Schmauss C, Yaksh T L, Shimohigashi Y, Harty G, Jensen T, Rodbard D
Life Sci. 1983;33 Suppl 1:653-6. doi: 10.1016/0024-3205(83)90587-8.
The intrathecal administration of several mu (morphine), delta (d-ala2-d-leu5-enkephalin, dimeric leu-enkephalin) and mixed mu/delta (beta-endorphin) agonists produced a dose-dependent inhibition of all cutaneous thermal (Tail Flick/Hot Plate) nociceptive responses in the rat. The kappa agonist U50488H had no analgesic potency in thermal nociceptive tests. On a visceral chemical test (writhing) and agonists exerted a powerful suppression of the response. In contrast at doses 10 to 50 times the ED50 on cutaneous thermal tests, delta agonists had no effect on the writhing response. At higher intrathecal doses, delta ligands produced flaccidity. These observations suggest the existence of three discriminable populations of opioid receptors in the spinal cord whose activation has different effects on the animals response to noxious stimuli.
鞘内注射几种μ（吗啡）、δ（D-丙氨酸2-D-亮氨酸5-脑啡肽、二聚亮氨酸脑啡肽）和混合μ/δ（β-内啡肽）激动剂，可对大鼠所有皮肤热（甩尾/热板）伤害性反应产生剂量依赖性抑制。κ激动剂U50488H在热伤害性测试中无镇痛效力。在内脏化学测试（扭体）中，这些激动剂可强力抑制反应。相比之下，在皮肤热测试中剂量为ED50的10至50倍时，δ激动剂对扭体反应无影响。鞘内注射更高剂量时，δ配体可导致肌肉松弛。这些观察结果表明，脊髓中存在三种可区分的阿片受体群体，其激活对动物对有害刺激的反应有不同影响。
