阿片类制剂特别是吗啡具有较强的镇痛作用。但是反复使用时

它们的一些药理效应如:镇痛、降体温等便明显降低、只有增加药物剂量才能保持其原有的药理作用

这种现象称为耐受.反复用药还可造成机体对药物形成依赖性即成瘾

当突然仃止药物使用或使用阿片Since the development of tolerance to and dependence on opiate has been the most prominent drawback for the clinical use of narcotic analgesics

numerous studies have been done to elucidate its underlying mechanisms. In the present paper a brief survey was made from the biochemical point of view in an attempt to clarify the possible participation of serotonin

catecholamines

acetylcholine

brain peptides

cyclic nucleotides and calcium ions in the development of morphine tolerance and dependence. Moreover

the effect of long term morphine treatment on the dynamics of the number and affinity of opiate receptors as well as the changes in brain peptide synthesis were also discussed. It has been aware of recently that not only morphine analgesia but also acupuncture analgesia and stress induced analgesia are subjected to the development of tolerance. It is expected that the understanding of the biochemical basis of morphine analgesia will throw some light on the investigation of the underlying mechanisms for acupuncture tolerance and tolerance to stress analgesia as well.