CNTF-Treated Astrocyte Conditioned Medium Enhances Large-Conductance Calcium-Activated Potassium Channel Activity in Rat Cortical Neurons
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Seizure activity is linked to astrocyte activation as well as dysfunctional cortical neuron excitability produced from changes in calcium-activated potassium (KCa) channel function. Ciliary neurotrophic factor-treated astrocyte conditioned medium (CNTF-ACM) can be used to investigate the peripheral effects of activated astrocytes upon cortical neurons. However, CNTF-ACM’s effect upon KCa channel activity in cultured cortical neurons has not yet been investigated. Whole-cell patch clamp recordings were performed in rat cortical neurons to evaluate CNTF-ACM’s effects upon charybdotoxin-sensitive large-conductance KCa (BK) channel currents and apamin-sensitive small-conductance KCa (SK) channel current. Biotinylation and RT-PCR were applied to assess CNTF-ACM’s effects upon the protein and mRNA expression, respectively, of the SK channel subunits SK2 and SK3 and the BK channel subunits BKα1 and BKβ3. An anti-fibroblast growth factor-2 (FGF-2) monoclonal neutralizing antibody was used to assess the effects of the FGF-2 component of CNTF-ACM. CNTF-ACM significantly increased KCa channel current density, which was predominantly attributable to gains in BK channel activity (p < 0.05). CNTF-ACM produced a significant increase in BKα1 and BKβ3 expression (p < 0.05) but had no significant effect upon SK2 or SK3 expression (p > 0.05). Blocking FGF-2 produced significant reductions in KCa channel current density (p > 0.05) as well as BKα1 and BKβ3 expression in CNTF-ACM-treated neurons (p > 0.05). CNTF-ACM significantly enhances BK channel activity in rat cortical neurons and that FGF-2 is partially responsible for these effects. CNTF-induced astrocyte activation results in secretion of neuroactive factors which may affect neuronal excitability and resultant seizure activity in mammalian cortical neurons.
KeywordsCiliary neurotrophic factor, CNTF Calcium-activated potassium channel
This work was supported by the National Natural Science Foundation of China (Grant No. 81171117), the Scientific Research Starting Foundation for the Returned Overseas Chinese Scholars (Chinese Ministry of Education, Grant No. 44), and the Science and Technology Program of Anhui Province (a Key Laboratory Project, Grant No. 1506c085014).
X. J. W.: Conceived and designed the study. M. Q. S., H. L. L., H. B. X., and H. T. W: Performed the experiments. X. J. W.: Analyzed the data and drafted the manuscript
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