Model showing how cytokines sensitize nociceptive sensory neurons to stimulation. The diagram displays the model of a sensory ending of a nociceptive sensory neuron in the joint. The membrane of the neuron expresses ion channels for the transduction of stimuli (their opening by stimuli causes depolarizing sensor potentials in the ending) and voltage-gated ion channels for the regulation of the membrane potential, the excitability and the generation of the action potentials. In addition, the ending expresses receptors for cytokines which activate intracellular pathways. The latter can change the response properties of the ion channels and/or their expression in the membrane. Membrane receptors for other mediators (for example, prostaglandins) are not displayed. TRP, transient receptor potential.