Age-related alterations of NMDA-receptor properties in the mouse forebrain: partial restoration by chronic phosphatidylserine treatment.
The effect of aging on the properties of N-methyl-D-aspartate (NMDA) receptors in the forebrain of female NMRI mice was investigated using the antagonist [3H]MK-801 as radioligand. Compared to young (3 months) mice, aged (20 months) mice showed changes of the properties of the NMDA receptor at three different levels: (1) the density was reduced by about 35%; (2) the efficacy of L-glutamate and glycine for stimulating specific [3H]MK-801 binding was enhanced, probably because more NMDA receptor-associated ion channels are closed under baseline conditions in the aged brain; (3) the affinity of L-glutamate and glycine to its binding sites at the NMDA receptor complex was also enhanced. Chronic treatment of aged mice with phosphatidylserine (20 mg/kg, i.p., once daily) for three weeks completely normalized enhanced efficacy and affinity of L-glutamate and glycine and elevated NMDA receptor density by approximately 25%. These findings are consistent with the assumptions that deficits of the NMDA receptor are one of the mechanisms of age-related cognitive impairment and that the beneficial effects of phosphatidylserine treatment on cognitive deficits of aged individuals might be partially due to the effects of this drug on age-related NMDA receptor deficits.
Cohen
S A
SA
Department of Psychopharmacology, Central Institute of Mental Health, Mannheim, FRG.
Müller
W E
WE
D000375:Aging / Q000378:metabolism*; D000818:Animals; D016291:Dizocilpine Maleate / Q000378:metabolism; D005260:Female; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D005998:Glycine / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D010718:Phosphatidylserines / Q000494:pharmacology*; D016548:Prosencephalon / Q000187:drug effects / Q000378:metabolism*; D011869:Radioligand Assay; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects* / Q000378:metabolism
D005971:Glutamates; D010718:Phosphatidylserines; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D016291:Dizocilpine Maleate; D005998:Glycine