Platelets are known to stop bleeding by clumping together to produce blood clots. But researchers have found they have an unexpected ability: They produce a biochemical that was found to rejuvenate aged rat brains, similar to the way physical exercise does. This discovery could lead to drugs that improve the cognitive function of older people who are unable to exercise because of mobility problems.
Many studies have proven that regular physical exercise can overcome age-related cognitive decline and the decline seen in neurodegenerative conditions such as Alzheimer’s disease. While the molecular mechanisms underlying how exercise benefits the brain are poorly understood, animal studies have found that exercise promotes the growth of new cells in the hippocampus, the part of the brain involved in learning and memory, by causing the release of exerkines.
This is where the role of platelets. Researchers from the University of Queensland recently discovered that the colorless cell fragments that circulate in our bloodstream and are known for clumping to prevent and stop bleeding in damaged vessels, have another unexpected function: they produce biochemicals called exerkines. . In a new study, researchers investigated how platelets, and the exerchins they produce, affect the brains of aged mice.
“We know exercise increases the production of new neurons in the hippocampus, a part of the brain important for learning and memory, but the mechanism is unclear,” said Odette Leiter, lead author of the study. “Our previous research has shown platelets to be involved, but this study shows platelets are actually required for this effect in aged mice.”
Their previous research showed that platelets affected by exercise release a specific exerkine called the chemokine platelet factor 4 (PF4), so that’s what they focused on in the current study. Knowing that when PF4 was delivered directly to young rat brains, it increased new cell growth (neurogenesis) in the hippocampus, they examined how aged brains would respond and whether PF4 would initiate neurogenesis and reduce cognitive decline.
They administered PF4 to aged mice and tested their hippocampus-related learning and memory. Mice treated with PF4 performed better than those who received saline injection alone, suggesting that PF4 treatment augments exercise benefits by rejuvenating hippocampal neurogenesis and restoring cognitive function.
“We found that exerkine CXCL4/Platelet factor 4 or PF4, released from platelets after exercise, resulted in regenerative and cognitive improvements when injected into aged mice,” said Leiter.
The researchers say their findings could help develop drug interventions, especially for people who are unable to exercise because of mobility problems.
“For many people with health conditions, mobility problems, or advanced age, exercise is not possible, so pharmacological interventions are an important area of research,” said Tara Walker, corresponding author of the study. “We can now target platelets to drive neurogenesis, improve cognition, and counteract age-related cognitive decline.”
They emphasize, however, that medication is not meant to replace exercise.
“It’s important to note this is not a substitute for exercise,” Walker said. “But it could help very old people or someone who has had a brain injury or stroke to improve cognition.”
The researchers next intend to study how mice with Alzheimer’s disease respond to PF4 before moving on to human trials.
This study is published in the journal Nature Communications.
Source: University of Queensland
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