Changes in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunit mRNA across dark and light phases in rat OB. Line plots of (A) GluR1, (B) GluR2, (C) GluR3, and (D) GluR4 mRNA expression over 48-h. Sample size and notation as in Fig. 1. GluR1, GluR2, and GluR3 mRNA changes were statistically significant across the 48-h (Kruskal–Wallis H test, P < 0.05) but only GluR1 was rhythmic for both 24-h periods (harmonic regression analysis, P < 0.05). GluR1 and GluR4 were rhythmic according to JTK_CYCLE analysis (P < 0.05).