Comparative metabolomic profiling reveals circadian regulation of metabolites in brain tissue of the amur minnow (Phoxinus lagowskii)

Circadian rhythms are an important aspect of fish biology, and circadian rhythms of the Amur minnow (Phoxinus lagowskii) are vital for improving the economic use of this emerging commercial fish. Using LC-MS-based metabolomics, we analyzed brain metabolites of P. lagowskii at 7:00, 15:00, and 23:00, identifying 375 differentially expressed metabolites. Metabolomics analysis identified nine metabolites that differed significantly among timepoints. These metabolites were involved in pathways such as the tricarboxylic acid cycle, the phosphocreatine system, and gluconeogenesis. The metabolites related to energy metabolism, such as AMP and 6-phosphogluconic acid, were down-regulated in samples from 7:00 compared to those from 15:00 and 23:00. Histamine and dopamine were both down-regulated to a minimum in 15:00 samples, whereas glutathione was down-regulated to a minimum in the 23:00 samples. Our results elucidate circadian variations in metabolites, providing new insights into the study of circadian rhythms in P. lagowskii, which is important for improving feed utilization and optimizing the culture structure.