Kume Satoshi, Yamato Masanori, Tamura Yasuhisa, Jin Guanghua, Nakano Masayuki, Miyashige Yukiharu, Eguchi Asami, Ogata Yoshiyuki, Goda Nobuhito, Iwai Kazuhiro, Yamano Emi, Watanabe Yasuyoshi, Soga Tomoyoshi, Kataoka Yosky
Cellular Function Imaging Team, Division of Bio-function Dynamics Imaging, RIKEN Center for Life Science Technologies, Kobe, Hyogo, Japan.
Cellular Function Imaging Team, Division of Bio-function Dynamics Imaging, RIKEN Center for Life Science Technologies, Kobe, Hyogo, Japan; Department of Physiology, Osaka City University Graduate School of Medicine, Osaka, Japan.
PLoS One. 2015 Mar 20;10(3):e0120106. doi: 10.1371/journal.pone.0120106. eCollection 2015.
In the present study, prior to the establishment of a method for the clinical diagnosis of chronic fatigue in humans, we validated the utility of plasma metabolomic analysis in a rat model of fatigue using capillary electrophoresis-mass spectrometry (CE-MS). In order to obtain a fatigued animal group, rats were placed in a cage filled with water to a height of 2.2 cm for 5 days. A food-restricted group, in which rats were limited to 10 g/d of food (around 50% of the control group), was also assessed. The food-restricted group exhibited weight reduction similar to that of the fatigued group. CE-MS measurements were performed to evaluate the profile of food intake-dependent metabolic changes, as well as the profile in fatigue loading, resulting in the identification of 48 metabolites in plasma. Multivariate analyses using hierarchical clustering and principal component analysis revealed that the plasma metabolome in the fatigued group showed clear differences from those in the control and food-restricted groups. In the fatigued group, we found distinctive changes in metabolites related to branched-chain amino acid metabolism, urea cycle, and proline metabolism. Specifically, the fatigued group exhibited significant increases in valine, leucine, isoleucine, and 2-oxoisopentanoate, and significant decreases in citrulline and hydroxyproline compared with the control and food-restricted groups. Plasma levels of total nitric oxide were increased in the fatigued group, indicating systemic oxidative stress. Further, plasma metabolites involved in the citrate cycle, such as cis-aconitate and isocitrate, were reduced in the fatigued group. The levels of ATP were significantly decreased in the liver and skeletal muscle, indicative of a deterioration in energy metabolism in these organs. Thus, this comprehensive metabolic analysis furthered our understanding of the pathophysiology of fatigue, and identified potential diagnostic biomarkers based on fatigue pathophysiology.
在本研究中，在建立人类慢性疲劳临床诊断方法之前，我们使用毛细管电泳-质谱联用技术（CE-MS）在大鼠疲劳模型中验证了血浆代谢组学分析的效用。为了获得疲劳动物组，将大鼠置于水深2.2厘米的笼子中5天。还评估了食物限制组，该组大鼠的食物摄入量限制为每天10克（约为对照组的50%）。食物限制组的体重减轻情况与疲劳组相似。进行CE-MS测量以评估食物摄入依赖性代谢变化的概况以及疲劳负荷下的代谢概况，从而鉴定出血浆中的48种代谢物。使用层次聚类和主成分分析的多变量分析表明，疲劳组的血浆代谢组与对照组和食物限制组有明显差异。在疲劳组中，我们发现与支链氨基酸代谢、尿素循环和脯氨酸代谢相关的代谢物有显著变化。具体而言，与对照组和食物限制组相比，疲劳组的缬氨酸、亮氨酸、异亮氨酸和2-氧代异戊酸显著增加，瓜氨酸和羟脯氨酸显著减少。疲劳组的总一氧化氮血浆水平升高，表明存在全身氧化应激。此外，疲劳组中参与柠檬酸循环的血浆代谢物，如顺乌头酸和异柠檬酸减少。肝脏和骨骼肌中的ATP水平显著降低，表明这些器官的能量代谢恶化。因此，这种全面的代谢分析加深了我们对疲劳病理生理学的理解，并基于疲劳病理生理学鉴定出潜在的诊断生物标志物。
