Age-Dependent Changes in Synaptic NMDA Receptor Composition in Adult Human Cortical Neurons

Area of Science:

• Neuroscience
• Aging Research
• Synaptic Plasticity

Background:

• Cognitive decline with aging is poorly understood at the molecular level.
• Rodent studies link decreased GluN2B-containing N-methyl-D-aspartate receptors (NMDARs) in aging synapses to memory impairment.
• The role of GluN2B-containing NMDARs in human cortical synaptic transmission during aging is unexamined.

Purpose of the Study:

• To investigate the age-dependent contribution of GluN2A and GluN2B-containing NMDARs to synaptic transmission in adult human cortical neurons.
• To determine if GluN2B-containing NMDARs decline with age in the human brain.

Main Methods:

• Analysis of fresh, nonpathological adult human temporal cortical tissue.
• Electrophysiological assessment of synaptic transmission.
• Quantification of NMDAR subunits (GluN2A, GluN2B) and AMPA receptors.

Main Results:

• An age-dependent decrease in the NMDA/AMPA receptor ratio was observed in human temporal cortical synapses.
• GluN2B-containing NMDARs contribute to synaptic responses in the adult human brain.
• The contribution of GluN2B-containing NMDARs diminishes in older individuals.

Conclusions:

• A progressive reduction of GluN2B-containing NMDARs occurs in the aging human brain.
• This decline in synaptic GluN2B may represent a molecular mechanism for age-related cognitive and memory deficits.
• Findings highlight the importance of synaptic GluN2B in maintaining cognitive function throughout the lifespan.