Interaction between tissue oxygen tension and NADH imaging during synaptic stimulation and hypoxia in rat hippocampal slices

Foster, Kelley A.; Beaver, Christopher J.; Turner, Dennis A.

doi:10.1016/j.neuroscience.2005.01.040

Cited by 71 publications

(151 citation statements)

References 39 publications

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“…23,27,28 We compared our observations of adenosine accumulation with O 2 utilization and the oxidative transient of NAD(P)H during SD, across the range of different baseline conditions established in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

Spreading Depolarization-Induced Adenosine Accumulation Reflects Metabolic Status In Vitro and In Vivo

Lindquist

Shuttleworth

2014

J Cereb Blood Flow Metab

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Spreading depolarization (SD), a pathologic feature of migraine, stroke and traumatic brain injury, is a propagating depolarization of neurons and glia causing profound metabolic demand. Adenosine, the low-energy metabolite of ATP, has been shown to be elevated after SD in brain slices and under conditions likely to trigger SD in vivo. The relationship between metabolic status and adenosine accumulation after SD was tested here, in brain slices and in vivo. In brain slices, metabolic impairment (assessed by nicotinamide adenine dinucleotide (phosphate) autofluorescence and O 2 availability) was associated with prolonged extracellular direct current (DC) shifts indicating delayed repolarization, and increased adenosine accumulation. In vivo, adenosine accumulation was observed after SD even in otherwise healthy mice. As in brain slices, in vivo adenosine accumulation correlated with DC shift duration and increased when DC shifts were prolonged by metabolic impairment (i.e., hypoglycemia or middle cerebral artery occlusion). A striking pattern of adenosine dynamics was observed during focal ischemic stroke, with nearly all the observed adenosine signals in the periinfarct region occurring in association with SDs. These findings suggest that adenosine accumulation could serve as a biomarker of SD incidence and severity, in a range of clinical conditions. Keywords: acute stroke; adenosine; brain slice; electrophysiology; energy metabolism; spreading depression INTRODUCTION Spreading depolarization (SD) of brain tissue is a self-propagating wave of neuronal and glial activation, carried by large transmembrane currents that depolarize cells and disrupt ionic gradients. 1,2 Spreading depolarization imposes a large metabolic burden on brain tissue, evidenced by depletion of energy substrates and O 2 3,4 and by accumulation of metabolic byproducts such as lactate and H + . 5,6 ATP concentration drops by nearly 50% during SD in normoxic conditions, 7 and metabolic depletion is expected to be more severe when occurring in tissue with limited substrate availability.Recent clinical studies strongly suggest that SD is involved in the pathophysiology of migraine with aura, thromboembolic stroke, traumatic brain injury, and subarachnoid hemorrhage. 8 While normoxic, normoglycemic SD can be noninjurious, 9 SD in the setting of metabolic compromise exacerbates neuronal injury. 10,11 Work in animal models has identified delayed repolarization, marked by prolonged extracellular direct current (DC) shifts, as a hallmark of injurious SD in metabolically compromised tissue. 10 Observational studies in human subjects have confirmed the association between prolonged DC shifts and poor outcome after SD, 12 but human studies have so far been limited by the requirement for invasive electrical recordings in patients with craniotomies. It would be helpful to establish additional biomarkers of metabolic status, to assess vulnerability to SD in injured brain.Extracellular adenosine accumulation can serve as a global indicator of energy charge....

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Section: Resultsmentioning

confidence: 99%

Spreading Depolarization-Induced Adenosine Accumulation Reflects Metabolic Status In Vitro and In Vivo

Lindquist

Shuttleworth

2014

J Cereb Blood Flow Metab

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“…In at least one early study, an evaluation of NAD(P)H changes resulting from extended electrical stimulation in brain slice tissue was made, which showed an early transient decrease in NAD(P)H fluorescence and a later and much longer, but still transient, increase (Lipton, 1973). Studies since then have confirmed the biphasic nature of the NAD(P)H signal after bursts of electrical discharge in single neurons (Duchen, 1992) and in hippocampal slices (Foster et al, 2005;Schuchmann et al, 2001;Sick and Perez-Pinzon, 1999). More recently, we have shown that quite robust ( > 1%) fluorescence signals from NAD(P)H and flavoproteins can be elicited in hippocampal slices by a small number of action potentials evoked in a time window of B100 ms to 1 secs (Shuttleworth et al, 2003).…”

Section: Introductionmentioning

confidence: 98%

NAD(P)H Fluorescence Transients after Synaptic Activity in Brain Slices: Predominant Role of Mitochondrial Function

Brennan

Connor

Shuttleworth

2006

J Cereb Blood Flow Metab

115

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Excitatory stimulation in hippocampal slices results in biphasic NAD(P)H fluorescence transients. Previous studies using differing stimulus protocols agreed that the oxidation phase is a consequence of mitochondrial metabolism, but the reduction phase has been attributed to (1) mitochondrial nicotinamide adenine dinucleotide (NADH) generation or (2) astrocytic glycolysis triggered by glutamate uptake. In an attempt to reconcile these two views, the present study examined NAD(P)H signals evoked by a wide range of stimulus durations (40 ms to 20 secs). A combination of ionotropic glutamate receptor (iGluR) antagonists (6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), 2-amino-5-phosphonopentanoic acid (APV)) virtually abolished responses to brief stimuli (40 to 200 ms, 50 Hz), but a significant fraction of the signal elicited by extended stimulation (20 secs, 32 Hz) was resistant to CNQX/APV. Glycolysis was inhibited by removal of glucose and addition of 2-deoxyglucose (2DG) (10 mmol/L) or iodoacetic acid (IAA, 1 mmol/L). Pyruvate was provided as an alternative substrate for oxidative phosphorylation and the A1 receptor antagonist 1,3-Dipropyl-8-cyclopentylxanthine (DPCPX) included to prevent decreases in synaptic efficacy. If sufficient pyruvate was supplied, responses to brief and extended stimuli were unaffected by glycolytic inhibition and not significantly reduced by an inhibitor of glucose uptake (3-O-methyl glucose, 3 mmol/L). When timed to arrive at the peak of overshoots generated by extended synaptic stimulation, brief pyruvate applications (10 mmol/L, 2 mins) had little effect on evoked NAD(P)H increases. Flavoprotein autofluorescence transients after extended stimuli matched (with inverted sign) NAD(P)H responses. Responses to extended stimuli were not reduced by a nonselective inhibitor of glutamate uptake DL-Threo-b-benzyloxyaspartic acid (TBOA). These results suggest that NAD(P)H transients report mitochondrial dynamics, rather than recruitment of glycolytic metabolism, over a wide range of stimulus intensities.

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“…Application of a low frequency stimulus train (250 pulses at 10 Hz) to slices under control conditions induced a transient (<5 min), reproducible, biphasic NADH response [12,39]. This response consisted of an initial small oxidation, followed by a larger, more prolonged reduction (values shown in Table 1).…”

Section: Transient Nadh Responsesmentioning

confidence: 99%

“…Slices imaged in control conditions (10 mM glucose) showed a steady decline in baseline NADH fluorescence [12,14]. The background fluorescence in the stratum radiatum decreased by 7.2 ± 1.5% during the experiment (approx.…”

Section: Baseline Measurementsmentioning

confidence: 99%

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Effects of relative hypoglycemia on LTP and NADH imaging in rat hippocampal slices

2007

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Cognitive and neuronal impairment in diabetes may be associated with iatrogenic hypoglycemia, particularly at low serum glucose levels (< 3 mM). To evaluate cellular impairment, we assessed acute hippocampal slice functioning during decreased ambient glucose, by monitoring evoked field excitatory post-synaptic potentials (fEPSP), and slice nicotinamide adenine dinucleotide (NADH) fluorescence. The effects of lowered glucose levels (60 min) were analyzed by examining the induction and maintenance of long-term potentiation (LTP), and NADH metabolic imaging in the CA1 region. The basal fEPSP response was reduced by lowered ambient glucose, an effect that was reversible in 2.5 mM glucose, partially reversible in 1.25 mM glucose and irreversible in 0 mM glucose, after 25 min recovery. LTP induction and maintenance declined during glucose restriction, demonstrating reversibly failed maintenance in 5 mM and 2.5 mM ambient glucose, and absent induction in 1.25 mM glucose. Peak NADH levels observed during train-induced biphasic transients were significantly reduced during 1.25 mM and 2.5 mM glucose. Significant functional compromise in our slice model occurred at 2.5 mM ambient glucose, equivalent to <1mM tissue glucose in the slice center, due to diffusion limitations and active glucose utilization. This tissue glucose level correlates with human observations of a serum threshold of <3mM for cognitive impairment, since brain tissue glucose is approximately one third of serum levels. The physiological effects of hypoglycemia in our slice model, assessed through fEPSP, LTP, and NADH responses, replicate closely the in vivo situation, confirming the usefulness of this model in assessing consequences of relative hypoglycemia.

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Interaction between tissue oxygen tension and NADH imaging during synaptic stimulation and hypoxia in rat hippocampal slices

Cited by 71 publications

References 39 publications

Spreading Depolarization-Induced Adenosine Accumulation Reflects Metabolic Status In Vitro and In Vivo

Spreading Depolarization-Induced Adenosine Accumulation Reflects Metabolic Status In Vitro and In Vivo

NAD(P)H Fluorescence Transients after Synaptic Activity in Brain Slices: Predominant Role of Mitochondrial Function

Effects of relative hypoglycemia on LTP and NADH imaging in rat hippocampal slices

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