Nociceptive sensitization

In Aplysia and vertebrates

Studying central sensitization within the vertebrate spinal cord

Electrophysiological observations

Similarity to long-term potentiation (LTP)

Neurochemical mechanisms

AMPA and NMDA receptors

NMDA receptor acts like a gated channel

Allows Ca entry

Activates Ca-calmodulin dependent protein kinase (CaMK II)

Modifies AMPA receptors (increases Na conductance)

Awakens silent AMPA receptors

Long-term modifications require gene expression

Involves PKA, MAP kinase, CREB signalling pathway

Secondary hyperalgesia and allodynia

Phenotypic switch alters A-beta fiber function

Descending modulation

Dampens nociceptive activity

Diffuse noxious inhibitory control (DNIC)

Provides an example of homeostatic regulation