Resveratrol Alleviates Corticosterone-Induced Hepatic Lipid Metabolism Disorder and Oxidative Stress by Regulating the Nrf2 and AMPK/Sirt1 Signaling Pathways in AA Broilers

Excessive glucocorticoids induced by stress trigger hepatic lipid metabolism disorder and oxidative stress in poultry, impairing growth performance and welfare. At the same time, resveratrol (RSV) has antioxidant and lipid-regulating properties, but the protective mechanisms in corticosterone (CORT)-challenged broilers remain unclear. This study investigated RSV’s effects on CORT-induced hepatic damage in AA broilers, with 240 one-day-old broilers randomized into three groups: control (basal diet), CORT (basal diet + 4 mg/kg BW CORT intraperitoneal injection), and RSV (400 mg/kg RSV-supplemented diet + CORT injection). Growth performance, hepatic redox status, serum biochemistry, liver histopathology, and gene/protein expression related to antioxidant/lipid metabolism were determined. The growth performance of AA broilers injected with CORT was significantly affected, showing reduced body weight gain (p < 0.05), increased abdominal fat content (p < 0.05), and hepatomegaly (p < 0.05). The addition of RSV in the diet significantly reduced abdominal fat accumulation and hepatomegaly (p < 0.05), improving the growth performance of broilers; Effects of RSV on liver function and lipid metabolism of CORT-treated AA broilers: After CORT injection, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) activity and total bile acid (TBA) content significantly increased (p < 0.05). Hepatic total cholesterol (TC) and triglycerides (TG) increased after CORT injection (p < 0.05), causing severe liver damage. RSV supplementation could reverse the increases in serum ALP, ALT, and AST activity (p < 0.05) and reduce TBA content in stressed broilers (p < 0.05). TC and TG levels in the liver decreased under the alleviation of RSV (p < 0.05), and serum TG levels declined (p < 0.05). Microscopic and ultrastructural observations showed that after CORT injection, hepatic tissue cells were swollen, scattered fat vacuoles were present, pores were enlarged, and intracellular lipid droplets appeared. The RSV group significantly alleviated hepatocyte damage, reduced vacuolation, showed uniform chromatin, and decreased lipid droplets. RSV significantly mitigated the CORT-induced increase in SREBP-1 mRNA and protein expression and the decrease in PPARα protein expression; CORT caused a decline in the antioxidant function of AA broiler livers, with significant decreases in SOD and GSH-PX (p < 0.05), and the expression of Nrf2 and its downstream genes also showed a decreasing trend. Compared to the CORT group, the RSV group exhibited significant increases in liver CAT, SOD, and GSH-PX (p < 0.05), and Nrf2 protein expression was elevated (p < 0.05). In summary, resveratrol can alleviate the decline in growth performance, liver steatosis, and hepatic oxidative stress in AA broilers induced by CORT, downregulate lipogenic genes such as SREBP-1c, regulate liver lipid metabolism, and mitigate CORT-induced hepatic oxidative stress in broilers by upregulating the Nrf2 pathway.