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Abstract
Cerebral astrocytes are known to show a region-specific phenotype, concerning the
expression of several receptors and the synthesis of secreted substances. In order
to find out whether this heterogeneity also exists for the immunological activation,
we studied several parameters that are known to characterize activated astroglia on
cultured primary rat astrocytes originating from cortex, hippocampus, striatum, septum
and brain stem: major histocompatibility complex (MHC) class II and intercellular
adhesion molecule (ICAM)-1 expression, nitric oxide (NO) production and interleukin-6
(IL-6) synthesis. Unstimulated cultures show a baseline expression of MHC class II
molecules that differs from one region to another, hippocampus and brain stem showing
the highest values. These differences are strongly enhanced after a 48-h incubation
with gamma-interferon (gamma-IFN). NO production is also induced by a 72-h incubation
with gamma-IFN, showing similar patterns of regional specialization. The baseline
expressions of ICAM-1 and IL-6 also show major regional differences, with the brain
stem and the striatum showing elevated values for ICAM-1, and the septum and the brain
stem producing the largest amounts of IL-6. The expressions of ICAM-1 and IL-6 are
not affected by an incubation with gamma-IFN. Our results demonstrate that the immunological
activities of astroglial cells show regional heterogeneities. This specialization
may be implicated in the pathophysiological pathways of several neurodegenerative
disorders.