Multiplexed calcium imaging of single-synapse activity and astroglial responses in the intact brain. (10th January 2019)

• Record Type: Journal Article
• Authors: Reynolds, James P.; Zheng, Kaiyu; Rusakov, Dmitri A.
• Is Part Of: Neuroscience letters. Volume 689(2019)
• Page Start: 26
• Page End: 32
• Publication Date: 2019-01-10
• Subjects: Multiphoton imaging -- Tripartite synapse -- Neurotransmission -- Astrocytes; Neurology -- Periodicals; Neurology -- Periodicals; Research -- Periodicals; Neurologie -- Périodiques; Neuroanatomie -- Périodiques; Neuropharmacologie -- Périodiques; Neurophysiologie -- Périodiques; Neurology; Periodicals; Electronic journals; 617.48
• DOI: 10.1016/j.neulet.2018.06.024
• Languages: English
• ISSNs: 0304-3940

Abstract

Highlights: We concurrently imaged the activity of individual synapses and surrounding astroglia in live animals. Perisynaptic astrocytic regions display localiased, context-dependent Ca 2+ elevations in vivo . Such elevations may precede 'spontaneous' spike-evoked Ca 2+ entry at presynaptic boutons. This method paves the way for optical investigation of glutamate release probability in vivo . Abstract: All-optical registration of neuronal and astrocytic activities within the intact mammalian brain has improved significantly with recent advances in optical sensors and biophotonics. However, relating single-synapse release events and local astroglial responses to sensory stimuli in an intact animal has not hitherto been feasible. Here, we present a multiplexed multiphoton excitation imaging approach for assessing the relationship between presynaptic Ca 2+ entry at thalamocortical axonal boutons and perisynaptic astrocytic Ca 2+ elevations, induced by whisker stimulation in the barrel cortex of C57BL/6 mice. We find that, unexpectedly, Ca 2+ elevations in the perisynaptic astrocytic regions consistently precede local presynaptic Ca 2+ signals during spontaneous brain activity associated with anaesthesia. The methods described here can be adapted to a variety of optical sensors and are compatible with experimental designs that might necessitate repeated sampling of single synapses over a longitudinal behavioural paradigm.