Astrocytes: Builders Of Nerve Pathways

Astrocytes, a type of brain cell, are the main components of a group of glial cells. Previously underestimated, today we know their significance.

Astrocytes are part of a group of glial cells. Their significance has been questioned over time. First, experts underestimated their function, since the overall relevance was to transport the neurons. However, it has been shown that they do not just complete a passive function, and their work is not just to replenish neurons.

In fact, these types of glial cells are responsible for constructing nerve pathways and other functions such as:

• to guide neurons during migration
• cause the formation of hematoencephalic levels
• the metabolic support of the neurons
• cooperation in neuron generation

As you can see, there is a lot to learn and know about astrocytes. For example, it is surprising how they react to neural activity, how they repair themselves and the communication they have. Let’s dive deeper into this.

Types of astrocytes

Astrocytes completely surround the brain capillaries and form a physical barrier between the blood and the neurons. They contain different typologies that generate different variants.

• Protoplasmic astrocytes. Located in the gray matter. They have the shape of a sphere with branches that extend to other branches that are irregular and curved. The outer branches cover the blood vessels, the meninges and the synapses.
• Fibrous astrocytes. Located in the white matter. They are long and thin and without branches, in the form of fibers. Their ends wrap around the Ranvier constrictions of the axons and blood vessels.

As a curiosity, the ends of the astrocytes that form these cells resemble the shape of a star. They are extensions that go over the neighboring cells.

In addition, astrocytes have a protein called glial fibrillar acidic protein in the cytoskeleton. This is the characteristic that makes them different, since they only exist in this type of cell.

Features

Astrocytes construct the pathways for the transmission of information in your brain. Thanks to the neural connections they deliver, they are responsible for guiding the way the axons perform. This is achieved through the molecules that attract or repel.

As good builders, astrocytes are aware of what is happening in the nervous system. Because of this, they take on the task of balancing neurons or brain homeostasis. Due to this function, they act as metabolic support, which is obtained through the preservation of ionic balance in the nerve cells.

In addition to performing all of the above tasks, astrocytes participate in the maturation and maintenance of synapse neurons. In addition, they provide oxygen, nutrients and protective insulation to the neurons.

However, using a process known as phagocytosis, these cells are able to eliminate residues from brain metabolism. As a result, this process is beneficial since it allows the disposal of waste and pathogens. They can also be eliminated by transporting the remains to the bloodstream. Furthermore, when a stroke occurs, the astrocytes travel to the lesion to get rid of the dead neurons.

On the other hand, they form part of the very important hematoencephalic barrier, which transforms them into an intermediary between the circulatory system and the neurons as a filtering mechanism. Therefore, they are also responsible for regulating the path of molecules from the blood to the brain.

Astrocytes are linked to neurotransmitters because they react to them in an active way and have receptors that combine with them. This is a real method of communication of this type of glial cells that is supplemented by another way of sending messages to isolate the space in the synaptic junctions and act as signal modulators between neurons.

Astrocytes and reactive gliosis

It is a pathological process that increases the rapid and excessive number of astrocytes. This process follows the inflammatory phenomena and is called reactive gliosis.

Researchers have found two types of astrocytes when it is this type of spread : A2, which has repair functions, and A1, which causes the breakdown of nerve tissue.

Reactive gliosis occurs when there is a lesion in the nervous system. Then it is accompanied by a spread of these cells in the regions where the damage takes place. In fact, many studies have shown this phenomenon.

What facilitates this and what does not?

The reactive gliosis is beneficial because it creates a synthesis of neurotrophic factors that are responsible for the survival of the neurons. On the other hand, it is harmful because it creates a glial scar that forms a barrier to axon growth.

This phenomenon is important in clinical trials, as it offers hope for new therapeutic models. For example, experts study stem cell transplants using neurotrophic factors that promote neural regeneration. In fact, there are studies to find cures for neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease.

What makes them good builders of the nervous system?

Astrocytes are responsible for establishing communication points between different cells and the nervous system. In addition to being responsible for isolating and eliminating harmful substances, they fight brain damage. They also allow the re-establishment of these communication paths.

Astrocytes are prepared to create connections between different areas and anatomically-functional elements. This will be, for example, the circulatory system, and the hematoencephalic barrier, between the neurons themselves and with the brain’s neurotransmitters. In addition, they are exceptional when it comes to maintaining nerve pathways. This is because they cause the nervous system to maintain its internal balance.

From all these findings, our hope is that neuroscience will continue to study these cells and their potential use. This will pave the way for new advances related to this type of glial cells.