Advancing Pain Research Methodologies
High-Throughput Analysis of Neuronal Activity
Traditional methods of whole-cell patch-clamp recording of neurons are invasive and time consuming. We are applying high-throughput methodologies to rapidly assess neuronal excitability without compromising neuronal integrity. These methodologies are enabling us to rapidly capture intricate details of neuronal excitability rendered by sodium channel mutations derived from various pathological states, and identify personalized treatment approaches that would be most effective in the context of a patient’s unique genetic blueprint. For example, our application of multi-electrode array technology enabled us to successfully tailor a treatment strategy for pain in a patient with inherited erythromelalgia. We are developing novel approaches not only to recreate “pain-in-a-dish” but also to rapidly measure excitability, intracellular calcium transients and membrane potential in neurons expressing various mutant sodium channels, and thus accelerating the pace toward improved genomically guided therapies for pain.
Molecular Tracking of Sodium Channels in Neurons
In order to induce remissions in pathologies where myelin insulation is damaged, we need to first understanding how excitable membranes are built. Our early studies revealed sodium channel reorganization as the molecular basis for remissions in multiple sclerosis, and that recovery of function in demyelinating conditions can be achieved when sufficient numbers of sodium channels are deployed to regions of bared axonal membrane to support action potential conduction (Foster et al.,1980; Hume and Waxman, 1988). Our ongoing studies probe the assembly of sodium channels into the neuronal membranes to understand how, when and where sodium channels are mobilized into action. For example, we have applied optical pulse chase and single molecular tracking to observe the path of Nav1.6 sodium channels as they make their way from their synthesis in the endoplasmic reticulum to distant locations along the neuronal membrane. Our studies revealed that mature Nav1.6 channels are preferentially inserted into the axon initial segment membrane via direct vesicular trafficking, and that channels delivered to the axon are immediately inserted into the axonal membrane, where as channels delivered to the soma are often mobile (Akin et al., 2015). We are optimistic that these studies will ultimately lead to strategies that can control the process of remissions in pathologies of demyelination such as multiple sclerosis and spinal cord injury.