Calcium-regulated chloride channel anoctamin-1 is present in the suprachiasmatic nuclei of rats.

Calcium-regulated chloride channel (CaCC) anoctamin-1 has been recently identified in neurons. In neurons, which express the Na-K-2Cl cotransporter, activation of CaCCs increases firing frequency, by reversion between the Cl equilibrium potential and the membrane resting potential, leading to membrane depolarization by Cl extrusion from the cell. Although there are no reports of CaCCs present in the suprachiasmatic nuclei (SCN), the fact that Na-K-2Cl cotransporter is present in SCN neurons, where it has been shown to be involved in the excitatory effects of γ-aminobutyric acid, together with the increase of neuronal firing rate induced by release of intracellular Ca after administration of 100 nM ryanodine, leads us to determine whether CaCCs are present in the SCN. Immunohistochemistry and western blots show the expression of the CaCCs anoctamin-1 protein. Quantitative PCR demonstrated the expression of anoctamin-1 mRNA in the SCN. These results clearly indicate the presence of CaCC in SCN of rats.