Changes in Membrane Potential and the Intracellular Calcium Concentration During CSD and OGD in Layer V and Layer II/III Mouse Cortical Neurons

Abstract

Cortical spreading depression (CSD) is an episode of electrical silence following intense neuronal activity that propagates across the cortex at ∼3-6 mm/min and is associated with transient neuronal depolarization. CSD is benign in normally perfused brain tissue, but there is evidence suggesting that repetitive CSD contributes to infarct growth following focal ischemia. Studies to date have assumed that the cellular responses to CSD are uniform across neuronal types because there are no data to the contrary. In this study, we investigated the effect of CSD on membrane potential and the intracellular calcium concentration ([Ca(2+)](i)) of mouse layer V and layer II/III pyramidal neurons in brain slices. To place the data in context, we made similar measurements during anoxic depolarization induced by oxygen and glucose deprivation (OGD). The [Ca(2+)](i) was quantified using the low-affinity ratiometric indicator Fura-4F. During both CSD- and OGD-induced depolarization, the membrane potential approached 0 mV in all neurons. In layer V pyramids OGD resulted in an increase in [Ca(2+)](i) to a maximum of 3.69 ± 0.73 (SD) μM (n = 12), significantly greater than the increase to 1.81 ± 0.70 μM in CSD (n = 34; P < 0.0001). Membrane potential and [Ca(2+)](i) returned to nearly basal levels following CSD but not OGD. Layer II/III neurons responded to CSD with a greater peak increase in [Ca(2+)](i) than layer V neurons (2.88 ± 0.6 μM; n = 9; P < 0.01). We conclude there is a laminar difference in the response of pyramidal neurons to CSD; possible explanations are discussed.

Leaky RyR2 channels unleash a brainstem spreading depolarization mechanism of sudden cardiac death

“…3 D and G). The traveling IOS in layer II/III typically preceded the IOS spreading across other cortical layers, as described in an earlier study (32). The duration of extracellular KCl pulses required for SD generation was somewhat shorter (42% of control) in the mutant than in WT control slices (WT, 204 ± 200 ms; RQ, 86 ± 53 ms; n = 14, P = 0.049; Fig.…”

Regulation of cerebral metabolism during cortical spreading depression

“…21 However, the total ATP use remains reduced for up to ∼1 h, due to a persistent shut down of energy demanding processes (described by P x in Supplementary material S1). The tissue reacts to this state of lower energy demand by reducing the net inflow of glucose to the brain ( K 1 ) and reducing ATP production via hexokinase activity ( k 3 in the model) and via the tricarboxylic acid (TCA) cycle ( k OXY in the model, see Supplementary material S1) such that the net ATP production matches the consumption (Figures 3(b) and 2(c)).…”

Identification of the extent of cortical spreading depression propagation by Npas4 mRNA expression

“…2D), while the amplitude of DC-potential shift was larger in layer V than that in layer II/III. This might be explained by the facts that (1) CSD induced greater surges of intracellular calcium concentration ([Ca 2+ ] i ) in neurons at cortical layer II/III than that at layer V (Gniel and Martin, 2010), and (2) both membrane depolarization and Ca 2+ influx required to induce Npas4 mRNA expression (Lin et al, 2008;Ramamoorthi et al, 2011).…”