Protective Effects Of Fish Oil On Intestinal Injury Of Piglets After Lipopolysaccharide Challenge

This experiment was conducted to study the protective effects of fish oil on intestinal mucosa injury of piglets after lipopolysaccharide (LPS) challenge. Thirty-two crossbred (Duroc′Large White′Landrace) piglets (11.57±0.74 kg BW) weaned at 28±3 d of age were used in a 2×2 factorial design. The main factors consisted of diet (5% corn oil or 5% fish oil) and immunological challenge (LPS or saline). On d 19, pigs were injected intraperitoneally with either 150μg/kg BW of LPS or an equivalent amount of sterile saline. At 4 h following LPS challenge, the pigs were slaughtered to collect intestinal mucosa for analysis. The results showed that: 1) LPS reduced the villus height (P<0.01), the ratio of villus height to crypt depth (P<0.05) in duodenum, and decreased the villus height (P<0.05) and crypt depth (P<0.05) in jejunum and ileum. Fish oil supplementation improved the ratio of villus height to crypt depth in duodenum (P<0.05), and increased the villus height (P=0.001), crypt depth (P=0.01) and ratio of villus height to crypt depth (P<0.05) in ileum. 2) LPS reduced the activity of maltase in duodenum, and inhibited the activity of maltase, lacrase and suctase in jejunum (P<0.05). Pigs fed fish oil had improved maltase activity in duodenum, lacrase activity in ileum and suctase activity jejunum (P<0.05). 3) LPS challenge increased claudin-1 expression in ileum (P<0.10). Fish oil suppressed claudin-1 expression in ileum (P<0.10). 4) LPS challenge reduced crypt cell proliferation in jejunum. Among sterile saline treated pigs, pigs fed with fish oil had lower crypt cell proliferation than those fed corn oil (P<0.05) in ileum. 5) LPS challenge increased tumor necrosis factor-α(TNF-α) and prostaglandin E2 (PGE2) concentration in duodenum, jejunum and ileum (P<0.05), and increased HSP70 expression (P<0.05); Fish oil alleviated the elevation PGE2 and TNF-α(P<0.01) induced by LPS challenge, and decreased PGE2 production in jejunum (P<0.10), and inhibited the expression of heat shock protein-70 (HSP70) in jejunum and ileum (P<0.05). 6) LPS challenge inhibited the total nitric oxide synthase (tNOS) activity in duodenum and ileum (P<0.05), the cNOS activity in ileum, reduced the constitutive nitric oxide synthase (cNOS) activity in duodenum and inducible nitric oxide synthase (iNOS) activity in duodenum and ileum (P<0.05). Fish oil mitigated the inhibition of the tNOS, iNOS and cNOS activity in ileum (P<0.05), improved the iNOS activity in jejunum (P<0.05) and the tNOS and iNOS activity in duodenum (P<0.05).7) LPS challenge increased nuclear transcription factor-kappa B (NF-κB) expression in jejunum and ileum (P<0.05). Fish oil suppressed NF-κB expression in ileum (P<0.05).These results suggest that fish oil can alleviate intestine damage induced by LPS challenge. Additionally, the protective effects of fish oil on the intestine are associated with decreasing the production of intestinal pro-inflammatory parameters through inhibiting NF-κB expression.