A new paper released by researchers from NYU Grossman School of Medicine targets what causes pressure build up in the eyes and nerve cell damage in neurodegenerative diseases such as glaucoma. Although these two have been long associated with the disease, it remained unclear why it happened or how.
In the new study, the researchers have discovered that astrocytes were to blame for the increased eye pressure. They claim that it releases unidentified neuron-killing toxins to clean out damaged cells possibly. Concurrently, too much pressure had little to no effect on the nerves when astrocytes were absent.
According to Shane Liddlelow, a senior author of the study, their study determines astrocytes as responsible for nerve cell death. Furthermore, the assistant professor of the Department of Neuroscience and Physiology at NYU Langone Health adds that targeting astrocytes after a brain injury could possibly keep neurons at tip-top shape. Moreover, it could also prevent further degradation.
He also adds that the findings of their study show that to understand neurodegenerative diseases fully, scientists, too, must look beyond neurons to the other cells surrounding them. Additionally, he says their research could help explain why brain cells continuously die long after pressure has been relieved.
The full findings of the study were published on June 23, 2020, in the journal Cell Reports. Liddlelow's co-authors include Kevin Guttenplan, Benjamin Stafford, Rana El-Danaf, Maya Weigel, and Andrew Huberman.
Astrocytes Function and Location
An astrocyte is a star-shaped glial cell of the central nervous system. Astrocytes, after oligodendrocytes, make up the major glial cell population in the brains of mammals. They are involved in tight control of the synaptic transmission.
Two studies have found that astrocytes are incidentally contributing to motor neuron loss in amyotrophic lateral sclerosis. With this, the incessant neuron-centric view of neurodegenerative diseases becomes challenged.
In the study, the researchers used rodents as subjects, whereby they increased their eye pressure for two weeks. Some of the mice were genetically engineered to be deficient in astrocytes.
In their findings, they found that while the unmodified mice lost up to half of their neurons in the damaged area, those without harmful astrocytes saw minimal cell death. Additionally, neurons that endured continued to send electrical signals.
To determine whether neurons survive if astrocytes are interrupted from releasing toxins, the researchers increased pressure once more. This time, it disrupted inflammation in some of the animals to prevent their astrocytes from becoming responsive once more.
Better Treatment for Neurodegenerative Diseases
Although the findings suggest that blocking astrocytes is a possible method of preventing nerve damage in glaucoma patients, the authors caution that they do not yet know if the resulting effects are long-lasting. They are also unaware of what side effects might occur.
For their next step, the research team plans to explore if this treatment can be helpful in improving vision in animals with glaucoma. Moreover, they also want to study astrocyte behavior in other related neurodegenerative diseases such as Parkinson's, Alzheimer's, and Lou Gehrig's disease.
