Figure 3. Neurofilament expression can be induced in Müller glia by insulin and FGF2

Exogenous insulin and FGF2 induces the expression of neurofilament in Müller glia in peripheral regions of the retina. Vertical sections of the peripheral retina were labeled with antibodies to neurofilament (NF-M). Retinas were obtained from eyes that were injected with 3 doses of saline (A), insulin alone (B), FGF2 alone (C), insulin and FGF2 (D,E,F). Injections were made at postnatal day 7 (P7), P8, and P9. Retinas were dissected and processed for immunocytochemistry 24 h (A-D,F) or 4 days (E) after the last injection. F is a high power field of view of retina that demonstrates neurofilament-expressing Müller glia-like cells. Arrows indicate neurofilament immunoreactive cells with the morphology of Müller glia. The calibration bar in E represents 50 μm and applies to A-E; the bar in F represents 50 μm. ONL indicates the outer nuclear layer; INL indicates the inner nuclear layer; IPL indicates the inner plexiform layer; NFL indicates the nerve fiber layer. G is a histogram demonstrating the number of Müller glia, neurofilament-expressing cells in the peripheral retina from eyes treated with combinations of exogenous insulin and FGF2. H is a plot demonstrating that the number of neurofilament-immunoreactive cells in the retina increases between 6 and 48 h after the final injection of insulin and FGF2, but decreases thereafter. ANOVA was done to determine significance (p<0.005) of difference among the data sets and a post hoc two tailed Student's t-test used to determine significance (asterisk is p<0.005) of difference between the mean numbers of neurofilament positive Müller glia in insulin treated retinas and those treated with FGF2 alone, insulin combined with FGF2, and insulin combined with EGF.