Journal: Cell metabolism
Article Title: Neuronal stimulation triggers neuronal glycolysis and not lactate uptake
doi: 10.1016/j.cmet.2017.06.021
Figure Lengend Snippet: (A) Typical electrode placement for synaptic stimulation. The picture shows an infra-red differential interference contrast image of a horizontal slice from the hippocampus, where the stimulating electrode (s.e.) is placed in the molecular layer (m.l.) and an extracellular recording electrode (r.e.) is inserted in the layer of dentate granule neurons (DGNs, following the arrow direction). (B) Inhibition of ionotropic glutamate receptors abolishes the metabolic transients. A representative trace of a synaptically stimulated DGN (using a train of 60 pulses at 20 Hz) shows that the Peredox signal disappears after blocking synaptic transmission with a mixture of 5 μM NBQX and 25 μM D-AP5 in the ACSF. The complete blockade of synaptic transmission is corroborated by the absence of the typical RCaMP1h signal after stimulation. The effect of synaptic blockers was partially reversed after 5 min of washout in regular ACSF, and both Ca2+ and NADH transients were completely recovered after 10 min in ACSF. (C) Dataset for the effect of ionotropic glutamate receptor block. Data were compared by a paired Student’s t-test (neurons=46, slices=6, mice=3). (D) Typical electrode placement for antidromic (axonal) stimulation. In this experimental paradigm, the stimulating electrode (s.e.) is placed in the the hilus (hil) and an extracellular recording electrode (r.e.) is inserted in the layer of dentate granule neurons (DGNs, following the arrow direction). (E) Average transient increases in Peredox lifetime after antidromic stimulation of 100 brief pulses delivered at 50 Hz. Traces represent the mean ± SEM (events=179, neurons=84, slices=18, mice=11; SEM calculated using number of neurons). The lower panel shows the putative average Ca2+ spike in the cells, as a proxy for neuronal excitation. (F) Elevation in the NADH/NAD+ ratio is directly correlated with the neuronal Ca2+ increase after electrical antidromic stimulation in DGNs, similarly to synaptic stimulation. Scatter plots of changes in Peredox lifetime versus variations in RCaMP lifetime for events recorded after antidromic stimulation (open circles; events=205, neurons=87, slices=19, mice=12), overlap with data collected using synaptic stimulation (dark squares).
Article Snippet: The synaptic blockers NBQX and D-AP5 were obtained from Toronto Research Chemicals (Toronto, ON) and Abcam (Cambridge, MA), respectively.
Techniques: Inhibition, Blocking Assay, Transmission Assay
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