Multiomics Analysis Reveals the Potential Sleep-Enhancing Peptide from Milk Casein Hydrolysate and Its Synergic Mechanism via Regulating the Key Hub CaMKII Pathway in Chronic Stressed Mice

Casein hydrolysate (CMH) was proved to exert strong sleep-enhancing effects by vital amino acid metabolisms, GABAergic system, and cAMP signaling pathway in our previous study. Whether there existed a novel active peptide in CMH and its underlying synergic mechanism remain unknown. This study aims to explore novel potent sleep-enhancing peptides in CMH and to systematically investigate its underlying mechanisms by multiomics analysis. Our results showed that many potent sleep-enhancing Tyr-based peptides were released by CMH. Considering potential structural features and contents, YQEPVLGPVR (YQ10) was screened, which significantly prolonged sleep duration and recovered the corticosterone level. Moreover, ten crucial DEGs and DEMs were revealed by omics analysis. YQ10 might regulate CaMKII and neuroinflammatory pathways to communicate with GABAergic and cAMP signaling pathways, particularly regulating CaMKII, IL-1β, and IL-6, which was validated by vital factors/protein expressions and antagonist experiments. These findings could provide a theoretic basis to explore potential sleep-enhancing mechanisms of Tyr-based peptides.