Idänpään-Heikkilä J J, Rauhala P, Männistö P T
Department of Pharmacology and Toxicology, University of Helsinki, Finland.
Pharmacol Toxicol. 1996 Mar;78(3):136-42. doi: 10.1111/j.1600-0773.1996.tb00194.x.
The role of alpha 2-adrenergic receptors (adrenoceptors) in the secretion of growth hormone, prolactin and thyrotropin was studied using highly selective agonists and antagonists of the alpha 2-adrenoceptor. The interplay between opiates and alpha 2-adrenergic drugs in the acute secretion of growth hormone and prolactin, as well as the possible cross-tolerance between morphine (mu-opioid receptor agonist) and dexmedetomidine (alpha 2-adrenoceptor agonist) in growth hormone secretion were also evaluated. Dexmedetomidine dose-dependently increased plasma growth hormone and prolactin levels and decreased thyrotropin levels. The enhanced secretion of both growth hormone and prolactin was antagonized by atipamezole (an alpha 2-adrenoceptor antagonist) but not by prazosin (an alpha 1-adrenoceptor antagonist). Morphine (5 mg/kg)-induced stimulation of growth hormone secretion was antagonized by both naloxone (mu-opioid antagonist) and atipamezole. Naloxone, but not atipamezole, antagonized the morphine-induced increase in prolactin secretion. Dexmedetomidine increased growth hormone secretion in the saline pretreated rats, but did not do so in the morphine-tolerant rats. The stimulation of alpha 2-adrenoceptor enhances secretion of both growth hormone and prolactin. The adrenergic regulation of thyrotropin secretion still remains unclear. Evidently, adrenergic mechanisms are involved in the morphine-induced stimulation of growth hormone secretion, but not in the morphine-induced stimulation of prolactin secretion. In addition, there is a clear cross-tolerance between dexmedetomidine and morphine in growth hormone secretion of the rat.
使用α2 - 肾上腺素能受体的高选择性激动剂和拮抗剂，研究了α2 - 肾上腺素能受体（肾上腺素受体）在生长激素、催乳素和促甲状腺激素分泌中的作用。还评估了阿片类药物与α2 - 肾上腺素能药物在生长激素和催乳素急性分泌中的相互作用，以及吗啡（μ - 阿片受体激动剂）和右美托咪定（α2 - 肾上腺素能受体激动剂）在生长激素分泌中可能存在的交叉耐受性。右美托咪定剂量依赖性地增加血浆生长激素和催乳素水平，并降低促甲状腺激素水平。阿替美唑（一种α2 - 肾上腺素能受体拮抗剂）可拮抗生长激素和催乳素的分泌增强，但哌唑嗪（一种α1 - 肾上腺素能受体拮抗剂）则不能。吗啡（5 mg/kg）诱导的生长激素分泌刺激可被纳洛酮（μ - 阿片拮抗剂）和阿替美唑拮抗。纳洛酮可拮抗吗啡诱导的催乳素分泌增加，但阿替美唑不能。右美托咪定可增加生理盐水预处理大鼠的生长激素分泌，但对吗啡耐受大鼠则无此作用。刺激α2 - 肾上腺素能受体可增强生长激素和催乳素的分泌。促甲状腺激素分泌的肾上腺素能调节仍不清楚。显然，肾上腺素能机制参与了吗啡诱导的生长激素分泌刺激，但不参与吗啡诱导的催乳素分泌刺激。此外，在大鼠生长激素分泌方面，右美托咪定和吗啡之间存在明显的交叉耐受性。
