Discovery of new brain cells may provide neurological breakthrough

28/09/2023

Recently discovered 'astrocytes' could hold the key to several pathologies such as Alzheimer's and epilepsy.

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Image by Stefanie Kaech and Gary Banker, OHSU, Oregon, USA via ZEISS Microscopy. A hippocampal neuron.

By Eloise Walker

An article published in the scientific journal Nature has taken the field of neuroscience by storm, with the discovery of a new type of cell essential for brain function.

Hybrid in their composition and function, these cells have been proven to promote some of the most important abilities in the brain, from memory to movement. Their presence not only denotes a whole new avenue of neuroscientific understanding, but a monumental leap in the potential treatment of complex and understudied brain disorders.

To fully understand the gravity of the discovery, we must understand how the brain processes information and why this discovery has proven so significant. For as long as neuroscience has existed as a discipline, neurons have been at the heart of it. The brain's primary mechanism consists of electric impulses of information (known as ‘action potentials’), rapidly transmitted via neurons. These are nerve cells that are uniquely adapted to maximise the efficiency with which these impulses are delivered and received. Some of the main supporters of this structure are the glial cells: often considered the ‘glue’ of the nervous system, neuroglia come in a variety of forms, and perform a series of functions designed to support and protect neurons to ensure they work at their highest possible capability.

One of these glial cells - and the subject of all this controversy - is the astrocyte. Situated intimately around the synapses of the brain (the ‘bridges’ between neurons that allow signals to be passed between them), astrocytes have long been speculated to have an active role in transmitting signals and processing information. However, research conclusions just haven’t been supportive. Conflicting results and a lack of definitive scientific consensus have held back much of the effort to ascribe a greater purpose and role to these astrocytic cells. That is, until now.

Neuroscientists from the Department of Basic Neurosciences at the University of Lausanne and the Wyss Center for Bio and Neuroengineering in Geneva appear to have brought the years of disagreements to an end.

It began with a study to scrutinise the role of astrocytes by determining whether or not they use neurotransmitters. Released from the synaptic vesicles of the neuron, these chemical messengers are imperative to the brain’s function – without them, information cannot be passed between neurons. The main neurotransmitter we see in the brain is glutamate, and its secretion requires highly-specialised machinery within the releasing cell.

Researchers scrutinised astrocytes for any evidence of this machinery, and struck gold. Using cutting-edge molecular biology approaches, specialised proteins, essential for the function of glutamate-producing vesicles, were discovered within astrocytic cells. However, their findings went a step further. The molecular structure and profile of these cells were so far diversified from typical astrocytes that they could not be classed as such, and thus had to be considered an entirely new type of cell. This addressed many of the initial research questions.

With presence confirmed, next was the test of whether or not glutamate was actually being released, and at the speed necessary to participate in synaptic transmission. By examining the brains of mice, evidence was found to support both hypotheses, as well as the function of regulation. As Dr Roberta de Ceglia, the first author of the study, puts it: “They are cells that modulate neuronal activity, they control the level of communication and excitation of the neurons.” In other words, these hybrid cells are the pedals in the footwell of the neuron - the brakes, accelerator, and clutch.

The final part of the study focused on what happens when these hybrid cells are inhibited, and the results carry implications for a vast range of brain functions and disorders. Lapses in memory consolidation were seen in mice when these cells were disrupted, suggesting that they play a significant role in the formulation and maintenance of memories. Evidence of a role in brain circuits, that are associated with movement control, was also found. There are even links to pathologies such as epilepsy, with worsening seizures seen as the cells were increasingly disrupted.

These findings open up a wide range of areas for research, especially into neurological disorders and possible therapeutic interventions. If any participatory role of these new cells is found in the development of illnesses, particularly those associated with memory, movement or seizures, we may see a breakthrough in their understanding and potential treatment. Professor Andrea Volterra, a researcher on the study, has already confirmed that “the potential protective role of this type of cell against memory impairment in Alzheimer's disease” will be the focus of their next study. Who knows what else will be uncovered, but with the avenue opened up by the work of this research team, it is sure to be just as incredible.