Ciliary neurotrophic factor-treated astrocyte-conditioned medium increases the intracellular free calcium concentration in rat cortical neurons.

Ciliary neurotrophic factor (CNTF) is involved in the activation of astrocytes. A previous study showed that CNTF-treated astrocyte-conditioned medium (CNTF-ACM) contributed to the increase of the calcium current and the elevation of corresponding ion channels in cortical neurons. On this basis, it is reasonable to assume that CNTF-ACM may increase the intracellular free calcium concentration ([Ca2+]i) in neurons. In the present study, the effects of CNTF-ACM on [Ca2+]i in rat cortical neurons were determined, and on this basis, the aim was to investigate the potential active ingredients in ACM that are responsible for this biological process. As expected, the data indicated that CNTF-ACM resulted in a clear elevation of [Ca2+]i in neurons. Additionally, the fibroblast growth factor-2 (FGF-2) contained in the CNTF-ACM was found to participate in the upregulation of [Ca2+]i. Taken together, CNTF induces the production of active factors (at least including FGF-2) released from astrocytes, which finally potentiate the increase of [Ca2+]i in cortical neurons.