Fueling thought: Management of glycolysis and oxidative phosphorylation in neuronal metabolism

“168:657–669. https:// doi .org/ 10 .1016/ j .cell .2016 .12 .039 Vander Heiden, M.G., L.C. Cantley, and C.B. Thompson.”

“Is it through feedback regulation of the glycolytic enzymes by changes in cytosolic ATP, ADP, and AMP or through feedforward regulation by intracellular Ca2+ (and if so, through which of many possible signaling pathways)?”

“…allows regional brain activity to be monitored using functional magnetic resonance imaging based on blood oxygenation level–dependent [BOLD] signals; Ogawa et al., 1992), but the mechanisms of fuel use and energy generation in individual brain cells are also exquisitely controlled by both feedback…”

“201803152 3 For instance, the initial demonstration of feasibility was from separately cultured astrocytes and neurons: glutamate application to cultured astrocytes triggers [3H]-2-deoxyglucose (2-DG; [3H]–2-DG) uptake and lactate release, and neurons are capable of consuming lactate as a fuel (Magistretti et al., 199…”

“The human brain is only ∼2% of the body’s mass, but it consumes ∼20% of the daily energy budget (Rolfe and Brown, 1997).”

“Transient uncoupling between glycolysis and oxphos during brain activation The drop in OGI during brain stimulation was the first indication of some transient uncoupling of glycolysis and oxphos in the brain (Fox et al., 1988).”

“Recent work on in vivo metabolite fluxes argues that uncoupling between glycolysis and oxidative metabolism is the norm for all organs except the brain (Hui et al., 2017).”

“If an ANLS operates at rest, it could also explain why chronic disruption of MCT, LDH, or glycogenolysis in astrocytes can affect neuronal function (Suzuki et al., 2011; Zhang et al., 2016; Mazuel et al., 2017); these and similar results showing that MCT and lactate transport contribute to neuronal health and function…”

“…inputs in the mammalian brain, mitochondria were found to be absent in an exhaustive EM survey of a volume of neocortex (Kasthuri et al., 2015), despite prior evidence in cultured neurons that mitochondria can localize to dendritic protrusions, particularly with stimulation (Li et al., 2004).”

“, 2014) If both components of the NAD(P)H signal are substantially mitochondrial in origin, then what accounts for the overshoot? One candidate is the known effect of matrix Ca2+ in stimulating the matrix dehydrogenases including pyruvate dehydrogenase and the TCA dehydrogenases (McCormack et al., 1990).”

“In myelinated axons, the myelin-forming cells (oligodendrocytes or Schwann cells) have been assumed to bear substantial responsibility for metabolic support (Nave, 2010), particularly as they cover ∼97–99% of the axon surface.”

“…most excitatory synaptic inputs in the mammalian brain, mitochondria were found to be absent in an exhaustive EM survey of a volume of neocortex (Kasthuri et al., 2015), despite prior evidence in cultured neurons that mitochondria can localize to dendritic protrusions, particularly with…”

“, 2011), but the underlying key regulatory mechanisms are only now being elucidated (Christofk et al., 2008; Vander Heiden et al., 2009; Hu et al., 2016).”

“Although one specific enzyme for up-regulation of glycolysis, the bifunctional 6-phosphofructo2-kinase/fructose-2,6-bisphosphatase (isoform PFK FB3), is posttranslationally down-regulated in neurons and thus cannot”

“In presynaptic terminals, both glycolysis and oxphos appear important for managing intense activity (Rangaraju et al., 2014; Sobieski et al., 2017).”

“Moreover, detailed transport modeling shows that MCT2 is capable of ample lactate export from neurons at physiological concentrations (Simpson et al., 2007).”

“Right: Proteomics data (Sharma et al., 2015) from cultured neurons and astrocytes confirm the general pattern from the transcriptomics data.”

“The astrocyte-to-neuron lactate shuttle (ANLS) hypothesis proposed that neuronal activity leads to increased glycolysis in astrocytes, leading to release of lactate that is taken up by neurons as their primary energy source (Magistretti et al., 1993; Pellerin and Magistretti, 1994, 2012).”

“Upon stimulation of neurons in a brain slice (Kann et al., 2003; Shuttleworth et al., 2003; Kasischke et al., 2004) or individual dissociated neurons (Duchen, 1992), the NAD(P)H signal has a stereotyped response: a rapid dip in fluorescence occurring within the first few seconds that yields in…”

“Either glucose or lactate can be used as an energy source for white matter (Brown et al., 2001; Saab et al., 2016), and glial glycogen can supply energy to axons during aglycemia (Brown et al.”

“, 2013), and there is ample evidence of glutamate oxidation by astrocytes (Hertz et al., 2007; Dienel, 2017).”

“For recent reviews and studies on the regulation of astrocytic metabolism, see Bolaños (2016), Dienel and Cruz (2016), and Nortley and Attwell (2017).”

“, 2016) that predispose them to higher resting lactate/pyruvate ratios and higher resting lactate levels (Mächler et al., 2016).”

“If the stimulated brain uses glycolysis as a low-capacity but fast mechanism for ATP production (as argued for fast-twitch skeletal muscle, for instance; Crow and Kushmerick, 1982; Spriet, 1989), it would make sense teleologically for this fast ATP resupply to occur within neurons, where the acute demand for energy is…”

“This led to the proposal of mainly unidirectional flux from astrocytes to neurons; however, both isoforms are rapidly equilibrative (as argued by Gandhi et al., 2009; Dienel, 2012; Hertz et al., 2014; Bak and Schousboe, 2017), and recent single-cell transcriptomics studies show roughly equal expression of the two isof…”

“Fluorescent biosensor measurement of NADHCYT in neurons during excitation has helped to resolve the role of glycolysis and intercellular lactate transport in the acute metabolic response (Díaz-García et al., 2017).”

“Dendrites are sites of intense energy utilization (Hall et al., 2012), and mitochondria in dendritic shafts likely perform oxphos to supply needed energy.”

“Neurons and astrocytes were reported to express different isoforms of LDH with different Michaelis constants (Kms) for pyruvate (Bittar et al., 1996).”

“…to the ANLS model for the central nervous system, the radial glial cells of the retina (Müller cells) might supply lactate to photoreceptors (Poitry-Yamate et al., 1995; Hurley et al., 2015), the opposite appears to be true: photoreceptors perform aerobic glycolysis and export lactate,…”

“For instance, astrocytes with pericapillary endfeet are ideally positioned to take up glucose from the vasculature; however, recent data with high-pressure cryopreservation show much less astrocytic coverage of both capillaries and synapses than seen with aldehyde fixation, which shrinks the extracellular space (Korog…”

“A deliberate review of the evidence with an optimized model concluded that neurons provide about a third of their own lactate/pyruvate during brain activation, with the other two thirds from astrocytes (Hyder et al., 2006).”

“Using a different, phosphorylatable glucose analogue (2DG-IR) in nonanesthetized mice, better labeling was seen in neurons than astrocytes, particularly with whisker stimulation (Lundgaard et al., 2015).”

“, 2011), but the underlying key regulatory mechanisms are only now being elucidated (Christofk et al., 2008; Vander Heiden et al., 2009; Hu et al., 2016).”

“In Drosophila melanogaster, glycolysis appears to be more essential in glial cells than it is in neurons; knockdown of glycolytic enzymes in neurons did not affect the viability or the general behavior of flies, whereas knockdown in glial cells produced noticeable phenotypic changes (Volkenhoff et al., 2015).”

“This is supported by measurements showing local elevation of brain lactate levels with stimulation (Korf and de Boer, 1990; Hu and Wilson, 1997; Mazuel et al., 2017) and even lactate export from the brain (e.”

“This is supported by measurements showing local elevation of brain lactate levels with stimulation (Korf and de Boer, 1990; Hu and Wilson, 1997; Mazuel et al., 2017) and even lactate export from the brain (e.g., Duffy et al., 1975, with stronger stimuli such as epileptic seizures).”

“…rat brain assessed by postmortem isolation of synaptosomes (Patel et al., 2014) indicated substantial direct metabolism of glucose, consistent with an important role for glucose transporters and glycolysis in presynaptic terminals (Jang et al., 2016; Ashrafi et al., 2017; Ashrafi and Ryan, 2017).”

“…of the retina (Müller cells) might supply lactate to photoreceptors (Poitry-Yamate et al., 1995; Hurley et al., 2015), the opposite appears to be true: photoreceptors perform aerobic glycolysis and export lactate, which is then oxidized by Müller cells (Hurley et al., 2015; Kanow et al., 2017).”

“Using unstimulated cultured neurons, Bouzier-Sore et al. (2006) reported that resting neurons preferentially consume lactate over glucose.”

“, 2015) and thus must depend on glycolysis, but ordinarily, brain mitochondria are quite motile, and movement of mitochondria into the vicinity of synaptic sites has been demonstrated to affect both ATP levels and synaptic vesicle fusion in response to trains of stimulation (Sun et al., 2013).”

“For recent reviews and studies on the regulation of astrocytic metabolism, see Bolaños (2016), Dienel and Cruz (2016), and Nortley and Attwell (2017).”

“The ANLS hypothesis has been quite controversial for a long time (Chih et al., 2001; Gjedde and Marrett, 2001; Hertz, 2004; Mangia et al., 2011; Dienel, 2012, 2017; Bak and Walls, 2018; Barros and Weber, 2018; see also Dienel [2017] for strong arguments against ANLS at the tissue level).”

“The clearest case for glial supply of energy to neurons is in ischemic situations, as shown best for white matter axons that can be supported by glial glycogen in the absence of an external supply of glucose (Brown et al., 2003).”

“A similar argument was made for monocarboxylate transporter (MCT) isoforms (Pierre et al., 2000); although again, the transporters are both equilibrative, and transcriptomics show comparable levels of MCT1 in both neurons and astrocytes (Fig.”

“This is supported by measurements showing local elevation of brain lactate levels with stimulation (Korf and de Boer, 1990; Hu and Wilson, 1997; Mazuel et al., 2017) and even lactate export from the brain (e.g., Duffy et al., 1975, with stronger stimuli such as epileptic seizures).”

“The first study (Chuquet et al., 2010) used the fluorescent glucose analogue 6-NBDG; because it cannot be phosphorylated by hexokinase (given that the 6 position was already occupied by the fluorophore), this analogue’s accumulation may not correspond with the actual rate of glucose utilization, and it has been shown…”

“The relationship between neuronal metabolism and that of the neighboring astrocytes (glial cells) will be discussed; however, the focus will be on neurons which comprise most (∼80–90%) of the energy demand of the brain (Attwell and Laughlin, 2001; Yu et al., 2017).”

“201803152 3 For instance, the initial demonstration of feasibility was from separately cultured astrocytes and neurons: glutamate application to cultured astrocytes triggers [3H]-2-deoxyglucose (2-DG; [3H]–2-DG) uptake and lactate release, and neurons are capable of consuming lactate as a fuel (Magistretti et al., 199…”

“Is it through feedback regulation of the glycolytic enzymes by changes in cytosolic ATP, ADP, and AMP or through feedforward regulation by intracellular Ca2+ (and if so, through which of many possible signaling pathways)?”

“There is also evidence that the glycolytic enzymes may be localized right where the neuron most requires acute resupply of ATP: at the plasma membrane and on the synaptic vesicles where major ion pumping is performed by transport ATPases (Ikemoto et al., 2003; Dhar-Chowdhury et al., 2007; Hinckelmann et al., 2016).”

“The high level of glycolysis in photoreceptors is important as they perform substantial biosynthesis during their diurnal degradation and nocturnal regeneration of outer segments (Chinchore et al., 2017).”

“, 1993), and this lactate production can be stimulated by glutamate and potassium, which become elevated during neuronal activity (Walz and Mukerji, 1988; Peng et al., 1994; Pellerin and Magistretti, 1996; Bittner et al., 2011).”

“In vivo uptake of 2-fluoro–2-DG into presynaptic terminals of rat brain assessed by postmortem isolation of synaptosomes (Patel et al., 2014) indicated substantial direct metabolism of glucose, consistent with an important role for glucose transporters and glycolysis in presynaptic terminals (Jang…”

“…that MCT and lactate transport contribute to neuronal health and function provide evidence for some critical biological role for lactate uptake, but do not provide specific evidence for astrocyte-to-neuron lactate movement during activation (Mangia et al., 2011; Hall et al., 2012; Dienel, 2017).”

“For instance, if the unstimulated tissue in the periphery or even within the stimulated region is capable of oxidative metabolism of the excess lactate (Madsen et al., 1999; Gandhi et al., 2009), then including the contribution from this tissue will normalize the OGI.”

“However, in a later study with covisualization of neurons, astrocytes, and NAD(P)H, the transient changes in NAD(P)H appeared spatially homogenous (Kasischke et al., 2011).”

“For recent reviews and studies on the regulation of astrocytic metabolism, see Bolaños (2016), Dienel and Cruz (2016), and Nortley and Attwell (2017).”

“The ANLS hypothesis has been quite controversial for a long time (Chih et al., 2001; Gjedde and Marrett, 2001; Hertz, 2004; Mangia et al., 2011; Dienel, 2012, 2017; Bak and Walls, 2018; Barros and Weber, 2018; see also Dienel [2017] for strong arguments against ANLS at the tissue level).”

“The function of the MAS is antagonized by glutamate oxidation (LaNoue and Williamson, 1971; Du et al., 2013), and there is ample evidence of glutamate oxidation by astrocytes (Hertz et al.”

“Similar experiments on acute hippocampal slices found little or no reduction in the NAD(P)H signals with removal of Ca2+ (Shuttleworth et al., 2003).”

“…rat brain assessed by postmortem isolation of synaptosomes (Patel et al., 2014) indicated substantial direct metabolism of glucose, consistent with an important role for glucose transporters and glycolysis in presynaptic terminals (Jang et al., 2016; Ashrafi et al., 2017; Ashrafi and Ryan, 2017).”

“The difference in resting NADHCYT makes some baseline redox exchange likely between the two compartments (Cerdán et al., 2006); even with equal total (lactate + pyruvate) levels in the two cell types, astrocytic lactate could exchange for neuronal pyruvate, effectively allowing transfer of the…”

“201803152 6 in corpus callosum white matter, exogenous lactate could not support axon function in the absence of glucose (Meyer et al., 2018).”

“Glycolysis is one of the most ancient metabolic pathways with a wide variety of allosteric and phosphorylation-based controls (Mulukutla et al., 2010; Icard and Lincet, 2012).”

“Glycolysis is one of the most ancient metabolic pathways with a wide variety of allosteric and phosphorylation-based controls (Mulukutla et al., 2010; Icard and Lincet, 2012).”

“Müller cells are deficient in pyruvate kinase, the final enzyme in the glycolytic pathway, and have limited ability to convert glucose to lactate (Lindsay et al., 2014).”

“Astrocytes can indeed produce lactate from glucose (Hertz et al., 1988; Magistretti et al., 1993), and this lactate production can be stimulated by glutamate and potassium, which become elevated during neuronal activity (Walz and Mukerji, 1988; Peng et al.”

“Astrocytes can indeed produce lactate from glucose (Hertz et al., 1988; Magistretti et al., 1993), and this lactate production can be stimulated by glutamate and potassium, which become elevated during neuronal activity (Walz and Mukerji, 1988; Peng et al., 1994; Pellerin and Magistretti, 1996;…”

“…produce lactate from glucose (Hertz et al., 1988; Magistretti et al., 1993), and this lactate production can be stimulated by glutamate and potassium, which become elevated during neuronal activity (Walz and Mukerji, 1988; Peng et al., 1994; Pellerin and Magistretti, 1996; Bittner et al., 2011).”

“…cancer cells, astrocytes perform glycolysis not primarily for energy but rather for anabolic biosynthesis: For instance, astrocytes and not neurons express the phosphoglycerate dehydrogenase involved in serine biosynthesis (Ehmsen et al., 2013), which branches off of the main glycolytic pathway.”

“The best estimates for the oxygen–glucose index (OGI; OGI = CMRO2/CMRglc) in the resting brain is around ∼5.5 in gray matter (Clarke and Sokoloff, 1994; Hyder et al., 2013), very close to the ideal stoichiometry of 6.”

“In essence, the very active malate–aspartate shuttle (MAS) of neurons could transfer reducing equivalents not only from neuronal glycolysis but also from astrocytic glycolysis.”

“Extended intense stimulation may increase demand to the point that some glycolytic NADH also contributes to the autofluorescence signal; in addition, the quantitative contributions of glycolysis and oxphos can vary with oxygenation (Ivanov et al., 2014) If both components of the NAD(P)H signal are substantially mitoch…”

“The ANLS hypothesis has been quite controversial for a long time (Chih et al., 2001; Gjedde and Marrett, 2001; Hertz, 2004; Mangia et al., 2011; Dienel, 2012, 2017; Bak and Walls, 2018; Barros and Weber, 2018; see also Dienel [2017] for strong arguments against ANLS at the tissue level).”

“…autoradiographic analysis of [14C]–2-DG uptake in awake but unstimulated rats revealed roughly comparable label uptake in neurons and astrocytes (Nehlig et al., 2004); another in vivo labeling study using the fluorescent glucose analogue 2-NBDG showed stronger signals in neurons (Itoh et al.,…”

“Either glucose or lactate can be used as an energy source for white matter (Brown et al., 2001; Saab et al., 2016), and glial glycogen can supply energy to axons during aglycemia (Brown et al., 2003, 2012); however,”

“, 1993), and this lactate production can be stimulated by glutamate and potassium, which become elevated during neuronal activity (Walz and Mukerji, 1988; Peng et al., 1994; Pellerin and Magistretti, 1996; Bittner et al., 2011).”

“Similar experiments using graded neuronal stimulation by NMDA, which produced moderate submicromolar increases in cytosolic calcium, showed that activation increased glucose metabolism over twofold, whereas lactate metabolism declined, consistent with a role for extracellular lactate supporting basal metabolism in neu…”

“There is also evidence that the glycolytic enzymes may be localized right where the neuron most requires acute resupply of ATP: at the plasma membrane and on the synaptic vesicles where major ion pumping is performed by transport ATPases (Ikemoto et al., 2003; Dhar-Chowdhury et al., 2007; Hinckelmann et al., 2016).”

“…rest, it could also explain why chronic disruption of MCT, LDH, or glycogenolysis in astrocytes can affect neuronal function (Suzuki et al., 2011; Zhang et al., 2016; Mazuel et al., 2017); these and similar results showing that MCT and lactate transport contribute to neuronal health and function…”

“…of glycolysis (but in the presence of 1 mM pyruvate as a mitochondrial fuel, which will incidentally suppress cytosolic NADH transients) showed that much of the overshoot signal could not arise from glycolysis and instead must be mitochondrial in origin (Brennan et al., 2006; Shuttleworth, 2010).”

“There is also evidence that the glycolytic enzymes may be localized right where the neuron most requires acute resupply of ATP: at the plasma membrane and on the synaptic vesicles where major ion pumping is performed by transport ATPases (Ikemoto et al., 2003; Dhar-Chowdhury et al., 2007; Hinckelmann et al., 2016).”

“Consistent with most of the cultured cell studies, in resting brain or in quiescent brain slice astrocytes appear to be more glycolytic than neurons, with higher resting cytosolic NADH/NAD+ (NADHCYT) ratios (Mongeon et al., 2016) that predispose them to higher resting lactate/pyruvate ratios and higher resting lactate…”

“Upon stimulation of neurons in a brain slice (Kann et al., 2003; Shuttleworth et al., 2003; Kasischke et al., 2004) or individual dissociated neurons (Duchen, 1992), the NAD(P)H signal has a stereotyped response: a rapid dip in fluorescence occurring within the first few seconds that yields in…”

“…of NADH than cytosol, and because of the higher fluorescence of protein-bound NADH, mitochondrial NADH is considered to be the major source of the NAD(P)H signal (though this is contested; see Kasischke et al., 2004; Brennan et al., 2006; Blacker et al., 2014; and the discussion below).”

“The ANLS hypothesis has been quite controversial for a long time (Chih et al., 2001; Gjedde and Marrett, 2001; Hertz, 2004; Mangia et al., 2011; Dienel, 2012, 2017; Bak and Walls, 2018; Barros and Weber, 2018; see also Dienel [2017] for strong arguments against ANLS at the tissue level).”

“Either glucose or lactate can be used as an energy source for white matter (Brown et al., 2001; Saab et al., 2016), and glial glycogen can supply energy to axons during aglycemia (Brown et al.”

“In presynaptic terminals, both glycolysis and oxphos appear important for managing intense activity (Rangaraju et al., 2014; Sobieski et al., 2017).”

“, 2004); another in vivo labeling study using the fluorescent glucose analogue 2-NBDG showed stronger signals in neurons (Itoh et al., 2004).”

“In vitro glycolytic behavior can change with choice of culture media (Sünwoldt et al., 2017) and astrocyte coculture (Mamczur et al., 2015), but gene expression data from acutely dissociated brain cells indicate that neurons are well equipped for glycolysis, with higher levels of mRNA expression…”

“, 2018); this study argued for lactate shuttling under limited conditions, but this conclusion is weak because MCT blockers that would also block mitochondrial pyruvate uptake were used (Halestrap and Denton, 1975; McKenna et al., 2001).”

“The function of the MAS is antagonized by glutamate oxidation (LaNoue and Williamson, 1971; Du et al., 2013), and there is ample evidence of glutamate oxidation by astrocytes (Hertz et al.”

“Oxygen consumption is monitored with a Clarkstyle electrochemical sensor of O2 concentration; in brain slices, [O2] shows a pronounced dip with stimulation, corresponding with increased O2 consumption (Hall et al., 2012; Liotta et al., 2012; Ivanov et al., 2014).”

“This led to the proposal of mainly unidirectional flux from astrocytes to neurons; however, both isoforms are rapidly equilibrative (as argued by Gandhi et al., 2009; Dienel, 2012; Hertz et al., 2014; Bak and Schousboe, 2017), and recent single-cell transcriptomics studies show roughly equal expression of the two isof…”

“This agrees with the results of Duchen (1992) and with the experimental and modeling studies in slice by Kann et al. (2003); see also Berndt et al., 2015).”

“Glycolysis alone can support presynaptic energy needs during very gentle stimulation (Lujan et al., 2016).”

“Many synaptic sites in brain have been shown to lack mitochondria (Chavan et al., 2015) and thus must depend on glycolysis, but ordinarily, brain mitochondria are quite motile, and movement of mitochondria into the vicinity of synaptic sites has been demonstrated to affect both ATP levels and synaptic vesicle fusion i…”

“Oxygen consumption is monitored with a Clarkstyle electrochemical sensor of O2 concentration; in brain slices, [O2] shows a pronounced dip with stimulation, corresponding with increased O2 consumption (Hall et al., 2012; Liotta et al., 2012; Ivanov et al., 2014).”

“This led to the proposal of mainly unidirectional flux from astrocytes to neurons; however, both isoforms are rapidly equilibrative (as argued by Gandhi et al., 2009; Dienel, 2012; Hertz et al., 2014; Bak and Schousboe, 2017), and recent single-cell transcriptomics studies show roughly equal expression of the two isof…”

“The inferred recruitment of direct neuronal glycolysis in response to stimulation in a relatively intact system is consistent with earlier carbon tracing studies on cultured neurons (Bak et al., 2009, 2012).”

“This is supported by measurements showing local elevation of brain lactate levels with stimulation (Korf and de Boer, 1990; Hu and Wilson, 1997; Mazuel et al., 2017) and even lactate export from the brain (e.”

“…as a low-capacity but fast mechanism for ATP production (as argued for fast-twitch skeletal muscle, for instance; Crow and Kushmerick, 1982; Spriet, 1989), it would make sense teleologically for this fast ATP resupply to occur within neurons, where the acute demand for energy is greatest.”

“Either glucose or lactate can support transmission at high-frequency auditory presynaptic terminals (Lucas et al., 2018); this study argued for lactate shuttling under limited conditions, but this conclusion is weak because MCT blockers that would also block mitochondrial pyruvate uptake were used…”

“…this conclusion depends on the assumption that acetate is metabolized only in glia; a recent study of acetate metabolism in brain slices showed a substantial ability of neurons to metabolize acetate directly, which calls the compartment-specific modeling into question (Rowlands et al., 2017).”

“In vitro glycolytic behavior can change with choice of culture media (Sünwoldt et al., 2017) and astrocyte coculture (Mamczur et al.”

“…metabolic response to acute energy demand Journal of Cell Biology https://doi.org/10.1083/jcb.201803152 8 as the source of the NAD(P)H overshoot (Galeffi et al., 2007), but this study used a poorly selective blocker of MCT that also affects mitochondrial pyruvate uptake; this hypothesis is also…”

“The function of the MAS is antagonized by glutamate oxidation (LaNoue and Williamson, 1971; Du et al., 2013), and there is ample evidence of glutamate oxidation by astrocytes (Hertz et al., 2007; Dienel, 2017).”

“Both the sufficient glycolysis and the effective oxidation of alcohol require fast reoxidation of NADH to NAD through the coordinated reduction of pyruvate to lactate by LDH or production of ATP by mitochondrial ETC.(213,216)”

“Mitochondria perform a variety of tasks, including generation of adenosine triphosphate (ATP), Ca 2 + buffering and epigenetic signaling [17–19].”