Astrid Bjornebekk of the Karolinska Institute in Sweden and her
colleagues studied rats that had been genetically tweaked to show
depressive behaviors, plus a second group of control rats. For 30 days,
some of the rats had free access to running wheels and others did not.
Then, to figure out if running turned the down-and-out rats into happy
campers, the scientists used a standard “swim test.” They measured the
amount of time the rats spent immobile in the water and the time they
spent swimming around in active mode. When depressed, rats spend most
of the time not moving.
“In the depressed rats, running had an antidepressant-like effect after running for 30 days,” Bjornebekk told LiveScience. The once-slothful rodents spent much more time in active swimming compared with the non-running depressed rats.
The researchers also examined the hippocampus region of the brain, involved in learning and memory. Neurons there increased dramatically in the depressed rats after wheel-running.
Past studies have found that the human brain’s
hippocampus shrinks in depressed individuals, a phenomenon thought to
cause some of the mental problems often linked with depression.
“The hippocampus formation is one of the regions they have actually
seen structural changes in depressed patients,” Bjornebekk said.
Running had a similar effect as common antidepressants called selective
serotonin reuptake inhibitors (SSRIs) on lifting depression.
The research is published in the International Journal of Neuropsychopharmacology.
