MODULATION OF SPINAL EXCITABILITY - COOPERATION BETWEEN NEUROKININ AND EXCITATORY AMINO-ACID NEUROTRANSMITTERS

Activation of C fibres with strong 'potentially tissue damaging' chemi cal, mechanical or thermal stimuli produces Painful sensations that ar e significantly enhanced during pathological conditions, such as neuro pathy and inflammation. The pronounced painful symptoms of hyperalgesi a and allodynia are induced, in part, by the development of spinal hyp erexcitability. This involves plastic changes in synaptic transmission between primary afferents and dorsal horn neurones induced by sustain ed activity of peripheral nociceptors. L. Urban, S. W. N. Thompson and A. Dray describe some of the central mechanisms that account for cent ral hyperexcitability occurring in hyperalgesia and allodynia based on evidence from experiments both in vivo and in vitro with neurokinin a nd N-methyl-D-aspartate receptor antagonists.