Benzodiazepine treatment causes uncoupling of recombinant GABAA receptors expressed in stably transfected cells.
Benzodiazepine treatment causes uncoupling of recombinant GABAA receptors expressed in stably transfected cells.
复制标题
苯二氮卓治疗导致稳定转染细胞中表达的重组 GABAA 受体解偶联。
DOI：
10.1046/j.1471-4159.1994.63062349.x
复制
发表时间：
1994
影响因子：
4.7
通讯作者：
Harris,RA
中科院分区：
文献类型：
--
作者：
Klein,RL;Whiting,PJ;Harris,RA
GABA A和苯二氮卓受体是变构偶联的，占据任一受体位点都会增加另一受体的亲和力。原代神经元培养物长期暴露于苯二氮卓类激动剂会降低这些变构相互作用。神经元表达多种GABA A受体亚单位，并且已经表明解偶联是由于受体亚单位组成的变化。为了确定是否可以观察到解偶联与特定亚基的表达，用氟硝西泮（Flu）或氯硝西泮处理稳定转染GABA A受体（牛α1、β1和γ2L亚基）的小鼠Ltk−细胞。在苯二氮卓类药物慢性处理的细胞中，GABA引起的[3 H]Flu结合亲和力增加（GABA移位或偶联）显著降低，而[3 H]Flu结合的KD和Bmax不受影响。氯硝西泮处理引起的解偶联在1/20 ~ 30分钟迅速发生。氯硝西泮处理的EC 50为1.003 μM，与苯二氮卓类拮抗剂Ro 15 - 1788（5.6 μM）联合处理可阻止氯硝西泮的作用。在该系统中观察到的解偶联并不伴随着受体内化，不太可能是由于受体亚基组成的变化，可能代表翻译后的变化。苯二氮卓类药物对稳定转染细胞的变构偶联的快速调节，将为GABAA和苯二氮卓类药物受体之间的偶联以及苯二氮卓类药物耐受的机制提供新的见解。
GABAAand benzodiazepine receptors are allosterically coupled, and occupation of either receptor site increases the affinity of the other. Chronic exposure of primary neuronal cultures to benzodiazepine agonists reduces these allosteric interactions. Neurons express multiple GABAAreceptor subunits, and it has been suggested that uncoupling is due to changes in the subunit composition of the receptor. To determine if uncoupling could be observed with expression of defined subunits, mouse Ltk−cells stably transfected with GABAAreceptors (bovine α1, β1, and γ2L subunits) were treated with flunitrazepam (Flu) or clonazepam. The increase in [3H]Flu binding affinity caused by GABA (GABA shift or coupling) was significantly reduced in cells treated chronically with the benzodiazepines, whereas theKDandBmaxof [3H]Flu binding were unaffected. The uncoupling caused by clonazepam treatment occurred rapidly with at1/2of ∼30 min. The EC50for clonazepam treatment was ∼0.3 µM, and cotreatment with the benzodiazepine antagonist Ro 15‐1788 (5.6 µM) prevented the effect of clonazepam. The uncoupling observed in this system was not accompanied by receptor internalization, is unlikely to be due to changes in receptor subunit composition, and probably represents posttranslational changes. The rapid regulation of allosteric coupling by benzodiazepine treatment of the stably transfected cells should provide insights to the mechanisms of coupling between GABAAand benzodiazepine receptors as well as benzodiazepine tolerance.