Juzekaeva Elvira, Nasretdinov Azat, Gainutdinov Azat, Sintsov Mikhail, Mukhtarov Marat, Khazipov Roustem
Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.
INMED - Institut National de la Santé et de la Recherche Médicale, Aix-Marseille University, Marseille, France.
Front Cell Neurosci. 2017 Dec 15;11:390. doi: 10.3389/fncel.2017.00390. eCollection 2017.
Anoxic depolarization (AD) is a hallmark of ischemic brain damage. AD is associated with a spreading wave of neuronal depolarization and an increase in light transmittance. However, initiation and spread of AD across the layers of the somatosensory cortex, which is one of the most frequently affected brain regions in ischemic stroke, remains largely unknown. Here, we explored the initiation and propagation of AD in slices of the rat barrel cortex using extracellular local field potential (LFP) recordings and optical intrinsic signal (OIS) recordings. We found that ischemia-like conditions induced by oxygen-glucose deprivation (OGD) evoked AD, which manifested as a large negative LFP shift and an increase in light transmittance. AD typically initiated in one or more barrels and further spread across the entire slice with a preferential propagation through L4. Elevated extracellular potassium concentration accelerated the AD onset without affecting proneness of L4 to AD. In live slices, barrels were most heavily labeled by the metabolic level marker 2,3,5-triphenyltetrazolium chloride, suggesting that the highest metabolic demand is in L4 when compared to the other layers. Thus, L4 is the layer of the barrel cortex most prone to AD, which may be due to the highest metabolic demand and cell density in this layer.
缺氧去极化（AD）是缺血性脑损伤的一个标志。AD与神经元去极化的扩散波以及透光率增加有关。然而，AD在体感皮层各层中的起始和传播情况，而体感皮层是缺血性中风中最常受影响的脑区之一，目前仍知之甚少。在此，我们使用细胞外局部场电位（LFP）记录和光学内在信号（OIS）记录，探索了大鼠桶状皮层切片中AD的起始和传播。我们发现，氧糖剥夺（OGD）诱导的缺血样状态诱发了AD，其表现为LFP大幅负向偏移和透光率增加。AD通常在一个或多个桶状区域起始，并进一步扩散至整个切片，且优先通过第4层传播。细胞外钾离子浓度升高加速了AD的起始，但不影响第4层对AD的易感性。在活切片中，桶状区域被代谢水平标记物2,3,5 - 氯化三苯基四氮唑标记得最为明显，表示与其他层相比，第4层的代谢需求最高。因此，第4层是桶状皮层中最易发生AD的层，这可能是由于该层最高的代谢需求和细胞密度所致。
