RT Journal Article
SR Electronic
T1 Activity-dependent Increases in Local Oxygen Consumption Correlate with Postsynaptic Currents in the Mouse Cerebellum <em>In Vivo</em>
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 18327
OP 18337
DO 10.1523/JNEUROSCI.4526-11.2011
VO 31
IS 50
A1 Claus Mathiesen
A1 Kirsten Caesar
A1 Kirsten Thomsen
A1 Tycho M. Hoogland
A1 Brent M. Witgen
A1 Alexey Brazhe
A1 Martin Lauritzen
YR 2011
UL http://www.jneurosci.org/content/31/50/18327.abstract
AB Evoked neural activity correlates strongly with rises in cerebral metabolic rate of oxygen (CMRO2) and cerebral blood flow (CBF). Activity-dependent rises in CMRO2 fluctuate with ATP turnover due to ion pumping. In vitro studies suggest that increases in cytosolic Ca2+ stimulate oxidative metabolism via mitochondrial signaling, but whether this also occurs in the intact brain is unknown. Here we applied a pharmacological approach to dissect the effects of ionic currents and cytosolic Ca2+ rises of neuronal origin on activity-dependent rises in CMRO2. We used two-photon microscopy and current source density analysis to study real-time Ca2+ dynamics and transmembrane ionic currents in relation to CMRO2 in the mouse cerebellar cortex in vivo. We report a direct correlation between CMRO2 and summed (i.e., the sum of excitatory, negative currents during the whole stimulation period) field EPSCs (∑fEPSCs) in Purkinje cells (PCs) in response to stimulation of the climbing fiber (CF) pathway. Blocking stimulus-evoked rises in cytosolic Ca2+ in PCs with the P/Q-type channel blocker ω-agatoxin-IVA (ω-AGA), or the GABAA receptor agonist muscimol, did not lead to a time-locked reduction in CMRO2, and excitatory synaptic or action potential currents. During stimulation, neither ω-AGA or (μ-oxo)-bis-(trans-formatotetramine-ruthenium) (Ru360), a mitochondrial Ca2+ uniporter inhibitor, affected the ratio of CMRO2 to fEPSCs or evoked local field potentials. However, baseline CBF and CMRO2 decreased gradually with Ru360. Our data suggest that in vivo activity-dependent rises in CMRO2 are correlated with synaptic currents and postsynaptic spiking in PCs. Our study did not reveal a unique role of neuronal cytosolic Ca2+ signals in controlling CMRO2 increases during CF stimulation.