Volume 2, Issue 9
Rearing Rodents for Behavioral Insights
Rats carry a lot of baggage. Grumpy, anti-social rats often have bad childhoods to blame. In this way, humans and rats have a lot in common. Our early life obviously has a huge affect on who we become as adults. But what is the biology behind our behavior? To find out, UC Berkeley biopsychologist Darlene Francis studies how rodents are reared.
In 2001, Darlene Francis received the Young Investigator Award from the Cure Autism Now Foundation.
"You may not care about what rats and mice are doing, but you can generalize what we learn from them to people," says Francis, who also holds a faculty position in the School of Public Health and an appointment in the Helen Wills Neuroscience Institute.
Francis joined the UC Berkeley faculty in January after several years in the Center for Neuroscience at Emory University. Her research career was interrupted by a stint as a youth counselor for children, where she became increasingly curious about how early life affects human development. Animal models enabled her to gather data and conduct controlled experiments that are simply not possible in clinical populations.
"You're never going to put a kid in a crappy environment just to see what happens," she says. "But you can ask the same questions of rats and mice. What goes so right or wrong so early in life? Can you affect change?"
One thrust of Francis's research reveals what it means to be a good mother and how differing parenting environments (both before and after birth) affect the stress levels of offspring. In a recent experiment, she took identical mouse embryos and "adopted them out" either before birth, after birth, or both, to foster moms who provided varying levels of maternal care. Once the baby mice reached adulthood, they were tested for behavioral characteristics like anxiety, ability to learn, and stress. The study showed that both the intrauterine environment and the postnatal care cooperatively influenced the mice's adult behavior.
Rats may hold valuable clues about how biology affects human behavior.
Along with conducting behavioral tests, Francis and her colleagues can gain a more direct view of the animals' neurobiology. By measuring the hormones the rodents produce or ultimately sacrificing them to directly examine their brain chemistry, Francis is able to decipher how subtle variations in neurobiology are expressed in life.
"In people, you're presented with a behavior and you have to deal with it," Francis says. "In animals though, we can set them on a path and look at the effects."
While the Human Genome Project has enabled scientists to speed up the search for genes linked to specific behaviors, Francis points out that "we're more similar than we are different."
"This line of research shows that it's not necessarily about the genes you have but about how those genes get regulated," she says.
One way to regulate the expression of genes is through intervention. In a laboratory study, Francis demonstrated that the behavior of rats raised in a challenging or stressful environment can be markedly improved by stimulation or social enrichment later in their lives. Not only does a rat's behavior change based on an environmental shift, but the interventions work by altering the animal's biology. In the end, Francis's rodent research supports the old maxim that life really is what you make it.
"The ongoing nature versus nurture debate is dead," she says. "We now have the neurobiological tools to really begin to understand the interaction between the two."