Figure 4. Resistance of OPN4-positive cells against N-methyl-D-aspartic acid toxicity does not depend on genetic background, pigmentation or presence of photoreceptor cells. A: Shown is the relative expression of Brn3a and Opn4 mRNAs in retinas of 6 week old albinotic CD1 wild type mice at 6 days after injection of N-methyl-D-aspartic acid (NMDA, black bars) or phosphate buffered saline (PBS, grey bars). B: Shown is the relative expression of Brn3a and Opn4 at 6 days after injection of NMDA (black bars) or PBS (grey bars) in rd10 mice at 20 days of age. C: Shown is the relative expression of Brn3a and Opn4 at 6 days after injection of NMDA (black bars) or PBS (grey bars) in rd10 mice at 6 months of age. Gene expression after NMDA injection was expressed relative to expression after PBS injection, which was set to 1. Shown are means±SD of n=4-10. *: p<0.05; **: p<0.01; ***: p<0.001. Statistical tests used were A: unpaired two-tailed Student t test, and B-C: two-way ANOVA with Bonferroni post hoc test.