Detection of Xenoestrogens in Serum after Immunoprecipitation of Endogenous Steroidal Estrogens.

STEROID hormones; ESTROGEN; CYTOCHEMICAL bioassay; NONYLPHENOL

In this article we report a simple and efficient method for detecting nonsteroidal estrogens in a biologic sample. This method uses polyclonal antibodies to estradiol (E[SUB2]) to immunoprecipitate these major biologically active steroidal estrogens, leaving behind the nonsteroidal estrogens, which are then detected in a cell-based transcriptional activation bioassay for estrogen receptor agonist. The immunoprecipitation method effeciently removed 99% of radiolabeled E[SUB2] and estrone (E[SUB1]) from human serum. In experiments in which supraphysiologic concentrations of E[SUB2] and E[SUB1] to human serum, all of the immunoreactive estrogens were still removed by the immuno- carried out an in vivo validation precipitation protocol. We study of this his method in which we treated female macaques with the xenoestrogen nonylphenot (NP), during the late follicular phase of the menstrualtrual cycle. We used blood samples collected before and after treatment to evaluate and characterize endogenous and exogenous serum estrogens. An immunoassay for E[SUB2] did not detect the NP in treated monkeys. The cell-based bioassay also did not detect the estrogenic activity of NP because of its saturation by the endogenous serum steroidal estrogens. However, when the estrogenic activity of steroidal estrogens were removed by immunoprecipitation, we detected NP in the bioassay. Thus, this approach ils appropriate for detecting exogenous, nonsteroidat estrogens in serum samples. [ABSTRACT FROM AUTHOR]

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