Upregulation of LIF mRNA in zebrafish RGCs after optic nerve injury.

<p>(A) IL-6 mRNA showed little or no change for at least 20 days after the nerve injury, but CNTF mRNA showed significant downregulation 1–5 days post-injury (dpi; <i>n</i> = 3, *<i>p</i><0.01). The expression level of LIF mRNA drastically increased at 3 dpi (<i>n</i> = 3, *<i>p</i><0.01). (B–E) <i>In situ</i> hybridization revealed very weak expression of LIF mRNA in the intact zebrafish retina (B). At 3 and 5 dpi, LIF mRNA was upregulated mostly in the ganglion cell layer [GCL; weakly in the inner nuclear layer (INL) and photoreceptor layer (PRL)] (C and D, respectively). Incubation with the sense probe yielded no signal even at 3 dpi (E). The scale bar in (B) is 50 µm.