N-methyl-D-aspartate receptor binding in brains of rats at different ages

Potential age differences in N-methyl-D-aspartate (NMDA) receptor binding were evaluated in rat brain using [H-3]dizocilpine and [H-3]D,L-(E)-2-amino-4-propyl-5-phosphono-3-pentanoic acid (CGP 39653) as the radioligands. Neither [H-3]dizocilpine nor [H-3]CGP 39653 binding in hippocampus revealed any age difference (7 vs. 23-25 months) in B-max or K-d. High-affinity [H-3]dizocilpine binding showed a developmental increase (8 vs. 2 months) in hippocampus but not in frontal cortex. No senescence-related change (25 vs. 8 months) was observed in either region. The lack of senescence-related differences in these biochemical markers does not preclude the possibility of functional changes in the NMDA receptor with aging. Published by Elsevier Science Inc.