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Around Tappan Square
 Contrary
to popular belief, some of life's heart-pounding meetings, gut-wrenching
arguments, and nerve-wracking car rides could actually be good for
you. A pilot study led by visiting assistant professor of neuroscience
Joel Dopp and five student researchers examined the ways in which
stress-inducing situations affect our body's immune system. Stress,
they discovered, appears to release certain bacteria-fighting cells
into the immune system--a "fight-or-flight" response that
may have evolved in animals to combat infection acquired during
predator/prey chases.
Senior neuroscience major Daniel
Rubin, senior economics and psychology major Goldie Greenstein,
senior biology major Fernando Grigera, junior psychology major Kimberly
Menig, and senior biology major Stephanie L. White studied subjects'
physiological responses to stress-inducing situations, keeping in
mind all outside psychological variables. The results could lead
to a better understanding of how acute stress can affect the immune
system and impact health.
"This is a new avenue of research," Dopp
says. "One that is focused on neutrophils, or white blood cells
that help the body fight infection." Neutrophils, he explains,
make up 65 percent of the white cells found in human blood. When
a wound to the body becomes infected, the puss that forms is composed
of millions of white blood cells, most of them neutrophils working
to eliminate the bacteria.
In a related study as a post-doctoral fellow at UCLA,
Dopp studied the physical response of married couples engaging in
an argument. Subjects' heart rates and blood pressures were measured
before, during, and after a 15-minute conflict. Blood samples were
taken at various times to measure the fight-or-flight reactions.
Conflict, the researchers concluded, increased not
only heart rate and blood pressure, but also the numbers of circulating
natural killer cells, the immune system's unspecialized fighters
that flood infected cells with toxins and destructive enzymes.
At Oberlin, Dopp used two laboratory stressors--mental
arithmetic and vigorous exercise--to elicit the needed fight-or-flight
response. He concentrated his focus on neutrophils, which are typically
underrepresented in stress studies. Fifteen students completed the
tasks one to two weeks apart. During one session, the students peddled
on a stationary bike for 10 minutes; during another, they subtracted
by sevens from 1,000 while keeping pace with a metronome that ticked
every second. Blood was drawn before and after the tasks, and heart
rate and skin conductance were measured throughout.
The team's findings revealed that the psychological
stressor (arithmetic) caused an increase in heart rate and skin
conductance that was roughly one-third the rate exhibited during
the exercise stressor. Stress associated with arithmetic also increased
the numbers and activity of the innate immune system cells. Specifically,
subjects showed higher numbers of circulating natural killer cells
and neutrophils and a higher migration of neutrophils toward bacteria.
According to Dopp, these results add to a growing literature that
indicates that transient stress of a mild to moderate magnitude
activates the innate immune system.
Aside from its scientific importance, Dopp's study
offered invaluable laboratory and analysis skills to his student
team, which was encouraged to question data and suggest improvements
after each trial.
"When you're in lab for a class, it's easy to
let things slide," says Daniel Rubin, who processed blood samples.
"But here, if we made an error, we saw it in the data that
came back. This is the real world, and there are consequences. It
makes you appreciate the amount of discipline and time it takes
to conduct good research."
Although he laughingly referred to his job--filling
half-diameter filters with purified neutrophils from blood--as "trying
to do a crossword puzzle with a squirt gun," he says the experience
was eye-opening and informative.
"This stress study encompassed several disciplines--immunology,
neuroscience, and psychology," says Kimberly Menig, who helped
analyze blood and compile data, which will be submitted for publication
this spring. "All of us participated because we were interested
in the subject matter. We dabbled in each other's areas while finding
a balance. I also liked the fact that I really did have something
to contribute. The faculty members were intent on giving us a good
background."
With the pilot study complete, Dopp will investigate
other questions: why people respond differently to the same stressor,
if stress-reduction interventions can change one's response to stress,
and at what point repeated stressors transition into immune-inhibiting
chronic stress.
by Yvonne Gay
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