The Journal of Neuroscience, September 15, 2001, 21(18):7182-7193
Astrocytes from Cerebral Cortex or Striatum Attract Adult Host
Serotoninergic Axons into Intrastriatal Ventral Mesencephalic
Co-Grafts
Audrey
Petit,
Philippe
Pierret,
Annie
Vallée, and
Guy
Doucet
Département de Pathologie et Biologie Cellulaire and Centre
de Recherche en Sciences Neurologiques, Faculté de
Médecine, Université de Montréal, Montréal,
Québec, Canada H3C 3J7
The identification of axon growth inhibitory molecules offers new
hopes for repair of the injured CNS. However, the navigational ability
of adult CNS axons and the guidance cues they can recognize are still
essentially unknown. Astrocytes may express guidance molecules and are
known to have different regional phenotypes. To evaluate their
influence on the affinity of adult serotoninergic (5-HT) axons for a
projection target, we co-implanted astrocytes from the neonatal
striatum, cortex, or ventral mesencephalon together with fetal ventral
mesencephalic tissue into the striatum of adult rats. Two months after
surgery, quantification after in vitro 5-[1,2-3H]serotonin ([3H]5-HT)
uptake and autoradiography showed that ventral mesencephalic grafts
with co-grafted cortical or striatal astrocytes were four times and
three times, respectively, more densely innervated by host 5-HT axons
than control ventral mesencephalic grafts with or without co-grafted
ventral mesencephalic astrocytes. Immunohistochemistry for glial
fibrillary acidic protein, vimentin, or chondroitin-sulfate proteoglycans revealed no qualitative or quantitative differences in
host astroglial scar or production of inhibitory molecules that could
explain these differences in 5-HT innervation. These results
demonstrate that astrocytes grown in culture from different brain
regions have the potential to influence the growth and maintenance of
adult 5-HT axons in a graft of neural tissue from another brain region.
It should now be feasible to identify the molecules expressed by
cultured cortical or striatal, but not by ventral mesencephalic, astrocytes that have these tropic actions on 5-HT axons of the neostriatum.
Key words:
axon guidance; regeneration; astrocyte; neural
transplantation; cell culture; serotonin neurons; neostriatum; substantia nigra
Copyright © 2001 Society for Neuroscience 0270-6474/01/21187182-12$05.00/0