Wang Yi, Li Jie, Wang Meng-Yue, Pan Zhi-Yong, Li Zhi-Qiang, Wang Ze-Fen
Department of Physiology, Wuhan University School of Basic Medical Sciences, Wuhan, Hubei, China.
Department of Neurosurgery, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China.
Biochem Biophys Res Commun. 2022 Jun 4;607:28-35. doi: 10.1016/j.bbrc.2022.03.122. Epub 2022 Mar 26.
Neuronal activity is closely associated with energy metabolism. In addition to glucose, astrocyte-derived lactate serves as an energy source for neurons. Chronic inflammation is a common pathological event that is associated with aging and neurodegenerative diseases. However, the mechanisms underlying inflammation-induced neuronal injury are not fully understood. Both microglia and astrocytes participate in the regulation of neuronal functions; therefore, we used astrocyte-neuron co-cultures to investigate the effects of chronic microglial activation on neuronal lactate metabolism. Chronic low-grade inflammation was induced by repeated stimulation of primary rat microglia with low-dose lipopolysaccharide (LPS, 10 ng/mL). The medium from the LPS-activated microglia was collected and used to mimic the inflammatory environment in primary cultures. In monocultures exposed to an inflammatory environment, intracellular lactate decreased in neurons but increased in astrocytes. However, astrocyte-neuron co-cultures exhibited increased lactate levels in neurons and decreased lactate levels in astrocytes when exposed to an inflammatory environment. Inhibition of lactate transporters expressed on neurons or astrocytes reduced the intracellular lactate in co-cultured neurons exposed to inflammation, but not in those exposed to physiological conditions. Adenosine triphosphate (ATP) production was reduced in both mono-cultured and co-cultured neurons. These results indicate that a chronic inflammatory environment increases neuronal lactate supply by promoting the astrocyte-neuron lactate shuttle, but it impairs lactate oxidation in neurons. Additionally, chronic inflammation disrupts the neuronal cytoskeleton. This study highlights the importance of glial cells in regulating neuroenergetics and neuronal function and provides a comprehensive explanation for the neurotoxic effects of neuroinflammation.
神经元活动与能量代谢密切相关。除葡萄糖外,星形胶质细胞衍生的乳酸盐也可作为神经元的能量来源。慢性炎症是一种与衰老和神经退行性疾病相关的常见病理事件。然而,炎症诱导的神经元损伤的潜在机制尚未完全明确。小胶质细胞和星形胶质细胞均参与神经元功能的调节;因此,我们使用星形胶质细胞-神经元共培养物来研究慢性小胶质细胞激活对神经元乳酸代谢的影响。通过用低剂量脂多糖(LPS,10 ng/mL)反复刺激原代大鼠小胶质细胞来诱导慢性低度炎症。收集LPS激活的小胶质细胞的培养基,并用于模拟原代培养中的炎症环境。在暴露于炎症环境的单培养物中,神经元内的乳酸盐减少,而星形胶质细胞内的乳酸盐增加。然而,在暴露于炎症环境时,星形胶质细胞-神经元共培养物中神经元的乳酸盐水平升高,而星形胶质细胞中的乳酸盐水平降低。抑制神经元或星形胶质细胞上表达的乳酸转运体可降低暴露于炎症的共培养神经元中的细胞内乳酸盐,但在暴露于生理条件的神经元中则不然。单培养和共培养的神经元中的三磷酸腺苷(ATP)生成均减少。这些结果表明,慢性炎症环境通过促进星形胶质细胞-神经元乳酸穿梭增加神经元乳酸供应,但会损害神经元中的乳酸氧化。此外,慢性炎症会破坏神经元细胞骨架。本研究强调了神经胶质细胞在调节神经能量学和神经元功能中的重要性,并为神经炎症的神经毒性作用提供了全面解释。