Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Serviço de Patologia, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos, 2350, Porto Alegre, RS 90035-007, Brazil.
Neuroscience. 2021 Sep 1;471:115-132. doi: 10.1016/j.neuroscience.2021.07.024. Epub 2021 Jul 30.
D-2-hydroxyglutaric acid (D-2-HG) accumulates and is the biochemical hallmark of D-2-hydroxyglutaric acidurias (D-2-HGA) types I and II, which comprehend two inherited neurometabolic diseases with severe cerebral abnormalities. Since the pathogenesis of these diseases is poorly established, we tested whether D-2-HG could be neurotoxic to neonatal rats. D-2-HG intracerebroventricular administration caused marked vacuolation in cerebral cortex and striatum. In addition, glial fibrillary acidic protein (GFAP), S-100 calcium binding protein B (S100B) and ionized calcium-binding adapter molecule 1 (Iba-1) staining was increased in both brain structures, suggesting glial reactivity and microglial activation. D-2-HG also provoked a reduction of NeuN-positive cells in cerebral cortex, signaling neuronal death. Considering that disturbances in redox homeostasis and energy metabolism may be involved in neuronal damage and glial reactivity, we assessed whether D-2-HG could induce oxidative stress and bioenergetics impairment. D-2-HG treatment significantly augmented reactive oxygen and nitrogen species generation, provoked lipid peroxidation and protein oxidative damage, diminished glutathione concentrations and augmented superoxide dismutase and catalase activities in cerebral cortex. Increased reactive oxygen species generation, lipoperoxidation and protein oxidation were also found in striatum. Furthermore, the antagonist of NMDA glutamate receptor MK-801 and the antioxidant melatonin were able to prevent most of D-2-HG-induced pro-oxidant effects, implying the participation of these receptors in D-2-HG-elicited oxidative damage. Our results also demonstrated that D-2-HG markedly reduced the respiratory chain complex IV and creatine kinase activities. It is presumed that these deleterious pathomechanisms caused by D-2-HGA may be involved in the brain abnormalities characteristic of early-infantile onset D-2-HGA.
D-2-羟戊二酸（D-2-HG）积累，是 D-2-羟戊二酸尿症（D-2-HGA）I 型和 II 型的生化标志，这两种疾病均为严重脑异常的遗传性神经代谢疾病。由于这些疾病的发病机制尚未完全建立，我们测试了 D-2-HG 是否对新生大鼠具有神经毒性。D-2-HG 脑室给药导致大脑皮层和纹状体出现明显空泡化。此外，两种脑结构中的胶质纤维酸性蛋白（GFAP）、S-100 钙结合蛋白 B（S100B）和离子钙结合接头分子 1（Iba-1）染色增加，提示胶质反应和小胶质细胞激活。D-2-HG 还导致大脑皮层中 NeuN 阳性细胞减少，提示神经元死亡。鉴于氧化还原平衡和能量代谢紊乱可能与神经元损伤和胶质反应有关，我们评估了 D-2-HG 是否会诱导氧化应激和生物能量障碍。D-2-HG 处理显著增加活性氧和氮物种的生成，引起脂质过氧化和蛋白质氧化损伤，降低大脑皮层中的谷胱甘肽浓度，并增加超氧化物歧化酶和过氧化氢酶的活性。纹状体中也发现了活性氧物种生成、脂质过氧化和蛋白质氧化增加。此外，NMDA 谷氨酸受体拮抗剂 MK-801 和抗氧化剂褪黑素能够预防 D-2-HG 诱导的大部分促氧化剂效应，表明这些受体参与了 D-2-HG 引起的氧化损伤。我们的研究结果还表明，D-2-HG 显著降低了呼吸链复合物 IV 和肌酸激酶的活性。据推测，D-2-HGA 引起的这些有害病理机制可能与早发性婴儿期 D-2-HGA 特征性的大脑异常有关。
