Brain Trauma Neuroprotection (BTN) Branch, Center for Military Psychiatry and Neuroscience (CMPN), Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA.
Department of Surgery, Uniformed Services University of the Health Science (USUHS), Bethesda, Maryland, USA.
J Neurotrauma. 2021 Aug 15;38(16):2323-2334. doi: 10.1089/neu.2020.7379. Epub 2021 Mar 10.
Mitochondrial dysfunction is a pivotal target for neuroprotection strategies for traumatic brain injury (TBI). However, comprehensive time-course evaluations of mitochondrial dysfunction are lacking in the pre-clinical penetrating TBI (PTBI) model. The current study was designed to characterize temporal responses of mitochondrial dysfunction from 30 min to 2 weeks post-injury after PTBI. Anesthetized adult male rats were subjected to either PTBI or sham craniectomy ( = 6 animals per group × 7 time points). Animals were euthanized at 30 min, 3 h, 6 h, 24 h, 3 days, 7 days, and 14 days post-PTBI, and mitochondria were isolated from the ipsilateral hemisphere of brain regions near the injury core (i.e., frontal cortex [FC] and striatum [ST]) and a more distant region from the injury core (i.e., hippocampus [HIP]). Mitochondrial bioenergetics parameters were measured in real time using the high-throughput procedures of the Seahorse Flux Analyzer (Agilent Technologies, Santa Clara, CA). The post-injury time course of FC + ST showed a biphasic mitochondrial bioenergetics dysfunction response, indicative of reduced adenosine triphosphate synthesis rate and maximal respiratory capacity after PTBI. An initial phase of energy crisis was detected at 30 min (-42%; < 0.05 vs. sham), which resolved to baseline levels between 3 and 6 h (non-significant vs. sham). This was followed by a second and more robust phase of bioenergetics dysregulation detected at 24 h that remained unresolved out to 14 days post-injury (-55% to -90%; < 0.05 vs. sham). In contrast, HIP mitochondria showed a delayed onset of mitochondrial dysfunction at 7 days (-74%; < 0.05 vs. sham) that remained evident out to 14 days (-51%; < 0.05 vs. sham) post-PTBI. Collectively, PTBI-induced mitochondrial dysfunction responses were time and region specific, evident differentially at the injury core and distant region of PTBI. The current results provide the basis that mitochondrial dysfunction may be targeted differentially based on region specificity post-PTBI. Even more important, these results suggest that therapeutic interventions targeting mitochondrial dysfunction may require extended dosing regimens to achieve clinical efficacy after TBI.
线粒体功能障碍是创伤性脑损伤 (TBI) 神经保护策略的关键靶点。然而，在临床穿透性 TBI (PTBI) 模型中，缺乏对线粒体功能障碍的全面时程评估。本研究旨在描述 PTBI 后 30 分钟至 2 周内线粒体功能障碍的时间反应。麻醉的成年雄性大鼠接受 PTBI 或假颅骨切开术（每组 6 只动物×7 个时间点）。动物在 PTBI 后 30 分钟、3 小时、6 小时、24 小时、3 天、7 天和 14 天被安乐死，从损伤核心附近的脑区（即额皮质 [FC] 和纹状体 [ST]）和远离损伤核心的区域（即海马 [HIP]）分离出同侧半球的线粒体。使用 Seahorse 通量分析仪（Agilent Technologies，Santa Clara，CA）的高通量程序实时测量线粒体生物能学参数。FC + ST 的损伤后时间过程显示出双相线粒体生物能学功能障碍反应，表明 PTBI 后三磷酸腺苷合成率和最大呼吸能力降低。在 30 分钟时检测到初始能量危机阶段（-42%；<0.05 与假手术相比），在 3 至 6 小时之间恢复到基线水平（与假手术相比无显著性差异）。随后在 24 小时检测到第二个更明显的生物能失调阶段，直至损伤后 14 天仍未解决（-55%至-90%；<0.05 与假手术相比）。相比之下，HIP 线粒体在 7 天（-74%；<0.05 与假手术相比）出现线粒体功能障碍的延迟发作，直至 14 天（-51%；<0.05 与假手术相比）后仍可检测到。总的来说，PTBI 诱导的线粒体功能障碍反应具有时间和区域特异性，在损伤核心和 PTBI 的远隔区域明显不同。目前的结果为基于损伤后区域特异性的线粒体功能障碍提供了基础，可能会有不同的靶向治疗。更重要的是，这些结果表明，针对线粒体功能障碍的治疗干预可能需要延长给药方案，才能在 TBI 后达到临床疗效。
