SIRT3-Mediated Mitochondrial Fatty Acid Oxidation Protects Against Hepatic Lipid Deposition in Fatty Liver Hemorrhagic Syndrome

Fatty liver hemorrhagic syndrome (FLHS) is a nutrition-related metabolic disorder in laying hens characterized by excessive hepatic lipid accumulation and hemorrhagic lesions, leading to reduced productivity and increased mortality. However, the regulatory mechanisms linking mitochondrial dysfunction to hepatic lipid metabolism remain unclear. This study investigated the role of SIRT3 in modulating mitochondrial fatty acid oxidation during FLHS progression. An in vivo FLHS model was established by feeding laying hens with a high-energy, low-protein (HELP) diet, and an in vitro hepatic steatosis model was induced by free fatty acid (FFA) treatment in primary hepatocytes. Both models exhibited pronounced lipid accumulation in hepatic cells and altered hepatocellular injury-related parameters, which were associated with mitochondrial dysfunction and impaired fatty acid oxidation. Mechanistically, hepatic tissues and hepatocytes showed suppression of the SIRT3–AMPKα–PGC-1α signaling cascade, accompanied by reduced expression of mitochondrial biogenesis markers (NRF1, TFAM), impaired respiratory chain components ( NDUFA9, SDHA, UQCRC1, COX4I1, ATP5B ), and decreased transcription of fatty acid oxidation-related genes ( PPARα, ACOX1, CPT1A, CPT2, ACADL, ACADM ). Pharmacological activation of SIRT3 with AR-C17 restored AMPKα–PGC-1α signaling, enhanced mitochondrial biogenesis and respiratory function, and promoted fatty acid oxidation, thereby alleviating lipid accumulation in hepatocytes in both models. Collectively, these results demonstrate that SIRT3 is a key metabolic regulator maintaining mitochondrial oxidative function and lipid homeostasis in laying hens. Targeted activation of SIRT3 may provide a novel nutritional strategy for preventing or ameliorating FLHS and related metabolic disturbances in poultry production.