Astrogliosis
Encyclopedia
Astrocytosis is an abnormal increase in the number of astrocyte
Astrocyte
Astrocytes , also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord...

s due to the destruction of nearby neurons, typically because of hypoglycemia
Hypoglycemia
Hypoglycemia or hypoglycæmia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood"...

 or oxygen deprivation (hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...

).

It usually takes place in prion infections. It is especially prevalent in fatal familial insomnia
Fatal familial insomnia
Fatal familial insomnia is a very rare autosomal dominant inherited prion disease of the brain. It is almost always caused by a mutation to the protein PrPC, but can also develop spontaneously in patients with a non-inherited mutation variant called sporadic fatal insomnia...

, a prion infection affecting the thalamus and circadian rhythms.

This manifests as astrocytic edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

, hypertrophy, proliferation, and increased motility.

In the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

, the proliferation of reactive astrocytes also leads to the formation of a glial scar
Glial scar
Glial scar formation is a reactive cellular process involving astrogliosis that occurs after injury to the Central Nervous System. As with scarring in other organs and tissues, the glial scar is the body's mechanism to protect and begin the healing process in the nervous system...

.

Astrogliosis is a major pathological finding in Amyotropic Lateral Sclerosis (ALS).
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