In vitro phenotypic assays of sensory neuron activity are important tools for identifying potential analgesic compounds. These assays are typically characterized by hyperexcitable and/or abnormally spontaneously active cells. While manual electrophysiology experiments provide high-resolution biophysical data to characterize both in vitro models and potential therapeutic modalities (e.g., action potential characteristics, the role of specific ion channels and receptors), these techniques are hampered by their low throughput. We have established a spontaneously active dorsal root ganglia (DRG) platform using mutil-well multielectrode arrays (MEAs) that greatly increases the ability to evaluate the effects of multiple compounds and conditions on DRG hyperexcitability within the context of a cellular network. We show that spontaneous DRG firing can be attenuated with selective Na+ and Ca2+ channel blockers, as well as enhanced with K+ channel blockers. In addition, spontaneous activity can be augmented with both the TRPV1 agonist capsaicin and the peptide bradykinin, and completely blocked with neurokinin receptor antagonists. Finally, we validated the utility of this assay by demonstrating that commonly used neuropathic pain therapeutics suppress DRG spontaneous activity. Overall, we have optimized primary rat DRG cells on a multi-well MEA platform in order to generate and characterize spontaneously active cultures that has the potential to be used as an in vitro phenotypic assay to evaluate potential therapeutics in rodent models of pain.
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