Journal of Neuroscience, Vol 9, 3371-3379, Copyright © 1989 by Society for Neuroscience
Type 1 astrocytes inhibit myelination by adult rat oligodendrocytes in vitro
CL Rosen, RP Bunge, MD Ard and PM Wood
Miami Project, University of Miami School of Medicine, Florida 33136.
We have determined the effect of Type 1 astrocytes on the myelination of
dorsal root ganglion cell axons by oligodendrocytes obtained from adult
animals. Experiments were initiated by the addition of oligodendrocytes
[purified either by density gradient centrifugation and treatment in
culture with 5-fluorodeoxyuridine (FdU) or by fluorescence-activated cell
sorting after immunostaining with antigalactocerebroside antibody] to
cultures of purified neurons. In control conditions, the added
oligodendrocytes proliferate and, after 4 weeks, accomplish substantial
myelination of the sensory axons. Type 1 astrocytes (purified from cultures
of dissociated newborn rat cerebral cortex by vigorous shaking to remove
less adherent cells) or fibroblasts (purified from cultures of cranial
periosteum by serial replating) were added to some of these cultures after
the oligodendrocytes had attached and started to proliferate. We observed
that the added Type 1 astrocytes, but not the added fibroblasts, strongly
inhibited myelination and caused decreased oligodendrocyte proliferation or
survival. These effects of added Type 1 astrocytes were reproduced with
Type 1 astrocyte-conditioned medium. We conclude that Type 1 astrocytes can
release soluble factors that inhibit oligodendrocyte myelination.