Brain’s Protective Cells May Also Do Harm

Alzheimer's Disease loss of brain tissue may be a product of protective cells' defense

(RxWiki News) Astrocytes are supporting cells that are protective and do housekeeping for neurons in the brain.  Beta amyloid build up in Alzheimer’s disease (AD) may cause the astrocytes to defend themselves.

A new study found that astrocytes defend themselves against increasing amounts beta amyloid.  They create a chemical package that damages both the astrocyte and the neuron.  This process may explain part of loss of brain tissue in AD.

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In AD, beta amyloid proteins build up in the brain and form plaques. AD also shows loss of brain tissue as it progresses, and it has been thought that the beta amyloid plaques are part of the process of brain degeneration.

Researchers, led by Guanghu Wang, PhD, at the Georgia Health Sciences University, conducted a study and found that astrocytes respond to the build-up of beta amyloid by creating a chemical package that damages the astrocyte.

Previous research has shown, in both human and rodent studies, that certain chemicals in the brain change in response to beta amyloid. 

The current study looked at astrocytes in the lab, extracted from the brains of rodents, to try to determine how the astrocytes were responding to beta amyloid.

Wang and colleagues found that beta amyloid irritates astrocytes, and the astrocytes respond by packaging a lipid ceramide and PAR-4 proteins together.  This potent package leads to the death of the astrocyte. When astrocytes die, their neurons die, too.

The authors conclude that this process where astrocytes are involved in the death of neurons in response to beta amyloid could be targeted by drugs.  This may present a new avenue for slowing brain damage during Alzheimer’s.  More research is needed. 

The study was published online in April in the Journal of Biological Chemistry.  The research was funded by the National Institutes of Health; no conflicts of interest were disclosed.

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Review Date: 
June 6, 2012