| Parabens are esters of p-hydroxybenzoic acid,also known as parabens,which are widely used as preservatives in various cosmetics,food and pharmaceutical products due to their antibacterial and antifungal properties.As a large amount of preservatives,parabens are in close contact with humans and can easily enter the water environment.Since the toxicity and effect mechanism of parabens on aquatic organisms have not been studied systematically,this paper used Nile tilapia(Oreochromis niloticus)as the test organism to explore the effects of two representative substances of parabens,butylparaben and benzylparaben,on the growth and lipid metabolism of tilapia.1.At 0,5,50,500 and 5000 ng/L exposure concentrations,Nile tilapia were exposed to butylparaben for 8 weeks.The experimental results showed that exposure to different concentrations of butylparaben had no significant effect on the growth of tilapia,but with the increase in butylparaben exposure,the triglyceride content in the serum and liver of tilapia increased,and fat deposition in the liver of fish resulted in abnormal liver morphology and liver damage.At the same time,the increase in lipid peroxide content in fish caused oxidative stress in fish,the antioxidant system responded to the stress in fish,and the activity of SOD enzyme increased significantly to accelerate the elimination of free radicals to maintain the redox balance of fish.Based on the analysis of the tilapia transcriptome,it was found that the high concentration group(500,5000ng/L)of butyl paraben had effects on the digestion and absorption of fat,cholesterol metabolism,glyceride metabolism,and steroid biosynthesis in the liver of tilapia.pathways were significantly affected,and upregulation of specific genes in these pathways resulted in lipid accumulation in the liver of tilapia.2.Juvenile tilapia(0.60 ± 0.11 g)were exposed to 0,5,50,500 and 5000 ng/L benzylparaben for 8 weeks in quadruplicate for each group.Benzylparaben increased the body crude fat content but decreased brain acetylcholinesterase activity in O.niloticus.Benzylparaben caused oxidative stress,leading to hepatic morphology damage and lipid metabolism disorders in fish.Lipidomic analysis identified 13 lipid classes in fish liver.Benzylparaben exposure induced metabolic disorders of glycerol phospholipids,glycerol fats and sphingomyelins in fish liver.These findings indicate that environmentally related benzylparaben levels(5 to 50 ng/L)could induce an antioxidant response,result in triglyceride accumulation,and increase adipocyte formation and fatty acid intake in tilapia.However,high benzylparaben concentrations will inhibit lipid deposition,presumably due to the effects of the antioxidant system,and induce tissue inflammation.Therefore,this study provides new insights into the toxic effects and potential mechanism of benzylparaben in fish,especially from the aspect of lipid metabolism.In conclusion,exposure to butylparaben and benzylparaben had no significant effect on the growth of tilapia.Under actual environmental concentration exposure,butylparaben did not affect the lipid metabolism of tilapia.Parkin benzyl ester causes fat accumulation and oxidative stress in tilapia.However,at high concentrations of exposure,butylparaben can cause fat accumulation in Nile tilapia,causing oxidative stress and liver damage in tilapia.Benzylparaben stress caused negative feedback regulation to maintain lipid metabolism balance in fish,thus inhibiting lipid deposition in fish. |
