Stress increases blood beta‐hydroxybutyrate levels and prefrontal cortex NLRP3 activity jointly in a rodent model

Aim This study aimed to assess the response of endogenous beta-hydroxybutyrate to psychological stress, and its association with nucleotide-binding domain, leucine-rich repeat, pyrin domain-containing 3 (NLRP3) inflammasome, and stress-induced behavior. Methods Male C57BL/6J mice were subjected to 1-hour restraint stress to examine changes in the endogenous beta-hydroxybutyrate and active NLRP3 levels in the prefrontal cortex. Subsequently, we created a depression model applying 10-day social defeat stress to the male C57BL/6J mice. Results One-hour restraint stress rapidly increased beta-hydroxybutyrate levels in the blood. The active NLRP3 levels in the prefrontal cortex also increased significantly. A correlation was found between the increased beta-hydroxybutyrate levels in the blood and the active NLRP3 levels in the prefrontal cortex. The mice exposed to social defeat stress exhibited depression- and anxiety-like behavioral changes in the open field, social interaction, and forced swim tests. There was a correlation between these behavioral changes and endogenous beta-hydroxybutyrate levels. Among the social defeat model mice, those with high beta-hydroxybutyrate levels tended to have more depression- and anxiety-like behavior. Conclusions The increased blood beta-hydroxybutyrate levels due to psychological stress correlate with the active NLRP3 levels in the prefrontal cortex, suggesting that the increased beta-hydroxybutyrate levels due to stress may reflect a reaction to brain inflammation. In addition, mice with higher blood beta-hydroxybutyrate levels tend to exhibit increased depression- and anxiety-like behaviors; thus, an increase in blood beta-hydroxybutyrate levels due to stress may indicate stress vulnerability.