title: Hydrocortisone stimulates neurite outgrowth from mouse retinal explants by modulating macroglial activity.
abstract: OBJECTIVE
  There is mounting evidence that retinal ganglion cells (RGCs) require a complex milieu of trophic factors to enhance cell survival and axon regeneration after optic nerve injury. The authors' goal was to examine the contribution of components of a combination of hormones, growth factors, steroids, and small molecules to creating a regenerative environment and to determine if any of these components modulated macroglial behavior to aid in regeneration.
  
  
  METHODS
  Postnatal day 7 mouse retinal explants embedded in collagen were used as an in vitro model of neurite regeneration. Explants were treated with the culture supplements fetal bovine serum, N2, and G5 and a mixture of G5 and N2 components, designated enhanced N2 (EN2). Explants were evaluated for neurite outgrowth over 7 days in culture. The effects of each treatment were also evaluated on cultured RGCs purified by Thy1 immunopanning. Immunohistochemistry and qPCR analysis were used to evaluate differences in gene expression in the explants due to different treatments.
  
  
  RESULTS
  EN2 stimulated significant neurite outgrowth from explants but not from purified RGCs. Elimination of hydrocortisone (HC) from EN2 reduced the mean neurites per explant by 37%. EN2-treated explants demonstrated increased expression of Gfap, Glul, Glt1, Cntf, Pedf, and VegfA compared with explants treated with EN2 without HC. Subsequent experiments showed that increased expression of Cntf and Glul was critical to the trophic effect of HC.
  
  
  CONCLUSIONS
  These data suggest that the HC in EN2 indirectly contributed to neurite outgrowth by activating macroglia to produce neurotrophic and neuroprotective molecules.
authors.affiliation: Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Toops
authors.forename: Cynthia
authors.initials: C
authors.lastname: Berlinicke
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Zack
authors.forename: Robert W
authors.initials: RW
authors.lastname: Nickells
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002470:Cell Survival; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006854:Hydrocortisone / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000378:metabolism*; D009409:Nerve Crush; D009414:Nerve Growth Factors / Q000494:pharmacology; D009416:Nerve Regeneration / Q000502:physiology*; D016501:Neurites / Q000502:physiology*; D020221:Optic Nerve Injuries / Q000503:physiopathology; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D012160:Retina / Q000187:drug effects / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D009414:Nerve Growth Factors; D012333:RNA, Messenger; D006854:Hydrocortisone