂可乐定，对用多巴胺-β-羟化酶抑制剂FLA-63选择性阻断去甲肾上腺素（NE）和肾上腺素（EP）合成后雄性大鼠的间歇性生长激素（GH）和催乳素（PRL）分泌的影响。自由活动、长期插管的大鼠在隔离试验箱中维持恒定的明暗周期。从10:00开始，每20分钟采集一次血样，持续5小时，期间不打扰动物。在08:45给予FLA-63（10或20mg/kg，腹腔注射）。在与对照动物中观察到的间歇性GH峰值或谷值自然出现的时间一致时给予可乐定（15或150μg/kg，静脉注射）。本研究结果总结如下：1）用FLA-63（20mg/kg）选择性阻断NE和EP合成可导致间歇性GH完全抑制，但对PRL释放无显著影响；2）可乐定（150μg/kg）恢复了FLA-63处理大鼠的GH分泌脉冲模式，3）可乐定（15和150μg/kg）以剂量依赖方式刺激PRL释放。这些发现表明α-肾上腺素能受体在间歇性GH和PRL分泌中起主要刺激作用。
