BALTIMORE, Sept. 2 (UPI) -- The antidepressant drug fluoxetine, often sold as Prozac, prolongs the amount of time after stroke that rehabilitation can restore movement and coordination, according to a recent study with mice.
While researchers are unsure of the exact reasons that fluoxetine helps patients in their recovery, they think it may change the way neurons respond to sensory input after an ischemic stroke, which is the sudden loss of blood circulation to the brain because of a clot.
Rehabilitation after patients have a stroke involves retraining the brain for motor function, which can include properly coordinating leg movements to walk or performing complex functions beyond simple movement.
"For rehabilitation to be effective, it needs to start as soon after a stroke as possible," said Dr. Steven Zeiler, an assistant professor of neurology at the Johns Hopkins University School of Medicine, in a press release. "But with this study, we've shown that in mice, we can extend the time period during which rehabilitative intervention has an effect on meaningful recovery."
A previous study showed that fluoxetine had helped patients regain motor recovery, but researchers had no idea why or how it worked. The researchers at Johns Hopkins designed a study using mice to learn whether fluoxetine would still help patients if rehabilitation was delayed after a stroke, and also to learn how it helps patients who have have taken it.
Mice were taught to take food pellets through a slit, something that quadrupeds such as cats, dogs and mice have trouble with. When the mice had mastered the skill, researchers induced a stroke in the motor area of the brain that would affect their ability to continue taking the food.
Some of the mice immediately started rehabilitation after the stroke, as humans would, and some regained the ability to grab food through the slit. For mice whose rehab was delayed, far fewer regained their full ability to perform the task -- also similar to what happens in humans after a stroke.
Mice who were started on fluoxetine within 24 hours of the stroke regained their ability to grab the food, even when rehabilitation was delayed for as long as a week.
Zeiler said the specific explanation of what the drug does to the brain in relation to the fallout of a stroke is still unknown. He said, however, after examining the brains of mice who'd had a stroke and been given fluoxetine that something is definitely happening.
"We believe the drug is changing plasticity [in the brain] -- changing the way individual neurons are responding to sensory input after the stroke," Zeiler said. "There are some who believe fluoxetine can reduce the amount of brain tissue that dies after a stroke. In fact, there was more, not less, brain tissue death in the animals that got fluoxetine than in those that did not. We didn't predict that, but the fact that the animals actually got better -- despite increased cell death -- tells us that fluoxetine is having some pretty amazing effects."
The study is published in Stroke.