Astrocytes, star cells with unexpected powers

Even today, if we talk about brain cells, the term “neurons” is the one that generally comes to mind. However, astrocytes – which belong to the glial cell group – also populate our brain in their tens of billions! If it’s often forgotten, it’s because researchers didn’t give it much importance until very recently, viewing it as a simple physical link between neurons. Now, scientists are studying these cells, whose functions are more complex than they appear.

For several years, they have been arguing about their possible role in neural communication. Astrocytes actually have extensions that encase synapses, the connections between neurons. However, at the level of these communication areas, chemical messages, neurotransmitters, are emitted from one nerve cell to another. In other words, astrocytes are located at a strategic point in transmitting information. An indication that they certainly play a role in this process. At least that’s what some specialists say; These cells would have the ability to release glutamate, the brain’s main excitatory neurotransmitter, which until now was thought to be released by neurons alone. Conversely, other researchers dispute this hypothesis. Today, a recent study was published in the journal nature Identifies a type of astrocyte capable, like neurons, of releasing glutamate and thus influencing… Communication between neurons. Which closes a debate that has been going on for several years.

To achieve this result, Roberta Di Ceglia and her team from the Department of Basic Neuroscience at the University of Lausanne demonstrated that, within astrocytes (from mice but also from humans), there are vesicles – small membrane pockets – necessary for glutamate transport. how ? This is thanks to advanced technology in molecular biology that allowed them to identify the proteins specific to these vesicles. Conclusion: There is a cellular mechanism in some astrocytes responsible for secreting this neurotransmitter, and it is identical to that found in neurons!

But can we be sure that this machine is working? The answer is yes; The researchers were able to visualize the release of the neurotransmitter as well as its essential role in neural communication. What are the implications for our understanding of brain function and the management of neurological diseases? The fact is that dysfunction of astrocytes can affect a large number of neural circuits, especially in the case of brain disorders. In fact, after blocking the functioning of these cells in mice, the team noticed that their memory underwent changes; In particular, they had very little memory of what they had learned the previous day. The neurobiologist also showed the possible role of these cells in the occurrence of epileptic seizures, as the frequency of the latter increases after changing astrocytes in mice…

With these discoveries, we can now say that these cells live up to their name (“astro” for star and “cyte” for cell), they are true stars of the brain and represent real therapeutic hope!