Scientists know that the key to unlocking neurological disorders begins with a full understanding of how neurons are generated and sustained.
A new discovery in the secret life of neurons has managed to surprise researchers at the Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital and Baylor College of Medicine.
Their findings reveal that the life cycle of adult hippocampal baby neurons was not what was previously thought.
In fact, very soon after birth, within 1 to 4 days of life, newborn cells reach a critical stage in which many of them die by apoptosis, natural cell death. Furthermore, the study showed that those dead cells are removed quite quickly.
The study blazes a new path for future research regarding the process by which neurons are generated.
“Years ago researchers believed we were born with only a certain number of neurons to last us throughout our lifetime, but we soon learned that new ones are also produced in adulthood. Our current research is focused on the life cycle of those neurons,” said Amanda Sierra Saavedra, postdoctoral associate in pediatrics-neurology at NRI/BCM.
The place where these new neurons are generated is the hippocampus, a brain region associated with learning and memory. Therefore, the crucial processes unveiled by the reported findings could very well play a role in learning and memory, as well as in disorders that affect the hippocampus, added Sierra Saavedra.
She and her team, under the direction of Maletic-Savatic, assistant professor of pediatrics-neurology at NRI/BCM, were able to pinpoint and track each new neuron using BrdU (Bromodeoxyuridine). BrdU is a synthetic that can be incorporated into the newly synthesized DNA of dividing cells, allowing researchers to follow the life cycle of a newborn cell.
“We found two critical periods when the newborn cells underwent apoptosis, and the majority of the cells died one to four days after being born,” said Sierra Saavedra. “This is much earlier than what we had first thought. We were completely puzzled to learn that many cells die almost immediately after they are born.”
As researchers were able to watch these cells, they soon discovered that the “clearing up,” or phagocytosis, started just after cell death. Microglia cells, which are the brain’s immune defense system, overcome the dead cells, demolishing them and leaving behind little to no trace that they ever existed.
“This process happens quickly, efficiently, and without any interference, indicating that the microglia play an important role in maintaining the proper functions of the neurogenic process,” Sierra Saavedra said.
“If this is interrupted by genetic, environmental, toxic, or immunologic defaults or any other reason, then we believe that certain diseases and disorders might appear.”
These findings present crucial knowledge necessary for future studies into new ways of harnessing newborn neurons for treating disorders related to the hippocampus, she said.
The study appears in the current issue of the journal Cell Stem Cell.
Source: Baylor College of Medicine