Dizocilpine binding to cerebral cortical membranes from developing and ageing mice

Area of Science:

• Neuroscience
• Neurochemistry
• Developmental Biology

Background:

• The N-methyl-D-aspartate (NMDA) receptor is a crucial ion channel in the central nervous system.
• MK-801 is a non-competitive antagonist that binds to the NMDA receptor's ion channel.
• Understanding NMDA receptor dynamics across the lifespan is vital for neurological research.

Purpose of the Study:

• To characterize the binding of [3H]dizocilpine (MK-801) to NMDA-gated ion channels in mouse cerebral cortex throughout development and aging.
• To investigate age-related changes in NMDA receptor binding capacity (Bmax) and affinity (KD).
• To assess the impact of age on the potentiation of MK-801 binding by glutamate and glycine.

Main Methods:

• Radioligand binding assays using [3H]dizocilpine (MK-801).
• Characterization of binding kinetics (Bmax, KD) in cerebral cortical membranes from mice aged 7 days to 22 months.
• Evaluation of the effects of glutamate and glycine on MK-801 binding across different age groups.

Main Results:

• MK-801 binding was saturable with a single component across all ages.
• Maximal binding capacity (Bmax) was highest at 14 days old, decreased in adults, and further declined with aging.
• Binding affinity (KD) remained stable during development and showed only a slight increase in aged mice.
• Glutamate and glycine potentiation of MK-801 binding was significantly reduced in immature and aged mice compared to young adults.

Conclusions:

• NMDA receptor ion channel binding sites undergo significant changes during mouse lifespan, with a peak in early development and a decline in aging.
• Age-dependent alterations in NMDA receptor function, indicated by reduced glutamate and glycine potentiation, may influence neuronal protection and excitotoxicity.
• The decrease in MK-801 binding sites during aging could be associated with neuronal loss in the cerebral cortex.