Department of Molecular and Cellular Biochemistry, University of Kentucky Medical Center, Lexington, KY, USA.
Neuroscience. 2012 Jan 27;202:77-86. doi: 10.1016/j.neuroscience.2011.11.055. Epub 2011 Dec 13.
Our previous work has correlated permanent alterations in the rat neurosecretory machinery with epileptogenesis. Such findings highlighted the need for a greater understanding of the molecular mechanisms underlying epilepsy so that novel therapeutic regimens can be designed. To this end, we examined kindling in transgenic mice with a defined reduction of a key element of the neurosecretory machinery: the v-SNARE (vesicle-bound SNAP [soluble NSF attachment protein] receptor), synaptobrevin/vesicle-associated membrane protein 2 (VAMP2). Initial analysis of biochemical markers, which previously displayed kindling-dependent alterations in rat hippocampal synaptosomes, showed similar trends in both wild-type and VAMP2(+/-) mice, demonstrating that kindled rat and mouse models are comparable. This report focuses on the effects that a ~50% reduction of synaptosomal VAMP2 has on the progression of electrical kindling and on glutamate release in hippocampal subregions. Our studies show that epileptogenesis is dramatically attenuated in VAMP2(+/-) mice, requiring both higher current and more stimulations to reach a fully kindled state (two successive Racine stage 5 seizures). Progression through the five identifiable Racine stages was slower and more variable in the VAMP2(+/-) animals compared with the almost linear progression seen in wild-type littermates. Consistent with the expected effects of reducing a major neuronal v-SNARE, glutamate-selective, microelectrode array (MEA) measurements in specific hippocampal subregions of VAMP2(+/-) mice showed significant reductions in potassium-evoked glutamate release. Taken together these studies demonstrate that manipulating the levels of the neurosecretory machinery not only affects neurotransmitter release but also mitigates kindling-induced epileptogenesis.
我们之前的工作已经将大鼠神经分泌机制的永久性改变与癫痫发生相关联。这些发现强调了需要更深入地了解癫痫发生的分子机制,以便设计新的治疗方案。为此,我们研究了具有神经分泌机制关键要素(囊泡结合 SNAP[可溶性 NSF 附着蛋白]受体)、突触融合蛋白/囊泡相关膜蛋白 2(VAMP2)明确减少的转基因小鼠的点燃。对生物化学标志物的初步分析表明,以前在大鼠海马突触体中显示与点燃相关的改变在野生型和 VAMP2(+/-)小鼠中也有类似的趋势,这表明点燃的大鼠和小鼠模型是可比的。本报告重点介绍了突触小体 VAMP2 减少约 50%对电点燃进展和海马亚区谷氨酸释放的影响。我们的研究表明,VAMP2(+/-)小鼠中的癫痫发生明显减弱,需要更高的电流和更多的刺激才能达到完全点燃状态(连续两次 Racine 阶段 5 发作)。与野生型同窝小鼠几乎线性进展相比,VAMP2(+/-)动物的进展速度较慢且变化较大。与预期减少主要神经元 v-SNARE 的作用一致,VAMP2(+/-)小鼠特定海马亚区的谷氨酸选择性微电极阵列(MEA)测量显示,钾诱发的谷氨酸释放显著减少。这些研究表明,操纵神经分泌机制的水平不仅会影响神经递质的释放,还会减轻点燃诱导的癫痫发生。