Effects of 17βestradiol on immunocompetence,oxidative stress and antioxidant defences in different size groups of Japanese sea.pdf

1、In recent years, the importance of the endocrine disrupting chemicals (EDCs) andits effects on fish has been well documented.A wide range of environmental contaminantscan interfere with hormonal regulation in both verteb

2、rates and invertebrates.These EDCsare of high relevance for human and wildlife health.There is growing evidence thatcontaminants may be partly responsible for the observed increase in disease in marineorganisms by advers

3、ely affecting their immunity.Fishes are common sentinels used invertebrate immunotoxicology, however, to date, studies have been undertaken only on asingle size group of fish and for acute exposure and little is known ab

4、out whetherestrogenic compounds 17 β estradiol (E2) cause oxidative stress in hepatic tissue of fish.
　　In this study, Lateolabraxjaponicus fingerlings and juveniles were exposed to twosublethal concentrations (200 ng

5、 L-1 and 2000 ng L-1) of 17β estradiol for 30 days underlaboratory conditions, and alterations in immune parameters comprising differentialleukocyte count, respiratory burst, myeloperoxidase, immunoglobulin levels, serum

6、iysozyme and bactericidal activity were investigated to establish whether estrogenproduced immunomodulation, and to understand the effects of long-term exposure on theseimmune parameters in fish fingerlings and juveniles

7、.The results revealed a significantelevation of respiratory burst activity, myeloperoxidase, immunoglobulin levels anddifferential leukocyte counts of the fish exposed to estrogen when compared to the control.The rest of

8、 the parameters were significantly reduced in the experimental groups whencompared to the control.The results indicated that sub-lethal E2 exposure inducedimmunomodulation in both fingerlings and juveniles of L.japonicus

9、 and the changescaused by estrogen might affect the function of immune system in fish.
　　The study also reported that E2 modulated the serotonin, 5-hydroxytryptamine (5-HT), stress hormone (cortisol) and the biotransf

10、ormation enzyme (7-ethoxyresorufin O-deethylase [EROD] activity).The modulation in 5-HT level in brain and spleen, plasmacortisol level, gill and hepatic EROD activity were investigated in fingerlings and juvenilesof L.j

11、aponicus.Results showed that E2 modulated both the monoaminergic system andthe biotransformation enzymes studied and, interestingly, there appeared to be some levelof recovery from the toxic effects of E2 after 30 d of e

12、xposure.
　　In addition this work also tested the hypothesis that E2 may cause oxidative stressin liver of L.japonicus, and then leading fluctuation of the parameters associated withantioxidant defense.To test this hyp

13、othesis, effects on ROS production, DNA damage infish have been investigated in the study.L.japonicus fingerlings and juveniles wereexposed to two sublethal concentrations of E2 for 30 d which established evidence forlas

14、ting oxidative stress caused by E2 exposure as SOD, CAT and GPx activities weresignificantly altered with symptomatic pro-oxidant associations among them.Correlationbetween elevated ROS, DNA damage and LPO in hepatic tis

15、sue of E2 exposed fish hasbeen elucidated.These results suggest that the enhancement LPO and DNA damageassociated with E2 may be due to a modulation of the redox environment that promotesROS-mediated damage.The antioxida

16、nt enzyme may play an important role in E2metabolism and consequently reduce ROS production.The present study provides strongevidence that level of ROS increased significantly in E2 exposed fish, and ROS may serveas a po