Circadian and Age-Related Variations of Amino Acids Levels in Drosophila Brains: Correlations and Descriptive Dimensions

A comprehensive view of whole-brain amino acid levels holds the potential to provide valuable insights into the brain’s state, given the mutual interconnections through metabolism, food intake, and neurotransmission. We tested this concept by evaluating free amino acid levels in single Drosophila brains across 24 h and at two different ages. A large proportion of these amino acids displayed time-of-day variations, and a subset exhibited age-dependent variations. Cross-correlation analysis of the data sets confirmed broad time-of-day and age dependent interconnections between amino acids. Factor Analysis of Mixed Data revealed further data structuration along key amino acids. For example, 50% of the variance could be accounted for by an inverse coupling between gamma-aminobutyric acid and several essential amino acids during the active phase, linking food intake and sleep. This proof of concept emphasizes the value of combining multivariate analysis to whole-brain amino acid level evaluation, shedding potentially new light on sleep–wake regulation and aging.鉴于氨基酸通过代谢、进食行为与神经传导形成相互关联，全面测定全脑氨基酸水平，有望为大脑状态研究提供极具价值的新见解。本研究通过检测24小时周期内及两个不同年龄段的单只果蝇全脑游离氨基酸水平，对该设想进行了验证。结果显示，多数氨基酸呈现昼夜节律性波动，另有部分氨基酸表现出年龄依赖性变化。对本次数据集的互相关分析证实，氨基酸之间存在广泛的昼夜节律及年龄依赖性关联。混合数据因子分析（Factor Analysis of Mixed Data）进一步揭示了基于关键氨基酸的数据结构特征：例如，在活动期，γ-氨基丁酸（gamma-aminobutyric acid）与数种必需氨基酸之间的反向耦合可解释50%的方差，该关联将进食行为与睡眠联系起来。本概念验证研究凸显了将多变量分析与全脑氨基酸水平测定相结合的研究价值，有望为睡眠-觉醒调控及衰老研究提供全新视角。