Zhong, Q.; Li, Q.; Jia, X.; Hu, L.; Zhang, Y.; Zu, J.; He, Y.; Wang, Y.; Feng, H.; Hao, J.; Zhao, Z.; He, J.; Zhong, Z.

Stress is a prevalent mental health concern emerging predominantly in late adolescence or early adulthood. Since 2007, the Food and Drug Administration (FDA) has not approved any novel anxiolytic pharmaceuticals, fueling interest in nutritional supplements as alternative therapies for stress management. Building on prior zebrafish research, this study investigates the synergistic effects of Theanine (Th) and Walnut Peptide (WP) on stress mitigation and cognitive enhancement. Utilizing the human brain organoid stress (BO-stress) model, WP+ Th were observed to reduce stress and regulate expression of neurotransmitters, including Gamma-Aminobutyric Acid (GABA), serotonin (5-HT), dopamine (DA), and acetylcholine (Ach), as well as brain-derived neurotrophic factor (BDNF) and serotonin transporter (SERT). Subsequent in vivo study using C57BL/6J mouse-stress model demonstrated that the treatment (Th 85 mg/mL + WP 200 mg/mL), or administrated with vehicles, significantly improved their performance in stress and cognitive assessments, partially normalized neurotransmitter imbalances by modulating SERT and BDNF expression. These findings highlighted the potential of using WP + Th, particularly when delivered with vehicles (eg: powder/yogurt/milk), as a novel combined therapeutic approach for stress management and cognitive enhancement. We performed a correlation analysis between BO-stress model and mouse-stress model, revealing a alignment in the SERT levels. In addition, SERT was highly correlated with other markers in the mouse hippocampus and may represent a key target for modulating the balance between stress and cognition.