编码γ2亚基的cRNA的相对量会影响非洲爪蟾卵母细胞中表达的GABA(A)受体对苯二氮䓬的反应。

The relative amount of cRNA coding for gamma2 subunits affects stimulation by benzodiazepines in GABA(A) receptors expressed in Xenopus oocytes.

作者信息

Boileau A J, Baur R, Sharkey L M, Sigel E, Czajkowski C

机构信息

Department of Physiology, University of Wisconsin, Madison 53706, USA.

出版信息

Neuropharmacology. 2002 Sep;43(4):695-700. doi: 10.1016/s0028-3908(02)00036-9.

DOI:10.1016/s0028-3908(02)00036-9

PMID:12367615

Abstract

Benzodiazepine (BZD) potentiation of GABA-activated Cl(-)-current (I(GABA)) in recombinant GABA(A) receptors requires the presence of the gamma subunit. When alpha1, beta2 and gamma2S cRNA are expressed in a 1:1:1 ratio in Xenopus oocytes, BZD potentiation of I(GABA) is submaximal, variable and diminishes over time. Potentiation by BZDs is increased, more reproducible and is stabilized over time by increasing the relative amount of cRNA coding for the gamma2S subunit. In addition, GABA EC(50) values for alpha1beta2gamma2 (1:1:1) receptors are intermediate to values measured for alpha1beta2 (1:1) and alpha1beta2gamma2 (1:1:10) receptors. We conclude that co-expression of equal ratios of alpha1, beta2 and gamma2 subunits in Xenopus oocytes produces a mixed population of alpha1beta2 and alpha1beta2gamma2 receptors. Therefore, for accurate measurements of BZD potentiation it is necessary to inject a higher ratio of gamma2 subunit cRNA relative to alpha1 and beta2 cRNA. This results in a purer population of alpha1beta2gamma2 receptors.

摘要

苯二氮䓬（BZD）对重组γ-氨基丁酸A（GABA_A）受体中GABA激活的氯离子电流（I_GABA）的增强作用需要γ亚基的存在。当α1、β2和γ2S的互补RNA（cRNA）以1:1:1的比例在非洲爪蟾卵母细胞中表达时，BZD对I_GABA的增强作用未达到最大值，存在变异性且会随时间减弱。通过增加编码γ2S亚基的cRNA的相对量，BZD的增强作用会增强、更具可重复性且随时间稳定。此外，α1β2γ2（1:1:1）受体的GABA半数有效浓度（EC₅₀）值介于α1β2（1:1）和α1β2γ2（1:1:10）受体测得的值之间。我们得出结论，在非洲爪蟾卵母细胞中以相等比例共表达α1、β2和γ2亚基会产生α1β2和α1β2γ2受体的混合群体。因此，为了准确测量BZD的增强作用，相对于α1和β2的cRNA，有必要注射更高比例的γ2亚基cRNA。这会产生更纯的α1β2γ2受体群体。