Electrophysiological studies have demonstrated that increases in the excitability of amygdala neurons correlate with persistent pain, suggesting that hyperexcitability of neurons in the amygdala plays a critical role in the modulation of pain-related behaviors. The waveforms of action potentials and the repetitive firing properties of neurons are determined by the repertoire of ion channels expressed. Determining the functional expression patterns, the molecular identities and the physiological roles of key voltage-gated ion channels in amygdala neurons is, therefore, an important first step towards understanding the mechanisms that regulate the intrinsic excitability of these cells and the modulation of pain-related behaviors. This project aims at addressing these questions directly by performing whole-cell voltage- and current-clamp experiments in visually identified amygdala neurons in acute mouse brain slices. Pharmacological approaches to block different types of voltage-gated ion currents selectively are used in combination with electrophysiological experiments to define the specific conductance pathways affected and the functional roles of these ionic conductances in regulating the excitability in amygdala neurons. Genetic disruption and acute knockdown approaches are used to define the molecular identities and physiological roles of the individual subunits encoding the functionally distinct voltage-gated ion currents in these cells. Parallel western blot and immunohistochemical experiments aim at examining the expression pattern of various ion channel subunits as well as endogenous molecular signaling proteins in amygdala neurons at different time points following injury. Further experiments aim at evaluating the physiological roles of individual molecules on long-term changes in distinct sensory and affective behaviors following injury. This is the first year of this project and it has been taking place while in the process of setting up a new laboratory. The accomplishments during this year include ordering, receiving and setting up equipment for electrophysiological, confocal imaging, biochemical and behavioral experiments as well as hiring and training staff. We have been able to successfully run preliminary experiments for the proposed aims. In addition, Gary Soroosh, a summer intern in our lab, successfully completed a project in collaboration with Jon Macleod (postbac IRTA) and presented a poster with their findings at the 2014 NIH Summer Poster Day. We have also worked on a new Animal Study Protocol (ASP) and identified potential internal and external collaborations.
