Faster flux of neurotransmitter glutamate during seizure - Evidence from 13C-enrichment of extracellular glutamate in kainate rat model.
Faster flux of neurotransmitter glutamate during seizure - Evidence from 13C-enrichment of extracellular glutamate in kainate rat model.
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DOI：
10.1371/journal.pone.0174845
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Kanamori K
中科院分区：
文献类型：
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作者：
Kanamori K
目的是研究神经递质谷氨酸从神经元到细胞外液的通量，通过细胞外谷氨酸13C富集率（GLUECF）来测量，如何在盐诱导的大鼠颞叶癫痫模型中对癫痫发作的反应变化。单侧海马内注射海碱盐后，在清醒大鼠的CA1/CA3区微透析收集GLUECF，并结合慢性复发性癫痫发作的脑电图记录和静脉输注[2,5- 13c]葡萄糖。采用气相色谱-质谱法测定了gluecfc5在~ 10皮摩尔浓度下的13C富集。频繁发作大鼠的13C富集率为0.0029±0.0001/min (n = 4)；与对照组（0.00167±0.0001/min, n = 6）和不频繁发作大鼠（0.00172±0.0001/min, n = 6）相比，差异有统计学意义（p < 0.01）。这一结果强烈提示，从神经元到细胞外液的兴奋性神经递质通量因频繁发作而显著增加。频繁发作大鼠细胞外[12C + 13C]谷氨酸浓度逐渐升高。综上所述，这些结果强烈表明，观察到的癫痫引起的谷氨酸高通量过度刺激了谷氨酸受体，从而引发了CA3循环谷氨酸能网络的兴奋连锁反应。频繁发作大鼠C5时细胞外谷氨酰胺（GLNECF） 13C富集率为0.00299±0.00027/min，显著高于对照组（0.00227±0.00008/min） （p < 0.05）。本研究首次在体内研究了癫痫发作对海马细胞外液中神经递质谷氨酸及其前体谷氨酰胺通量的影响。讨论了该方法在颞叶癫痫临床前和临床研究中的优点、局限性和改进潜力。
The objective is to examine how the flux of neurotransmitter glutamate from neurons to the extracellular fluid, as measured by the rate of 13C enrichment of extracellular glutamate (GLUECF), changes in response to seizures in the kainate-induced rat model of temporal-lobe epilepsy. Following unilateral intrahippocampal injection of kainate, GLUECF was collected by microdialysis from the CA1/CA3 region of awake rats, in combination with EEG recording of chronic-phase recurrent seizures and intravenous infusion of [2,5-13C]glucose. The 13C enrichment of GLUECF C5 at ~ 10 picomol level was measured by gas-chromatography mass-spectrometry. The rate of 13C enrichment, expressed as the increase of the fractional enrichment/min, was 0.0029 ± 0.0001/min in frequently seizing rats (n = 4); this was significantly higher (p < 0.01) than in the control (0.00167 ± 0.0001/min; n = 6) or in rats with infrequent seizures (0.00172 ± 0.0001/min; n = 6). This result strongly suggests that the flux of the excitatory neurotransmitter from neurons to the extracellular fluid is significantly increased by frequent seizures. The extracellular [12C + 13C]glutamate concentration increased progressively in frequently seizing rats. Taken together, these results strongly suggest that the observed seizure-induced high flux of glutamate overstimulated glutamate receptors, which triggered a chain reaction of excitation in the CA3 recurrent glutamatergic networks. The rate of 13C enrichment of extracellular glutamine (GLNECF) at C5 was 0.00299 ± 0.00027/min in frequently seizing rats, which was higher (p < 0.05) than in controls (0.00227 ± 0.00008/min). For the first time in vivo, this study examined the effects of epileptic seizures on fluxes of the neurotransmitter glutamate and its precursor glutamine in the extracellular fluid of the hippocampus. The advantages, limitations and the potential for improvement of this approach for pre-clinical and clinical studies of temporal-lobe epilepsy are discussed.