Effect Of L-Theanine On Heat Stress Hepatic Inflammation And Chemical Colitis In Mice

Theanine is a unique bioactive ingredient in the leaves of Camellia sinensis.It is widely used as a food functional component and dietary supplement,and has an effective anti-inflammatory effect.However,the potential of theanine in the treatment of heat stress hepatic inflammation and colitis has not been reported.In order to research the anti-inflammatory mechanism of L-theanine,this study was based on a mouse model of heat stress hepatitis inflammation and chemical colitis(DSS-induced colitis)study the anti-inflammatory effect of L-theanine and related mechanisms.The first part experimental process of this study was that the mice in the two intervention groups were given theanine at a dose of 100 mg/kg and 200 mg/kg body weight each day before the systemic heat stress.And the mice in the control group and the heat stressed hepatitis inflammation group were given with the same amount of normal saline.After 7 days of continuous gavage,the mice were subjected to systemic heat stress treatment(relative humidity 60%,temperature 42 ?,kept in the heating room for 2 hours),and then the blood was collected from the mice.The animals were sacrificed and liver tissues of each group were collected.The activities of ALT?AST?T-SOD?CAT and the contents of MDA?GSH?IL-1??IL-6?NO?C-reactive protein?Glucocorticoid(CORT)and ACTH were detected with the corresponding kits.Observe the pathological changes of liver tissue slices of mice by H&E staining method to evaluate the liver damage.The m RNA levels of inflammatory cytokines(IL-1?,IL-6,TNF-?,heat shock protein,inducible nitric oxide synthetase(i NOS),cyclooxygenase-2,reduced coenzyme-1(NQO1),heme oxygenase-1(HO1)in liver were detected by real-time quantitative PCR.The results showed that:(1)L-theanine supplementation effectively alleviated the liver histopathological damage caused by heat stress,decreased the increase of plasma ALT and AST activity and significantly reversed the liver oxidative stress.To protect Liver injury caused by heat stress,L-theanine through reducing the activity of MDA in liver,increased the activity of T-SOD ? CAT and GSH.(2)In the heat shock response,theanine effectively inhibited the m RNA high expression of HSP70?HSP90?HSP90? induced by heat stress.(3)In the systemic inflammatory response,theanine supplementation significantly reduced the levels of IL-1? and IL-6,decreased the m RNA levels of IL-1? ? IL-6 ? TNF-? ? i NOS and COX-2,ameliorated systemic inflammation.(4)According to the adaptive response and acute-phase response,theaninesignificantly reduced the expression of NQO1 and HO1 m RNA in the liver and inhibited the excessive increase of CRP and NO in the plasma.(5)Theanine inhibited the increase of plasma CORT and ACTH levels induced by heat stress,so that correcting the hyperactivity of HPA axis.On the other hand,in the second part of the study,we researched theanine versus dextran sulfate sodium(DSS)induced colitis mice,C57BL/6J male mice were given 2% DSS in drinking water for 30 days to induce colitis;in another group,theanine(0.1%,w/v)was added to drinking water on the basis of DSS.After the experiment,blood was taken and the colon tissue of the mice was taken out after being sacrificed.Measure the colon length,evaluate disease activity index(DAI)and observe pathological sections of colon in mice;the concentrations of ALT?AST?Cr?BUN?IL-1??IL-6?TNF-??MPO?GSH?T-SOD?MDA ? LPS and DAO were detected by the corresponding kits in blood or tissue;evaluation of colitis level and intestinal mucosal barrier function by real-time quantitative PCR.Finally,16 S sequencing technology was used to analyze the contents and changes of intestinal microorganisms in each group.The results showed that:(1)Theanine supplementation significantly reduced the DAI and restored colonic length,while reducing DSS induced colonic inflammatory cell infiltration and inflammatory cytokine levels(decreased i NOS?COX-2 and TLR-2/-4/-6-9 m RNA expression levels)compared to mice in the chemical colitis.(2)Theanine significantly reduced the over elevation of ALT?MPO and MDA in the plasma of colitis mice,increased the activity of GSH and reversed the oxidative stress caused by DSS.(3)Theanine supplementation significantly increased the expression of ZO-1 and tight protein-1 m RNA in the colon of mice,indicating that theanine could improve the colonic permeability of mice with chemical colitis.(4)16S r RNA sequencing showed that the composition of microbial community induced by DSS has changed,but no significant difference was observed after theanine supplementation.In summary,the first part of this study shows that theanine can protect mice from heat stress hepatitis,and its mechanism involve inhibition of acute phase response,inhibition of inflammatory response and normalization of hyperactive HPA axis.The second part of this study,theanine has been found have a protective effect on chemical colitis(DSS-induced colitis),the mechanism involves theanine inhibiting the increase of serum lipopolysaccharide(LPS)content induced by DSS and i NOS?(COX)-2,toll like receptor(TLR)-2/4/6 expression and prevent the destruction of intestinal barrier.Therefore,these results show that theanine has a certain broad-spectrumanti-inflammatory effect,and it has a certain beneficial effect on heat stressed liver inflammation and inflammatory bowel disease(IBD).Further study is needed at the clinical level.Theanine is a food nutrient with application value and prospect.