Title: E-Screen - potential tool for assessment of relative serum estrogenicity Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 17, 2013
Publication Date: N/A
Technical Abstract: The E-Screen bioassay, used to measure estrogenic activity of environmental water samples, feedstuffs, and pure chemicals, was evaluated for its usefulness in estrogenicity assessment of porcine, ovine, bovine, and piscine serum. High concentrations of swine, cattle, and fish serum were toxic to the E-screen (human) cell line, which is routinely maintained in fetal bovine serum. In contrast, high concentrations of sheep serum altered cell morphology, a change that was not seen at lower serum concentrations. Ovarectomized sheep on basal diets had serum estradiol (E2) of 1.8 +/- 0.79 pg/mL (SD, ELISA) and 18 +/- 10.7 pg/mL E2Eq (SD, E-Screen); after flax seed oil supplementation, E2 rose to 85 +/- 21.6 and E2Eq 391 +/- 46.4, respectively. Acetonitrile extraction of porcine serum (ACN:serum 2:1 v/v) removed the toxicity to E-screen cells. Extracted serum E2Eq from peripubertal gilts increased at the onset of estrus in most animals with a maximum E2Eq of 20 pg/mL. Validation experiments were conducted by comparing E2Eq from serum fortified with E2 prior to extraction and E2Eq from unextracted serum, with or without E2 fortification. At high unextracted serum concentrations, E2 addition produced a synergistic proliferative response in cells, while the expected additive proliferation was found with extracted serum. Sex differences in serum E2Eq were clear in two different species of catfish. Mean E2Eqs (pg/mL) from male fish were 333 +/- 281 (SD) in African catfish (Clarias gariepinus) and 244 +/- 49 in channel catfish (Ictalurus punctatus), whereas mean E2Eqs from female fish were 1560 +/- 1054 and 1157 +/- 71 for the two species, respectively. Collectively, these results suggest that the E-Screen assay is useful for evaluating serum samples for total estrogenicity. When assessing in vivo effects of possible endocrine disruptor exposure, ELISAs provide specific concentrations for steroid hormones, such as estradiol, while the E-Screen assay evaluates the net effects of estrogen agonists and antagonists in serum.