Johnson N, Pasternak G W
Mol Pharmacol. 1984 Nov;26(3):477-83.
[3H]Naloxonazine binds to opioid-binding sites in rat brain homogenates. Prior administration of either morphine or D-Ala2-D-Leu5-enkephalin to the homogenates inhibits in a concentration-dependent manner the specific binding of [3H]naloxonazine. Most important, all the binding competed by unlabeled naloxonazine at 1 microM is also competed by morphine and D-Ala2-D-Leu5-enkephalin. [3H]Naloxonazine binding is linear with tissue up to 10 mg/ml wet weight of tissue, is temperature dependent, and has a pH maximum of approximately 7.7. Maximal binding is reached within 90 min at 25 degrees. The affinity of [3H]naloxonazine for its binding sites is quite high with half-maximal binding obtained at a concentration of approximately 2 nM. Approximately 40% of the total specific binding of [3H]naloxonazine is resistant to multiple washes and to displacement by levallorphan (1 microM) added 60 min after the [3H]naloxonazine, suggesting that a portion of [3H]naloxonazine binding is not freely reversible. The percentage of total [3H] naloxonazine binding which is not freely reversible varies 3-fold between regions, with the hypothalamus (60%) being the highest and the brainstem (18%) the lowest.
[3H]纳洛酮嗪与大鼠脑匀浆中的阿片样物质结合位点相结合。预先向匀浆中给予吗啡或D-Ala2-D-Leu5-脑啡肽，会以浓度依赖的方式抑制[3H]纳洛酮嗪的特异性结合。最重要的是，在1微摩尔浓度下未标记的纳洛酮嗪所竞争的所有结合，也能被吗啡和D-Ala2-D-Leu5-脑啡肽竞争。[3H]纳洛酮嗪的结合在组织湿重高达10毫克/毫升时呈线性关系，具有温度依赖性，且在pH约为7.7时达到最大值。在25摄氏度下90分钟内达到最大结合。[3H]纳洛酮嗪与其结合位点的亲和力相当高，在浓度约为2纳摩尔时获得半数最大结合。[3H]纳洛酮嗪总特异性结合的约40%对多次洗涤以及在加入[3H]纳洛酮嗪60分钟后加入的左洛啡烷（1微摩尔）的置换具有抗性，这表明一部分[3H]纳洛酮嗪的结合并非自由可逆。不可自由逆转的[3H]纳洛酮嗪总结合百分比在不同脑区之间相差3倍，其中下丘脑（60%）最高，脑干（18%）最低。
