One of the hallmarks of Alzheimer’s is the accumulation of amyloid plaques between neurons (cells that transmit electrochemical signals throughout the nervous system) in the brain.
Researchers now report that the impact of the amyloid plaques that appear in the brains of Alzheimer’s patients may extend beyond the plaques’ effects on neurons.
Amyloid plaques in Alzheimer’s and other neurological disorders may also increase the activity of astrocytes, star-shaped nervous system cells traditionally considered to provide a supporting role in normal brain function.
They also show that amyloid-induced astrocyte hyperactivity extends throughout the Alzheimer’s brain rather than being confined to regions directly adjacent to plaques.
Astrocytes are abundant, making up about half the volume of the brain, and found throughout the brain.
Using cutting-edge imaging techniques that give a real-time view of the activity of brain cells in living mice, astrocytes were labeled with a dye that lights up when a cell is active and shuts off when it is not.
The astrocytes flickered on and off at much higher rates in Alzheimer’s mice with an abundance of plaques than in plaque-free animals.
The plaque-associated astrocyte activity appeared to be synchronized and passed to distant areas of the brain in a wave-like fashion.
Another imaging technology revealed that resting calcium levels were elevated throughout the astrocyte network of animals with plaques but not in normal mice.
“We’ve only begun to scratch the surface of how plaque deposition impacts astrocyte function,” says Kishore Kuchibhotla, report author. “One key question will be how increased astrocyte signaling impacts neuronal function, and another will be whether astrocyte activity limits or intensifies plaque deposition.”
Brian Bacskai, senior author of the report, says, “This study not only provides insight into the role of astrocytic networks in the brain, it also suggests new opportunities to manipulate these networks to treat or prevent Alzheimer’s as well as other neurological disorders. Further studies of pharmacological compounds that interact with astrocytes may someday lead to potential new therapies”
References:
1. Brian Bacskai, et al. Massachusetts General Hospital.
2. Image from Cornell University.
