| Tea is one of the three largest non-alcoholic beverages in the world,and its sales are second only to water.The antiinflammatory effect of tea has been recorded in ancient pharmacopoeia.Inflammation is closely related to human health,and many pathological conditions are accompanied by inflammation.With the deepening of research,the main anti-inflammatory substances and anti-inflammatory mechanism of tea have been gradually reported.In order to explore the new anti-inflammatory mechanism of tea and its anti-inflammatory substances,the anti-inflammatory effect and mechanism of green tea,tea polyphenols and theanine were studied based on the mouse liver inflammation model induced by alcohol,perfluorodecanoic acid and lipopolysaccharide.This study was based on the continuous intragastric administration of 50%alcohol once a day for seven days while drinking tea soup freely.The drinking water was supplemented with green tea polyphenols,EGCG and PFDA for 12 days,and lipopolysaccharide was injected once after intraperitoneal injection of theanine for seven days.The results showed that green tea could significantly reduce liver injury,oxidative stress,lipid accumulation and inflammation in alcoholic hepatitis compared with drinking water alone.Drinking green tea also significantly reduced the expression of hepatic nuclear factor-kappa B(NF-kappa B)and the expression of downstream inflammatory mediators inducible nitric oxide synthase(iNOS)and cyclooxygenase-2(COX-2)in ethanol-treated mice.Drinking green tea also significantly activated phospholipid inositol 3 kinase(PI3K)and phosphoprotein kinase B(Akt)in liver,which were related to the up-regulation of phosphorylated endothelial nitric oxide synthase(p-eNOS)expression and the increase of plasma nitric oxide level in ethanol-treated mice.The protective effect of NG-nitro-L-arginine methyl ester,an eNOS inhibitor,on green tea soup was also significantly inhibited.Furthermore,GTPs and EGCG can protect perfluorodecanoic acid-induced hepatotoxicity,GTPs and EGCG can reduce the mortality of mice poisoned by lethal dose of PFDA;GTPs can prolong survival time and inhibit weight loss of mice poisoned by low dose of PFDA;GTPs and EGCG can improve liver toxicity,oxidative damage and histological changes induced by medium dose of PFDA;GTPs and EGCG can also reduce the mortality of mice poisoned by medium dose of PFDA.Liver inflammation and NLRP3 inflammation body activation were observed.In addition,theanine can also protect acute liver inflammation induced by lipopolysaccharide.Compared with lipopolysaccharide treatment group,plasma alanine aminotransferase(ALT),aspartate aminotransferase(AST),total superoxide dismutase(T-SOD),malondialdehyde(MDA)levels and histological scores of theanine treatment group were significantly lower.Theanine treatment before model establishment could significantly reduce the release of interleukin-1 beta(IL-lbeta)and tumor necrosis factor-alpha(TNF-alpha),inhibit the expression of many inflammatory factors including IL-1 beta,TNF-alpha and IL-6,and increase the ratio of IL-10/IFN-gamma in liver tissue.At the same time,theanine inhibited the expression of inflammatory mediators such as iNOS and matrix metalloproteinase-3(MMP-3)in the NF-kappa B pathway,and reduced the phosphorylation of NF-kappa B in liver tissue.We also found that theanine inhibits acute phase response by increasing levels of nitric oxide and C-reactive protein,and down-regulates inflammation induced by lipopolysaccharide by inhibiting the excitation of hypothalamic-pituitary-adrenal(HPA)axis.In conclusion,this study suggests that the protective effect of green tea on alcoholic liver injury and inflammation is related to the upregulation of PI3K/Akt/eNOS pathway.GTPs and EGCG have protective effects on hepatotoxicity induced by PFDA.Theanine can ameliorate LPS-induced inflammation and acute liver injury;the molecular mechanisms involved in the down-regulation of HPA axis activity and NF-kappa B signaling pathway. |
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