Blackard W G, Heidingsfelder S A
J Clin Invest. 1968 Jun;47(6):1407-14. doi: 10.1172/JCI105832.
The influence of catecholamines on growth hormone secretion has been difficult to establish previously, possibly because of the suppressive effect of the induced hyperglycemia on growth hormone concentrations. In this study, an adrenergic receptor control mechanism for human growth hormone (HGH) secretion was uncovered by studying the effects of alpha and beta receptor blockade on insulin-induced growth hormone elevations in volunteer subjects. Alpha adrenergic blockade with phentolamine during insulin hypoglycemia, 0.1 U/kg, inhibited growth hormon elevations to 30-50% of values in the same subjects during insulin hypoglycemia without adrenergic blockade. More complete inhibition by phentolamine could not be demonstrated at a lower dose of insulin (0.05 U/kg). Beta adrenergic blockade with propranolol during insulin hypoglycemia significantly enhanced HGH concentrations in paired experiments. The inhibiting effect of alpha adrenergic receptor blockade on HGH concentrations could not be attributed to differences in blood glucose or free fatty acid values; however, more prolonged hypoglycemia and lower plasma free fatty acid values may have been a factor in the greater HGH concentrations observed during beta blockade. In the absence of insulin induced hypoglycemia, neither alpha nor beta adrenergic receptor blockade had a detectable effect on HGH concentrations. Theophylline, an inhibitor of cyclic 3'5'-AMP phosphodiesterase activity, also failed to alter plasma HGH concentrations. These studies demonstrate a stimulatory effect of alpha receptors and a possible inhibitory effect of beta receptors on growth hormone secretion.
儿茶酚胺对生长激素分泌的影响此前一直难以确定，这可能是由于所诱发的高血糖对生长激素浓度具有抑制作用。在本研究中，通过研究α和β受体阻断对志愿者胰岛素诱导的生长激素升高的影响，发现了人类生长激素（HGH）分泌的肾上腺素能受体控制机制。在胰岛素低血糖（0.1U/kg）期间用酚妥拉明进行α肾上腺素能阻断，抑制生长激素升高至相同受试者在无肾上腺素能阻断的胰岛素低血糖期间所测值的30%-50%。在较低剂量胰岛素（0.05U/kg）时，酚妥拉明无法表现出更完全的抑制作用。在配对实验中，胰岛素低血糖期间用普萘洛尔进行β肾上腺素能阻断显著提高了HGH浓度。α肾上腺素能受体阻断对HGH浓度的抑制作用不能归因于血糖或游离脂肪酸值的差异；然而，低血糖持续时间延长和血浆游离脂肪酸值降低可能是β受体阻断期间观察到的HGH浓度升高幅度更大的一个因素。在无胰岛素诱导的低血糖情况下，α和β肾上腺素能受体阻断对HGH浓度均无明显影响。茶碱，一种环3',5'-AMP磷酸二酯酶活性抑制剂，也未能改变血浆HGH浓度。这些研究表明α受体对生长激素分泌具有刺激作用，而β受体可能具有抑制作用。
