Protective Effect And Potential Mechanism Of Theacrine On Oxidative Injuries Induced By Cadmium In Mice

Cadmium is a difficult degradation of environmental pollutants,that is very bad for human beings,animals and plants.A study claims that the cadmium-induced toxicity in kidney and liver is connected with the excessive production of free radical and the accumulation of oxidative stress.Therefore,looking for safer and more effective antioxidants has become a hot research topic at the present stage for alleviating cadmium-induced oxidative damage.Among them,a natural active ingredient called theacrine（TC）isolated from Yunnan bitter tea is very outstanding in scavenging free radicals,so it is expected to become a new protective reagent of cadmium damage.The aim of this study is to investigate the protective effect of theacrine on mouse induced by cadmium and explore the possible mechanism.This experiment constructed the mouse model of oxidative damage induced by cadmium by intraperitoneal injection of CdCl₂.Theacrine extracted from Yunnan Bitter Tea treated as the protective drug,could conduct model validation by physiological and biochemical indexes and histomorphology.At the same time,this study approached the pathogenesis of oxidative damage of mouse induced by cadmium and the protective mechanism of theacrine by antioxidant in vitro and vivo,oxidation index and inflammatory factors and elemental analysis and other aspects,and it could provide data support and theoretical basis for clinical diagnosis of oxidative damage induced by cadmium and the development for the anti-cadmium drug.（1）Establishment and model validation of injury model induced by cadmium in mouseKunming mouse were randomly divided into blank control group,cadmium injury group,three protection groups formed by 3 kinds of low,medium and high concentration gradients of theacrine.The mouse of cadmium injury group injected CdCl₂ by intraperitoneal injection,and other three protection groups injected theacrine of different concentrations by intragastric administration.The model was successfully constructed by the physiological and biochemical indexes and morphological analysis.The physiological indexes showed that the food intake of the mouse in the injury group injected CdCl₂decreased obviously,and took on the dosage-dependent increase after the administration of the protective drugs.Biochemical testing results showed that the serum triglyceride,total cholesterol,high-density lipoprotein compared with the control group,cadmium damage group were lower（P<0.05,P<0.01）,low density lipoprotein,serum creatinine,aspartate aminotransferase,alanine aminotransferasecompared with the control group,damage group increased significantly（P<0.01,P<0.01,P<0.01,P<0.01）,suggesting to oxidative damage of cadmium can make the biochemical indexes of mice happens disorder,after giving theacrine protection,the damage has been improved,while detecting DNA damage analysis and morphological intuitive observation mice liver and kidney tissue pathological changes.It showed that the oxidative injury model induced by cadmium was constructed successfully.When giving protection of theacrine,the injury had been significantly improved.It indicated that theacrine had a protective effect on injury model induced by cadmium in mouse,and the dose of 30 mg/kg/day had the most significant protective effect.（2）The primary protective mechanism of theacrine on oxidative damage induced by cadmium in mouseThe vitro antioxidant assay of theacrine showed that theacrine could clean up superoxide anion,hydroxyl radical and DPPH·.At the same time,through the detection of the oxidative damage group induced by cadmium in mouse,the oxidation indexes of liver and kidney in theacrine group including protein carbonyl,malondialdehyde,the inflammatory factors including NO and antioxidant system including superoxide dismutase,glutathione,catalase,that showed that the oxidative indexes MDA and PCO of the injury group induced by cadmium were significantly higher than those in control group（P<0.05）.And the content of NO treated as inflammatory factor increased（P<0.05）.And the activity of antioxidant enzymes including SOD,GSH and CAT were significantly lower than the control group（P<0.05）.But when giving the protection of theacrine,the increase of oxidation index was inhibited and the activity of antioxidant enzyme increased.This showed that theacrine could protect against oxidative damage induced by cadmium in mouse.The metal chelating ability of theacrine was further studied.The results showed that the chelation rate with Cd²⁺was about 60%.Through the analysis of the content of Cd²⁺,Cu²⁺,Fe²⁺,Zn²⁺in the liver and kidney tissue,showed that the toxic effects of cadmium had significant changes in various elements of mouse liver,kidney tissue,and the protection of theacrine could alleviate the change trend of elements.In order to further discuss the genotoxicity of cadmium,the whole genome was extracted,and the qualitative analysis of DNA damage of liver cell was carried out by agarose gel electrophoresis.The theacrine protection group could prevent the fragmentation of DNA molecules.The results showed that the protective mechanism of theacrine on oxidative damage induced by cadmium in mouse was influenced by many aspects.On the one hand,it may inhibit the production of free radicals and inflammatory factors in vivo,on the other hand,it was due to the chelate of Cd²⁺in vivo,reducing the accumulation of Cd²⁺in the liver and kidney and the interference of the necessary metal element balance in the body.Therefore,this study provided a scientific basis for further understanding the protective effect and possible mechanism of theacrine on oxidative damage induced by cadmium in mouse.