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Retinoic acid application affects optic nerve microglia and macrophages after optic nerve injury in frog Rana pipiens
Author(s) -
De La RosaReyes Valeria,
Duprey Mildred V.,
Blagburn Jonathan M.,
Blanco Rosa E.
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.450.6
Subject(s) - optic nerve , axotomy , retinoic acid , microglia , pathology , wallerian degeneration , immunocytochemistry , medicine , microbiology and biotechnology , biology , anatomy , regeneration (biology) , immunology , inflammation , biochemistry , gene
Retinoic acid (RA) plays major roles during nervous system development. We have previously shown that RA signaling pathway components are upregulated after optic nerve injury and that exogenous application of RA improves the long‐term survival of axotomized retinal ganglion cells to more than 90%. In addition, there is some evidence that RA may be a factor involved in the induction of phagocytic macrophages, promoting the production of pro‐repair chemokines that could play a role in successful regeneration. The objective of the present study is to determine the effects of RA application on the macrophage populations in the optic nerve after injury. We performed optic nerve crush and applied into the nerve either saline solution or retinoic acid. We examined the optic nerves at 48h, one week, and two weeks after axotomy with immunocytochemistry and electron microscopy. Electron microscope studies of the proximal, injury, and distal sites of the optic nerves show macrophages filled with secondary lysosomes and residual bodies. Immunocytochemistry of various macrophage subtypes was carried out followed by confocal microscopy. Our results indicate that application of RA to the optic nerve causes a significant increase in the number of macrophages and microglia present one week after optic nerve injury. Most cells were CD68‐positive in saline‐ and RA‐treated nerves. We also identified activated microglia (Iba1‐positive) and a sub‐population of anti‐inflammatory M2 macrophages (arginase‐positive) at the injury and distal sites. In conclusion, the application of RA affects the number and the distribution of macrophages after optic nerve injury and it may play a role in the success of optic nerve regeneration. Support or Funding Information REB is supported by NIH grant GM116692, JMB by NIH grant NS081726 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .