Adams Alexandra A, Li Ying, Kim Haesun A, Pfister Bryan J
Center for Injury Biomechanics, Materials and Medicine, Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, United States.
Department of Biological Sciences, Rutgers University Newark, Newark, NJ, United States.
Front Cell Neurosci. 2023 Mar 29;17:1111403. doi: 10.3389/fncel.2023.1111403. eCollection 2023.
models of traumatic brain injury (TBI) commonly use neurons isolated from the central nervous system. Limitations with primary cortical cultures, however, can pose challenges to replicating some aspects of neuronal injury associated with closed head TBI. The known mechanisms of axonal degeneration from mechanical injury in TBI are in many ways similar to degenerative disease, ischemia, and spinal cord injury. It is therefore possible that the mechanisms that result in axonal degeneration in isolated cortical axons after stretch injury are shared with injured axons from different neuronal types. Dorsal root ganglia neurons (DRGN) are another neuronal source that may overcome some current limitations including remaining healthy in culture for long periods of time, ability to be isolated from adult sources, and myelinated . The current study sought to characterize the differential responses between cortical and DRGN axons to mechanical stretch injury associated with TBI. Using an model of traumatic axonal stretch injury, cortical and DRGN neurons were injured at a moderate (40% strain) and severe stretch (60% strain) and acute alterations in axonal morphology and calcium homeostasis were measured. DRGN and cortical axons immediately form undulations in response to severe injury, experience similar elongation and recovery within 20 min after the initial injury, and had a similar pattern of degeneration over the first 24 h after injury. Additionally, both types of axons experienced comparable degrees of calcium influx after both moderate and severe injury that was prevented through pre-treatment with tetrodotoxin in cortical neurons and lidocaine in DRGNs. Similar to cortical axons, stretch injury also causes calcium activated proteolysis of sodium channel in DRGN axons that is prevented by treatment with lidocaine or protease inhibitors. These findings suggest that DRGN axons share the early response of cortical neurons to a rapid stretch injury and the associated secondary injury mechanisms. The utility of a DRGN TBI model may allow future studies to explore TBI injury progression in myelinated and adult neurons.
创伤性脑损伤（TBI）模型通常使用从中枢神经系统分离的神经元。然而，原代皮质培养的局限性可能给复制与闭合性颅脑损伤相关的神经元损伤的某些方面带来挑战。TBI中机械损伤导致轴突退化的已知机制在许多方面与退行性疾病、缺血和脊髓损伤相似。因此，拉伸损伤后分离的皮质轴突中导致轴突退化的机制可能与不同神经元类型的受损轴突相同。背根神经节神经元（DRGN）是另一种神经元来源，可能克服一些当前的局限性，包括在培养中长期保持健康、能够从成年来源分离以及有髓鞘。本研究旨在表征皮质和DRGN轴突对与TBI相关的机械拉伸损伤的不同反应。使用创伤性轴突拉伸损伤模型，皮质和DRGN神经元在中度（40%应变）和重度拉伸（60%应变）下受伤，并测量轴突形态和钙稳态的急性变化。DRGN和皮质轴突在严重损伤后立即形成波动，在初始损伤后20分钟内经历相似的伸长和恢复，并且在损伤后的头24小时内具有相似的退化模式。此外，在中度和重度损伤后，两种类型的轴突都经历了相当程度的钙内流，通过在皮质神经元中用河豚毒素预处理和在DRGN中用利多卡因预处理可以阻止这种情况。与皮质轴突类似，拉伸损伤也会导致DRGN轴突中钠通道的钙激活蛋白水解，用利多卡因或蛋白酶抑制剂处理可以阻止这种情况。这些发现表明，DRGN轴突与皮质神经元对快速拉伸损伤的早期反应以及相关的继发性损伤机制相同。DRGN TBI模型的实用性可能使未来研究能够探索有髓鞘和成年神经元中的TBI损伤进展。
