Jazvinsćak Jembrek Maja, Svob Strac Dubravka, Vlainić Josipa, Pericić Danka
Ruder Bosković Institute, Laboratory for Molecular Neuropharmacology, Division of Molecular Medicine, P.O. Box 180, 10002 Zagreb, Croatia.
Neurosci Res. 2008 Jul;61(3):234-41. doi: 10.1016/j.neures.2008.03.005. Epub 2008 Mar 29.
The aim of this study was to further elucidate the mechanisms involved in adaptive changes of GABA(A) receptors following prolonged exposure to flumazenil, the antagonist of benzodiazepine binding sites on GABA(A) receptors. The effects of prolonged flumazenil treatment were studied on recombinant alpha(1)beta(2)gamma(2S) GABA(A) receptors stably expressed in human embryonic kidney (HEK 293) cells. Using radioligand binding experiments we found enhancement in the maximum number of [(3)H]muscimol labeled binding sites in different preparations of HEK 293 cells. The parallel increase of [(3)H]flunitrazepam binding sites in the membranes was reduced in the presence of actinomycin D and cycloheximide, inhibitors of RNA and protein synthesis, respectively. Chronic flumazenil also raised the steady-state level of mRNA encoding alpha(1) receptor subunit. The results suggest that the up-regulation of GABA(A) receptors, observed after prolonged flumazenil treatment is at least partly due to increased de novo synthesis of receptor proteins at both transcriptional and translational level.
本研究的目的是进一步阐明在长期暴露于氟马西尼（GABA(A)受体上苯二氮䓬结合位点的拮抗剂）后，GABA(A)受体适应性变化所涉及的机制。研究了长期氟马西尼处理对稳定表达于人类胚胎肾（HEK 293）细胞中的重组α(1)β(2)γ(2S) GABA(A)受体的影响。通过放射性配体结合实验，我们发现在不同的HEK 293细胞制剂中，[(3)H]蝇蕈醇标记的结合位点的最大数量有所增加。分别在RNA合成抑制剂放线菌素D和蛋白质合成抑制剂环己酰亚胺存在的情况下，膜中[(3)H]氟硝西泮结合位点的平行增加受到了抑制。长期氟马西尼处理还提高了编码α(1)受体亚基的mRNA的稳态水平。结果表明，长期氟马西尼处理后观察到的GABA(A)受体上调至少部分归因于转录和翻译水平上受体蛋白从头合成的增加。
