FIG. 5.

A decrease in βGeo protein levels precedes cell death stimulated by excitotoxins. (A) BluoGal-stained retinal whole mounts harvested from mice at selected time points after intravitreal injection of 160 nmol of the glutamate analog NMDA. BluoGal staining rapidly decreases in the ganglion cell layer after exposure to NMDA. T, temporal; N, nasal; S, superior. (B) Graph comparing the rate of cell loss in the ganglion cell layer (filled circles) to the rate of decrease in βGeo protein (filled squares) after NMDA injection. Cell loss was quantified from histological sections, and protein was quantified using a β-galactosidase ELISA. As seen under the conditions described for optic nerve crushing, the decrease in βGeo transgene expression precedes cell loss in the Rosa3 retina after exposure to NMDA. NMDA injection results in cell loss and reduced βGeo transgene expression more rapidly than optic nerve crushing, but the relationship between protein loss and cell loss is similar.