Cohen M L, Mendelsohn L G, Mitch C H, Zimmerman D M
Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285.
Receptor. 1994 Spring;4(1):43-53.
The present study was designed to identify a single smooth muscle preparation possessing mu, delta, and kappa receptors that can be used in the development of opioid selective antagonists. In vitro studies with the mouse vas deferens indicated that the delta selective agonists, DPLPE and DSLET, had potent agonist activity (ED50 approximately 1 nM) to inhibit the twitch response. The mu selective agonists, normorphine and fentanyl, also inhibited the twitch response in the mouse vas deferens, but were approx 100-fold less potent than the delta selective agonists, consistent with the enrichment of this preparation with delta receptors. U50,488, a kappa selective agonist, also inhibited the twitch response with a potency similar to that of the mu agonists. Naloxone, MR 2266, and WIN 44,441 all antagonized the agonist activity of U50,488 with antagonist dissociation constants distinct from those calculated using mu or delta receptor agonists. To confirm the presence of all three opioid receptors in this preparation, we examined a series of 14 phenylpiperidine opioid antagonists. An excellent correlation was observed between affinities of these piperidine opioid antagonists at mu and kappa receptors determined via radioligand binding studies, and affinities determined by blockade of fentanyl- or U50,488-induced twitch inhibition. Of the piperidine opioid antagonists studied, two possessed relatively high kappa receptor antagonist affinity. Furthermore, the study of an enantiomeric pair of an N-substituted 4-phenylpiperidine derivative demonstrated differences in absolute configuration to be more important for binding at mu and delta than kappa receptors. Thus, we have established the presence of kappa, in addition to the known mu and delta receptors, in the mouse vas deferens, and identified certain piperidines to have high kappa receptor antagonist affinity.
本研究旨在鉴定一种具有μ、δ和κ受体的单一平滑肌制剂，可用于阿片类选择性拮抗剂的开发。对小鼠输精管的体外研究表明，δ选择性激动剂DPLPE和DSLET具有强大的激动剂活性（半数有效量约为1 nM）以抑制抽搐反应。μ选择性激动剂去甲吗啡和芬太尼也抑制小鼠输精管的抽搐反应，但效力比δ选择性激动剂低约100倍，这与该制剂中δ受体的富集情况一致。κ选择性激动剂U50,488也抑制抽搐反应，其效力与μ激动剂相似。纳洛酮、MR 2266和WIN 44,441均拮抗U50,488的激动剂活性，其拮抗剂解离常数与使用μ或δ受体激动剂计算得出的不同。为了证实该制剂中存在所有三种阿片类受体，我们研究了一系列14种苯基哌啶类阿片拮抗剂。通过放射性配体结合研究测定的这些哌啶类阿片拮抗剂对μ和κ受体的亲和力，与通过阻断芬太尼或U50,488诱导的抽搐抑制所测定的亲和力之间观察到极好的相关性。在所研究的哌啶类阿片拮抗剂中，有两种具有相对较高的κ受体拮抗剂亲和力。此外，对一对N-取代的4-苯基哌啶衍生物对映体的研究表明，绝对构型的差异对与μ和δ受体的结合比对κ受体更为重要。因此，我们已确定除了已知的μ和δ受体外，小鼠输精管中还存在κ受体，并鉴定出某些哌啶具有高κ受体拮抗剂亲和力。
