Dietary curcumin supplementation enhances intestinal immunity and gill protection in juvenile greater amberjack (Seriola dumerili)

Abstract

A 8-week feeding trial was conducted to determine the effects of dietary supplementation with curcumin on growth, intestinal health, and gills resistance to ammonia stress in juvenile Seriola dumerili. Three isonitrogenous and isolipidic test diets were prepared by supplementing incremental levels of dietary curcumin at 0% (CUR0%, control), 0.01% (CUR0.01%), 0.02% (CUR0.02%), respectively. Fish were fed with experimental diet. Recovery and protection capacity after ammonia challenge assay was adopted to test the effect of curcumin. At the end of the feeding trial, the results showed that dietary supplementation with proper curcumin level had a significant positive effect on fish survival and intestinal histology structure. Meanwhile, dietary supplementation with proper curcumin level can improve intestinal health by increasing immune enzyme activity, up-regulating the expression of anti-inflammatory cytokines, down-regulating the expression of pro-inflammatory cytokines and regulating other immune-related genes. Subsequently, after the ammonia challenge and recovery experiment, the results of antioxidant-related genes and antioxidant enzymes showed that dietary supplementation with proper curcumin level can improve the gill protective and recovery capacity from ammonia stress through increasing antioxidant capacity. These results suggest that dietary supplementation with proper curcumin can promote the growth, intestinal health, gill resistance and recovery to ammonia stress of S. dumerili.

Keywords: Ammonia stress; Growth performance; Intestinal histology; Intestinal immune responses; Protective effect; Recovery capacity.

Figure 1

A schematic representation of the rearing system and measured parameters in S. dumerili feeding different diet.

Figure 2

Intestinal segments obtained from fish fed with different diet groups (letters a, b, and c represent the CUR0% diet group, CUR0.01% diet group, and CUR0.02% diet group, respectively). The hF means fold height, hE means enterocyte height and Mt means muscular thickness. Measuring stick = 100μm.

Figure 3

Effects of different content of curcumin supplementation on relative gene expression of C4, C3, Hepc, IFN-γ, IgT, IL-10, IL-8, IL-1β, NF-κB1, MX, TGF-β and TNF-α in the intestine of S. dumerili (n = 3). Column bars, within the same gene, sharing a common letter (a,b,c) are not significantly different (ANOVA, P＞0.05).

Figure 4

The activity of antioxidant-related enzymes (letter a and b represent GSH-Px and SOD, respectively) in gill tissue of S. dumerili subjected to ammonia challenge experiment and recovery experiment (n = 3). Different letters above bars indicate significant differences (ANOVA, P＞0.05).

Figure 5

The relative expression of antioxidant-related genes (letters a, b, c, d and e represent Keap1, HSP70, Cyt C, Cu-SOD and GSH-Px, respectively) in gill tissue of S. dumerili subjected to ammonia challenge experiment and recovery experiment (n = 3). Different letters above bars indicate significant differences (ANOVA, P＞0.05).