Period3 modulates the NAD+-SIRT3 axis to alleviate depression-like behaviour by enhancing NAMPT activity in mice

• Per3 deficiency reduces NAD + levels in the brain and induces depression-like behaviors in mice. • Enhancing NAD + levels through NAM supplementation or NAMPT activation alleviates depression-like behaviors in Per3 knockout mice. • NAD + -mediated modulation of SIRT3 activity links mitochondrial dysfunction to Per3-induced depression. • PER3 regulates Nampt expression by binding to its promoter region, controlling NAD + levels and mitochondrial function. PERIOD (PER)3 deficiency is associated with depression-like behaviors, but the underlying mechanisms remain unclear. This study aims to elucidate the role and mechanism of PER3 in regulating depression-like behaviors in mice. Depression-like behaviors were assessed using the sucrose preference test, tail suspension test, and forced swimming test. Metabolomic analysis was conducted on hippocampal tissues from Per3 knockout mice using chromatography-mass spectrometry. The regulatory role of PER3 on the expression of nicotinamide phosphoribosyltransferase (Nampt) was investigated through co-immunoprecipitation and chromatin immunoprecipitation assays. Metabolomic analysis revealed that Per3 deficiency disrupts mitochondrial function, as evidenced by reduced activities of key tricarboxylic acidcycle enzymes (succinate dehydrogenase, citrate synthase, and α-ketoglutarate dehydrogenase), diminished expression of mitochondrial respiratory chain complexes I-V, and decreased nicotinamide adenine dinucleotide (NAD) + levels in Per3 knockout mice. Supplementation with the NAD + precursor nicotinamide rescued mitochondrial function and alleviated depression-like behaviors in Per3 knockout mice. Similar effects were observed with intraperitoneal administration of the NAMPT activator P7C3-A20, while these effects were abolished by the NAMPT inhibitor FK866. Mechanistically, PER3 was found to regulate Nampt expression by binding to E-box elements within its intronic regions in conjunction with BMAL1. This interaction enhanced NAD + production, activating SIRT3 to mitigate mitochondrial dysfunction in Per3 knockout mice. These findings uncover a novel mechanism by which PER3 ameliorates depressive behaviors through the regulation of NAMPT-controlled NAD + levels and mitochondrial function, underscoring the critical role of PER3 in depression-related pathophysiology.