Genetically different strains of laboratory mice vary dramatically in their sensitivity to estrogen, report researchers at the University of California, Davis, in the Aug. 20 issue of the journal Science.
The findings by Jimmy Spearow, a reproductive geneticist, and Marylynn Barkley, a reproductive endocrinologist, call into question the validity of current laboratory-animal-based safety tests of estrogen-like chemicals and suggest that an individual's genetic makeup should be considered when prescribing estrogen and related hormones for medical purposes.
"The use of laboratory animals that genetically are quite resistant to estrogen for the evaluation of possible reproductive effects of various chemicals might be misleading and may mask our appreciation of how global exposure to estrogen-like chemicals threatens wildlife, domestic animals and humans," said Spearow, a research geneticist in UC Davis' Neurobiology, Physiology and Behavior Section.
Estrogen is a naturally occurring hormone that is mimicked by other chemicals dubbed "endocrine disruptors" because they appear to hinder reproduction in fish, wildlife and other mammals by interfering with the normal function of the endocrine system. Such chemicals are found in certain pesticides, plastics, detergents and estrogens derived from plants.
The U.S. Environmental Protection Agency is preparing to screen thousands of pesticides and industrial chemicals for several endocrine-disrupting effects. Previous studies have indicated that estrogen-like endocrine disruptors found in the environment can cause decreased sperm counts, deformed genitals, aberrant mating behavior and sterility in wildlife.
Spearow and Barkley, who study reproductive hormones using mice as a
research model, became interested in the
possible genetic control over susceptibility to endocrine disrupti
Contact: Jimmy Spearow
University of California - Davis