N-acetylcysteine increased the growth performance of Leuciscus waleckii by improving mitochondrial function, enhancing antioxidant and anti-inflammatory, and inhibiting apoptosis in the hepatopancreas and intestine

This experiment investigated the effects of N-Acetylcysteine (NAC) addition to diets on growth performance, mitochondrial function, antioxidant capacity, immune function and apoptosis in Leuciscus waleckii. Diets containing different levels of NAC (0.00 g/kg, 1.50 g/kg, 3.00 g/kg, 4.50 g/kg, 6.00 g/kg) were formulated. An 8-week feeding trial was conducted with these diets. The results revealed that 3 g/kg-6 g/kg NAC increased FW, WGR, SGR, PER, and FER and improved growth performance and feed utilization in Leuciscus waleckii. 4.50 g/kg-6.00 g/kg NAC increased the intestinal and hepatopancreatic digestive enzyme activities, enhancing digestive function. 3.00 g/kg-4.50 g/kg NAC increased serum ACP and AKP activities, decreased IL-1β and TNF-α levels, and optimized serum biochemical indices in Leuciscus waleckii. Appropriate level of NAC upregulated mRNA expression of PPARγ, ATGL and CPT-1, and HDL-C, CPT-1, ATGL and FAS activities to promote lipid metabolism. 3.00 g/kg-6.00 g/kg NAC promotes hepatopancreatic and intestinal anti-inflammatory and antioxidant capacities by activating Nrf2 and inhibiting the NF-κB signaling pathway. NAC supplementation also maintains mitochondrial membrane potential and increases ATP synthase activities and ATP content, thereby improving hepatopancreatic and intestinal mitochondrial function in Leuciscus waleckii. Meanwhile, 4.50 g/kg-6.00 g/kg NAC reduced the mRNA expression of hepatopancreatic and intestinal Bax, Caspase-3 and Caspase-9, and Caspase-3, Caspase-8 and Caspase-9 enzyme activities, and inhibited apoptosis. NAC supplementation upregulates the mRNA expression of Claudin-3, Claudin-f, ZO-1, and Occludin-a and reduces intestinal permeability-related markers, thereby maintaining intestinal physical barrier function. HE staining results showed that NAC maintained the morphological and structural integrity of the hepatopancreas and intestine. In conclusion, dietary supplementation with 4.50 g/kg NAC promotes the growth of Leuciscus waleckii by improving mitochondrial function, enhancing antioxidant and anti-inflammatory effects, inhibiting apoptosis, and improving hepatopancreatic and intestinal health.