BPA affects sex-based behavior in mice

May 28, 2013 by Marcia Malory report
3D chemical structure of bisphenol A. Credit: Wikipedia.

(Medical Xpress)—Bisphenol A (BPA) is a common chemical found in household plastics. Previous studies on rodents show that BPA exposure is associated with problems with brain and behavioral development. There is evidence that, in human children, exposure to BPA adversely affects neurological development and emotional regulation and leads to increased aggression. In a study published in the Proceedings of the National Academy of Sciences, Frances Champagne and her team at Columbia University in New York reveal that mice exposed to BPA when in the womb experience sex-based epigenetic changes that affect brain tissue development and sex-specific behaviors.

Often used to line food and drinks cans, BPA is so pervasive that 90 percent of Americans have detectable levels of the chemical in their urine. However, some scientists claim that these levels are too low to have an effect. Nevertheless, because BPA affects estrogen receptors, others are concerned about its potential effects on fetal development and . Earlier research has suggested that, in humans and animals, BPA exposure leads to loss of and has sex-based neurodevelopmental effects.

To counter criticism of previous studies on the effects of BPA, which used extremely high doses, Champagne and her colleagues gave pregnant mice a variety of doses, including some lower than that considered safe for humans. The researchers killed some of the offspring after weaning and dissected their brains. They found sex-specific changes in the expression patterns of genes and in , signifying that BPA exposure results in sex-based epigenetic effects.

Behavioral tests on the remaining offspring revealed a disruption in sexual dimorphism. For example, the only rats engaged in fighting, a typically male behavior, were that received the highest dose. Male mice were less likely to chase other mice and to engage in sniffing behavior, while the frequency of these behaviors increased in females. BPA exposure made males less anxious, while it increased anxiety in females. Both males and females became more aggressive as the BPA dose increased.

Champagne's team suggests that other researchers can extrapolate these results to humans, noting that the aggressive behavior demonstrated by the juvenile mice in the study could mirror aggressive behavior in human children.

However, some disagree with this conclusion. For example, Professor Richard Sharpe of the University of Edinburgh's Medical Research Council's Centre for Reproductive Health says that the lowest dose given in the study, 2 micrograms per kilogram per day, is still 10 to 20 times higher than normal BPA exposure. In addition, estrogen levels in pregnant humans are much higher than in ; therefore the estrogenic effects of BPA would be much greater in mice than in people.

Explore further: Bisphenol A affects sex-specific reproductive behaviors in monogamous animal species

More information: Sex-specific epigenetic disruption and behavioral changes following low-dose in utero bisphenol A exposure, PNAS, Published online before print May 28, 2013, doi: 10.1073/pnas.1214056110

Bisphenol A (BPA) is an estrogenic endocrine disruptor widely used in the production of plastics. Increasing evidence indicates that in utero BPA exposure affects sexual differentiation and behavior; however, the mechanisms underlying these effects are unknown. We hypothesized that BPA may disrupt epigenetic programming of gene expression in the brain. Here, we provide evidence that maternal exposure during pregnancy to environmentally relevant doses of BPA (2, 20, and 200 µg/kg/d) in mice induces sex-specific, dose-dependent (linear and curvilinear), and brain region-specific changes in expression of genes encoding estrogen receptors (ERs; ERα and ERβ) and estrogen-related receptor-γ in juvenile offspring. Concomitantly, BPA altered mRNA levels of epigenetic regulators DNA methyltransferase (DNMT) 1 and DNMT3A in the juvenile cortex and hypothalamus, paralleling changes in estrogen-related receptors. Importantly, changes in ERα and DNMT expression in the cortex (males) and hypothalamus (females) were associated with DNA methylation changes in the ERα gene. BPA exposure induced persistent, largely sex-specific effects on social and anxiety-like behavior, leading to disruption of sexually dimorphic behaviors. Although postnatal maternal care was altered in mothers treated with BPA during pregnancy, the effects of in utero BPA were not found to be mediated by maternal care. However, our data suggest that increased maternal care may partially attenuate the effects of in utero BPA on DNA methylation. Overall, we demonstrate that low-dose prenatal BPA exposure induces lasting epigenetic disruption in the brain that possibly underlie enduring effects of BPA on brain function and behavior, especially regarding sexually dimorphic phenotypes.

Related Stories

Bisphenol A affects sex-specific reproductive behaviors in monogamous animal species

February 11, 2013
Parents, teachers and psychologists know boys and girls behave differently. However, that difference isn't taken into account by most methods used to assess the risk to children from chemical exposure, according to Cheryl ...

BPA exposure effects may last for generations

June 15, 2012
Exposure to low doses of Bisphenol A (BPA) during gestation had immediate and long-lasting, trans-generational effects on the brain and social behaviors in mice, according to a recent study accepted for publication in the ...

BPA exposure in pregnant mice changes gene expression of female offspring

June 26, 2012
Prenatal exposure to bisphenol A, or BPA, a chemical found in many common plastic household items, can cause numerous genes in the uterus to respond differently to estrogen in adulthood, according to a study using a mouse ...

BPA lowers male fertility: report

June 6, 2011
Daily exposure to a chemical that is prevalent in the human environment, bisphenol A (BPA), causes lowered fertility in male mice, according to the results of a new study that will be presented Saturday at The Endocrine Society's ...

BPA may affect the developing brain by disrupting gene regulation

February 25, 2013
Environmental exposure to bisphenol A (BPA), a widespread chemical found in plastics and resins, may suppress a gene vital to nerve cell function and to the development of the central nervous system, according to a study ...

Exposure to BPA has been underestimated, new research says

June 6, 2011
A new University of Missouri study shows that the exposure to the controversial chemical Bisphenol A (BPA) through diet has been underestimated by previous lab tests. In the study, researchers compared BPA concentrations ...

Recommended for you

Blowing smoke? E-cigarettes might help smokers quit

July 26, 2017
People who used e-cigarettes were more likely to kick the habit than those who didn't, a new study found.

Brain disease seen in most football players in large report

July 25, 2017
Research on 202 former football players found evidence of a brain disease linked to repeated head blows in nearly all of them, from athletes in the National Football League, college and even high school.

Safety of medical devices not often evaluated by sex, age, or race

July 25, 2017
Researchers at Yale and the University of California-San Francisco have found that few medical devices are analyzed to consider the influence of their users' sex, age, or race on safety and effectiveness.

Why you should consider more than looks when choosing a fitness tracker

July 25, 2017
A UNSW study of five popular physical activity monitors, including Fitbit and Jawbone models, has found their accuracy differs with the speed of activity, and where they are worn.

Dog walking could be key to ensuring activity in later life

July 24, 2017
A new study has shown that regularly walking a dog boosts levels of physical activity in older people, especially during the winter.

Study finds 275,000 calls to poison control centers for dietary supplement exposures from 2000 through 2012

July 24, 2017
U.S. Poison Control Centers receive a call every 24 minutes, on average, regarding dietary supplement exposures, according to a new study from the Center for Injury Research and Policy and the Central Ohio Poison Center, ...


Adjust slider to filter visible comments by rank

Display comments: newest first

5 / 5 (2) May 28, 2013
Finally, hard science on why Justins Bieber and Timberlake are "famous"
1 / 5 (2) May 28, 2013
Finally, hard science on why Justins Bieber and Timberlake are "famous"

While I continue to wonder if this science is as bad as the science that got cyclamates banned (in the US).

Or Freon.
Or Chlordane.
Or, or ad infinitum.
1 / 5 (1) May 28, 2013
Finally, hard science on why Justins Bieber and Timberlake are "famous"

OMG! Hahahahahahaha! FIVE STARS FOR YOU DUDE....YES, we may someday disagree on a thing or two but this SHOULD keep us on speaking terms....oh yeah..

3 / 5 (2) May 28, 2013
Finally, hard science on why Justins Bieber and Timberlake are "famous"

While I continue to wonder if this science is as bad as the science that got cyclamates banned (in the US).

Or Freon.
Or Chlordane.
Or, or ad infinitum.

Wha? What are you trying to say? DDT IS A PERSISTENT ORGANIC POLLUTANT! You like it...? Then YOU eat it...the rest of the sentient beings on this planet have begun to realize that there ARE things we just MUST control that man makes( BPA included)! Now, what ARE you trying to say?

not rated yet Jun 03, 2013
People should avoid drinking from clear plastic bottles(drink from cloudy ones if you have to, even though they are not fully BPA free, they are much much better than clear ones.

Also try to consume fresh food more and canned food less!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.