| The study was conducted to investigate the effects ofN-acetylcysteine (NAC) on intestinal structure and barrier function ofpiglets challenged with lipopolysaccharide (LPS) and the relatedmechanism.Twenty-four healthy piglets were randomly assigned to fourtreatment groups:(1) control group,(2) LPS group,(3)0.025%NACgroup,(4)0.05%NAC group. The control and LPS groups were fed thebasal diet,0.025%NAC group was fed the basal diet supplemented with0.025%NAC, and0.05%NAC group was fed the basal diet supplementedwith0.05%NAC．6replicates per treatment group with one pig perreplicate. On d17, piglets in the LPS,0.025%and0.05%NAC groupswere injected intraperitoneally with LPS (100μg/kg BW)，whereas pigletsin the control group were injected intraperitoneally with the same volumeof physiological saline. At2h after LPS challenge, D-xylose was orallyadministrated at the dose of0.1g/kg·BW, at3h after LPS challenge,blood samples were collected, and at6h after LPS challenge, all thepiglets were slaughtered to collect small intestinal tissue samples andscrape intetinal mucosa for analysis．The results showed as follows:1. The effect of NAC on hematological parameters, bloodbiochemical parameters and levels of plasma hormones of piglets afterLPS challenge.The results showed that:(1) LPS challenge reduced WBC (P<0.01),W-SCC (P<0.05), RBC (P<0.01), W-MCC (P<0.01) and W-LCC (P<0.01)in blood samples, Whereas dietary supplementation with NAC increasedRBC (P<0.05) and HGB (P<0.01) content．(2) LPS challenge reduced thelevels of ALT, GLU (P<0.01) in blood samples and increased UREA andCREA content (P<0.01), whereas dietary supplementation with NAC increased ALT content (P<0.01) and reduced UREA content (P<0.01).(3)LPS challenge reduced the levels of insulin-like growth factor-1(IGF-I)(P<0.01), epidermal growth factor (EGF)(P<0.05) and insulin (INS)(P<0.01) in blood samples, they were increased in NAC group. Inconclusion, dietary supplementation with NAC can effectively alleviatenegative effects of LPS challenge on hematological parameters, bloodbiochemical parameters, and related plasma hormones.2. Effects of NAC on intestinal mucosal growth of piglets challengedwith LPS．The results showed that:(1) LPS challenge reduced the villus heightin duodenal, jejunal and ileal mucosae (P<0.01), the ratio of villus heightto crypt depth in duodenal and jejunal mucosa (P<0.01), and the villoussurface area in duodenal (P<0.01) and ileal mucosae (P<0.05), whileincreased the crypt depth in duodenal and jejunal mucosa (P<0.05);dietary supplementation with NAC increased the villus height in duodenaland jejunal mucosa (P<0.01), the ratio of villus height to crypt depth induodenal (P<0.01), jejunal (P<0.01) and ileal (P<0.05) mucosa, and thevillous surface area in duodenal mucosa (P<0.01), while reduced thecrypt depth in jejunal mucosa (P<0.05).(2) LPS challenge reduced DNAcontent in jejunal mucosa (P<0.05), while increased RNA/DNA (P<0.01),TP/DNA (P<0.05) in jejunal mucosa; dietary supplementation with NACincreased DNA content in jejunal mucosa (P<0.05), while reducedRNA/DNA (P<0.01), TP/DNA (P<0.05) in jejunal mucosa (P<0.01).(3)LPS challenge reduced the activity of maltase in mucosa of jejunum(P<0.05), the activity of lactase in mucosae of duodenum (P<0.01) andjejunum (P<0.05); dietary supplementation with NAC increased theactivity of maltase in mucosa of jejunum (P<0.05), the activity of lactasein mucosae of duodenum (P<0.01) and jejunum (P<0.05).(4) LPSchallenge increased relative expression of caspase-3in mucosae of duodenum (P<0.01), jejunum (P<0.05) and ileum (P<0.05); dietarysupplementation with NAC reduced relative expression of caspase–3inmucosae of duodenum (P<0.01) and ileum (P<0.05). In conclusion,dietary supplementation of NAC can effectively alleviate the growthinhibition in intestinal mucosa of piglets induced by LPS challenge,which may be associated with the cell apoptosis signaling．3. Effects of NAC on intestinal barrier function of piglets challengedwith LPS．The results showed that:(1) LPS challenge reduced D-xylose contentin plasma (P<0.05), whereas NAC supplementation had no effect.(2) LPSchallenge increased activities of DAO in plasma and in mucosa of ileum(P<0.05); dietary supplementation with NAC reduced activity of DAO inmucosa of ileum (P<0.05).(3) LPS challenge reduced the relativeexpression of occludin in mucosa of jejunum (P<0.05), whereas therelative expression of occludin was increased in NAC group (P<0.05)． Inconclusion, dietary supplementation of NAC can effectively alleviate theinjury of intestinal barrier function induced by LPS challenge, which maybe associated with NAC’s effects on expression of tight junction protein．... |
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