Introduction

The reactive gliosis, sometimes called Astrogliosis or simply Gliosis is refered to a physiological process appearing as a result of damage to the CNS (eg. traumatic brain Injury “TBI”, ischemia, neurodegenerative diseases). Reactive gliosis is as response by glial cells, mainly astrocytes, reacting to an injury and can be reviewed as a healing process. After a CNS injury, the astrocytes around the lesion respond to injury and undergo a typical change of hyperthrophy. These reactive astrocytes are gradually intergrated and form a physical barrier, commonly refered to as glial scar.

Glial Cells

The brain tissue contain two categories of cells, nervous cells and glial cells or, neuroglia. Glial cells are about 10-50 time more numerous than nerve cells and are involved in processes like:

Supply nutrients and oxygen

Following glial cells are the main cells involved in reactive gliosis:

´´´Astrocytes´´´

This is the most abundant glial cell type in the CNS. There two different types of astrocytes according to their location and morphology: protoplasmic astrocytes with characteristic branched processes, which are mainly found in the grey matter, and fibrous astrocytes found mainly in the white matter with fiber-like processes. Astrocytes act as the main regulator of the CNS to sustain homeostatic environment, which is a nessesity for regular neurological cell activity. This includes the ionic concentration regulation and secretion and degeneration of neurotransmitters. Astrocytes are connected to eachother through gap junctions forming a network called astrocyte syncytium which enables them to directly communicate which eachother. They also interact as a bidirectional bridge between the neurons and bloodstream. One of the functions of this communication is energy supply of the neurons, astrocytes is therefore highly related with the neuronal metabolism. Glucose and it´s metabolites are transmitted from the blood to the neurons and neighbouring through glucose transporters. Another function related to its close situation with blood vessels it the aid of the blood brain barrier. Astrocytes take part in numerous actions of the brain and the view and describtion of it´s functions have changed over time along with knowledge and research to a cell type with much more and advanced functions than earlier believed.