Washington: Exposure to the chemical bisphenol A (BPA) early in life tends to foster anxiety by altering gene expression in a brain area which detects and respond to signals of danger and threats, says a study.
"We knew that BPA could cause anxiety in a variety of species, and wanted to begin to understand why and how that happens," said Heather Patisaul, associate professor of biology at North Carolina State University, who led the study. They also found that a soy-rich diet can mitigate these effects.
BPA, found in many plastic food containers and bottles, can leach into foods and drinks and cause health problems. Even in low doses, as studies have shown, BPA can disrupt the endocrine systems and can lead to obesity, breast cancer, reproductive issues, and lead to hyperactivity.
In the study, rats were exposed to low doses of BPA during gestation, lactation (nursing) and through puberty. One group of animals was fed only soy; one group was fed a soy-free diet; one group was fed only soy and exposed to BPA; and one group was fed no soy and exposed to BPA, the journal Public Library of Science ONE reported.
Blood tests showed that the animals exposed to BPA had levels well within the range found in humans. Similarly, blood tests of animals fed soy showed levels of genistein, an estrogen-like chemical found in soy, that were at levels within the human range for vegetarians and others who regularly consume soy foods, according to a North Carolina statement.
Among adolescent rats on the soy-free diet, both males and females that had been exposed to BPA exhibited significantly higher levels of anxiety. The researchers also found, for the first time, gene changes within the brain associated with this elevated anxiety.
The researchers also found that adolescent rats on the soy-rich diet did not exhibit anxiety - suggesting that the soy-rich diet may mitigate the effects of BPA.