Doctors have long known that the nine months humans spend developing in the womb are incredibly important to the health of infants, but could a brief exposure to certain hormones impact our health years, even decades later?
A group of Bucknell researchers is taking part in a scientific movement producing ever-mounting evidence that the environment of the womb is critical in determining our long-term health, how long we live and even our personalities.
"Maternal nutrition can have lasting effects on us for the rest of our lives; exposure to different hormones can have lasting effects on us," said professor Mark Haussmann, biology. "These effects are often seen at birth, but there's been the thought that a few months later the baby has made it past that stage. But what all the literature is suggesting now is that if you do follow-up studies at 10, 20, 30 years of age, you're still seeing lasting effects from that period of gestation, or even from a one-day exposure to certain hormones during gestation."
Haussmann — together with Professor of Biology Morgan Benowitz-Fredericks and student researchers Brittany Whitley '12 and Lisa Treidel '12 — recently published a paper in the Royal Society journal Biology Letters linking prenatal exposure to the male sex hormone testosterone with shorter lifespans in chickens. While testosterone is associated with male characteristics, it's also found in women, just as the hormone estrogen is found in men. It's too early to extrapolate the study's findings to humans, Haussmann said, but the study's results are nonetheless striking. While normal chickens might live up to 10 years, the chickens exposed to prenatal testosterone have cells that are damaged faster, and aren't likely to live beyond a few years.
"The connection to humans is that this prenatal period of development is really important," Haussmann said. "It can set individuals on a trajectory toward early onset aging."
The Bucknell study focused on the connection between prenatal testosterone and oxidative stress. Structures within cells called mitochondria produce energy to fuel the body, but they also produce wayward electrons called free radicals. Let loose in the body, those free radicals can collide with and damage other cells. As we age, our ability to repair those damages diminishes, leading to age-related illnesses such as heart disease and cancer. In the experiment, prenatal testosterone exposure did not increase the damage done by oxidative stress, but impaired the ability of the exposed chickens to repair the damage done by free radicals.
"There is 'machinery' in your cells to repair damage done to your DNA, to repair the body's genetic blueprint," Haussmann explained. "We found that the birds that had prenatal testosterone exposure couldn't repair that damage, resulting in cells that age much more rapidly than they would normally."
The study is not the first to examine a link between prenatal testosterone exposure and oxidative stress, but it has yielded the most conclusive results thus far. It is also unique, Haussmann said, in that it was largely led and written by undergraduate students.
"We were really hands-on," said Whitley, who is now working on a two-year post-baccalaureate fellowship at the National Institutes of Health in Maryland. "One of the main techniques we used in this project was new to our lab, and Lisa and I optimized it for our experiment."
Whitley and Treidel began working on the project as summer research fellows in 2011, and continued writing and revising their paper even after graduation.
"It was really rewarding to finally get that out, and important for my career," said Treidel, who is currently pursuing a master's in biology at Illinois State University.
Both graduates plan to make careers in science, and said their Bucknell experience left them well prepared for their postgraduate research.
"I think it's striking that the paper has four authors, all from Bucknell, and two of them are undergraduates," Haussmann said. "Bucknell provides an environment that allows students to explore, ask their own questions and make their own discoveries."