Nature medicine
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Glutamatergic signaling and intracellular calcium mobilization in the spinal cord are crucial for the development of nociceptive plasticity, which is associated with chronic pathological pain. Long-form Homer proteins anchor glutamatergic receptors to sources of calcium influx and release at synapses, which is antagonized by the short, activity-dependent splice variant Homer1a. We show here that Homer1a operates in a negative feedback loop to regulate the excitability of the pain pathway in an activity-dependent manner. ⋯ Thus, activity-dependent uncoupling of glutamate receptors from intracellular signaling mediators is a novel, endogenous physiological mechanism for counteracting sensitization at the first, crucial synapse in the pain pathway. Furthermore, we observed that targeted gene transfer of Homer1a to specific spinal segments in vivo reduces inflammatory hyperalgesia. Thus, Homer1 function is crucially involved in pain plasticity and constitutes a promising therapeutic target for the treatment of chronic inflammatory pain.