FIGURE 1.

Cl^– conductances expressed in DRGs. Expression of the depicted Cl^– channels/transporters has been demonstrated in DRGs. The channels in red have been associated with pain: Their activity in nociceptors affects pain sensation and/or their expression is modulated in primary afferents in pain conditions. In contrast, for the conductances written in black neither a clear contribution to pain behavior, nor a regulation in pain models has been demonstrated so far. The gray candidates show low expression and no particular role in nociceptors has been assigned to them yet. As most data exists on the mRNA/protein level within the DRG, little is known about the distribution of the Cl^– conductances within the central or peripheral axons and their terminals. So far, only Ano1 and GABA_A have been functionally established at the peripheral axon terminal, while GABA_A is also involved in presynaptic inhibition of the primary afferents in the dorsal horn of the spinal cord.