Epilepsy in mice deficient in the 65-kDa isoform of glutamic acid decarboxylase
Epilepsy in mice deficient in the 65-kDa isoform of glutamic acid decarboxylase
复制标题
DOI：
10.1073/pnas.94.25.14060
复制
发表时间：
1997-12-09
影响因子：
11.1
通讯作者：
Baekkeskov, S
中科院分区：
文献类型：
--
作者：
Kash, SF;Johnson, RS;Baekkeskov, S
γ-氨基丁酸（GABA）是哺乳动物大脑中主要的抑制性神经递质，由两种谷氨酸脱羧酶亚型GAD 65和GAD 67合成。这两种亚型的单独作用尚不清楚，但辅因子饱和度和亚细胞定位的差异表明，GAD 65 mag为抑制性神经传递的调节提供了GABA的储备库。我们已经破坏了编码GAD 65的基因，并将突变体回交到C57 BL/6小鼠品系中。与GAD 67-/-动物相反，GAD 65-/-小鼠出生时发育异常并在出生后不久死亡，GAD 65-/-小鼠出生时表现正常。基础GABA水平和holo-GAD活性正常，但吡哆醛5'磷酸诱导的ape酶库显著降低。GAD 65-/-小鼠发生自发性癫痫发作，导致死亡率增加。恐惧或轻微的压力会导致癫痫发作。癫痫发作的易感性显着增加GAD 65-/-小鼠回交到第二个遗传背景，非肥胖糖尿病（NOD/LtJ）小鼠品系，使脑电图分析癫痫发作。该回交中通常较高的基础脑GABA水平被GAD 65-/-突变显著降低，表明GAD 65合成的GABA对总脑GABA水平的相对贡献是遗传决定的。癫痫发作相关的c-fos样免疫反应揭示了大脑边缘区的参与。这些数据表明，GABA合成的GAD 65是重要的神经网络兴奋性的动态调节，牵连至少一个修饰位点的NOD/LtJ株，目前GAD 65-/-动物癫痫涉及GABA能通路的模型。
gamma-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the mammalian brain, is synthesized by two glutamate decarboxylase isoforms, GAD65 and GAD67. The separate role of the two isoforms is unknown, but differences in saturation with cofactor and subcellular localization suggest that GAD65 mag provide reserve pools of GABA for regulation of inhibitory neurotransmission. We have disrupted the gene encoding GAD65 and backcrossed the mutation into the C57BL/6 strain of mice, In contrast to GAD67-/- animals, which are born with developmental abnormalities and die shortly after birth, GAD65-/- mice appear normal al birth. Basal GABA levels and holo-GAD activity are normal, bat the pyridoxal 5' phosphate-inducible ape-enzyme reservoir is significantly decreased. GAD65-/- mice develop spontaneous seizures that result in increased mortality. Seizures can be precipitated by fear or mild stress. Seizure susceptibility is dramatically increased in GAD65-/- mice backcrossed into a second genetic background, the nonobese diabetic (NOD/LtJ) strain of mice enabling electroencephalogram analysis of the seizures. The generally higher basal brain GABA levels in this backcross are significantly decreased by the GAD65-/- mutation, suggesting that the relative contribution of GABA synthesized hy GAD65 to total brain GABA levels is genetically determined. Seizure-associated c-fos-like immunoreactivity reveals the involvement of limbic regions of the brain. These data suggest that GABA synthesized by GAD65 is important in the dynamic regulation of neural network excitability, implicate at least one modifier locus in the NOD/LtJ strain, and present GAD65-/- animals as a model of epilepsy involving GABA-ergic pathways.