Chronic pain resulting from a variety of health conditions is the primary reason people seek medical care; yet current therapies either are inadequate or cause intolerable side effects [1-8]. Understanding cellular and molecular processes that lead to the initiation and maintenance of chronic pain will provide substantial promise for the development of more effective and specific pain therapies. Chronic pain is an expression of neuronal plasticity. One component of the plasticity is that the afferent input generated by injury and intense noxious stimuli triggers an increased excitability of nociceptive neurons in the spinal cord. Glutamate is the principal excitatory amino acid neurotransmitter within the mammalian nervous system.