Synaptic activity is modulated by the activation of neuromodulator receptors present in dendrites of neurons. The majority of neuromodulator receptors are G protein coupled receptors (GPCRs), in which membrane trafficking regulates their activities. Membrane trafficking of neuromodulator receptors and their signaling occurs on a rapid time scale and emerging studies indicate that neuromodulator receptors function not just from the plasma membrane but also from the endocytic compartments. Here, we describe a live cell imaging approach using spinning disk confocal microscopy to investigate the effect of neuromodulator receptor activation on synaptic activity by measuring calcium dynamics in primary rat striatal neurons. The advantages of spinning disk confocal microscopy and recent improvements in the genetically encoded calcium sensor, GCaMP6, provide an imaging approach to image both the receptor membrane trafficking to endocytic compartments, and calcium dynamics at a high spatial and temporal resolution. We believe this approach of imaging both the neuromodulator receptor membrane trafficking and synaptic activity using GCaMP6 is a powerful tool to address many questions regarding possible roles of membrane trafficking of neuromodulator receptors in synaptic activity.
Keywords: Calcium imaging; Delta opioid receptor; Endocytosis; Genetically encoded calcium sensor (GCaMP6); Live-cell imaging; Neuromodulator receptor trafficking; Spinning disk confocal microscopy.