| Author/Editor | Vardjan, Nina; Kreft, Marko; Zorec, Robert | |
| Title | Dynamics of [beta]-adrenergic/cAMP signaling and morphological changes in cultured astrocytes | |
| Type | članek | |
| Vol. and No. | Letnik 62, št. 4 | |
| Publication year | 2014 | |
| Volume | str. 566-579 | |
| ISSN | 0894-1491 - Glia | |
| Language | eng | |
| Abstract | The morphology of astrocytes, likely regulated by cAMP, determines the structural association between astrocytes and the synapse, consequently modulating synaptic function. Beta-Adrenergic receptors (beta-AR), which increase cytosolic cAMP concentration ([cAMP]i ), may affect cell morphology. However, the real-time dynamics of beta-AR-mediated cAMP signaling in single live astrocytes and its effect on cell morphology have not been studied. We used the fluorescence resonance energy transfer (FRET)-based cAMP biosensor Epac1-camps to study time-dependent changes in [cAMP]i ; morphological changes in primary rat astrocytes were monitored by real-time confocal microscopy. Stimulation of beta-AR by adrenaline, noradrenaline, and isoprenaline, a specific agonist of beta-AR, rapidly increased [cAMP]i (15 s). The FRET signal response, mediated via beta-AR, was faster than in the presence of forskolin (twofold) and dibutyryl-cAMP (>35-fold), which directly activate adenylyl cyclase and Epac1-camps, respectively, likely due to slow entry of these agents into the cytosol. Oscillations in [cAMP]i have not been recorded, indicating that cAMP-dependent processes operate in a slow time domain. Most Epac1-camps expressing astrocytes revealed a morphological change upon -AR activation and attained a stellate morphology within 1 h. The morphological changes exhibited a bell-shaped dependency on [cAMP]i . The 5-10% decrease in cell cross-sectional area and the 30-50% increase in cell perimeter are likely due to withdrawal of the cytoplasm to the perinuclear region and the appearance of protrusions on the surface of astrocytes. Because astrocyte processes ensheath neurons, beta-AR/cAMP-mediated morphological changes can modify the geometry of the extracellular space, affecting synaptic, neuronal, and astrocyte functions in health and disease. GLIA 2014. | |
| Keywords | astrocyte b-adrenergic receptors cAMP astrociti b-adrenergični receptorji cAMP |