Detection of Sensitized Nerve Responses: Dorsal Root Reflexes, Live Cell Calcium, and ROS Imaging

Significant changes in afferent nerve activity and/or neuronal sensitization occur in response to peripheral injury and inflammation. One approach to study of sensitized nerve responses is to record increased peripheral nerve activity in vivo in experimental animal models with electrophysiological recording techniques. Recording of responses of nerves that have been sensitized for at least 30 min reveals development of dorsal root reflex activity, that is, nerve responses that propagate back out to the periphery. This method can also be used to examine the ability of pharmacological agents to reduce sensitization. An alternative to the use of live animals is primary culture models of inflammation. Live cell imaging of fluorescent dye conversion can be utilized to study activation events in dorsal root ganglia harvested from injury models for comparison to cells from controls. Activation responses, including evidence of reactive oxidative/nitroxidative species generation and intracellular calcium mobilization, are increased in sensitized cells and can continue for a prolonged time. These experimental methodologies will be described here and their research utility emphasized.