Bender R, Hoffmann M C, Frotscher M, Nitsch C
Institute of Anatomy I, University of Freiburg, Albertstr. 17, D-79104, Freiburg, Germany.
Neuroscience. 2000;99(3):423-31. doi: 10.1016/s0306-4522(00)00208-6.
Mongolian gerbils are genetically predisposed to develop epileptic seizures in limbic structures. A species-specific property of the Mongolian gerbil is the expression of the calcium-binding protein parvalbumin in the perforant path where it is predominantly concentrated in nerve terminals. To test the hypothesis that this atypical expression of parvalbumin is induced by seizure-correlated hyperactivity in the entorhinohippocampal loop, we investigated whether it is dependent on extrinsic afferents to the entorhinal cortex. We cultivated organotypic slice cultures of neonate gerbil entorhinal cortex, isolated from all regions it is normally connected with in vivo. In these cultures, parvalbumin-expressing neurons demonstrated their characteristic features like in vivo. Blockade of spontaneous local activity with the sodium-channel blocker tetrodotoxin, however, considerably reduced the number of parvalbumin-expressing neurons in culture. These results indicate that spontaneous local activity, but not activity mediated by extrinsic afferents, is an essential factor for the expression of parvalbumin in the entorhinal cortex of the Mongolian gerbil.
蒙古沙鼠在基因上倾向于在边缘结构中发生癫痫发作。蒙古沙鼠的一个物种特异性特征是钙结合蛋白小白蛋白在穿通通路中表达，它主要集中在神经末梢。为了验证小白蛋白的这种非典型表达是由内嗅海马环路中与癫痫发作相关的活动过度所诱导的这一假设，我们研究了它是否依赖于内嗅皮质的外在传入神经。我们培养了新生沙鼠内嗅皮质的器官型脑片培养物，这些脑片是从其在体内通常与之相连的所有区域分离出来的。在这些培养物中，表达小白蛋白的神经元表现出与体内相同的特征。然而，用钠通道阻滞剂河豚毒素阻断自发的局部活动，会显著减少培养物中表达小白蛋白的神经元数量。这些结果表明，自发的局部活动而非由外在传入神经介导的活动，是蒙古沙鼠内嗅皮质中表达小白蛋白的一个关键因素。
