Effects of Nonylphenol and Phytoestrogen-Enriched Diet on Plasma Vitellogenin, Steroid Hormone, Hepatic Cytochrome P450 1A, and Glutathione-S-Transferase Values in Goldfish (Carassius auratus)

摘要

Theeffectsofnonylphenol(NP)onplasmavitellogenin(VTG)andsteroidhormonevalues,aswellashepaticcytochromeP4501A(CYP1A)andglutathione-S-transferase(GST)activities,weremeasuredingoldfish(Carassiusauratus)fedadietwithalow(formulateddiet,FD)orhigh(commercialdiet,CD)contentofphytoestrogens,includinggenisteinanddaidzein.MalegoldfishwithsecondarysexualcharacteristicswereexposedtonominalNPconcentrationsof0.1,1.0,10,and100#59157;g/Linthewaterfor28dayswhilebeingfedeithertheFDorCDdietat1.0%ofbodyweightdaily.PlasmaVTGconcentrationinmalegoldfishexposedto100#59157;gofNP/LandfedFDwassignificantlyhigherthanthatintheFD-fedcontrolfishatseven,21,and28days.However,fishoftheCD-fedgroupexposedto100#59157;gofNP/LhadsignificantlyhigherplasmaVTGconcentrationthandidfishoftheCD-fedcontrolgroupat28daysonly.Moreover,plasmaVTGconcentrationinfishoftheCD-fedcontrolgroupwasabout100-foldhigherthanthatinfishoftheFD-fedcontrolgroup.Althoughtheestrogeniceffectsofaphytoestrogen-enricheddietcausedadecreaseintestosteroneand/or11-ketotestosteronevaluesintheCD-fedfish,therewasnodose-responserelationshipbetweenandrogenandamountofNPtowhichtheFD-fedfishwereexposed.NonylphenoldoesnothaveappreciableeffectsonhepaticCYP1AandGSTactivitiesinmalegoldfishatconcentrationsaslowas100#59157;g/L.TheseresultssuggestthatNPhasestrogenicactivityinmalegoldfishatthenominalconcentrationof100#59157;g/L,andthatphytoestrogens,suchasgenisteinanddaidzein,intheCDinhibitanaspect(s)ofsteroidreleaseand/orsynthesiscommontotestosteroneand11-ketotestosterone.However,resultsofinvivoscreeningassaysforendocrine-disruptingchemicalsmaybeseriouslyaffectedbyphytoestrogensinthediet,dependingoncontentorpotencyofestrogenicactivity;therefore,werecommenduseinresearchofastandardized,open-formuladietinwhichestrogenicsubstanceshavebeenreducedtoamountsthatdonotaltertheresultsofstudiesthatareinfluencedbyexogenousestrogens.