GRIN2A and Alzheimer disease: Since the NR2A subunit becomes more prevalent in adulthood and with advanced aging (Cui et al., 2013) but is markedly attenuated in the autoptic cortical or hippocampal regions of people with AD (e.g., Hynd et al., 2004), our results of increased NR2A expression in the frontal cortex of Samaritan rats could be thus interpreted via the animal model mimicking early rather than terminal stages of AD.