自1975年Hughes等从猪脑中提取出脑啡肽(enkephalin),已先后发现十几种内源性阿片样肽。研究这些内源性阿片肽的生理功能,最常用的方法是用阿片拮抗剂(如纳洛酮)去阻断阿片受体,以观察哪些功能发生了改变,进而推测内源性阿片肽本身的功能。纳洛酮阻断法有不足之处:用纳洛酮阻断阿片受体后,所有阿片样激动剂都将失效。因此,不能区分究竟是哪一种阿片肽在起作用;纳洛酮对不同类型的阿片受体有不同的亲和力,较小剂 Since 1975, Hughes et al. Extracted enkephalin from the porcine brain and have discovered more than a dozen endogenous opioid peptides. The most commonly used method to study the physiological functions of these endogenous opioids is to block opioid receptors with opioid antagonists such as naloxone to see which functions have changed and to speculate that endogenous opioid peptides themselves Features. Naloxone blockade has shortcomings: With naloxone blocking opioid receptors, all opioid agonists will fail. Thus, it is not possible to distinguish which opioid peptide is at work; naloxone has different affinities for different types of opioid receptors, smaller ones