| Author/Editor | Stenovec, Matjaž; Trkov, Saša; Kreft, Marko; Zorec, Robert | |
| Title | Alterations of calcium homoeostasis in cultured rat astrocytes evoked by bioactive sphingolipids | |
| Type | članek | |
| Publication year | 2014 | |
| ISSN | 1748-1716 - Acta physiologica (Oxford, England) | |
| Language | eng | |
| Abstract | Aim: In the brain, alterations in sphingolipid metabolism contribute to several neurological disorders; however, their effect on astrocytes is largely unknown. Here, we identified bioactive sphingolipids that affect intracellular free calcium concentration ([Ca2+ ]i ), mobility of peptidergic secretory vesicles, signalling pathways involved in alterations of calcium homoeostasis and explored the relationship between the stimulus-evoked increase in [Ca2+ ]i and attenuation of vesicle mobility. Methods: Confocal time-lapse images were acquired to explore [Ca2+ ]i signals, the mobility of fluorescently tagged peptidergic vesicles and the structural integrity of the microtubules and actin filaments before and after the addition of exogenous sphingolipids to astrocytes. Results: Fingolimod (FTY720), a recently introduced therapeutic for multiple sclerosis, and sphingosine, a releasable constituent of membrane sphingolipids, evoked long-lasting increases in [Ca2+ ]i in the presence and absence of extracellular Ca2+ ; the evoked responses were diminished in the absence of extracellular Ca2+ . Activation of phospholipase C and inositol-1,4,5-triphosphate receptors was necessary and sufficient to evoke increases in [Ca2+ ]i as revealed by the pharmacologic inhibitors; Ca2+ flux from the extracellular space intensified these responses several fold. The lipid-evoked increases in [Ca2+ ]i coincided with the attenuated vesicle mobility. High and positive correlation between increase in [Ca2+ ]i and decrease in peptidergic vesicle mobility was confirmed independently in astrocytes exposed to evoked, transient Ca2+ signalling triggered by purinergic and glutamatergic stimulation. Conclusion: Exogenously added cell-permeable sphingosine-like lipids exert complex, Ca2+ -dependent effects on astrocytes and likely alter their homeostatic function in vivo. | |
| Keywords | astrocytes calcium phospholipase astrociti kalcij fosfolipaze |