Summary
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1.
Our previous study demonstrated that cultured macrophages release neurotrophic factors spontaneously. In a histological study of Wallerian degeneration, macrophages phagocytosed myelin debris and expressed activated markers.
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2.
To investigate the role of myelin-stimulated macrophages on neurite regeneration, we prepared conditioned media from cultured mouse peritoneal macrophages which had phagocytosed a myelin fraction. This conditioned media enhanced both neurone survival and neurite regeneration of adult dorsal root ganglia (DRG) neurons compare to conditioned media from macrophage cultures without myelin.
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3.
The production of the neurotrophic supernatant was dose-dependent on myelin fraction and specific for myelin because supernatants from macrophages incubated with LPS (lipopolysaccharide), MDP (N-acetylmuramyl-L-alanyl-D-isoglutamine) or latex beads were not neurotrophic.
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4.
The neurotrophic factors from myelin-stimulated macrophages were different from spontaneously released macrophage factors as they differed in heat-sensitivity.
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5.
These results suggest that myelin-stimulated macrophages contribute to axon regeneration after Wallerian degeneration.
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Hikawa, N., Takenaka, T. Myelin-stimulated macrophages release neurotrophic factors for adult dorsal root ganglion neurons in culture. Cell Mol Neurobiol 16, 517–528 (1996). https://doi.org/10.1007/BF02150231
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DOI: https://doi.org/10.1007/BF02150231