Protective Effects of Milk Casein on the Brain Function and Behavior in a Mouse Model of Chronic Stress

Chronic stress is a major cause of mental health problems and primary medical issues. Milk has been studied for its stress-reducing effects. Tryptophan, which is abundant in milk, is a precursor of the neuroactive compounds serotonin and melatonin. This study investigated the preventive effects of milk casein on brain dysfunction and anxiety-like behavior induced by chronic stress. Mice were exposed to unpredictable chronic mild stress (UCMS) and milk casein was administered for 10 weeks. Milk casein significantly reduced stress-induced changes in serum corticosterone and serotonin levels. The negative effects of UCMS on the expression of proteins associated with neuroendocrine function, neurodegeneration, neuronal inflammation, and barrier function of the blood–brain barrier were statistically normalized by casein treatment. Pretreatment with casein significantly prevented anxiety-like behavior induced by UCMS. These results suggest that milk casein has the potential to prevent stress-induced brain dysfunction and anxiety-like behavior.