自远古以来,人们就知道鸦片(Papaversomniferum罂粟)中含有强效止痛物质,其中吗啡是最重要的一种。大约在十年前,从脑中分离出两种有止痛作用的五肽,甲硫氨酸脑啡肽和亮氨酸脑啡肽,不久又分离出一种较大分子的肽,β内啡肽。这些肽和其它有关的鸦片类肽一般被认为是动物组织中鸦片类物质受体的天然配体,吗啡(一种植物生物硷)也与其结合。但是Spector和Goldstein小组最近的观察由于指明脑和其它组织中有低浓度的吗啡,对这种差别发生了怀疑。吗啡的结合特性表明它主要是与μ-鸦片类受体而不与δ或κ受体相互作用。这种相互作用 Since ancient times, people know that opium (Papaversomniferum poppy) contains potent analgesic substances, of which morphine is the most important one. About ten years ago, two analgesic pentapeptides, methionine enkephalin, and leucine enkephalin were isolated from the brain and soon after, a larger molecule of peptide, beta endorphin Peptide. These peptides and other related opioid peptides are generally considered to be natural ligands for opiate receptors in animal tissues, to which morphine, a plant alkaloid, also binds. However, recent observations by the Spector and Goldstein groups have cast doubt on this difference because of the low concentrations of morphine in the brain and other tissues. The binding properties of morphine indicate that it is predominantly interacting with the [mu] -opioid receptor and not with the [delta] or [kappa] receptors. This interaction