Figure 1.

(A) Morphological changes in astrocytes (stellation) induced by the β-adrenergic receptor (β-AR) agonist isoprenaline (Iso), which increases cAMP. Green fluorescing astrocytes transfected with the cAMP nanosensor Epac1-camps (top) and their corresponding differential interference contrast images (bottom) before (left) and after 1 μM β-AR agonist isoprenaline (Iso). Note the thinning and elongation of processes indicating astrocyte stellation. Scale bar represents 20 μm. Astrocytes were cultured from rat cortex. Modified from Vardjan et al. (2014) with permission. (B) Time course of cytosolic levels of cAMP. Noradrenaline (NA) persistently increases intracellular cAMP levels in astrocytes. Representative time courses of the Epac1-camps (i.e., a Förster resonance energy transfer (FRET)-based cAMP nanosensor) from three cells after the addition of 1 μM NA. Changes in FRET are expressed as percentages relative to the initial values. (C) Time course of cytosolic levels of Ca²⁺. The application of fingolimod (FTY720) evokes prolonged transient increases (oscillations). Superimposed time-resolved fluorescence intensity obtained in five cells treated with FTY720 (white bar). The thin dotted line indicates the zero fluorescence level (F₀). Modified from Vardjan and Zorec (2015) with permission.