Lamki L, Sullivan S
J Nucl Med. 1983 Aug;24(8):689-92.
Animal and in vitro experiments suggest that opiates exert their actions by interaction with possibly five different subtypes of opiate receptors, identified as mu, kappa, sigma, delta, and epsilon. As yet there is no conclusive evidence for their existence in man. Our experiments on morphine and the enkephalin analog DAMME have suggested at least two types of opiate receptors involved in gastric secretion. In this study we have used the very powerful and nonselective opiate agonist etorphine to stimulate as many of the different opiate receptors as possible. We have then attempted to block selectively the mu receptor by administering a small dose of naloxone. Etorphine delayed gastric emptying whereas naloxone alone had no effect. In combination, the inhibitory effect of etorphine on gastric emptying was incompletely prevented while the subjective effects of etorphine were completely abolished. These results may indicate that mu receptors are important in the regulation of gastric emptying, but that other (non-mu) receptors are also involved. The radionuclide study of gastric emptying, as used here, is a potentially powerful tool in physiological research on the gastrointestinal tract.
动物实验和体外实验表明，阿片类药物可能通过与五种不同亚型的阿片受体相互作用来发挥其作用，这五种受体分别被识别为μ、κ、σ、δ和ε受体。然而，目前尚无确凿证据证明它们在人体内的存在。我们对吗啡和脑啡肽类似物DAMME的实验表明，至少有两种阿片受体参与胃分泌。在本研究中，我们使用了强效且非选择性的阿片激动剂埃托啡来尽可能多地刺激不同的阿片受体。然后，我们尝试通过给予小剂量纳洛酮来选择性阻断μ受体。埃托啡延迟了胃排空，而单独使用纳洛酮则没有效果。联合使用时，埃托啡对胃排空的抑制作用未被完全阻断，而埃托啡的主观效应则完全消失。这些结果可能表明，μ受体在胃排空的调节中很重要，但其他（非μ）受体也参与其中。本文所采用的胃排空放射性核素研究，是胃肠道生理学研究中一种潜在的强大工具。
