Biology Reference
In-Depth Information
1. Introduction
The term “gliosis” is generally defi ned as the cellular process by
which glial cells in the CNS respond to injury or insult and often
involves the production of a scar. In the most general terms, gliosis
can be used to describe the functional, morphological, biochemi-
cal, and molecular changes that occur in glia (typically microglia
and in astrocytes) in response to injury or disease. However, gliosis
is most associated with the activation of astrocytes in response to
CNS insults. Indeed, a recent review of scientifi c manuscripts listed
in PubMed (
http://www.ncbi.nlm.nih.gov/pubmed/
)
from 2008
to March 2010 showed that for the keywords “gliosis and brain
injury” or “gliosis and spinal cord injury,” 81% of the work evaluated
the astrocyte response to injury (see Fig.
1
). Consequently for the
purpose of this chapter, the discussion of gliosis will be limited to
reactive astrogliosis, or the astrocyte response to injury. Other
chapters review evaluation of microglial activation and immune
responses to CNS injury.
In the adult brain and spinal cord, astrocytes are terminally
differentiated and highly complex cells that serve as active partners
to neurons in normal CNS function. Indeed, astrocytes are essen-
tial in providing energy metabolites to neurons, maintaining
1.1. What is Gliosis?
Fig. 1. Techniques most frequently used to study gliosis in CNS injury. A review of citations in PubMed from January 2008
to March 2010 was conducted using the keywords “gliosis and brain injury” and “gliosis and spinal cord injury” and the
techniques used to evaluate gliosis were tallied. The majority of studies in both traumatic brain injury (TBI) and spinal cord
injury (SCI) use GFAP-immunoreactivity (GFAP-IR) to indicate gliosis. The evaluation of microglial markers was also termed
gliosis. Fewer studies (
dark gray portion
) used techniques other than GFAP-IR.
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