AS and I Chahoud. 1998. Antiestrogenic Effects of Low Doses of
2,3,7,8-TCDD in Offspring of Female Rats Exposed Throughout Pregnancy
and Lactation Bulletin of Environmental Contamination and Toxicology
study reports several significant antiestrogenic effects of low
dose in utero and lactational TCDD exposure on female rat
offspring. Sexual maturity was delayed significantly in exposed
females and uterine weight was significantly reduced. The number
of days spent in estrous was decreased in the experimental group
exposed to the lowest and intermediate doses, while the group with
highest exposure had no significant change. The dose response curve
in estrous length is an inverted u-shaped curve, or non-monotonic
dose response curve, reported in many low dose studies.
and Chahoud also present evidence that most exposure from dam to
offspring occurs during lactation. They did this by comparing the
weights of fetal vs. weanling livers. TCDD levels in the liver at
birth were under the limit of detection (0.08ng/g). In contrast,
liver concentrations were significantly elevated at the age of weaning.
CM, JL Bowers, PC Kulakosky, KK Kumboj and HI Swanson. 1999. The
Aryl Hydrocarbon Receptor (AHR/AHR nuclear translocator (ARNT) Heterodimer
Interacts with Naturally Occurring Estrogen Response Element Molecular
and Cellular Endocrinology 157(1-2): 105-19
(dioxin) binds to the Ah receptor and not to the estrogen receptor
(ER). TCDD nonetheless can cause significant antiestrogenic effects.
This study investigates the molecular mechanism that allows this
"cross-talk." Klinge et al. report that TCDD does
not compete with estrogen at the ER, but the Ah receptor in part
inhibits estrogen receptor binding to estrogen response elements,
thereby inhibiting estrogen action.
JM, TR Rankouhi, KM Nichols, H Kamen, NE Kaminski, JP Giesy and M
van der Berg. 1999. In vitro Vitellogenin Production by
carp (Cyprinus carpio) hepatocytes as a Screening Method for
Determining (anti) Estrogenic Activities by Xenobiotics Toxicology
and Applied Pharmacology. May 15: 157(1): 68-76
is the yolk protein precurser produced in the liver of fish. The
presence of estradiol stimulates the production of vitellogenin
in both male and female fish, and antiestrogens inhibit production.
Smeets et al. used hepatocytes taken from carp livers to
develop a screening method for testing antiestrogenicity. They exposed
cells to tamoxifen and report reduction in vitellogenin production.
Similiarly, they tested TCDD and found it to be 10,000 times
more potent than tamoxifen in reducing vitellogenin production.
also tested bisphenol A for estrogenicity. Vitellogenin production
increased in both male and female hepatocytes, with a higher level
of production in the male than female, compared to controls.