The landmark study discussed in this chapter is ‘The contribution of excitatory amino acids to central sensitization and persistent nociception after formalin-induced tissue injury’, published by Coderre and Melzack in 1992. Previous studies in this field implicate a contribution of excitatory amino acids (EAAs), specifically l-glutamate and l-aspartate, to injury-induced sensitization of nociceptive responses in the dorsal horn of the spinal cord. Repetitive stimulation of primary afferent fibres demonstrated that l-glutamate and NMDA can produce ‘wind-up’ of neuronal dorsal horn activity, and this is blocked by application of NMDA antagonists. This study uses the formalin test as a behavioural model to investigate the mechanisms underlying central sensitization and the role of EAAs, NMDA, their receptors, and their antagonists in this process.
