Curcumin attenuates chronic heat stress-induced cardiac injury in Siberian sturgeon (Acipenser baerii): Mechanisms of oxidative stress, mitochondrial dysfunction and metabolic reprogramming.

Global warming increasingly threatens cold-water aquaculture, yet nutritional strategies for protecting the fish heart from chronic heat stress remain insufficiently understood. This study evaluated the protective effects of dietary curcumin against chronic heat stress (28 °C) in the hearts of Siberian sturgeon (Acipenser baerii) using histological, biochemical, molecular, and metabolomic analyses. Heat stress caused cardiac injury, as indicated by inflammatory infiltration, mitochondrial vacuolization, increased serum cardiac enzymes (CK, CK-MB, and α-HBDH) and glucose, and elevated myocardial reactive oxygen species (ROS), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content. Curcumin supplementation attenuated these alterations and enhanced catalase (CAT) and glutathione peroxidase (GSH-Px) activities. Curcumin also reduced cardiomyocyte apoptosis by downregulating caspase-3, caspase-7, and caspase-9 and restoring heat shock protein 90 (Hsp90) levels. In addition, curcumin improved mitochondrial membrane potential (MMP), Ca2+/Mg2+-ATPase activity, and ATP content. Metabolomic profiling indicated that heat stress altered energy-related metabolites such as ATP and isocitrate, whereas curcumin partially restored the metabolic profile, most notably ATP. These findings support dietary curcumin as a practical nutritional strategy for improving cardiac protection and thermal resilience in Siberian sturgeon aquaculture.