From Cara Murez
HealthDay reporter
FRIDAY, March 26, 2021 (HealthDay News) – When people die, some cells in their brain go on for hours, even becoming more active and growing to gigantic proportions, new research shows.
Awareness of this activity triggered by “zombie genes” could influence research into diseases affecting the brain.
For the study, researchers analyzed gene expression using fresh brain tissue collected during routine surgery and found that in some cells, gene expression increased after death. The researchers observed that inflammatory glial cells grew and sprouted long arm-like limbs for many hours after death.
“Most studies assume that everything in the brain stops when the heart stops beating, but it doesn’t,” said author Dr. Jeffrey Loeb. He is the director of the Department of Neurology and Rehabilitation at the Chicago College of Medicine at the University of Illinois.
Gene expression is the process by which the instructions in DNA are converted into instructions for making proteins or other molecules, according to Yourgenome.org.
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“The fact that glial cells enlarge after death is not too surprising, as they are inflammatory and their job is to clean up things after brain injuries such as a lack of oxygen or a stroke,” Loeb said in a press release from the university.
The impact is significant, he added.
Most research that uses human brain tissue after death to find treatments and possible cures for disorders (such as autism, schizophrenia, and Alzheimer’s disease) does not consider continued gene expression or cell activity.
“Our findings are needed to interpret research on human brain tissue,” said Loeb. “We just haven’t quantified these changes so far.”
Loeb is the director of UI NeuroRepository, a bank that, with consent, stores brain tissue from patients with neurological disorders. The tissue is collected and stored either after the patient dies or during surgery. Not all of the tissue is needed for disease diagnosis, so some can be used for research.
Loeb and his team found that the gene expression patterns in fresh brain tissue did not match the published results of gene expression in tissue analyzed after death.
So they conducted a simulated experiment that looked at the expression of all human genes immediately after death up to 24 hours later.
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About 80% of the genes analyzed remained relatively stable for 24 hours. This included genes that provide basic cellular functions. Another group of genes involved in brain activity (such as memory, thinking, and seizure activity) were rapidly broken down in the hours after death.
A third group of genes – the “zombie genes” – became more active as the other genes slowed down. These changes peaked after 12 hours.
According to Loeb, researchers need to take these changes into account and cut the time between death and study as much as possible to limit the magnitude of these changes.
“The good news from our results is that we now know which genes and cell types are stable, which are broken down, and which increase over time so that the results of post-mortem brain studies can be better understood,” he said.
The results were published in Scientific Reports on March 23.
More information
The United States Centers for Disease Control and Prevention’s “Healthy Brain” initiative is more concerned with Alzheimer’s disease and related dementias.
Source: University of Illinois Chicago, press release, March 23, 2021
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