Gene knockout of the alpha 6 subunit of the gamma-aminobutyric acid type A receptor: Lack of effect on responses to ethanol, pentobarbital, and general anesthetics
Gene knockout of the alpha 6 subunit of the gamma-aminobutyric acid type A receptor: Lack of effect on responses to ethanol, pentobarbital, and general anesthetics
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DOI：
10.1124/mol.51.4.588
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发表时间：
1997-04-01
影响因子：
3.6
通讯作者：
Firestone, LL
中科院分区：
文献类型：
--
作者：
Homanics, GE;Ferguson, C;Firestone, LL
γ-氨基丁酸A型受体（GABA（A）-R）的α 6亚基参与介导乙醇的致醉作用和全身麻醉药的运动共济失调作用。为了验证这一假设，我们在胚胎干细胞中使用基因靶向技术来制造缺乏功能性α 6基因的小鼠。纯合子小鼠是活的和可生育的，并且具有大体上正常的小脑细胞结构。北方印迹和逆转录-聚合酶链反应分析表明，靶向事件破坏了功能性α 6 mRNA的产生。成人脑组织切片的放射自显影表明，在纯合子小鼠中，[H-3] Ro 15 -4513与野生型小鼠小脑颗粒细胞层的地西泮不敏感结合完全不存在。在突变小鼠中，小脑GABA（A）-R密度没有变化;然而，对蝇蕈醇的表观亲和力显著降低。睡眠时间响应注射乙醇后预处理与车辆或Ro 15 -4513基因型之间没有差异。在用挥发性麻醉剂麻醉的小鼠中，对戊巴比妥注射的睡眠时间反应和翻正反射的丧失以及对尾钳刺激的反应在基因型之间也没有差异。因此，GABA（A）-R的α 6亚基在小鼠的正常发育、生存力和生育力中并不需要，并且似乎不是介导乙醇催眠作用及其被Ro 15 -4513拮抗作用的神经元通路的关键或独特组分。同样，α 6亚基似乎不参与对全身麻醉剂或戊巴比妥的行为反应。
The alpha 6 subunit of the gamma-aminobutyric acid type A receptor (GABA(A)-R) has been implicated in mediating the intoxicating effects of ethanol and the motor ataxic effects of general anesthetics. To test this hypothesis, we used gene targeting in embryonic stem cells to create mice lacking a functional alpha 6 gene. Homozygous mice are viable and fertile and have grossly normal cerebellar cytoarchitecture. Northern blot and reverse transcriptase-polymerase chain reaction analyses demonstrated that the targeting event disrupted production of functional alpha 6 mRNA. Autoradiography of histological sections of adult brains demonstrated that diazepam-insensitive binding of [H-3]Ro15-4513 to the cerebellar granule cell layer of wild-type mice was completely absent in homozygous mice. Cerebellar GABA(A)-R density was unchanged in the mutant mice; however, the apparent affinity for muscimol was markedly reduced. Sleep time response to injection of ethanol after pretreatment with vehicle or Ro15-4513 did not differ between genotypes. Sleep time response to injection of pentobarbital and loss of righting reflex and response to tail clamp stimulus in mice anesthetized with volatile anesthetics also did not differ between genotypes. Thus, the alpha 6 subunit of the GABA(A)-R is not required far normal development, viability, and fertility and does not seem to be a critical or unique component of the neuronal pathway mediating the hypnotic effect of ethanol and its antagonism by Ro15-4513 in mice. Similarly, the alpha 6 subunit does not seem to be involved in the behavioral responses to general anesthetics or pentobarbital.