Largemouth bronze gudgeon (Coreius guichienoti) responds positively to liver damage induced by high feeding rates via enhancing self-repair capability

Abstract

Overfeeding intermittently induces metabolic liver diseases in aquaculture practice. Currently, less information regarding the impact of feeding rates on hepatic lipid metabolism was reported. Therefore, this study investigated the effects of feeding rates (2 %, 3 %, 4 %, and 5 % of body weight per day) on growth performance, hepatic lipid metabolism, immunity, inflammation, and apoptosis in juvenile largemouth bronze gudgeon (Coreius guichenoti) over 8 weeks. The results demonstrated that increasing feeding rates significantly enhanced weight gain rate and specific growth rate. Furthermore, the lipid content of the whole body increased progressively, with the highest levels observed in the 5 % group. High feeding rates also resulted in significant increases in hepatic TG, TC, and NEFA levels. This was accompanied by upregulated mRNA levels and enzyme activities of lipid synthesis-related genes (ACC1α and FASN). However, no significant differences were observed in mRNA levels and enzyme activities of lipolysis-related genes (HSL and CPT1). Histological observations identified two distinct hepatic phenotypes: no obvious abnormality liver and fatty liver. Overall, the proportion of fatty liver phenotype increased with the increasing feeding rate. Additionally, feeding rates significantly increased IgG, IgM, and lysozyme levels, and upregulated mRNA levels of inflammatory cytokines (TNFα and IL1β), apoptosis-related genes (CASP3, CASP8, and CASP9), and hepatic repair factors (YAP1, FGF10, FGF13, FGF18, FGF19, and PCNA). Nevertheless, hepatic function indices, including ALT, AST, and AKP levels, remained unchanged. In conclusion, these findings indicated that a feeding rate exceeding 3 % led to hepatic lipid metabolism disorders, characterized by the accumulation of TG and TC, thus promoting the development of fatty liver, inflammation response, and cellular apoptosis in largemouth bronze gudgeon. Moreover, the largemouth bronze gudgeon may exhibit self-repair capability to mitigate liver damage induced by lipid metabolism disorders. Consequently, we infer that largemouth bronze gudgeon possesses a robust capability for lipid accumulation and utilization.