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. Author manuscript; available in PMC: 2006 Jun 7.
Published in final edited form as: Neuron. 2006 Mar 16;49(6):823–832. doi: 10.1016/j.neuron.2006.02.006

Figure 7.

Figure 7.

Astrocytes Promote Myelination in Response to ATP Receptor Stimulation by Releasing LIF (A) A positive effect of astrocytes on myelination was show by supplementing cocultures of DRG neurons and oligodendrocytes with astrocytes. Myelination after 2 weeks in coculture increased in proportion to the percentage of additional astrocytes added 3 hr after plating OPCs on DRG neurons (solid dots). Similar effects were seen in cultures supplemented with astrocytes from mice heterozygous for LIF (open circle). However, supplementing cultures with astrocytes derived from homozygous LIF-/- mice failed to increase myelination (solid triangle). The inability of astrocytes from LIF-/- mice to increase myelination could be restored by adding 0.1 ng/ ml LIF to the cultures (open triangle) (n = 1200 microscope fields). Error bars represent SEM. (B) Eliminating astrocytes from cultures also eliminates the positive effect of 2MeSATP on myelination. This was shown by making co-cultures from O1+ oligodendrocytes purified by immunopanning. Cultures made from mature O1+ oligodendrocytes were still responsive to LIF, as shown by the increase in myelination produced by adding 0.1 ng/ml LIF to these cultures. The positive effect of 100 μM 2MeSATP on myelination could be restored by supplementing these cocultures of O1-positive oligodendrocytes with 8% astrocytes, strongly implicating astrocytes as the primary source of LIF in response to electrical stimulation causing the release of ATP from axons. Double asterisks, p < 0.001; n = 400 microscope fields. Error bars represent SEM.