Dietary Tea Polyphenols Alleviate Acute-Heat-Stress-Induced Death of Hybrid Crucian Carp HCC2: Involvement of Modified Lipid Metabolisms in Liver.

Abstract

Background: Global warming poses significant challenges to aquaculture, as elevated water temperatures adversely affect fish health and survival. This study investigated the effects and potential mechanisms of dietary tea polyphenols (TPs) on acute heat stress and survival in hybrid crucian carp HCC2.

Methods: The fish in the control (CON) group and heat stress group (HS group, three replicates, each containing 20 fish, n = 60 per group) were fed diets with 0 mg/kg TPs, and the three experimental groups (HSLTP, HSMTP, and HSHTP, n = 20 × 3 replicates) were fed the diets with 100, 200, or 400 mg/kg TPs for 60 days. Further, fish in the experimental groups (HS, HSLTP, HSMTP, and HSHTP) were exposed at 38 °C for 24 h to induce acute heat stress. Survival data and serum and tissue samples were collected for the analysis. Metabolomics using UPLC-Q-TOF/MS was employed to evaluate the metabolite changes in the fish livers.

Results: Notably, dietary TPs significantly improved survival rates and antioxidant enzyme levels and reduced serum ALT, AST, cortisol, glucose, MDA, and liver HSP-70 levels in the heat-stressed fish. Metabolomic analysis revealed that TPs modulated lipid metabolism, particularly glycerophospholipid and arachidonic acid pathways, which may contribute to a higher tolerance to acute heat stress.

Conclusions: These findings suggest that TPs are a promising, eco-friendly feed additive for protecting fish from heat stress and optimizing aquaculture practices.