Effects of berberine combined with Pennisetum sinese Roxb meal on growth, hepatic lipid metabolism, and intestinal health of grass carp, Ctenopharyngodon idella

Intestinal inflammation and hepatic fat accumulation syndrome is a major issue in farmed fish. In this study, grass carp (20.3 ± 0.1 g) were fed for 8 weeks with six feeds containing different Pennisetum sinese Roxb meal (PSRM) levels (0, 5, 10 %) and 0 or 0.1 % berberine (BBR). Growth remained unaffected by BBR and PSRM. PSRM reduced the CF, HI, and VSI, whereas BBR had no such effect or interaction. PSRM (not BBR) suppressed the activities of serum AST and ALT, as well as the contents of LDL - c, T - CHO, and TG ( P < 0.05). However, BBR only interacted with the effects of PSRM on the AST and ALT activities ( P < 0.01). BBR and PSRM decreased hepatic lipid droplet deposition and TG/T - CHO contents ( P < 0.01), without interaction. Transcriptionally, both BBR and PSRM suppressed the lipogenic genes PPARγ, ACC, and SCD ( P < 0.01) and upregulated the lipolytic genes PPARα, ATGL, and APOE ( P < 0.01), mostly without interaction. Intestinal immunohistochemistry revealed TNF - α below intestinal villi and IL - 6 on the upper side of villi and in lamina propria, both reduced in fish fed PSRM - and BBR - supplemented diets ( P < 0.05). BBR and PSRM suppressed pro - inflammatory (TNF - α, IL - 6, IL - 8) and ER stress genes (GPR78, ATF6, IRE - 1α, PERK), and promoted anti - inflammatory (TGF - β1, IL - 4/13 A), with interaction on TNF - α, IL - 8, GRP78, PERK, TGF - β1 ( P < 0.05). BBR and PSRM triggered the FXR signaling pathway in liver and intestine, with BBR interacting with PSRM on most genes. Overall, BBR didn't disrupt PSRM-induced benefits on body morphology, had no superimposed effect on intestinal health but a synergistic effect on fat reduction. • The combined effects of Pennisetum sinese Roxb meal (PSRM) and berberine (BBR) on grass carp were evaluated. • Growth was not affected by BBR and PSRM, but PSRM was beneficial to body indices while BBR did not interfere. • BBR and PSRM have a synergistic effect on serum and hepatic fat reduction. • Both BBR and PSRM are beneficial to intestinal health, but there is no superimposed effect. • Both BBR and PSRM activated the FXR signaling pathways in the intestine and liver.