Journal of Neuroscience, Vol 6, 22-29, Copyright © 1986 by Society for Neuroscience
Is reactive gliosis a property of a distinct subpopulation of astrocytes?
RH Miller, ER Abney, S David, C Ffrench-Constant, R Lindsay, R Patel, J Stone and MC Raff
We have shown previously that the A2B5 monoclonal antibody distinguishes
two types of glial fibrillary acidic protein-containing astrocytes in
semithin frozen sections of adult rat optic nerve: A2B5- (type-1)
astrocytes are found mainly at the periphery of the nerve, where they form
the glial limiting membrane, while A2B5+ (type-2) astrocytes are found
mainly in the interior of the nerve and constitute more than 65% of the
astrocytes in the adult optic nerve. In the present study we show that
although most astrocytes in semithin frozen sections of adult rat corpus
callosum and optic nerve are A2B5+, the great majority of reactive
astrocytes in similar sections of corpus callosum examined 20 weeks after a
stab lesion, and in optic nerve examined 20 weeks after adult transection,
are A2B5-. Although both A2B5+ and A2B5- astrocytes are stimulated to
synthesize DNA in the first week after transection, adult optic nerves
examined 20 weeks after transection contain only half as many astrocytes as
do normal optic nerves: While A2B5+ astrocytes are reduced almost 10-fold,
A2B5- astrocytes are increased by about 25%. We consider the simplest
interpretation of these findings to be that type-1 astrocytes are largely
responsible for forming glial scars in adult white matter following either
a stab lesion or Wallerian degeneration and that in transected optic
nerves, most type-2 astrocytes eventually die, possibly because they depend
on axons for their long-term survival.