Effect of diabetes on the transcript levels of AMPA receptor subunits. Total RNA was isolated from rat retinas with one, four and 12 weeks of diabetes (black bars) and from rat retinas of age-matched controls (white bars). The transcript levels of (A) GluR1, (B) GluR2, (C) GluR3, (D) GluR4 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.