Research report B subcommissural organ displays spontaneous and synchronous intracellular calcium oscillations

The subcommissural organ (SCO) is an ependymal brain gland that secretes into the cerebrospinal fluid glycoproteins that polymerize, forming Reissner's fiber (RF). The SCO-RF complex seems to be involved in vertebrate nervous system development, although its role in adults is unknown. Furthermore, its physiology is still greatly undetermined, and little is known about the release control of SCO secretion and the underlying intracellular mechanisms. In this report, we show that up to 90% of 3-5-day-old in vitro SCO cells from both 21 intact and partially-dispersed SCO explants displayed spontaneous cytosolic Ca oscillations. The putative role of these spontaneous calcium oscillations in SCO secretory activity is discussed taking into consideration several previous findings. Two distinct subpopulations of SCO cells were detected, each one containing cells with synchronized calcium oscillations. A possible existence of 21 different functional domains in SCO is therefore discussed. Oscillations persisted in the absence of extracellular Ca , indicating the 21 major involvement of Ca released from internal stores. Depolarization failed to induce intracellular calcium increases, although it disturbed the oscillation frequency, suggesting a putative modulator role of depolarizing agonists on the calcium oscillating pattern