| Background and ObjectivePreviously we showed that ciliary neurotrophic factor was a potent neurotrophic factor for retinal ganglion cell (RGC) axonal regeneration. We now know that CNTF binds with the CNTF receptor complex (CNTFR-α, gpl30, LIFR-β) to promoted RGC survival and axonal regeneration after injury through JAK/STAT3, PI3K/Akt and MAPK/ERK pathways. We also showed that macrophage activation in eyes promoted both RGC survival and axonal regeneration. Recently, a macrophage-derived factor, oncomodulin, was identified as a most potent molecule known so far in promoting RGC axonal regeneration. Macrophages are known to secrete various cytokines including CNTF. In addition, with the expression of gp130 and LIFR-β, macrophages also can be recruited by CNTFR-α alone or in combination with CNTF. In this study, we investigated whether CNTF acted as a chemotactic factor to attract macrophages into the eyes and whether macrophage is also involved in CNTF-induced RGC survival and axonal regeneration in the optic nerve injury model with multiple drugs including CNTF, Zymosan, U0126, MIF, MSF, liposome and Clodronate.Materials and MethodsBoth in vivo and in vitro experiments were carried out in adult rats. All rats in in vivo experiments received an autologous peripheral nerve (PN) graft onto transected optic nerve (ON) to provide an ideal environment for injured axons to grow. CNTF, MIF, MSF and U0126 were injected intraocularly 3 days after PN-ON procedure and 2 additional injections of the same molecule were followed at 9 and 15 days post PN-ON. Sometimes macrophage "bomb" clodronate liposomes were injected immediately after PN-ON procedure to deplete macrophages in the eyes. To retrograde label the regenerating RGCs, fluorogold (FG) was slowly injected into the distal end of the PN graft three days before the perfusion. The amount of survival and regenerating RGCs and macrophages on the flat mounted retinas were counted after the...
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