Rutin alleviates heat stress induced hepatic abnormal lipid metabolism of broilers via improving antioxidant capacity to maintain mitochondrial homeostasis

Heat stress (HS) leads to abnormal lipid metabolism in broilers, while rutin as a natural flavonoid with multiple biological functions shows potential to regulate antioxidant capacity and lipid metabolism. Therefore, this study aimed to investigate the effects of rutin supplementation on antioxidant and lipid metabolism functions in heat-stress broilers and to further explore its potential mechanisms. A total of 192 male broilers were randomly divided into three groups and treated with normal control (CON), heat stress (34 °C, HS), and HS with 500 mg kg⁻¹ rutin supplementation (HS + Rutin), respectively. The results showed that dietary supplementation of 500 mg kg⁻¹ rutin could significantly reverse the HS-induced liver damage. Rutin also mitigated HS-induced increases in liver triglyceride content and decreases in high-density lipoprotein and fatty acid binding protein contents. This might be achieved by increasing the expression of PPARα and decreasing the expression of SREBP1, which regulated the expression of downstream factors (such as CPT1, ACOX1, and ACC). Compared with the HS group, rutin increased mitochondrial DNA copy number and maintained mitochondrial homeostasis by regulating the expression of related genes (such as AMPK, PGC1-α, and SIRT3). In addition, rutin increased the activity of antioxidant enzymes, decreased the content of malondialdehyde, and activated the nuclear respiratory factor 2 (Nrf2) signaling pathway in the liver, which alleviated HS-induced oxidative stress. The effect of rutin in alleviating abnormal lipid deposition in HS broiler livers were correlated with indicators that reflected the antioxidant capacity and mitochondrial homeostasis. In conclusion, dietary 500 mg kg⁻¹ rutin alleviates heat stress-induced hepatic abnormal lipid metabolism of broilers via improving antioxidant capacity to maintain mitochondrial homeostasis.