PDF(Pubmed)
Abstract：
OBJECTIVE: In mammals, central chemoreception plays a crucial role in the regulation of breathing function in both health and disease conditions. Recently, a correlation between high levels of superoxide anion (O2.-) in the Retrotrapezoid nucleus (RTN), a main brain chemoreceptor area, and enhanced central chemoreception has been found in rodents. Interestingly, deficiency in superoxide dismutase 2 (SOD2) expression, a pivotal antioxidant enzyme, has been linked to the development/progression of several diseases. Despite, the contribution of SOD2 on O2.- regulation on central chemoreceptor function is unknown. Accordingly, we sought to determine the impact of partial deletion of SOD2 expression on i) O2.-accumulation in the RTN, ii) central ventilatory chemoreflex function, and iii) disordered-breathing. Finally, we study cellular localization of SOD2 in the RTN of healthy mice.
METHODS: Central chemoreflex drive and breathing function were assessed in freely moving heterozygous SOD2 knockout mice (SOD2+/- mice) and age-matched control wild type (WT) mice by whole-body plethysmography. O2.- levels were determined in RTN brainstem sections and brain isolated mitochondria, while SOD2 protein expression and tissue localization were determined by immunoblot, RNAseq and immunofluorescent staining, respectively.
RESULTS: Our results showed that SOD2+/- mice displayed reductions in SOD2 levels and high O2.- formation and mitochondrial dysfunction within the RTN compared to WT. Additionally, SOD2+/- mice displayed a heightened ventilatory response to hypercapnia and exhibited overt signs of altered breathing patterns. Both, RNAseq analysis and immunofluorescence co-localization studies showed that SOD2 expression was confined to RTN astrocytes but not to RTN chemoreceptor neurons. Finally, we found that SOD2+/- mice displayed alterations in RTN astrocyte morphology compared to RTN astrocytes from WT mice.
UNASSIGNED: These findings provide first evidence of the role of SOD2 in the regulation of O2.- levels in the RTN and its potential contribution on the regulation of central chemoreflex function. Our results suggest that reductions in the expression of SOD2 in the brain may contribute to increase O2.- levels in the RTN being the outcome a chronic surge in central chemoreflex drive and the development/maintenance of altered breathing patterns. Overall, dysregulation of SOD2 and the resulting increase in O2.- levels in brainstem respiratory areas can disrupt normal respiratory control mechanisms and contribute to breathing dysfunction seen in certain disease conditions characterized by high oxidative stress.
METHODS: Central chemoreflex drive and breathing function were assessed in freely moving heterozygous SOD2 knockout mice (SOD2+/- mice) and age-matched control wild type (WT) mice by whole-body plethysmography. O2.- levels were determined in RTN brainstem sections and brain isolated mitochondria, while SOD2 protein expression and tissue localization were determined by immunoblot, RNAseq and immunofluorescent staining, respectively.
RESULTS: Our results showed that SOD2+/- mice displayed reductions in SOD2 levels and high O2.- formation and mitochondrial dysfunction within the RTN compared to WT. Additionally, SOD2+/- mice displayed a heightened ventilatory response to hypercapnia and exhibited overt signs of altered breathing patterns. Both, RNAseq analysis and immunofluorescence co-localization studies showed that SOD2 expression was confined to RTN astrocytes but not to RTN chemoreceptor neurons. Finally, we found that SOD2+/- mice displayed alterations in RTN astrocyte morphology compared to RTN astrocytes from WT mice.
UNASSIGNED: These findings provide first evidence of the role of SOD2 in the regulation of O2.- levels in the RTN and its potential contribution on the regulation of central chemoreflex function. Our results suggest that reductions in the expression of SOD2 in the brain may contribute to increase O2.- levels in the RTN being the outcome a chronic surge in central chemoreflex drive and the development/maintenance of altered breathing patterns. Overall, dysregulation of SOD2 and the resulting increase in O2.- levels in brainstem respiratory areas can disrupt normal respiratory control mechanisms and contribute to breathing dysfunction seen in certain disease conditions characterized by high oxidative stress.
摘要：
目的：在哺乳动物中，在健康和疾病条件下，中枢化学感受在调节呼吸功能中起着至关重要的作用。最近,高水平的超氧阴离子(O2。-)在后梯形核(RTN)中，大脑主要的化学感受器区域，在啮齿动物中发现了增强的中央化学接受。有趣的是,超氧化物歧化酶2（SOD2）表达缺乏，一种关键的抗氧化酶，与几种疾病的发展/进展有关。尽管,SOD2对O2的贡献。-中枢化学感受器功能的调节是未知的。因此，我们试图确定SOD2表达部分缺失对i)O2的影响。-RTN中的积累，ii)中央通气化学反射功能，和iii)呼吸紊乱。最后,我们研究SOD2在健康小鼠RTN中的细胞定位。
方法：通过全身体积描记术在自由移动的杂合子SOD2敲除小鼠（SOD2+/-小鼠）和年龄匹配的对照野生型（WT）小鼠中评估中枢化学反射驱动和呼吸功能。O2.-在RTN脑干切片和大脑分离的线粒体中确定水平，免疫印迹法测定SOD2蛋白表达和组织定位,RNAseq和免疫荧光染色，分别。
结果：我们的结果表明，SOD2+/-小鼠表现出SOD2水平降低和高O2。-与WT相比,RTN内的形成和线粒体功能障碍。此外,SOD2/-小鼠对高碳酸血症表现出增强的通气反应，并表现出明显的呼吸模式改变的迹象。两者,RNAseq分析和免疫荧光共定位研究表明，SOD2的表达仅限于RTN星形胶质细胞，而不限于RTN化学感受器神经元。最后,我们发现,与WT小鼠的RTN星形胶质细胞相比,SOD2+/-小鼠显示出RTN星形胶质细胞形态的改变.
■这些发现为SOD2在调节O2中的作用提供了第一个证据。-RTN中的水平及其对中枢化学反射功能调节的潜在贡献。我们的结果表明，脑中SOD2表达的减少可能有助于增加O2。-RTN中的水平是中枢化学反射驱动的慢性激增和改变的呼吸模式的发展/维持的结果。总的来说,SOD2的失调和由此导致的O2增加。-脑干呼吸区域中的水平可以破坏正常的呼吸控制机制，并导致在以高氧化应激为特征的某些疾病中看到的呼吸功能障碍。
方法：通过全身体积描记术在自由移动的杂合子SOD2敲除小鼠（SOD2+/-小鼠）和年龄匹配的对照野生型（WT）小鼠中评估中枢化学反射驱动和呼吸功能。O2.-在RTN脑干切片和大脑分离的线粒体中确定水平，免疫印迹法测定SOD2蛋白表达和组织定位,RNAseq和免疫荧光染色，分别。
结果：我们的结果表明，SOD2+/-小鼠表现出SOD2水平降低和高O2。-与WT相比,RTN内的形成和线粒体功能障碍。此外,SOD2/-小鼠对高碳酸血症表现出增强的通气反应，并表现出明显的呼吸模式改变的迹象。两者,RNAseq分析和免疫荧光共定位研究表明，SOD2的表达仅限于RTN星形胶质细胞，而不限于RTN化学感受器神经元。最后,我们发现,与WT小鼠的RTN星形胶质细胞相比,SOD2+/-小鼠显示出RTN星形胶质细胞形态的改变.
■这些发现为SOD2在调节O2中的作用提供了第一个证据。-RTN中的水平及其对中枢化学反射功能调节的潜在贡献。我们的结果表明，脑中SOD2表达的减少可能有助于增加O2。-RTN中的水平是中枢化学反射驱动的慢性激增和改变的呼吸模式的发展/维持的结果。总的来说,SOD2的失调和由此导致的O2增加。-脑干呼吸区域中的水平可以破坏正常的呼吸控制机制，并导致在以高氧化应激为特征的某些疾病中看到的呼吸功能障碍。
