AGING OF GLUTAMATE RECEPTORS - CORRELATIONS BETWEEN BINDING AND SPATIAL MEMORY PERFORMANCE IN MICE

C57B1/6 mice aged 3, 10, and 26 months were tested for spatial learnin g in the Morris water maze. Ten and 26 month old mice were ad libitum- fed or diet restricted (60% of ad libitum-fed calories). Diet restrict ion significantly improved memory performance among the 10 and 26 mont h olds. In age/diet group comparisons, aged ad libitum-fed mice had si gnificantly higher average proximity scores, indicating poorer perform ance, in probe trials for place learning than the 3 month olds and die t restricted 10 month olds. Diet restricted 26 month olds did not diff er significantly from 3 month olds or any other groups in probe trial measures. The group means for average proximity scores were significan tly correlated with binding densities for the iv-methyl-D-aspartate (N MDA) subtype of glutamate receptors in the frontal cortex and CA1 regi on of the hippocampus. ha-Amino-3-hydroxy-5-methyl-4-isoxazoleproprion ate (AMPA) binding correlated with group proximity scores in frontal a nd parietal cortices and within the CA1 and CA3 regions of the hippoca mpus. Kainate and metabotropic binding sites showed no significant cor relations with behavior. These results suggest that there is a sparing of spatial memory with diet restriction in aging C57B1/6 mice and tha t the effects of aging on NMDA and AMPA receptors map be associated wi th age-related declines in spatial learning. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.