Age-related deficits in the expression of NMDA receptor subunits. Relative expression of NR2B protein between young and aged groups reveals a significant age-related decrease [37.5% reduction aged/young; number of animals: n = 38/14;p = 0.002, ANOVA with Fisher's protected least significant difference (PLSD) post hoc test]. A significant age-related decrease in NR1 levels is also found (25.2% reduction aged/young; number of animals: n = 38/14;p = 0.01, ANOVA with Fisher's PLSD post hoc test) that is not found in the relative expression of NR2A, GluR1, GluR2, or synapsin (p = 0.35;p = 0.44; p = 0.72;p = 0.98, respectively). Asterisksdesignate significant (<0.05) p values.