Single nanoparticle tracking: A method for investigating the surface dynamics of glutamate receptors

Abstract

The spatiotemporal organization of neurotransmitter receptors within synapses is a critical determinant of synaptic transmission and adaptation, and thus of information processing and storage in the brain. Long considered as immobile at the plasma membrane, glutamate ionotropic receptors—the principal mediators of fast excitatory neurotransmission—are instead highly dynamic. Indeed, the recent development of single molecule imaging techniques has revealed that their number, composition, and distribution at the neuronal surface are constantly regulated through a combination of exo-/endocytosis processes and lateral diffusion in and out of synaptic sites within the membrane plane, allowing a fine control of the intensity of synaptic transmissions. Among these techniques, quantum dot-based single nanoparticle tracking methods provide unique means to explore the surface behavior of individual receptors either in vitro or ex vivo. Here, we describe the experimental procedures to perform single nanoparticle tracking in primary dissociated neuronal cultures, organotypic hippocampal preparations, and acute brain slices. We also provide insights on how these methods can be used to investigate the dynamics of glutamate receptors at the plasma membrane, and to explore their interactions with surface partners.