Sapp D W, Yeh H H
Department of Pharmacology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
J Pharmacol Exp Ther. 1998 Feb;284(2):768-76.
This study compared the interaction between ethanol and gamma-aminobutyric acid (GABA)-mediated current responses elicited in several immortalized cell lines and stably transfected cells, as well as in cultured and acutely dissociated rat cerebellar Purkinje cells. Only cell lines that were found previously to possess functional GABAA receptors were examined in this study. Under identical recording conditions, ethanol (10-200 mM) exerted no effect on GABA-induced currents in any of the cell lines or stably transfected cells tested in this study. However, GABA responses monitored in both primary culture and acutely dissociated Purkinje cells were significantly potentiated by ethanol (25 and 50 mM). Mouse pancreatic cells (RINm5F) were insensitive to both diazepam and ethanol suggesting the expression of a GABAA receptor isoform lacking a gamma subunit. Immortalized neuroblastoma IMR-32 cells displayed GABA responses that could be distinguished based on differential sensitivity to diazepam. However, none of the IMR-32 cells displayed GABA responses that were sensitive to modulation by ethanol. GABA responses in the stably transfected cell lines, PA3 (alpha1beta1gamma2L) and WSS-1 (alpha1beta2gamma2), were also unaffected by exposure to ethanol. In Purkinje cells acutely dissociated from the neonatal cerebellum, the ethanol-induced potentiation of GABA-induced current response could be observed before postnatal day 7, when only the gamma2S but not the gamma2L splice variant is expressed. This indicates that the gamma2L subunit is not necessary for an ethanol-induced potentiation of GABAA receptor-mediated response to become manifest. In addition, the results point to inherent differences that should be taken into account in interpreting comparative data between native and recombinant GABAA receptors.
本研究比较了乙醇与γ-氨基丁酸（GABA）介导的电流反应之间的相互作用，该电流反应在几种永生化细胞系、稳定转染细胞以及培养的和急性分离的大鼠小脑浦肯野细胞中引发。本研究仅检测了先前发现具有功能性GABAA受体的细胞系。在相同的记录条件下，乙醇（10 - 200 mM）对本研究中测试的任何细胞系或稳定转染细胞中的GABA诱导电流均无影响。然而，在原代培养和急性分离的浦肯野细胞中监测到的GABA反应被乙醇（25和50 mM）显著增强。小鼠胰腺细胞（RINm5F）对安定和乙醇均不敏感，这表明缺乏γ亚基的GABAA受体亚型的表达。永生化神经母细胞瘤IMR - 32细胞表现出的GABA反应可根据对安定的不同敏感性加以区分。然而，没有一个IMR - 32细胞表现出对乙醇调节敏感的GABA反应。稳定转染的细胞系PA3（α1β1γ2L）和WSS - 1（α1β2γ2）中的GABA反应也不受乙醇暴露的影响。在从新生小脑急性分离的浦肯野细胞中，在出生后第7天之前就能观察到乙醇诱导的GABA诱导电流反应增强，此时仅表达γ2S而非γ2L剪接变体。这表明γ2L亚基对于乙醇诱导的GABAA受体介导反应增强的显现并非必要。此外，结果指出在解释天然和重组GABAA受体之间的比较数据时应考虑到内在差异。
