al-Damluji S, Bouloux P, White A, Besser M
Department of Endocrinology, St. Bartholomew's Hospital, London, UK.
Neuroendocrinology. 1990 Jan;51(1):76-81. doi: 10.1159/000125319.
This study examined the effects of an alpha-2-adrenoceptor antagonist on the secretion of ACTH basally and in response to the opioid antagonist naloxone, which is known to stimulate ACTH secretion by an adrenergic mechanism. Eight normal men were given, in double-blind, random order, intravenous infusions of normal saline (placebo), idazoxan (alpha-2-adrenoceptor antagonist), naloxone and the combination of idazoxan and naloxone. Naloxone increased plasma ACTH and cortisol concentrations in comparison to placebo. Idazoxan significantly enhanced the ACTH and cortisol responses to naloxone but had no effect on plasma ACTH or cortisol concentrations when given alone. These findings suggest that during some conditions of increased ACTH secretion, inhibitory alpha-2-adrenoceptors are activated and that these receptors limit the ACTH response. This provides an explanation for some of the apparent contradictions in interpreting the data from previous studies on the effects of catecholamines on the secretion of ACTH.
本研究考察了一种α-2-肾上腺素能受体拮抗剂对促肾上腺皮质激素（ACTH）基础分泌的影响，以及对阿片类拮抗剂纳洛酮反应时的影响，已知纳洛酮可通过肾上腺素能机制刺激ACTH分泌。8名正常男性被给予静脉输注生理盐水（安慰剂）、咪唑克生（α-2-肾上腺素能受体拮抗剂）、纳洛酮以及咪唑克生和纳洛酮的组合，给药顺序为双盲随机。与安慰剂相比，纳洛酮增加了血浆ACTH和皮质醇浓度。咪唑克生显著增强了对纳洛酮的ACTH和皮质醇反应，但单独给药时对血浆ACTH或皮质醇浓度无影响。这些发现表明，在某些ACTH分泌增加的情况下，抑制性α-2-肾上腺素能受体被激活，且这些受体限制了ACTH反应。这为解释以往关于儿茶酚胺对ACTH分泌影响的研究数据中一些明显矛盾之处提供了一个解释。
