Seki T, Awamura S, Kimura C, Ide S, Sakano K, Minami M, Nagase H, Satoh M
Department of Molecular Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Japan.
Eur J Pharmacol. 1999 Jul 2;376(1-2):159-67. doi: 10.1016/s0014-2999(99)00369-6.
We analyzed the pharmacological properties of 17-cyclopropylmethyl-3,14beta-dihydroxy-4,5alpha-epoxy-6b eta-[N-methyl-trans-3-(3-furyl)acrylamido]morphinan hydrochloride (TRK-820) using Chinese hamster ovary (CHO) cells expressing cloned rat mu-, delta- and kappa-opioid receptors and human nociceptin receptor. TRK-820 showed high affinity for the kappa-opioid receptor, with a Ki value of 3.5 +/- 0.9 nM. In CHO cells expressing kappa-opioid receptors, TRK-820 inhibited forskolin-stimulated cAMP accumulation, and the maximal inhibitory effect was equivalent to that of (+)-(5alpha,7alpha,8beta)-N-methyl-N-[7-(1-pyrrolidiny l)-1-oxaspiro-(4,5)dec-8-yl]benzeneacetamide (U69,593), a full agonist of kappa-opioid receptor. In CHO cells expressing mu-opioid receptors, TRK-820 inhibited cAMP accumulation, but the maximal inhibitory effect was significantly smaller than that of [D-Ala2, N-MePhe4, Gly-ol5]enkephalin (DAMGO), a full agonist of mu-opioid receptor. In CHO cells expressing delta-opioid receptor, the inhibitory effect of TRK-820 on cAMP accumulation was very weak. Using site-directed mutagenesis, the high affinity of TRK-820 for the kappa-opioid receptor was revealed to require Glu297. TRK-820 bound to the nociceptin receptor with a Ki value of 380 +/- 50 nM. TRK-820 by itself had no effect on cAMP accumulation in CHO cells expressing nociceptin receptors, but significantly antagonized the nociceptin (10 nM)-mediated inhibition of cAMP accumulation at high concentrations. These results indicate that TRK-820 acts as a full agonist for the kappa-opioid receptor, a partial agonist for the mu-opioid receptor and a low-affinity antagonist for the nociceptin receptor.
我们使用表达克隆大鼠μ-、δ-和κ-阿片受体以及人孤啡肽受体的中国仓鼠卵巢（CHO）细胞，分析了盐酸17-环丙基甲基-3,14β-二羟基-4,5α-环氧-6β-[N-甲基-反式-3-(3-呋喃基)丙烯酰胺]吗啡喃（TRK-820）的药理学特性。TRK-820对κ-阿片受体显示出高亲和力，其Ki值为3.5±0.9 nM。在表达κ-阿片受体的CHO细胞中，TRK-820抑制了福司可林刺激的cAMP积累，最大抑制作用与κ-阿片受体的完全激动剂(+)-(5α,7α,8β)-N-甲基-N-[7-(1-吡咯烷基)-1-氧杂螺-(4,5)癸-8-基]苯乙酰胺（U69,593）相当。在表达μ-阿片受体的CHO细胞中，TRK-820抑制了cAMP积累，但最大抑制作用明显小于μ-阿片受体的完全激动剂[D-Ala2,N-MePhe4,Gly-ol5]脑啡肽（DAMGO）。在表达δ-阿片受体的CHO细胞中，TRK-820对cAMP积累的抑制作用非常弱。通过定点诱变，发现TRK-820对κ-阿片受体的高亲和力需要Glu297。TRK-820与孤啡肽受体结合，Ki值为380±50 nM。TRK-820本身对表达孤啡肽受体的CHO细胞中的cAMP积累没有影响，但在高浓度下能显著拮抗孤啡肽（10 nM）介导的cAMP积累抑制作用。这些结果表明，TRK-820作为κ-阿片受体的完全激动剂、μ-阿片受体的部分激动剂以及孤啡肽受体的低亲和力拮抗剂发挥作用。
