Résumé
Pain is a quite frequent complaint accompanying numerous pathologies. Among these pathological cases numerous neuropathies are retrieved with identified etiologies (chemotherapy induced peripheral neuropathies (CIPN), diabetes, surgeries) and also more diffuse syndromes such as fibromyalgia, migraine. More broadly, pain is one of the first and dramatic consequences of the majority of inherited diseases. Despite their importance for the quality of life, current therapies in symptomatic pain management are limited to drugs that are either old, or with a limited efficacy or that possess a bad benefit/risk ratio. Morphine and opioids for example have severe side effects. As no new pharmacological concept has led to new analgesics in the Past, the discovery of new medications is needed. It is necessary to identify new targets (such as ionic channels, the primary molecules of cellular excitability) in pain transmission before hoping to find specific molecules to treat different kinds of pain. Therefore studies of ion channels in pain pathways are extremely active. This is particularly true with ion channels in peripheral sensory neurons in dorsal root ganglia known now to express unique sets of these channels. Moreover, both spinal and supra spinal levels are clearly important in pain modulation with a key role of limbic areas such as thalamus filtering upcoming noxious information in their way to the cortex in the so called pain matrix representing a network of cerebral regions involved in the building of pain sensation, which comprises cortical somatic areas, insula, cingulate cortex, and associated with multiple other regions. Among these ion channels, we and others revealed the important role of low voltage-gated calcium channels (T-type channels) in cellular excitability in different steps of the pain pathways. These channels, by being activated nearby resting membrane potential have biophysical characteristic suited to facilitate action potential generation and rhythmicity. In this chapter we will review the current knowledge on the role of these channels in the perception and modulation of pain.