Spatiotemporal calcium dynamics in single astrocytes and its modulation by neuronal activity.
Astrocytes produce a complex repertoire of Ca2+ events that coordinate their major functions. The principle of Ca2+ events integration in astrocytes, however, is unknown. Here we analyze whole Ca2+ events, which were defined as spatiotemporally interconnected transient Ca2+ increases. Using such analysis in single hippocampal astrocytes in culture and in slices we found that spreads and durations of Ca2+ events follow power law distributions, a fingerprint of scale-free systems. A mathematical model demonstrated that such Ca2+ dynamics can arise from intracellular inositol-3-phosphate diffusion. The power law exponent (α) was decreased by activation of metabotropic glutamate receptors (mGluRs) either by specific receptor agonist or by low frequency stimulation of glutamatergic fibers in hippocampal slices. Decrease in α indicated an increase in proportion of large Ca2+ events. Notably, mGluRs activation did not increase the frequency of whole Ca2+ events. This result suggests that neuronal activity does not trigger new Ca2+ events in astrocytes (detectable by our methods), but modulates the properties of existing ones. Thus, our results provide a new perspective on how astrocyte responds to neuronal activity by changing its Ca2+ dynamics, which might further affect local network by triggering release of gliotransmitters and by modulating local blood flow.
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
Yu-Wei
YW
Wu
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
Xiaofang
X
Tang
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
Misa
M
Arizono
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
Hiroko
H
Bannai
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
Pei-Yu
PY
Shih
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia.
Yulia
Y
Dembitskaya
University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia.
Victor
V
Kazantsev
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
Mika
M
Tanaka
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
Shigeyoshi
S
Itohara
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
Katsuhiko
K
Mikoshiba
RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia. Electronic address: semyanov@brain.riken.jp.
Alexey
A
Semyanov
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D004622:Embryo, Mammalian / Q000166:cytology; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000494:pharmacology; D018613:Microscopy, Confocal; D008962:Models, Theoretical; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D059008:Time-Lapse Imaging
D018094:Receptors, Metabotropic Glutamate; D008734:Methoxyhydroxyphenylglycol; D002118:Calcium; C010117:3,4-dihydroxyphenylglycol
Astrocyte; Calcium; Modulation; Power law; mGluR