Effect of diabetes on the transcript levels of NMDA receptor subunits. Total RNA extracts were prepared from rat retinas with one, four, and 12 weeks of diabetes (black bars) and from age-matched controls (white bars), and the transcript levels of (A) NR1, (B) NR2C, and (C) NR3A subunits were analyzed by qPCR. The results represent the normalized expression levels for each subunit, as explained in Methods, and are presented as the mean±SEM, for the indicated number of animals. The asterisk indicates a p<0.05, significantly different from control, using the two-tailed Student’s t-test.