29-30 January, 2020 - Szeged, Hungary


Abstract details



Zsolt Szabó1, Julianna Kardos1, László Héja1

1 Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Budapest

Astrocytic syncytium collects information from across a large population of synapses and is also able to synchronize neuronal firing. Despite the fast synaptical activity, however, astrocytes are generally considered to be slow responders. Consequently, the readout of astrocytic activity, intracellular calcium oscillation is commonly measured on the second-scale. We argue here that the low (~1 Hz) image sampling rate, customarily used in astrocytic calcium imaging, obscures high-frequency components of astroglial calcium dynamics and leads to serious misinterpretation of astrocytic activity. Astrocytes in acute hippocampal rat brain slices were bulk loaded with the astrocyte-specific morphological tracer SR101 and the calcium dye Oregon Green 488 BAPTA-1 AM, and image acquisition rate during low magnesium-induced epileptiform activity was varied between ca. 0.5-40 Hz. Seizure-like events robustly triggered both slow and fast somatic calcium responses in SR101+ stratum radiatum astrocytes. Higher rate (>10 Hz) of acquisition revealed fast glial transients (~400 ms FWHM) on the soma that were not present at low acquisition rate (1 Hz). Therefore, at low acquisition rate, glial responses were critically undersampled, effectively resulting in information loss in the astroglial fast response range. Offline downsampling of calcium traces recorded at high acquisition rate also indicated that lowering acquisition rate reduces the information content of the detected astrocytic signals and distorts lower frequency components. These observations underlie the necessity of using physiologically relevant, higher image sampling rate in studying astroglial control of neuronal activity. This work was supported by grants VEKOP-2.1.1-15-2016-00156 and National Research, Development and Innovation Office grant OTKA K124558