New MU Study: BPA “Demasculinized” Mice Making Them Undesirable

The University of Missouri, where I earned my Master’s in Education, has been at the forefront in exposing Bisphenol-A dangers.  Frederick vom Saal, professor of biological sciences, exposed BPA in 2005 making such strong statements as:

“The science is clear and the findings are not just scary, they are horrific.  When you feed a baby out of a clear, hard plastic bottle, it’s like giving the baby a birth control pill.”

“If BPA was treated as a drug, it would have been pulled immediately.  We are not saying get rid of plastics. This chemical can be replaced right now by safer materials and the public would never notice the difference.”

MU has continued this tradition of exposing BPA with an alarming new study involving male deer mice.

Researchers have discovered that male mice exposed to BPA lose spatial navigational abilities, a skill crucial to reproduction. Furthermore, female mice found them less attractive.

“The BPA-exposed deer mice in our study look normal; there is nothing obviously wrong with them. Yet, they are clearly different,” said Cheryl Rosenfeld, associate professor in biomedical sciences in the College of Veterinary Medicine and investigator in the Bond Life Sciences Center. “Females do not want to mate with BPA-exposed male deer mice, and BPA-exposed males perform worse on spatial navigation tasks that assess their ability to find female partners in the wild. This study sets the stage for BPA researchers to examine how BPA might differentially impact the behavioral and cognitive patterns of boys versus girls. Investigators looking for obvious BPA-induced differences, such as chromosome deletions or DNA mutations, could be missing subtle behavioral differences that eventually lead to long-term adverse outcomes, including demasculinization of male behaviors with ensuing decreased reproductive fitness.”

What is very interesting about this study is the male deer mice were exposed to BPA in utero and during lactation.  After that, they were fed non-BPA diets.  Their behavior was then tested once they were adults, thus the study focused on early exposure to BPA.  When placed in the maze as adults:

Many male mice that had been exposed to BPA early in their development never found the correct exit. By comparison, male mice that had not been exposed to BPA consistently found the hole leading to their home cage within the time limit, some on the first day. In addition, the untreated mice quickly learned the most direct approach to finding the correct hole, while the exposed males appeared to employ a random, inefficient trial and error strategy, Rosenfeld said.

Females preferred non-BPA exposed males two-to-one in the “mate choice experiment”.

Implications

  • One implication of Rosenfeld’s research is that environmental exposure to endocrine disruptors such as BPA can cause subtle rather than overt problems, she said. “They (the mice) look normal. There’s nothing obviously wrong with them. But they are clearly different.” BPA researchers who are looking for “overt pathological outcomes” such as chromosome deletions or DNA mutations “could be missing subtle but long-term adverse outcomes,” she said.
  • “Our study could suggest that boys may be more susceptible (to BPA exposure) than girls would be,” Rosenfeld said.
  • In the case of the endangered panda, which is already a “genetically bottlenecked species,” meaning decreased numbers of animals and thus less genetic variation, Rosenfeld said BPA exposure “could demasculinize them as it relates to behaviors essential for the species to reproduce. Exposure to endocrine disrupting compounds could significantly contribute to their demise.”
  • The mothers’ exposure to BPA in the diet, adjusted for body weight, was roughly equivalent to the Food and Drug Administration’s “lowest observed adverse effect level” for BPA exposure in humans. This means the pregnant mice were fed a dose that is “in line with what FDA considers safe for people,” Rosenfeld said.

Photo:  AttributionShare Alike Some rights reserved by WallTea

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