Grudt T J, Williams J T
Vollum Institute, Oregon Health Sciences University, Portland 97201, USA.
Rev Neurosci. 1995 Jul-Sep;6(3):279-86. doi: 10.1515/revneuro.1995.6.3.279.
In the past two years, knowledge about the regulation of ion conductances by opioid receptors has expanded in several directions. First, it has now been shown that all three of the major receptor subtypes act on all three of the well recognized effectors, i.e., adenylyl cyclase, calcium channels and potassium channels. Second, the opioid-mediated receptor inhibition of adenylyl cyclase has been linked to the modulation of ion channel activity /20/. Third, opioids have also been found to increase the activity of adenylyl cyclase in some preparations. Fourth, opioid receptors can mediate a rise in internal free-calcium concentration /21/. These observations suggest that the regulation of cell excitability by opioids is dependent on the cell under study and that the generalization between receptor subtype and specificity of action is no longer valid. The additional second messenger pathways affected by opioids suggest that the adaptive changes resulting from chronic opioid treatment are more complex than previously thought. This review evaluates these relatively new observations and suggests how these results may change the interpretations from previous work on opioid actions.
在过去两年中，关于阿片受体对离子电导调节的知识在几个方向上得到了扩展。首先，现已表明，所有三种主要受体亚型均作用于所有三种广为人知的效应器，即腺苷酸环化酶、钙通道和钾通道。其次，阿片介导的对腺苷酸环化酶的受体抑制已与离子通道活性的调节相关联/20/。第三，在某些制剂中还发现阿片类物质可增加腺苷酸环化酶的活性。第四，阿片受体可介导细胞内游离钙浓度升高/21/。这些观察结果表明，阿片类物质对细胞兴奋性的调节取决于所研究的细胞，并且受体亚型与作用特异性之间的普遍关系不再成立。受阿片类物质影响的额外第二信使途径表明，慢性阿片治疗导致的适应性变化比以前认为的更为复杂。本综述评估了这些相对较新的观察结果，并提出这些结果可能如何改变以往关于阿片作用研究的解释。
