Ivanov Anton I, Bernard Christophe, Turner Dennis A
Aix Marseille Université, INS, Marseille, France; Inserm, UMR_S 1106, INS, Marseille, France.
Neurosurgery and Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
Neurobiol Dis. 2015 Mar;75:1-14. doi: 10.1016/j.nbd.2014.12.013. Epub 2014 Dec 19.
Interictal spikes, ictal responses, and status epilepticus are characteristic of abnormal neuronal activity in epilepsy. Since these events may involve different energy requirements, we evaluated metabolic function (assessed by simultaneous NADH and FAD+ imaging and tissue O2 recordings) in the immature, intact mouse hippocampus (P5-P7, in vitro) during spontaneous interictal spikes and ictal-like events (ILEs), induced by increased neuronal network excitability with either low Mg2+ media or decreased inhibition with bicuculline. In low Mg2+ medium NADH fluorescence showed a small decrease both during the interictal build-up leading to an ictal event and before ILE occurrences, but a large positive response during and after ILEs (up to 10% net change). Tissue O2 recordings (pO2) showed an oxygen dip (indicating oxygen consumption) coincident with each ILE at P5 and P7, closely matching an NADH fluorescence increase, indicating a large surge in oxidative metabolism. The ILE O2 dip was significantly larger at P7 as compared to P5 suggesting a higher metabolic response at P7. After several ILEs at P7, continuous, low voltage activity (late recurrent discharges: LRDs) occurred. During LRDs, whilst the epileptiform activity was relatively small (low voltage synchronous activity) oxygen levels remained low and NADH fluorescence elevated, indicating persistent oxygen utilization and maintained high metabolic demand. In bicuculline, NADH fluorescence levels decreased prior to the onset of epileptiform activity, followed by a slow positive phase, which persisted during interictal responses. Metabolic responses can thus differentiate between interictal, ictal-like and persistent epileptiform activity resembling status epilepticus, and confirm that spreading depression did not occur. These results demonstrate clear translational value to the understanding of metabolic requirements during epileptic conditions.
发作间期棘波、发作期反应和癫痫持续状态是癫痫中异常神经元活动的特征。由于这些事件可能涉及不同的能量需求，我们在未成熟的完整小鼠海马体（P5 - P7，体外）中，在自发发作间期棘波和发作样事件（ILEs）期间，评估了代谢功能（通过同时进行的NADH和FAD +成像以及组织O2记录来评估），这些发作间期棘波和发作样事件是由用低镁培养基增加神经网络兴奋性或用荷包牡丹碱降低抑制作用诱导产生的。在低镁培养基中，NADH荧光在导致发作事件的发作间期积累期间以及ILEs发生之前显示出小幅下降，但在ILEs期间和之后有较大的正向反应（净变化高达10%）。组织O2记录（pO2）显示在P5和P7时，每次ILEs都伴有氧含量下降（表明有氧消耗），与NADH荧光增加密切匹配，表明氧化代谢大幅增加。与P5相比，P7时ILEs的氧含量下降明显更大，表明P7时的代谢反应更高。在P7经历几次ILEs后，出现了持续的低电压活动（晚期反复放电：LRDs）。在LRDs期间，虽然癫痫样活动相对较小（低电压同步活动），但氧水平仍然较低，NADH荧光升高，表明持续的氧利用和维持较高的代谢需求。在用荷包牡丹碱处理时，NADH荧光水平在癫痫样活动开始前下降，随后是一个缓慢的正向阶段，在发作间期反应期间持续存在。因此，代谢反应可以区分发作间期、发作样和类似癫痫持续状态的持续性癫痫样活动，并证实未发生扩散性抑制。这些结果证明了在理解癫痫状态下的代谢需求方面具有明确的转化价值。
