Chang H M, Berde C B, Holz G G, Steward G F, Kream R M
Department of Anesthesia, Harvard Medical School, Children's Hospital, Boston, Massachusetts 02115.
Anesthesiology. 1989 Apr;70(4):672-7. doi: 10.1097/00000542-198904000-00022.
An in vitro model system for analysis of presynaptic inhibitory actions of spinal opioids has been applied. Embryonic sensory neurons derived from chick dorsal root ganglia were grown in primary cell culture, and the release of substance P was evoked by electrical field stimulation during exposure to drugs with well-demonstrated affinity for opioid receptors. This allowed a pharmacologic characterization of the inhibitory actions of specific opioid agonists on the release of substance P as measured by radioimmunoassay (RIA). Sufentanil (0.5 microM), a high affinity mu receptor agonist, U-50,488H (25 microM), a selective kappa receptor agonist, and morphine (10 microM), an agonist with high affinity for mu and delta receptors, inhibited the evoked release of substance P by approximately 60%, 40%, and 50%, respectively. For sufentanil the response was demonstrated to be dose-dependent. As is the case for its analgesic action in vivo, morphine was approximately 50-fold less potent than sufentanil on a molar basis in this assay. The actions of sufentanil, U-50-488H and morphine were mimicked by the endogenous opioid peptide met-enkephalin, and its stable synthetic analog D-ala2-met5-enkephalinamide (DAME). Naloxone (25 microM), an opioid receptor antagonist, blocked the inhibitory action of sufentanil (0.5 microM), morphine (5 microM), and DAME (5 microM), but not U-50,488H (10 microM). The action of U-50,488H was partially blocked by the antagonist naltrexone (25 microM). Stereo-selectivity of agonist action was confirmed by the failure of dextrorphan (50 microM), an inactive opioid isomer, to inhibit the release of substance P.(ABSTRACT TRUNCATED AT 250 WORDS)
一种用于分析脊髓阿片类药物突触前抑制作用的体外模型系统已被应用。源自鸡背根神经节的胚胎感觉神经元在原代细胞培养中生长，在暴露于对阿片受体具有明确亲和力的药物期间，通过电场刺激诱发P物质的释放。这使得能够通过放射免疫测定法（RIA）对特定阿片类激动剂对P物质释放的抑制作用进行药理学表征。高亲和力μ受体激动剂舒芬太尼（0.5微摩尔）、选择性κ受体激动剂U-50,488H（25微摩尔）和对μ和δ受体具有高亲和力的激动剂吗啡（10微摩尔）分别抑制诱发的P物质释放约60%、40%和50%。对于舒芬太尼，该反应被证明是剂量依赖性的。在此测定中，与它在体内的镇痛作用情况一样，吗啡在摩尔基础上的效力比舒芬太尼低约50倍。舒芬太尼、U-50-488H和吗啡的作用被内源性阿片肽甲硫氨酸脑啡肽及其稳定的合成类似物D-丙氨酸2-甲硫氨酸5-脑啡肽酰胺（DAME）模拟。阿片受体拮抗剂纳洛酮（25微摩尔）阻断了舒芬太尼（0.5微摩尔）、吗啡（5微摩尔）和DAME（5微摩尔）的抑制作用，但不阻断U-50,488H（10微摩尔）的作用。拮抗剂纳曲酮（25微摩尔）部分阻断了U-50,488H的作用。无活性的阿片异构体右啡烷（50微摩尔）未能抑制P物质的释放，从而证实了激动剂作用的立体选择性。（摘要截短于250字）
