Toxicity Of Benzoic Acid On The Liver And Intestinal Of Zebrafish And Study Of Mechanisms

Benzoic acid（C₇H₆O₂）is an aromatic acid organic compound,but also the simplest aromatic acid,which will not only occur naturally in plants,but also be widely used in all walks of life through industrial synthesis.Benzoic acid in industrial production is mainly discharged into soil and water,and benzoic acid,which acts as a preservative or flavoring agent,appears in various foods and cosmetics,and even infant milk powder,the content of benzoic acid can be as high as 100 mg/L.Therefore,it is widely distributed in the environment,and all ages may be exposed to benzoic acid for a short or long time.Although benzoic acid is currently recognized as a safe substance,there are still many reports of its toxicity.Benzoic acid is mainly metabolized in the liver,this process may lead to pathological changes in the liver,and the liver and intestine originate from the same germ layer,there are many anatomical and functional connections between the two,and liver toxicity may also cause intestinal toxicity,resulting in enterohepatic axis disorders.Therefore,in this study,larvae and adult zebrafish were used as model animals,simulating daily intake and environmental exposure concentration,exploring the toxic effects of benzoic acid on the liver and intestine of larvae from the toxicological phenotypic observation and gene level,and exploring the toxicity and mechanism of benzoic acid on the liver and intestine of adult zebrafish from the pathological section,liver function enzyme activity and gene level.The specific results of the study are as follows:（1）The acute toxicity of benzoic acid exposure to zebrafish juveniles on the liver and intestines was evaluated.Experimental results showed that exposure to benzoic acid resulted in a semi-lethal concentration LC₅₀ of 119.2 mg/L in 144 hpf zebrafish juveniles,and further observations showed that 90 and 100 mg/L（both non-lethal doses）of benzoic acid could lead to toxic characterization of pericardial edema,swim bladder disappearance and yolk sac edema in zebrafish during development.In addition,benzoic acid can also cause genetically modified zebrafish Tg（fabp10a:ds Red;ela3l:EGFP）juvenile liver damage and AB wild-type zebrafish intestinal inflammation,causing neutrophils to migrate to the liver and intestinal sites and accumulate in large quantities.Exploring the molecular mechanism,it was found that benzoic acid exposure would lead to upregulation of tnf-α、il-1β、il-10 inflammatory gene expression in zebrafish juveniles,induce the occurrence of inflammation,and upregulate the ratio of apoptotic gene bax/bcl-2,causing apoptosis of hepatocytes.（2）Assessment of the subacute toxic effects of benzoic acid exposure on the liver and intestine of adult zebrafish.Simulating the environmental concentration dose,adult zebrafish exposed to benzoic acid at settings of 6.25 and 12.5 mg/L were observed to have damage to both liver and intestinal tissues through pathological sections,and there was a significant increase in liver damage enzyme activity and abnormal liver function.The intestinal epithelial cells were damaged,resulting in the inability of the intestinal mucosal barrier to perform its normal physiological functions.The liver inflammation and apoptosis-related genes were examined,and nf-κb p100、tnf-α、il-1β、il-10、caspase-3 and caspase-3 were found to be significantly up-regulated compared with the control group,and the intestinal inflammation-related genes were examined,and tnf-α、il-1β、il-10expressions were found to be significantly up-regulated.Benzoic acid may regulate the transcriptional expression of nf-κb p100、tnf-α、il-1β、il-10、caspase-3 and other targets and signaling pathways by mediating inflammation,and it is tentatively predicted that benzoic acid may affect pathophysiological processes such as inflammatory response,intestinal tight junctions and glycolipid metabolism.