Ethyl Has Ester Phthalate (dehp) Impact On Larval Growth And Metabolism Of Rana Chensinensis

As a plasticizer and softener, PAEs (phthalatic esters) is widely applied to the manufacture of chemical products such as coating material and cosmetics. It can be released into the environment and contaminate biological communities. DEHP (di-2-ethylhexyl phthalate) is one of PAEs, producing development toxicity, oxidative damage, immune toxicity, gene toxicity and carcinogenicity. The process of amphibians’s reproduction and development in the water, And the amphibians is sensitive to pollutants and thus can be ideal experimental material to toxic effect. In this study, Larvae of Rana chensinensis are used as experimental material, exploring the effects of DEHP on the growth, development and sex differentiation of tadpoles. And through observation the structure of the thyroid and test activities of antioxidant enzymes, discuss DEHP interference on the endocrine of tadpoles and mechanism for oxidative stress. In this experiment, tadpoles in stage of27were respectively exposed to10-6,10-5,10-4mol·L-1DEHP lasting until stages of31,37,42,46, then get the statistics for survival rate, deformity, index of total length, weight, index of liver and intestine, and development time. Take the thyroid and tadpole’s gonad to make tissue sections, and get the statistics about gender ratio. Get the tadpoles’liver of stage37,46, and test activities of antioxidant enzymes in liver tissue. Evaluate oxidative stress in the liver of tadpole when DEHP is exposed in different periods. The results and conclusions are listed as follows:1. In the10-4mol·L-1DEHP chronic exposure, the survival rate was74%from stage27of tadpoles to complete metamorphosis, their mortality and exposure concentrations are dependent on the dose-effect relation. We also found that malformed tadpoles appeared in10-4mol·L-1DEHP group, which indicated that DEHP has chronic toxicity and it can cause malformations.2. Chronic exposure to stage31, total length, weight, liver index and intestinal index in each concentration group have no obvious differences. Continuous exposure to stage37,42,46, intestinal index and total length in10-4mol·L-1DEHP group were significantly reduced, liver index in10-4mol·L-1DEHP group was significantly higher, no significant difference in other groups, but the development time was significantly prolonged with the increase of exposure concentration. It indicates that DEHP can affect growth and development of tadpoles of R. chensinensis. It can delay the development time, speculation it be toxic to the liver development.3. According to observation on thyroid tissue, thyroid follicular colloid reduced after the exposure of10-4mol·L-1DEHP; there is even vacuolation. The deformation rate of thyroid follicular has significant increased. It indicates that DEHP has thyroid developmental toxicity. DEHP can influence gonadal differentiation, in10-5,10-4mol·L-1, female proportion of increased significantly, the result show that DEHP may interfere with the steroid hormone synthesis pathways in the body, DEHP may present estrogen effect.4. DEHP have led to the liver oxidatie stress, after exposure high concentrations DEHP, the activity of SOD and CAT in the tadpole’s liver at stage37increased, the results indicated that DEHP performance activation effect, the of SOD and CAT of liver have been inhibited at stage46Compared to control; the inhibit O2-activity and inhibit·OH radicals ability also has similar results; With that increase exposure time, antioxidant enzymes performance after the effect has been activated. The GST activity after exposure DEHP without obvious change, the result show that DEHP in metabolism may change into glucose acerbity, no change into glutathione compound. After exposure DEHP the levels of NO have increased, NOS vitality in concentration-effect change, but decrease in high concentrations of groups, it is show that DEHP activate oxidative stress, leading to the signal molecular NO inceased, which is NOS mediated and used to eliminate the production of large Numbers of reactive oxygen species. In conclusion, DEHP performance the oxidative activity and inhibit the anti-oxidization stress ability.