Recent advances in the physiology and pharmacology of pain: plasticity and its implications for clinical analgesia.

There have been considerable advances in our understanding of the transmission and modulation of nociceptive messages at both the central and peripheral endings of sensory afferent fibres. This review concentrates on the evidence for plasticity in these systems and emphasizes the recent spinal electrophysiological studies on the interplay between excitatory amino acids, opioids, noradrenaline and non-opioid peptides in these events.