Postgraduate Program in Biological Sciences: Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600 - Anexo Santa Cecília, Porto Alegre, RS, 90035-003, Brazil.
Brain Institute of Rio Grande do Sul, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, RS, 90619-900, Brazil.
Mol Neurobiol. 2018 Mar;55(3):2025-2041. doi: 10.1007/s12035-017-0458-x. Epub 2017 Mar 7.
This study was performed to evaluate the bilateral effects of focal permanent ischemia (FPI) on glial metabolism in the cerebral cortex. Two and 9 days after FPI induction, we analyze [F]FDG metabolism by micro-PET, astrocyte morphology and reactivity by immunohistochemistry, cytokines and trophic factors by ELISA, glutamate transporters by RT-PCR, monocarboxylate transporters (MCTs) by western blot, and substrate uptake and oxidation by ex vivo slices model. The FPI was induced surgically by thermocoagulation of the blood in the pial vessels of the motor and sensorimotor cortices in adult (90 days old) male Wistar rats. Neurochemical analyses were performed separately on both ipsilateral and contralateral cortical hemispheres. In both cortical hemispheres, we observed an increase in tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and glutamate transporter 1 (GLT-1) mRNA levels; lactate oxidation; and glutamate uptake and a decrease in brain-derived neurotrophic factor (BDNF) after 2 days of FPI. Nine days after FPI, we observed an increase in TNF-α levels and a decrease in BDNF, GLT-1, and glutamate aspartate transporter (GLAST) mRNA levels in both hemispheres. Additionally, most of the unilateral alterations were found only in the ipsilateral hemisphere and persisted until 9 days post-FPI. They include diminished in vivo glucose uptake and GLAST expression, followed by increased glial fibrillary acidic protein (GFAP) gray values, astrocyte reactivity, and glutamate oxidation. Astrocytes presented signs of long-lasting reactivity, showing a radial morphology. In the intact hemisphere, there was a decrease in MCT2 levels, which did not persist. Our study shows the bilateralism of glial modifications following FPI, highlighting the role of energy metabolism adaptations on brain recovery post-ischemia.
这项研究旨在评估局灶性永久缺血（FPI）对大脑皮层神经胶质代谢的双侧影响。在 FPI 诱导后 2 天和 9 天，我们通过 micro-PET 分析 [F]FDG 代谢，通过免疫组织化学分析星形胶质细胞形态和反应性，通过 ELISA 分析细胞因子和营养因子，通过 RT-PCR 分析谷氨酸转运体，通过 Western blot 分析单羧酸转运体（MCT），并通过体外切片模型分析底物摄取和氧化。FPI 通过热凝大脑皮层运动和感觉皮层的软脑膜血管在成年（90 天大）雄性 Wistar 大鼠中诱导。神经化学分析分别在两侧大脑半球上进行。在两个大脑半球中，我们观察到肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）和谷氨酸转运体 1（GLT-1）mRNA 水平增加；乳酸氧化；谷氨酸摄取增加，脑源性神经营养因子（BDNF）减少，2 天后发生 FPI。FPI 后 9 天，我们观察到两侧 TNF-α水平增加，BDNF、GLT-1 和谷氨酸天冬氨酸转运体（GLAST）mRNA 水平降低。此外，大多数单侧改变仅在同侧半球发现，并持续到 FPI 后 9 天。它们包括体内葡萄糖摄取和 GLAST 表达减少，随后星形胶质细胞反应性、谷氨酸氧化增加，GFAP 灰度值增加。星形胶质细胞表现出持久反应的迹象，呈现出放射状形态。在完整的半球中，MCT2 水平下降，但不持续。我们的研究表明 FPI 后神经胶质改变的双侧性，强调了能量代谢适应在缺血后大脑恢复中的作用。
