The same medication used to save lives by reversing opioid overdoses may also benefit nonopioid users. In a new study done in rats, the medicine, called naloxone, was shown to help the brain to recover from a stroke.
Researchers found that when male rats were treated for one week with naloxone after having an ischemic stroke, they had an improved recovery, compared with rats who did not receive naloxone. (An ischemic stroke occurs when blood flow to the brain is interrupted, usually because of a blood clot, which deprives the brain of oxygen and damages nerve cells in the area.) [Strange Stroke Stories: Ebola, Hickeys and Other Weird Causes]
Because the study was done in rats, more research is needed to confirm the findings in people. However, naloxone might play a role in stroke recovery because the drug has anti-inflammatory properties and can reduce the activity of the microglia, which are the primary immune cells of the brain, according to the study findings, published today (April 16) in the journal eNeuro.
Previous research has shown that naloxone affects the microglia, which are very active contributors to the inflammation that occurs in the brain following a stroke, said study co-author Brandon Harvey, a researcher at the National Institute on Drug Abuse in Baltimore. So, in this study, the researchers wanted to see whether giving naloxone after a stroke could decrease the activity of the brain's immune cells and reduce the associated inflammation, leading to improved recovery from the stroke, he said.
Improved stroke recovery
In the new study, the researchers gave 65 male rats naloxone twice a day through the nose at a dose considered to be safe in humans. (Naloxone is often given as a nasal spray to reverse an overdose, according to the study.) The study showed that the drug was most effective when treatment was started within 16 to 36 hours after a stroke and lasted for seven days.
The findings showed that when naloxone was given after a stroke, during a period when immune-cell activity in the brain was peaking, it had beneficial effects on recovery, said study co-author Mikko Airavaara, principal investigator at the Institute of Biotechnology at the University of Helsinki in Finland. (Immune cells in the rats' brains were active as early as two days after a stroke and reached their peak activity seven days after a stroke, according to the findings.)
Airavaara said that naloxone works reducing inflammation in the brain and reducing the loss of nerve cells, which can improve the brain's ability to recover after a stroke.
These findings are important because there is no drug treatment now that helps the brain recover after a stroke, Airavaara told Live Science. So, developing a drug therapy that could promote recovery for the 10 million people worldwide who have strokes each year would be groundbreaking, he said.
Indeed, because naloxone has been used to treat opioid overdoses for nearly 50 years, the idea of repurposing the drug for stroke is intriguing, Harvey said.
What about people?
Still, more research is needed in animals before naloxone is studied in people who have had a stroke. [7 Things That May Raise Your Risk of Stroke]
It would be important to establish that the drug's beneficial effects would work not only in male rats but in female rats as well, Harvey told Live Science.
The current study was able to establish an effective delivery method for the drug — through the nose, which is one of the methods already used to reverse opioid overdose — and a suggested dosing pattern (when to give the drug) to possibly translate these findings into clinical practice in the future, Harvey said.
Daniel Lackland, a professor of epidemiology in the neurology department at the Medical University of South Carolina in Charleston, who was not involved in the new research, said that there is a need to identify other treatments for stroke recovery. Currently, rehabilitation includes physical-, occupational- and speech-therapy programs; however, treatments that target physiological changes in the brain are lacking, he said.
In addition, recovering from a stroke has not had the same success rates as recovering from heart disease, said Lackland, who is a spokesperson for the American Stroke Association.
This study explored the possibility that a new drug may contribute to stroke recovery, and this drug appears to have some benefits in animals, Lackland told Live Science. Though the findings need to be replicated in additional animal studies, these results give hope for the future of possible trials in humans, he said.
Originally published on Live Science.