Effects Of N-acetylcysteine On Intestinal Barrier Function And Antioxidant Capactiy In Piglets Challenged With Lipopolysaccharide

The study was conducted to investigate the effects of dietary N-acetylcystine (NAC) on intestinal barrier function and antioxidant capactiy in piglets challenged with lipopolysaccharide (LPS).Eighteen healthy piglets were randomly allocated to 3 groups (control group, LPS group and NAC group), each group included 6 replicates. The control group and LPS group were fed the basal diet, and NAC group was fed the basal diet with 0.05% NAC. On d 10, 13 and 20, piglets in the LPS and NAC groups were injected intraperitoneally with LPS at 100μg/kg BW, whereas piglets in the control group were injected intraperitoneally with normal sterile saline at the same volume. On d 20, D-xylose was orally administrated at the dose of 0.1g/kg·BW 2 h after LPS challenge, and blood samples were collected 3 h after LPS challenge. All the piglets were sacrificed on d 21 to obtain intestinal mucosa for analysis. The results showed that:1. Effects of dietary NAC on intestinal mucosal growth of piglets challenged with LPS. (1) LPS challenge reduced the villus height in jejunum (P<0.01) and ileum (P<0.05), the ratio of villus height to crypt depth in duodenum and jejunum (P<0.01), the villous surface area in jejunum (P<0.01) and ileum (P<0.05). while increased the crypt depth in duodenum (P<0.01) and jejunum (P<0.05); Supplementation with NAC increased the ratio of villus height to crypt depth and villous surface area in jejunum, the villus height in ileum (P<0.05), while reduced the crypt depth in jejunum (P<0.05). (2) LPS challenge reduced DNA content in jejunum and ileum mucosa (P<0.01), and RNA/DNA in duodenum (P<0.05) and jejunum and ileum mucosa (P<0.01), while increased TP/DNA in jejunum and ileum mucosa (P<0.01); Supplementation with NAC increased DNA content in jejunum mucosa (P<0.01), RNA/DNA in jejunum and ileum mucosa (P<0.01), while reduced TP/DNA in jejunum musoca (P<0.01). (3) LPS challenge increased caspase-3 relative expression in duodenum, jejunum(P<0.01) and ileum mucosa (P<0.05), which was reduced in NAC group. In conclusion, supplementation of 0.05% NAC in the diet can effectively alleviate the growth inhibition in intestinal mucosa of piglets induced by LPS challenge, and it was associated with the apoptosis signal.2. Effects of dietary NAC on intestinal barrier function of piglets challenged with LPS. The results showed that: (1) LPS challenge reduced activities of DAO in duodenal (P<0.05) and jejunal (P<0.01) mucosa, while increased in plasma (P<0.01); Supplementation with NAC increased activity of DAO in jejunal mucosa (P<0.05), while reduced in plasma (P<0.05). (2) LPS challenge reduced plasma D-xylose content (P<0.01); Supplementation with NAC increased plasma D-xylose content (P<0.05). (3) LPS challenge reduced cystine content in duodenal(P<0.05) and jejunal (P<0.01) mucosa; Supplementation of NAC increased cystine content in duodenal mucosa (P<0.05). (4) LPS challenge reduced claudin-1 and occludin relative expression in small intestinal mucosa (P<0.05); Supplementation with NAC increased claudin-1 relative expression in small intestinal mucosa (P<0.05), increased occludin relative expression in ileal mucosa (P<0.05). In conclusion, supplementation of 0.05% NAC in the diet can effectively alleviate the intestinal barrier function damage of piglets induced by LPS challenge, it was associated with the effects of NAC on expression of tight junction protein.3. Effects of NAC on antioxidant capacity of intestinal mucosa of piglets challenged with LPS. The results showed as follows: (1) LPS challenge reduced super oxide dlsmutase (SOD) and catalase (CAT) activities (P<0.01), and increased Nitric oxide synthase (NOS) (P<0.05) and inducible nitric oxide synthase (iNOS) activities (P<0.01) in jejunal mucosa of piglets; Supplementation of NAC increased SOD and CAT activities (P<0.05), and reduced iNOS activities (P<0.01) in jejunal mucosa of piglets challenged with LPS. (2) LPS challenge increased malondialdehyde(MDA) (P<0.05), hydrogen peroxide (H2O2) (P<0.05), superoxide anion (O2-) contents (P<0.01) and glutathione oxidized/glutathione (GSSG/GSH) (P<0.01) in jejunal mucosa of piglets; Supplementation of NAC reduced MDA (P<0.05), H2O2 (P<0.05), O2- contents (P<0.01) and GSSG/GSH (P<0.01) in jejunal mucosa of piglets challenged with LPS. In conclusion, supplementation of 0.05% NAC in the diet can effectively alleviate the oxidative stress in intestinal mucosa of piglets induced by LPS challenge.