TY  - GEN
KW  - Astrozyten Neurone Interaktion
KW  -  Calcium imaging
KW  -  fluorescent indicators
A1  - Sonntag, Hannah
N2  - Astrocytes are organized in what can be regarded as parallel networks to local neuronal networks. On the cellular level astrocytes immediately react to stimulated neuronal activity by transient increases in intracellular calcium concentration ([Ca2+]i) which results in vitro in a vesicular release of so-called gliotransmitters such as ATP, D-serine and glutamate. In turn these gliotransmitters directly modulate synaptic transmission. Those synapses are regarded as tri-partite connections composed of the pre- and post-synapse enveloped by astrocyte processes. Several mouse models suggested astrocytes as key entities to tune synaptic transmission to vigilance states of synchronized neuronal activity oscillations. However, due to conflicting findings it is still under debate whether gliotransmission takes place under physiological conditions and, in particular, whether and how the activity of a single astrocyte or the general astrocyte population is an indicator for altered coordinated activity of a neural network.
	In the presented study the bidirectional communication of astrocytes and neurons was investigated. First, by a glia-neuron tracing approach in vivo and second by the simultaneous recording of neuronal and astrocytic activity during pharmacologically-induced oscillatory activity of cultured hippocampal slices. The tracing approach demonstrated in multiple independent experiments, that the rAAV-delivered retrograde tetanus toxin heavy chain tracer (eGFP-TTC) in hippocampal neurons is transferred to retrogradely connected neurons but is not translocated to, or between astrocytes. This excludes the existence of the neuron-like presynaptic target structures in astrocytes, exploited by eGFP-TTC. Likewise, eGFP-TTC is not transferred from astrocytes to neurons. Thus, the eGFP-TTC experiments cannot be used for tracing of neurons in putative networks build of tripartite synapses and moreover do not support the gliotransmission hypothesis. For the population analysis during neuronal oscillations, astrocyte [Ca2+]i and neuronal [Ca2+]i transients were recorded simultaneously by neuron- and astroglia-transduced Ca2+ indicators jRGeco and GCaMP6f, respectively. In both cell types the frequency and the kinetics of [Ca2+]i transient were not affected by the pharmacologically induced oscillations. Temporal cross-correlation analysis of the activity failed to identify any correlations in astrocytes and neuronal [Ca2+]i signals and could not identify any preferred [Ca2+]i transient sequence patterns. From these observations it can be concluded, that in the pharmacologically induced oscillation model either the [Ca2+]i transients in both cell populations are independent from the conditions and from each other, or that the applied virus delivered activity indicators combined with epifluorescence imaging are insufficient to allow detection of subtle correlations in these cells.
TI  - Elucidating astrocyte and neuron interactions using genetically encoded fluorescent indicators
CY  - Heidelberg
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/27204/
ID  - heidok27204
Y1  - 2019///
AV  - public
ER  -