hypothalamic dopaminergic (DA) neurons used have established roles
in neuroendocrine regulation, express estrogen receptors and are
sensitive to perinatal manipulations of the hormonal environment
as they mature in live animals and in cell culture.
and Gillies measured the uptake of dopamine in cells treated with
different concentrations of the two compounds. They found effects
by both compounds, with significant effects of 17ß-estradiol
at less than one part per trillion and the octylphenol effect visible
10 parts per trillion. These are astoundingly low levels.
also observed that over the range of concentrations used in the
experiments (which varied by 8 and 7 orders of magnitude for 17ß-estradiol
and octylphenol, respectively), the dose response relationship strongly
followed a non-monotonic form. High levels of exposure eliminated
the response whereas intermediate levels revealed it.
Compare the height of the green bars (controls) to different
levels of estradiol and octylphenol treatment. Cells in culture
were sampled at successively later days in the experiment
(DIV 4 through DIV 13).
Christian and Gillies
is the first report of a functional, neurochemical response to an
environmental estrogen. ... The data thus support the hypothesis
that inappropriate exposure to environmental estrogens at critical
stages of development could potentially perturb the organizational
activities of endogenous estrogen on selected neuronal populations
in the CNS"