According to the U.S. Centers for Disease Control and Prevention, 795,000 people in the USA suffer from a stroke every year. Most people who have a stroke experience an ischemic stroke, which is brain damage caused by the loss of blood flow to the brain due to a blood clot or plaque. Some individuals who have an ischemic stroke lose the function of their motor skills.
Even though strokes are common, there are no medicines to treat stroke patients beyond the first 3 to 4 hours after the stroke occurs. This lack of post-stroke medication prompted scientists at Lund University in Sweden to investigate long-term stroke recovery treatments.
The researchers hypothesized that a protein called metabotropic glutamate receptor 5 or mGluR5 could slow recovery after a stroke by disrupting functions in areas of the brain remote from physical damage caused by the stroke. If so, the researchers thought that inhibiting mGluR5 with a specific medication, called MTEP, might help patients recover from strokes.
The scientists conducted their experiment on 289 rodents that they induced to experience a stroke. They divided the rodents into a control group, which was given only the non-medicinal components of the medication, and 2 experimental groups, which were treated with MTEP. After inducing strokes, the researchers provided the rodents with enriched environments featuring ladders, tubes, and other items that stimulated their brains. They explained that these enriched environments stimulated the rodents’ activity and promoted the development of motor skills.
In the first experimental group, the researchers treated the rodents with MTEP 2 days after stroke. In the second experimental group, the researchers treated the rodents with MTEP 10 days after stroke. To assess the success of the treatments, the scientists observed the rodents’ paw movements as they went through a series of behavioral tests. The rodents also underwent brain imaging so the scientist could assess what was occurring in their brains.
Through these tests, the scientists found that inhibiting mGluR5 with MTEP helped restore post-stroke brain function in both experimental groups of rodents. The scientists noted that rodents treated with MTEP started to recover the motor skills they lost due to the stroke, while those in the control group showed little to no improvement throughout the experiment. For example, the MTEP-treated rodents had 56% fewer missteps when walking on a beam than rodents in the control group. The rodents’ brain images also showed that every stroke resulted in permanent brain damage, but only the experimental group developed new neural connectivity afterward.
The researchers suggested that pairing MTEP treatment with enriched environments like those already used in cognitive and physical therapies could help people who have lost motor skills after a stroke. They stated that if researchers see similar success in human trials, this could become the first long-term pharmacological treatment for stroke patients.
The researchers cautioned that this treatment does not reverse the physical damage to the brain caused by a stroke, which is permanent and currently can’t be undone. However, a treatment that restores motor skills is a step towards curing stroke victims. They suggested scientists who continue to investigate similar treatments may someday find a way to reverse brain damage caused by a stroke.
