Akiyama K, Gee K W, Mosberg H I, Hruby V J, Yamamura H I
Proc Natl Acad Sci U S A. 1985 Apr;82(8):2543-7. doi: 10.1073/pnas.82.8.2543.
Specific binding properties of the tritium-labeled delta opiate receptor agonist [3H][2-D-penicillamine, 5-D-penicillamine]enkephalin [( 3H][D-Pen2, D-Pen5]enkephalin) were characterized in the rat brain and in a mouse neuroblastoma-rat glioma hybrid cell line (NG 108-15). Saturation isotherms of [3H][D-Pen2, D-Pen5]enkephalin binding to rat brain and NG 108-15 membranes gave apparent Kd values of 1-6 nM. These values are in good agreement with the Kd value obtained from the kinetic studies. The Bmax value in NG 108-15 membranes was 235.3 fmol/mg of protein. An apparent regional distribution of [3H][D-Pen2, D-Pen5]enkephalin binding was observed in the rat brain. A number of enkephalin analogues inhibited [3H][D-Pen2, D-Pen5]enkephalin binding with high affinity (IC50 values of 0.5-5.0 nM) in both NG 108-15 and rat brain membranes. However, putative mu receptor-selective ligands such as morphine, [D-Ala2, MePhe4, Gly5-ol]enkephalin, [MePhe3, D-Pro4]morphiceptin, and naloxone were less effective inhibitors of [3H][D-Pen2, D-Pen5]enkephalin binding in both systems tested. These data suggest that [3H][D-Pen2, D-Pen5]enkephalin is a potent and selective ligand for the delta opioid receptor.
在大鼠脑和小鼠神经母细胞瘤 - 大鼠胶质瘤杂交细胞系（NG 108 - 15）中，对氚标记的δ阿片受体激动剂[3H][2 - D - 青霉胺，5 - D - 青霉胺]脑啡肽[（3H][D - Pen2，D - Pen5]脑啡肽）的特异性结合特性进行了表征。[3H][D - Pen2，D - Pen5]脑啡肽与大鼠脑和NG 108 - 15细胞膜结合的饱和等温线给出的表观解离常数（Kd）值为1 - 6 nM。这些值与动力学研究获得的Kd值高度一致。NG 108 - 15细胞膜中的最大结合容量（Bmax）值为235.3 fmol/mg蛋白质。在大鼠脑中观察到[3H][D - Pen2，D - Pen5]脑啡肽结合存在明显的区域分布。在NG 108 - 15和大鼠脑膜中，许多脑啡肽类似物以高亲和力抑制[3H][D - Pen2，D - Pen5]脑啡肽结合（半数抑制浓度（IC50）值为0.5 - 5.0 nM）。然而，在两个测试系统中，推定的μ受体选择性配体，如吗啡、[D - Ala2，MePhe4，Gly5 - ol]脑啡肽、[MePhe3，D - Pro4]吗啡肽和纳洛酮，对[3H][D - Pen2，D - Pen5]脑啡肽结合的抑制作用较弱。这些数据表明，[3H][D - Pen2，D - Pen5]脑啡肽是δ阿片受体的一种强效且选择性的配体。
