Muller Cell Expression of Gliol Fibrillory Acidic Protein offer Genetic ...

No. 11 GFAP IN MULLEP, CELLS / Eisenfeld er d. 1325
tig. 3. Huorescence micrographs of RCS retinas treated with antibodies to GFAP. A, Control section. A 38-day-old retina treated with
preimmune serum. B, A 25-day-old RCS retina. Only astrocytes (—») express GFAP immunoreactivity. C, A 38-day-old RCS retina. Muller
cell processes (—») first stain for GFAP at this age. D, A 6-month-old RCS retina. At this later stage of degeneration, Muller cells (—•) stain
intensely for GFAP. Accumulations of lipofuscin (•) are seen in the pigment epithelium. ON, outer nuclear layer (X576).
(Fig. ID) and at 8 wk when very few photoreceptors
could be found.
In the RCS rat, the GFAP staining was restricted
to the astrocytes until day 32, as seen in control
retinas (Figs. 2B, 3B). Beginning on day 32, an
occasional Muller fiber stained lightly for GFAP.
Muller cell processes throughout the retina were
stained consistently with anti-GFAP only after day
38 (Fig. 3C). At this time the Muller end feet and
innermost Muller radial processes stained most intensely.
As the photoreceptor degeneration progressed,
the number of GFAP positive fibers increased, and
they spanned the retina from the inner to the external
limiting membranes. At advanced stages of degeneration
(6 months; Fig. 3D), the Muller processes were
thickened and very heavily stained.
Characterization of anti-GFAP
In order to ascertain that the protein stained by
anti-GFAP was indeed GFAP, electroblot analysis
was performed on proteins from normal and degenerated
retinas. Results from the anti-GFAP electroblot
experiments are presented in Figure 4. Although