Effects of dietary pantothenic acid on growth, antioxidant ability and innate immune response in juvenile black carp

Abstract

An 8-week feeding study was conducted to examine how dietary pantothenic acid (PA) affects growth, antioxidant ability and innate immunity in juvenile black carp (Mylopharyngodon piceus). Juvenile fish (7.35 ± 0.06 g) were fed diets with PA at 0, 5, 10, 20, 40 and 80 mg/kg, respectively. The highest weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) were obtained with 10 mg/kg dietary PA (p < 0.05), as well as the lowest feed conversion ratio (FCR). Adequate dietary PA (10 and 20 mg/kg) markedly upregulated neuropeptide Y (NPY), orexin (ORX) and ghrelin (GRL) and downregulated cholecystokinin (CCK) in the brain of these animals (p < 0.05). Intestinal sodium-dependent multivitamin transporter (SMVT) expression and α amylase, trypsin, chymotrypsin and lipase activities were all improved after supplementation of PA at 10 or 20 mg/kg (p < 0.05). In addition, adequate dietary PA (10 and 20 mg/kg) significantly increased the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR), as well as the amounts of reduced glutathione (GSH) and total antioxidant capacity (T-AOC) in the liver of these animals (p < 0.05). Meanwhile, liver glutathione S-transferase (GST) activity and malondialdehyde (MDA) amounts levels were both markedly decreased with dietary PA at 10 or 20 mg/kg (p < 0.05). Furthermore, adequate dietary PA significantly elevated the mRNA amounts of NFE2-related nuclear factor 2 (Nrf2) and downregulated Kelch-like-ECH-associated protein 1a (Keap1a) and Keap1b (p < 0.05), and remarkably upregulated innate defense molecules, including lysozyme (LYZ), natural resistance-associated macrophage protein (NRAMP), liver-expressed antimicrobial peptide 2 (LEAP-2), hepcidin (HEPC), complement 3 (C3) and complement 9 (C9) in the liver (p < 0.05). Meanwhile, elevated dietary PA resulted in increased LYZ activity and C3 content and decreased aspartate aminotransferase (ALT) and aspartate aminotransferase (AST) activities in serum samples from juvenile black carp compared with the groups fed PA-deficient diets (p < 0.05). Moreover, 10, 20 and 40 mg/kg PA-containing diets starkly downregulated intestinal interleukin 8 (IL-8) and IL-11 at the mRNA level in comparison with the PA-deficient diet (0 mg/kg) (p < 0.05). However, PA supplementation at 10, 20 or 40 mg/kg resulted in increased intestinal zonula occludens-1 (ZO-1), ZO-2, ZO-3, claudin 3, claudin 4, claudin 8, claudin 15 and occludin mRNA levels in M. piceus in comparison with the 0 mg/kg PA group (p < 0.05). Jointly, the above findings suggested adequate dietary PA (10 and 20 mg/kg) enhances feed utilization and growth performance, as well as antioxidant capacities and non-specific immune reactions in juvenile M. piceus.