Perkins S N, Evans W S, Thorner M O, Gibbs D M, Cronin M J
Endocrinology. 1985 Nov;117(5):1818-25. doi: 10.1210/endo-117-5-1818.
Our studies demonstrated that beta-adrenergic agonists stimulate the release of GH from rat anterior pituitary (AP) cells in vitro. Concentration-response experiments with beta-adrenergic agonists demonstrated that beta 2-adrenergic receptors mediated this phasic GH release, while having no apparent effect on PRL or LH release. The ACTH response to beta-adrenergic agonists was equivocal. Half-maximal stimulation of GH release occurred at 14 +/- 2 (+/-SE) nM isoproterenol, 160 +/- 30 nM epinephrine, and over 1 microM l-norepinephrine (n = 4). Direct binding studies in membrane particulates of rat AP confirmed receptors of the beta 2-subtype. Iodocyanopindolol binding to beta-adrenergic receptors of rat AP yielded a dissociation constant of 4.6 +/- 0.1 pM and a maximal capacity of 1.9 +/- 0.4 fmol/mg protein (n = 3). In contrast, porcine AP contained beta 1-adrenergic receptors. These results support the hypothesis that the endogenous beta 2-adrenergic agonist l-epinephrine may be a GH-releasing factor of physiological significance in the rat.
我们的研究表明，β-肾上腺素能激动剂在体外可刺激大鼠垂体前叶（AP）细胞释放生长激素（GH）。对β-肾上腺素能激动剂进行的浓度-反应实验表明，β2-肾上腺素能受体介导了这种阶段性GH释放，而对催乳素（PRL）或促黄体生成素（LH）的释放没有明显影响。促肾上腺皮质激素（ACTH）对β-肾上腺素能激动剂的反应不明确。异丙肾上腺素浓度为14±2（±标准误）nM、肾上腺素浓度为160±30 nM以及左旋去甲肾上腺素浓度超过1μM时，可实现GH释放的半数最大刺激（n = 4）。对大鼠AP膜颗粒进行的直接结合研究证实了β2-亚型受体的存在。碘氰吲哚洛尔与大鼠AP的β-肾上腺素能受体结合，解离常数为4.6±0.1 pM，最大结合容量为1.9±0.4 fmol/mg蛋白质（n = 3）。相比之下，猪的AP含有β1-肾上腺素能受体。这些结果支持以下假说：内源性β2-肾上腺素能激动剂l-肾上腺素可能是大鼠体内具有生理意义的生长激素释放因子。
