TY - JOUR
T1 - Effects of aging and caloric restriction on dentate gyrus synapses and glutamate receptor subunits
AU - Newton, Isabel G.
AU - Forbes, M. Elizabeth
AU - Linville, M. Constance
AU - Pang, Hui
AU - Tucker, Elizabeth W.
AU - Riddle, David R.
AU - Brunso-Bechtold, Judy K.
N1 - Funding Information:
This work was supported by National Institute on Aging grants AG11370 and AG019886 (J.K.B.-B. and D.R.R.). It was completed in partial fulfillment of the requirements for the Ph.D. degree in the Department of Neurobiology and Anatomy, Wake Forest University School of Medicine (I.G.N.). We thank Ashley Long and Dr. Lei Shi for assistance with statistical analysis and Dr. Michelle Adams for critical reading of the manuscript.
PY - 2008/9
Y1 - 2008/9
N2 - Caloric restriction (CR) attenuates aging-related degenerative processes throughout the body. It is less clear, however, whether CR has a similar effect in the brain, particularly in the hippocampus, an area important for learning and memory processes that often are compromised in aging. In order to evaluate the effect of CR on synapses across lifespan, we quantified synapses stereologically in the middle molecular layer of the dentate gyrus (DG) of young, middle aged and old Fischer 344 × Brown Norway rats fed ad libitum (AL) or a CR diet from 4 months of age. The results indicate that synapses are maintained across lifespan in both AL and CR rats. In light of this stability, we addressed whether aging and CR influence neurotransmitter receptor levels by measuring subunits of NMDA (NR1, NR2A and NR2B) and AMPA (GluR1, GluR2) receptors in the DG of a second cohort of AL and CR rats across lifespan. The results reveal that the NR1 and GluR1 subunits decline with age in AL, but not CR rats. The absence of an aging-related decline in these subunits in CR rats, however, does not arise from increased levels in old CR rats. Instead, it is due to subunit decreases in young CR rats to levels that are sustained in CR rats throughout lifespan, but that are reached in AL rats only in old age.
AB - Caloric restriction (CR) attenuates aging-related degenerative processes throughout the body. It is less clear, however, whether CR has a similar effect in the brain, particularly in the hippocampus, an area important for learning and memory processes that often are compromised in aging. In order to evaluate the effect of CR on synapses across lifespan, we quantified synapses stereologically in the middle molecular layer of the dentate gyrus (DG) of young, middle aged and old Fischer 344 × Brown Norway rats fed ad libitum (AL) or a CR diet from 4 months of age. The results indicate that synapses are maintained across lifespan in both AL and CR rats. In light of this stability, we addressed whether aging and CR influence neurotransmitter receptor levels by measuring subunits of NMDA (NR1, NR2A and NR2B) and AMPA (GluR1, GluR2) receptors in the DG of a second cohort of AL and CR rats across lifespan. The results reveal that the NR1 and GluR1 subunits decline with age in AL, but not CR rats. The absence of an aging-related decline in these subunits in CR rats, however, does not arise from increased levels in old CR rats. Instead, it is due to subunit decreases in young CR rats to levels that are sustained in CR rats throughout lifespan, but that are reached in AL rats only in old age.
KW - AMPA
KW - Dietary restriction
KW - Fischer 344 × Brown Norway rat
KW - GluR1
KW - GluR2
KW - Hippocampus
KW - Lifespan
KW - NMDA
KW - NR1
KW - NR2A
KW - NR2B
KW - Stereology
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U2 - 10.1016/j.neurobiolaging.2007.03.009
DO - 10.1016/j.neurobiolaging.2007.03.009
M3 - Article
C2 - 17433502
AN - SCOPUS:47049084692
SN - 0197-4580
VL - 29
SP - 1308
EP - 1318
JO - Neurobiology of aging
JF - Neurobiology of aging
IS - 9
ER -