Conway E L, Brown M J, Dollery C T
Neuropharmacology. 1984 Nov;23(11):1291-6. doi: 10.1016/0028-3908(84)90047-9.
Centrally-administered opioid peptides produce elevations in levels of catecholamines in plasma in conscious rats. To investigate the opioid receptor involved in mediating this response, morphine (3.5-105 nmol), [D-Ala2-D-Leu5]enkephalin (DADL, 1.05-35 nmol) and U50, 488H (35-1160 nmol), relatively selective ligands for the mu, delta and kappa receptors respectively, were injected intracerebroventricularly into conscious rats and the levels of catecholamines in plasma determined at the peak of the response. Each agonist produced dose-dependent elevations in levels of noradrenaline and adrenaline, the order of potency being DADL approximately equal to morphine greater than U50,488H. These results exclude involvement of the kappa receptor but do not distinguish between an effect mediated by a mu or delta receptor. The responses to morphine were blocked in the presence of 300 nmol naloxone but were not altered by 41.5 nmol RX 781094, a selective alpha 2-adrenoceptor antagonist. The elevation in levels of adrenaline in plasma produced by small doses of the agonists was not related to behavioural changes.
中枢给予的阿片肽可使清醒大鼠血浆中的儿茶酚胺水平升高。为研究介导该反应的阿片受体，分别将相对选择性作用于μ、δ和κ受体的吗啡（3.5 - 105 nmol）、[D - Ala2 - D - Leu5]脑啡肽（DADL，1.05 - 35 nmol）和U50,488H（35 - 1160 nmol）脑室内注射到清醒大鼠体内，并在反应峰值时测定血浆中儿茶酚胺的水平。每种激动剂均使去甲肾上腺素和肾上腺素水平呈剂量依赖性升高，其效价顺序为DADL≈吗啡＞U50,488H。这些结果排除了κ受体的参与，但无法区分是由μ受体还是δ受体介导的效应。在存在300 nmol纳洛酮的情况下，对吗啡的反应被阻断，但41.5 nmol的选择性α2 - 肾上腺素能受体拮抗剂RX 781094并未改变该反应。小剂量激动剂引起的血浆肾上腺素水平升高与行为变化无关。
