Experimental Evaluation of Vitellogenin as a Predictive Biomarker for Reproductive Disruption

• Published in: Environmental health perspectives Vol. 109; no. 7; pp. 681 - 690
• Main Authors: Cheek, Ann Oliver, Brouwer, Thea Hoexum, Carroll, Suzanne, Manning, Steve, McLachlan, John A., Brouwer, Marius
• Format: Journal Article
• Language: English
• Published: United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01.07.2001; National Institute of Environmental Health Sciences
• Subjects: Animals; Biomarkers - analysis; Chemical hazards; DDT - adverse effects; Dosage; Dose-Response Relationship, Drug; Embryo, Nonmammalian - drug effects; Embryonic Development; Environmental health; Estrogens; Estrogens, Non-Steroidal - adverse effects; Female; Female animals; Fertility - drug effects; Gonads; Hatching; imposex; Male; Male animals; Mating behavior; Oryzias latipes; Sex Ratio; Sexual Maturation - drug effects; Vitellogenesis - drug effects; vitellogenin; Vitellogenins - analysis; Vitellogenins - biosynthesis; xenoestrogens
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.01109681

Vitellogenin (VTG) synthesis in male oviparous vertebrates is used as an indicator of environmental estrogen exposure, but the relationship between elevated VTG levels and the effects of environmental estrogens on reproductive success are poorly understood. To examine whether altered VTG expression predicts reproductive impairment, we exposed medaka (Oryzias latipes) for 2 or 8 weeks posthatch to 0, 0.5, 1.0, 2.5, and 7.5 ppb of the environmental estrogen o,p'-DDT. Fish were sampled 2, 4, and 8 weeks after hatch to examine VTG expression and gonad development. After exposure, fish were transferred to clean water, grown to sexual maturity, and placed in mating pairs. We collected eggs for 7 days and scored them for fecundity (number of eggs), fertility (percent fertilized), and hatching success (percent hatched). DDT had no effect on VTG expression after a 2-week exposure, whereas all doses induced VTG after 8 weeks. At both exposure durations, the highest doses of DDT caused a female-skewed sex ratio in adults. Gonadal feminization appeared to be progressive: some ovotestes were observed after 2- or 4-week exposure to the two highest doses, but the proportion of ovaries increased after 8 weeks. Both 2- and 8-week exposures significantly reduced fertility and hatching success at all doses, with lower doses having a greater effect after longer exposure. Fertility and hatching success were more sensitive to estrogenic disruption than were gonad differentiation and vitellogenin expression. We suggest that VTG expression may be interpreted as a warning of reproductive consequences, but absence of expression cannot be interpreted as absence of consequences.