Age-related changes in [3H]MK-801 binding in the Fischer 344 rat brain.
In this study we tested the hypothesis that the efficacy of L-glutamate to stimulate [3H]MK-801 binding to the NMDA receptor/channel complex is altered as a function of aging. L-Glutamate, or related excitatory amino acid (EAA), is the endogenous neurotransmitter of the NMDA receptor/channel complex. These studies examined the efficacy and potency with which L-glutamate produces receptor activation, channel opening and subsequent MK-801 binding as a function of increasing age by comparing dose-response curves (EC50 and Emax) from 6-, 12-, and 24-month-old F-344 rats. The number of NMDA receptors, as determined by [3H]MK-801 binding in the presence of a saturating concentration of L-glutamate, was reduced in the inner frontal cortex, entorhinal cortex and the lateral striatum in aged rats when compared with young adults. When a range of L-glutamate concentrations were used, differences in Emax were noted in the same brain regions in addition to several others in aged and middle-aged animals when compared with young-adult animals. No changes in EC50 values were noted in any of the brain regions at either age when compared with young-adults.
Mitchell
J J
JJ
Department of Neuroscience, University of Florida, Gainesville 32610-0144, USA.
Anderson
K J
KJ
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D001923:Brain Chemistry / Q000502:physiology*; D002452:Cell Count; D016291:Dizocilpine Maleate / Q000378:metabolism*; D018728:Entorhinal Cortex / Q000166:cytology / Q000378:metabolism; D006207:Half-Life; D008297:Male; D017072:Neostriatum / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D017397:Prefrontal Cortex / Q000166:cytology / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism
D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate