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Uddin MM, Ali MH, Mahmood ASMH, Bheemanapally K, Leprince J, Briski KP. Glycogen phosphorylase isoenzyme GPbb versus GPmm regulation of ventromedial hypothalamic nucleus glucoregulatory neurotransmitter and counter-regulatory hormone profiles during hypoglycemia: Role of L-lactate and octadecaneuropeptide. Mol Cell Neurosci 2023; 126:103863. [PMID: 37268282 PMCID: PMC10527669 DOI: 10.1016/j.mcn.2023.103863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/14/2023] [Accepted: 05/25/2023] [Indexed: 06/04/2023] Open
Abstract
Glucose accesses the brain primarily via the astrocyte cell compartment, where it passes through the glycogen shunt before catabolism to the oxidizable fuel L-lactate. Glycogen phosphorylase (GP) isoenzymes GPbb and GPmm impose distinctive control of ventromedial hypothalamic nucleus (VMN) glucose-regulatory neurotransmission during hypoglycemia, but lactate and/or gliotransmitter involvement in those actions is unknown. Lactate or the octadecaneuropeptide receptor antagonist cyclo(1-8)[DLeu5] OP (LV-1075) did not affect gene product down-regulation caused by GPbb or GPmm siRNA, but suppressed non-targeted GP variant expression in a VMN region-specific manner. Hypoglycemic up-regulation of neuronal nitric oxide synthase was enhanced in rostral and caudal VMN by GPbb knockdown, yet attenuated by GPMM siRNA in the middle VMN; lactate or LV-1075 reversed these silencing effects. Hypoglycemic inhibition of glutamate decarboxylase65/67 was magnified by GPbb (middle and caudal VMN) or GPmm (middle VMN) knockdown, responses that were negated by lactate or LV-1075. GPbb or GPmm siRNA enlarged hypoglycemic VMN glycogen profiles in rostral and middle VMN. Lactate and LV-1075 elicited progressive rostral VMN glycogen augmentation in GPbb knockdown rats, but stepwise-diminution of rostral and middle VMN glycogen after GPmm silencing. GPbb, not GPmm, knockdown caused lactate or LV-1075 - reversible amplification of hypoglycemic hyperglucagonemia and hypercorticosteronemia. Results show that lactate and octadecaneuropeptide exert opposing control of GPbb protein in distinct VMN regions, while the latter stimulates GPmm. During hypoglycemia, GPbb and GPmm may respectively diminish (rostral, caudal VMN) or enhance (middle VMN) nitrergic transmission and each oppose GABAergic signaling (middle VMN) by lactate- and octadecaneuropeptide-dependent mechanisms.
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Affiliation(s)
- Md Main Uddin
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States of America
| | - Md Haider Ali
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States of America
| | - A S M H Mahmood
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States of America
| | - Khaggeswar Bheemanapally
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States of America
| | - Jérôme Leprince
- Normandy University, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, INSERM U1239, PRIMACEN, Rouen, France
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States of America.
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Roy SC, Napit PR, Pasula M, Bheemanapally K, Briski KP. G protein-coupled lactate receptor GPR81 control of ventrolateral ventromedial hypothalamic nucleus glucoregulatory neurotransmitter and 5'-AMP-activated protein kinase expression. Am J Physiol Regul Integr Comp Physiol 2023; 324:R20-R34. [PMID: 36409024 PMCID: PMC9762965 DOI: 10.1152/ajpregu.00100.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 11/23/2022]
Abstract
Astrocytes store glycogen as energy and promote neurometabolic stability through supply of oxidizable l-lactate. Whether lactate regulates ventromedial hypothalamic nucleus (VMN) glucostatic function as a metabolic volume transmitter is unknown. Current research investigated whether G protein-coupled lactate receptor GPR81 controls astrocyte glycogen metabolism and glucose-regulatory neurotransmission in the ventrolateral VMN (VMNvl), where glucose-regulatory neurons reside. Female rats were pretreated by intra-VMN GPR81 or scramble siRNA infusion before insulin or vehicle injection. VMNvl cell or tissue samples were acquired by laser-catapult- or micropunch microdissection for Western blot protein or uHPLC-electrospray ionization-mass spectrometric glycogen analyses. Data show that GPR81 regulates eu- and/or hypoglycemic patterns of VMNvl astrocyte glycogen metabolic enzyme and 5'-AMP-activated protein kinase (AMPK) protein expression according to VMNvl segment. GPR81 stimulates baseline rostral and caudal VMNvl glycogen accumulation but mediates glycogen breakdown in the former site during hypoglycemia. During euglycemia, GPR81 suppresses the transmitter marker neuronal nitric oxide synthase (nNOS) in rostral and caudal VMNvl nitrergic neurons, but stimulates (rostral VMNvl) or inhibits (caudal VMNvl) GABAergic neuron glutamate decarboxylase65/67 (GAD)protein. During hypoglycemia, GPR81 regulates AMPK activation in nitrergic and GABAergic neurons located in the rostral, but not caudal VMNvl. VMN GPR81 knockdown amplified hypoglycemic hypercorticosteronemia, but not hyperglucagonemia. Results provide novel evidence that VMNvl astrocyte and glucose-regulatory neurons express GPR81 protein. Data identify neuroanatomical subpopulations of VMNvl astrocytes and glucose-regulatory neurons that exhibit differential reactivity to GPR81 input. Heterogeneous GPR81 effects during eu- versus hypoglycemia infer that energy state may affect cellular sensitivity to or postreceptor processing of lactate transmitter signaling.
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Affiliation(s)
- Sagor Chandra Roy
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
| | - Prabhat R Napit
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
| | - MadhuBabu Pasula
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
| | - Khaggeswar Bheemanapally
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
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Sex-Dimorphic Glucocorticoid Receptor Regulation of Hypothalamic Primary Astrocyte Glycogen Metabolism: Interaction with Norepinephrine. NEUROGLIA (BASEL, SWITZERLAND) 2022; 3:144-157. [PMID: 36685006 PMCID: PMC9850496 DOI: 10.3390/neuroglia3040010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Astrocyte glycogen is a critical metabolic variable that impacts hypothalamic control of glucostasis. Glucocorticoid hormones regulate peripheral glycogen, but their effects on hypothalamic glycogen are not known. A hypothalamic astrocyte primary culture model was used to investigate the premise that glucocorticoids impose sex-dimorphic independent and interactive control of glycogen metabolic enzyme protein expression and glycogen accumulation. The glucocorticoid receptor (GR) agonist dexamethasone (DEX) down-regulated glycogen synthase (GS), glycogen phosphorylase (GP)-brain type (GPbb), and GP-muscle type (GPmm) proteins in glucose-supplied male astrocytes, but enhanced these profiles in female. The catecholamine neurotransmitter norepinephrine (NE) did not alter these proteins, but amplified DEX inhibition of GS and GPbb in male or abolished GR stimulation of GPmm in female. In both sexes, DEX and NE individually increased glycogen content, but DEX attenuated the magnitude of noradrenergic stimulation. Glucoprivation suppressed GS, GPbb, and GPmm in male, but not female astrocytes, and elevated or diminished glycogen in these sexes, respectively. Glucose-deprived astrocytes exhibit GR-dependent induced glycogen accumulation in both sexes, and corresponding loss (male) or attenuation (female) of noradrenergic-dependent glycogen build-up. Current evidence for GR augmentation of hypothalamic astrocyte glycogen content in each sex, yet divergent effects on glycogen enzyme proteins infers that glucocorticoids may elicit opposite adjustments in glycogen turnover in each sex. Results document GR modulation of NE stimulation of glycogen accumulation in the presence (male and female) or absence (female) of glucose. Outcomes provide novel proof that astrocyte energy status influences the magnitude of GR and NE signal effects on glycogen mass.
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Ali MH, Alshamrani AA, Briski KP. Hindbrain lactate regulation of hypoglycemia-associated patterns of catecholamine and metabolic-sensory biomarker gene expression in A2 noradrenergic neurons innervating the male versus female ventromedial hypothalamic nucleus. J Chem Neuroanat 2022; 122:102102. [PMID: 35483611 DOI: 10.1016/j.jchemneu.2022.102102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/17/2022] [Accepted: 04/21/2022] [Indexed: 12/30/2022]
Abstract
Caudal hindbrain A2 noradrenergic neurons provide critical metabolic-sensory input to the brain glucostatic circuitry. In males, insulin-induced hypoglycemia (IIH)-associated patterns of A2 cell dopamine-beta-hydroxylase (DβH) protein expression reflect diminution of the oxidizable fuel L-lactate, yet DβH exhibits sex-dimorphic responses to IIH. Here, retrograde tracing and combinatory single-cell laser-microdissection/multiplex qPCR techniques were used to examine whether lactate imposes sex-specific control of hypoglycemia-associated metabolic-sensory function and noradrenergic neurotransmission in A2 neurons that innervate the ventromedial hypothalamic nucleus (VMN), a key glucose-regulatory structure. VMN-projecting A2 neurons from each sex were characterized by presence or absence of nuclear glucokinase regulatory protein (nGKRP) immunoreactivity (-ir). IIH caused lactate-reversible up- or down-regulation of DβH mRNA in male and female nGKRP-ir-positive A2 neurons, respectively, and stimulated glucokinase (GCK) and sulfonylurea receptor-1 (SUR-1) gene expression in these cells in each sex. Hypoglycemia did not alter DβH, GCK, and SUR-1 transcript profiles in nGKRP-ir-negative male or female A2 neurons innervating the VMN. Estrogen receptor (ER) gene profiles in nGKRP-ir-positive neurons showed sex-specific [ER-alpha; G-protein-coupled estrogen-receptor-1 (GPER)] or sex-monomorphic (ER-beta) transcriptional responses to IIH. Fewer ER gene profiles were affected by IIH in nGKRP-ir-negative A2 neurons from male or female rats. Results show that during IIH, VMN-projecting A2 neurons may deliver altered, sex-dependent (nGKRP-positive) or unaffected (nGKRP-negative) noradrenergic input to the VMN. In each sex, metabolic-sensory gene profiles were reactive to hypoglycemia in nGKRP-ir-positive, not -negative A2 cells. Further studies are needed to elucidate the role of GKRP in transduction of metabolic imbalance into noradrenergic signaling, and to determine if input by one or more ER variants establishes sex differences in DβH transcriptional sensitivity to IIH.
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Affiliation(s)
- Md Haider Ali
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, USA
| | - Ayed A Alshamrani
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, USA
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, USA.
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Uddin MM, Ibrahim MMH, Briski KP. Glycogen Phosphorylase Isoform Regulation of Ventromedial Hypothalamic Nucleus Gluco-Regulatory Neuron 5'-AMP-Activated Protein Kinase and Transmitter Marker Protein Expression. ASN Neuro 2021; 13:17590914211035020. [PMID: 34596459 PMCID: PMC8495507 DOI: 10.1177/17590914211035020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Brain glycogen is remodeled during metabolic homeostasis and provides oxidizable
L-lactate equivalents. Brain glycogen phosphorylase (GP)-brain (GPbb;
AMP-sensitive) and -muscle (GPmm; norepinephrine-sensitive) type isoforms
facilitate stimulus-specific control of glycogen disassembly. Here, a whole
animal model involving stereotactic-targeted delivery of GPmm or GPbb siRNA to
the ventromedial hypothalamic nucleus (VMN) was used to investigate the premise
that these variants impose differential control of gluco-regulatory
transmission. Intra-VMN GPmm or GPbb siRNA administration inhibited glutamate
decarboxylate65/67 (GAD), a protein marker for the
gluco-inhibitory transmitter γ--aminobutyric acid (GABA), in the caudal VMN.
GPbb knockdown, respectively overturned or exacerbated hypoglycemia-associated
GAD suppression in rostral and caudal VMN. GPmm siRNA caused a segment-specific
reversal of hypoglycemic augmentation of the gluco-stimulatory transmitter
indicator, neuronal nitric oxide synthase (nNOS). In both cell types, GP siRNA
down-regulated 5′-AMP-activated protein kinase (AMPK) during euglycemia, but
hypoglycemic suppression of AMPK was reversed by GPmm targeting. GP knockdown
elevated baseline GABA neuron phosphoAMPK (pAMKP) content, and amplified
hypoglycemic augmentation of pAMPK expression in each neuron type. GPbb
knockdown increased corticosterone secretion in eu- and hypoglycemic rats.
Outcomes validate efficacy of GP siRNA delivery for manipulation of glycogen
breakdown in discrete brain structures in vivo, and document VMN GPbb control of
local GPmm expression. Results document GPmm and/or -bb regulation of GABAergic
and nitrergic transmission in discrete rostro-caudal VMN segments. Contrary
effects of glycogenolysis on metabolic-sensory AMPK protein during eu- versus
hypoglycemia may reflect energy state-specific astrocyte signaling. Amplifying
effects of GPbb knockdown on hypoglycemic stimulation of pAMPK infer that
glycogen mobilization by GPbb limits neuronal energy instability during
hypoglycemia.
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Affiliation(s)
- Md Main Uddin
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, 15512University of Louisiana Monroe, Monroe, LA, USA
| | - Mostafa M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, 15512University of Louisiana Monroe, Monroe, LA, USA
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, 15512University of Louisiana Monroe, Monroe, LA, USA
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Ibrahim MMH, Bheemanapally K, Sylvester PW, Briski KP. Norepinephrine Regulation of Adrenergic Receptor Expression, 5' AMP-Activated Protein Kinase Activity, and Glycogen Metabolism and Mass in Male Versus Female Hypothalamic Primary Astrocyte Cultures. ASN Neuro 2021; 12:1759091420974134. [PMID: 33176438 PMCID: PMC7672765 DOI: 10.1177/1759091420974134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Norepinephrine (NE) control of hypothalamic gluco-regulation involves astrocyte-derived energy fuel supply. In male rats, exogenous NE regulates astrocyte glycogen metabolic enzyme expression in vivo through 5’-AMP-activated protein kinase (AMPK)-dependent mechanisms. Current research utilized a rat hypothalamic astrocyte primary culture model to investigate the premise that NE imposes sex-specific direct control of AMPK activity and glycogen mass and metabolism in these glia. In male rats, NE down-regulation of pAMPK correlates with decreased CaMMKB and increased PP1 expression, whereas noradrenergic augmentation of female astrocyte pAMPK may not involve these upstream regulators. NE concentration is a critical determinant of control of hypothalamic astrocyte glycogen enzyme expression, but efficacy varies between sexes. Data show sex variations in glycogen synthase expression and glycogen phosphorylase-brain and –muscle type dose-responsiveness to NE. Narrow dose-dependent NE augmentation of astrocyte glycogen content during energy homeostasis infers that NE maintains, over a broad exposure range, constancy of glycogen content despite possible changes in turnover. In male rats, beta1- and beta2-adrenergic receptor (AR) profiles displayed bi-directional responses to increasing NE doses; female astrocytes exhibited diminished beta1-AR content at low dose exposure, but enhanced beta2-AR expression at high NE dosages. Thus, graded variations in noradrenergic stimulation may modulate astrocyte receptivity to NE in vivo. Sex dimorphic NE regulation of hypothalamic astrocyte AMPK activation and glycogen metabolism may be mediated, in part, by one or more ARs characterized here by divergent sensitivity to this transmitter.
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Affiliation(s)
- Mostafa M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, United States
| | - Khaggeswar Bheemanapally
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, United States
| | - Paul W Sylvester
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, United States
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, United States
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Bheemanapally K, Napit PR, Ibrahim MMH, Briski KP. UHPLC-electrospray ionization-mass spectrometric analysis of brain cell-specific glucogenic and neurotransmitter amino acid content. Sci Rep 2021; 11:16079. [PMID: 34373537 PMCID: PMC8352916 DOI: 10.1038/s41598-021-95646-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 07/26/2021] [Indexed: 11/25/2022] Open
Abstract
Astrocyte glycogen, the primary energy reserve in brain, undergoes continuous remodeling by glucose passage through the glycogen shunt prior to conversion to the oxidizable energy fuel L-lactate. Glucogenic amino acids (GAAs) are a potential non-glucose energy source during neuro-metabolic instability. Current research investigated whether diminished glycogen metabolism affects GAA homeostasis in astrocyte and/or nerve cell compartments. The glycogen phosphorylase (GP) inhibitor 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) was injected into the ventromedial hypothalamic nucleus (VMN), a key metabolic-sensing structure, before vehicle or L-lactate infusion. Pure VMN astrocyte and metabolic-sensory neuron samples were obtained by combinatory immunocytochemistry/laser-catapult-microdissection for UHPLC-electrospray ionization-mass spectrometry (LC-ESI-MS) GAA analysis. DAB inhibition of VMN astrocyte aspartate and glutamine (Gln) levels was prevented or exacerbated, respectively, by lactate. VMN gluco-stimulatory nitric oxide (NO; neuronal nitric oxide synthase-immunoreactive (ir)-positive) and gluco-inhibitory γ-aminobutyric acid (GABA; glutamate decarboxylase65/67-ir-positive) neurons exhibited lactate-reversible asparate and glutamate augmentation by DAB, but dissimilar Gln responses to DAB. GP inhibition elevated NO and GABA nerve cell GABA content, but diminished astrocyte GABA; these responses were averted by lactate in neuron, but not astrocyte samples. Outcomes provide proof-of-principle of requisite LC-ESI-MS sensitivity for GAA measurement in specific brain cell populations. Results document divergent effects of decreased VMN glycogen breakdown on astrocyte versus neuron GAAs excepting Gln. Lactate-reversible DAB up-regulation of metabolic-sensory neuron GABA signaling may reflect compensatory nerve cell energy stabilization upon decline in astrocyte-derived metabolic fuel.
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Affiliation(s)
- Khaggeswar Bheemanapally
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA, 71201, USA
| | - Prabhat R Napit
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA, 71201, USA
| | - Mostafa M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA, 71201, USA
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA, 71201, USA.
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Bheemanapally K, Ibrahim MMH, Alshamrani A, Briski KP. Ventromedial hypothalamic nucleus glycogen regulation of metabolic-sensory neuron AMPK and neurotransmitter expression: role of lactate. Am J Physiol Regul Integr Comp Physiol 2021; 320:R791-R799. [PMID: 33825506 PMCID: PMC8285616 DOI: 10.1152/ajpregu.00292.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 03/18/2021] [Accepted: 03/31/2021] [Indexed: 12/23/2022]
Abstract
Astrocyte glycogen is dynamically remodeled during metabolic stability and provides oxidizable l-lactate equivalents during neuroglucopenia. Current research investigated the hypothesis that ventromedial hypothalamic nucleus (VMN) glycogen metabolism controls glucostimulatory nitric oxide (NO) and/or glucoinhibitory gamma-aminobutyric acid (GABA) neuron 5'-AMP-activated protein kinase (AMPK) and transmitter marker, e.g., neuronal nitric oxide synthase (nNOS), and glutamate decarboxylase65/67 (GAD) protein expression. Adult ovariectomized estradiol-implanted female rats were injected into the VMN with the glycogen phosphorylase inhibitor 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) before vehicle or l-lactate infusion. Western blot analysis of laser-catapult-microdissected nitrergic and GABAergic neurons showed that DAB caused lactate-reversible upregulation of nNOS and GAD proteins. DAB suppressed or increased total AMPK content of NO and GABA neurons, respectively, by lactate-independent mechanisms, but lactate prevented drug enhancement of pAMPK expression in nitrergic neurons. Inhibition of VMN glycogen disassembly caused divergent changes in counter-regulatory hormone, e.g. corticosterone (increased) and glucagon (decreased) secretion. Outcomes show that VMN glycogen metabolism controls local glucoregulatory transmission by means of lactate signal volume. Results implicate glycogen-derived lactate deficiency as a physiological stimulus of corticosterone release. Concurrent normalization of nitrergic neuron nNOS and pAMPK protein and corticosterone secretory response to DAB by lactate infers that the hypothalamic-pituitary-adrenal axis may be activated by VMN NO-mediated signals of cellular energy imbalance.
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Affiliation(s)
- Khaggeswar Bheemanapally
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
| | - Mostafa M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
| | - Ayed Alshamrani
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana
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Petit JM, Eren-Koçak E, Karatas H, Magistretti P, Dalkara T. Brain glycogen metabolism: A possible link between sleep disturbances, headache and depression. Sleep Med Rev 2021; 59:101449. [PMID: 33618186 DOI: 10.1016/j.smrv.2021.101449] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/27/2022]
Abstract
The functions of sleep and its links with neuropsychiatric diseases have long been questioned. Among the numerous hypotheses on sleep function, early studies proposed that sleep helps to replenish glycogen stores consumed during waking. Later studies found increased brain glycogen after sleep deprivation, leading to "glycogenetic" hypothesis, which states that there is a parallel increase in synthesis and utilization of glycogen during wakefulness, whereas decrease in the excitatory transmission creates an imbalance causing accumulation of glycogen during sleep. Glycogen is a vital energy reservoir to match the synaptic demand particularly for re-uptake of potassium and glutamate during intense glutamatergic transmission. Therefore, sleep deprivation-induced transcriptional changes may trigger migraine by reducing glycogen availability, which slows clearance of extracellular potassium and glutamate, hence, creates susceptibility to cortical spreading depolarization, the electrophysiological correlate of migraine aura. Interestingly, chronic stress accompanied by increased glucocorticoid levels and locus coeruleus activity and leading to mood disorders in which sleep disturbances are prevalent, also affects brain glycogen turnover via glucocorticoids, noradrenaline, serotonin and adenosine. These observations altogether suggest that inadequate astrocytic glycogen turnover may be one of the mechanisms linking migraine, mood disorders and sleep.
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Affiliation(s)
- J-M Petit
- Lausanne University Hospital, Center for Psychiatric Neuroscience, Prilly, Switzerland.
| | - E Eren-Koçak
- Hacettepe University, Institute of Neurological Sciences and Psychiatry, and Faculty of Medicine, Department of Psychiatry, Ankara, Turkey.
| | - H Karatas
- Hacettepe University, Institute of Neurological Sciences and Psychiatry, Ankara, Turkey.
| | - P Magistretti
- King Abdullah University of Science and Technology, Saudi Arabia.
| | - T Dalkara
- Hacettepe University, Institute of Neurological Sciences and Psychiatry, Ankara, Turkey.
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Briski KP, Ibrahim MMH, Mahmood ASMH, Alshamrani AA. Norepinephrine Regulation of Ventromedial Hypothalamic Nucleus Astrocyte Glycogen Metabolism. Int J Mol Sci 2021; 22:ijms22020759. [PMID: 33451134 PMCID: PMC7828624 DOI: 10.3390/ijms22020759] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/04/2021] [Accepted: 01/09/2021] [Indexed: 12/15/2022] Open
Abstract
The catecholamine norepinephrine (NE) links hindbrain metabolic-sensory neurons with key glucostatic control structures in the brain, including the ventromedial hypothalamic nucleus (VMN). In the brain, the glycogen reserve is maintained within the astrocyte cell compartment as an alternative energy source to blood-derived glucose. VMN astrocytes are direct targets for metabolic stimulus-driven noradrenergic signaling due to their adrenergic receptor expression (AR). The current review discusses recent affirmative evidence that neuro-metabolic stability in the VMN may be shaped by NE influence on astrocyte glycogen metabolism and glycogen-derived substrate fuel supply. Noradrenergic modulation of estrogen receptor (ER) control of VMN glycogen phosphorylase (GP) isoform expression supports the interaction of catecholamine and estradiol signals in shaping the physiological stimulus-specific control of astrocyte glycogen mobilization. Sex-dimorphic NE control of glycogen synthase and GP brain versus muscle type proteins may be due, in part, to the dissimilar noradrenergic governance of astrocyte AR and ER variant profiles in males versus females. Forthcoming advances in the understanding of the molecular mechanistic framework for catecholamine stimulus integration with other regulatory inputs to VMN astrocytes will undoubtedly reveal useful new molecular targets in each sex for glycogen mediated defense of neuronal metabolic equilibrium during neuro-glucopenia.
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Alhamyani A, Mahmood AH, Alshamrani A, Ibrahim MMH, Briski KP. Central Type II Glucocorticoid Receptor Regulation of Ventromedial Hypothalamic Nucleus Glycogen Metabolic Enzyme and Glucoregulatory Neurotransmitter Marker Protein Expression in the Male Rat. JOURNAL OF ENDOCRINOLOGY AND DIABETES 2021; 8:148. [PMID: 34258390 PMCID: PMC8274514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The ventromedial hypothalamic nucleus (VMN) glucoregulatory neurotransmitters γ-aminobutyric acid (GABA) and nitric oxide (NO) signal adjustments in glycogen mobilization. Glucocorticoids control astrocyte glycogen metabolism in vitro. The classical (type II) glucocorticoid receptor (GR) is expressed in key brain structures that govern glucostasis, including the VMN. Current research addressed the hypothesis that forebrain GR regulation of VMN glycogen synthase (GS) and phosphorylase (GP) protein expression correlates with control of glucoregulatory transmission. Groups of male rats were pretreated by intracerebroventricular (icv) delivery of the GR antagonist RU486 or vehicle prior to insulin-induced hypoglycemia (IIH), or were pretreated icv with dexamethasone (DEX) or vehicle before subcutaneous insulin diluent injection. DEX increased VMN GS and norepinephrine-sensitive GP-muscle type (GPmm), but did not alter metabolic deficit-sensitive GP-brain type (GPbb) expression. RU486 enhanced GS and GPbb profiles during IIH. VMN astrocyte (MCT1) and neuronal (MCT2) monocarboxylate transporter profiles were up-regulated in euglycemic and hypoglycemic animals by DEX or RU486, respectively. Glutamate decarboxylase65/67 and neuronal nitric oxide synthase (nNOS) proteins were both increased by DEX, yet RU486 augmented hypoglycemic nNOS expression patterns. Results show that GR exert divergent effects on VMN GS, MCT1/2, and nNOS proteins during eu- (stimulatory) versus hypoglycemia (inhibitory); these findings imply that up-regulated NO transmission may reflect, in part, augmented glucose incorporation into glycogen and/or increased tissue lactate requirements. Data also provide novel evidence for metabolic state-dependent GR regulation of VMN GPmm and GPbb profiles; thus, GABA signaling of metabolic stability may reflect, in part, stimulus-specific glycogen breakdown during eu- versus hypoglycemia.
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Affiliation(s)
- Abdulrahman Alhamyani
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201
| | - A.S.M. Hasan Mahmood
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201
| | - Ayed Alshamrani
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201
| | - Mostafa M. H. Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201
| | - Karen P. Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201
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12
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Duran J, Brewer MK, Hervera A, Gruart A, Del Rio JA, Delgado-García JM, Guinovart JJ. Lack of Astrocytic Glycogen Alters Synaptic Plasticity but Not Seizure Susceptibility. Mol Neurobiol 2020; 57:4657-4666. [PMID: 32770452 PMCID: PMC7530046 DOI: 10.1007/s12035-020-02055-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/31/2020] [Indexed: 12/18/2022]
Abstract
Brain glycogen is mainly stored in astrocytes. However, recent studies both in vitro and in vivo indicate that glycogen also plays important roles in neurons. By conditional deletion of glycogen synthase (GYS1), we previously developed a mouse model entirely devoid of glycogen in the central nervous system (GYS1Nestin-KO). These mice displayed altered electrophysiological properties in the hippocampus and increased susceptibility to kainate-induced seizures. To understand which of these functions are related to astrocytic glycogen, in the present study, we generated a mouse model in which glycogen synthesis is eliminated specifically in astrocytes (GYS1Gfap-KO). Electrophysiological recordings of awake behaving mice revealed alterations in input/output curves and impaired long-term potentiation, similar, but to a lesser extent, to those obtained with GYS1Nestin-KO mice. Surprisingly, GYS1Gfap-KO mice displayed no change in susceptibility to kainate-induced seizures as determined by fEPSP recordings and video monitoring. These results confirm the importance of astrocytic glycogen in synaptic plasticity.
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Affiliation(s)
- Jordi Duran
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028, Barcelona, Spain.
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029, Madrid, Spain.
| | - M Kathryn Brewer
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028, Barcelona, Spain
| | - Arnau Hervera
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, 08028, Barcelona, Spain
- Institute of Neurosciences, University of Barcelona, 08028, Barcelona, Spain
| | - Agnès Gruart
- Division of Neurosciences, Pablo de Olavide University, Seville, Spain
| | - Jose Antonio Del Rio
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, 08028, Barcelona, Spain
- Institute of Neurosciences, University of Barcelona, 08028, Barcelona, Spain
| | | | - Joan J Guinovart
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029, Madrid, Spain
- Department of Biochemistry and Molecular Biomedicine, University of Barcelona, 08028, Barcelona, Spain
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13
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Saad-El-Din AA, Mazhar A, Khalil W. Role of Spirulina on gamma-irradiated rats using Fourier transform infrared attenuated total reflectance and Electron spin resonance for brain. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2020. [DOI: 10.1080/16878507.2020.1756186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Aisha A. Saad-El-Din
- Radiation Physics Department, National Center for Radiation Research & Technology (NCRRT), Egyptian Atomic Energy Authority (EAEA), Cairo, Egypt
| | - Aliaa Mazhar
- Radiation Physics Department, National Center for Radiation Research & Technology (NCRRT), Egyptian Atomic Energy Authority (EAEA), Cairo, Egypt
| | - Wafaa Khalil
- Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt
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14
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Perenthaler E, Nikoncuk A, Yousefi S, Berdowski WM, Alsagob M, Capo I, van der Linde HC, van den Berg P, Jacobs EH, Putar D, Ghazvini M, Aronica E, van IJcken WFJ, de Valk WG, Medici-van den Herik E, van Slegtenhorst M, Brick L, Kozenko M, Kohler JN, Bernstein JA, Monaghan KG, Begtrup A, Torene R, Al Futaisi A, Al Murshedi F, Mani R, Al Azri F, Kamsteeg EJ, Mojarrad M, Eslahi A, Khazaei Z, Darmiyan FM, Doosti M, Karimiani EG, Vandrovcova J, Zafar F, Rana N, Kandaswamy KK, Hertecant J, Bauer P, AlMuhaizea MA, Salih MA, Aldosary M, Almass R, Al-Quait L, Qubbaj W, Coskun S, Alahmadi KO, Hamad MHA, Alwadaee S, Awartani K, Dababo AM, Almohanna F, Colak D, Dehghani M, Mehrjardi MYV, Gunel M, Ercan-Sencicek AG, Passi GR, Cheema HA, Efthymiou S, Houlden H, Bertoli-Avella AM, Brooks AS, Retterer K, Maroofian R, Kaya N, van Ham TJ, Barakat TS. Loss of UGP2 in brain leads to a severe epileptic encephalopathy, emphasizing that bi-allelic isoform-specific start-loss mutations of essential genes can cause genetic diseases. Acta Neuropathol 2020; 139:415-442. [PMID: 31820119 PMCID: PMC7035241 DOI: 10.1007/s00401-019-02109-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/02/2019] [Accepted: 12/03/2019] [Indexed: 12/24/2022]
Abstract
Developmental and/or epileptic encephalopathies (DEEs) are a group of devastating genetic disorders, resulting in early-onset, therapy-resistant seizures and developmental delay. Here we report on 22 individuals from 15 families presenting with a severe form of intractable epilepsy, severe developmental delay, progressive microcephaly, visual disturbance and similar minor dysmorphisms. Whole exome sequencing identified a recurrent, homozygous variant (chr2:64083454A > G) in the essential UDP-glucose pyrophosphorylase (UGP2) gene in all probands. This rare variant results in a tolerable Met12Val missense change of the longer UGP2 protein isoform but causes a disruption of the start codon of the shorter isoform, which is predominant in brain. We show that the absence of the shorter isoform leads to a reduction of functional UGP2 enzyme in neural stem cells, leading to altered glycogen metabolism, upregulated unfolded protein response and premature neuronal differentiation, as modeled during pluripotent stem cell differentiation in vitro. In contrast, the complete lack of all UGP2 isoforms leads to differentiation defects in multiple lineages in human cells. Reduced expression of Ugp2a/Ugp2b in vivo in zebrafish mimics visual disturbance and mutant animals show a behavioral phenotype. Our study identifies a recurrent start codon mutation in UGP2 as a cause of a novel autosomal recessive DEE syndrome. Importantly, it also shows that isoform-specific start-loss mutations causing expression loss of a tissue-relevant isoform of an essential protein can cause a genetic disease, even when an organism-wide protein absence is incompatible with life. We provide additional examples where a similar disease mechanism applies.
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Affiliation(s)
- Elena Perenthaler
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Anita Nikoncuk
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Soheil Yousefi
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Woutje M Berdowski
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Maysoon Alsagob
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Ivan Capo
- Department for Histology and Embryology, Faculty of Medicine Novi Sad, University of Novi Sad, Novi Sad, Serbia
| | - Herma C van der Linde
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Paul van den Berg
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Edwin H Jacobs
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Darija Putar
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Mehrnaz Ghazvini
- iPS Cell Core Facility, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The Netherlands
| | - Wilfred F J van IJcken
- Center for Biomics, Department of Cell Biology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Walter G de Valk
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Lauren Brick
- Division of Genetics, McMaster Children's Hospital, Hamilton, ON, L8S 4J9, Canada
| | - Mariya Kozenko
- Division of Genetics, McMaster Children's Hospital, Hamilton, ON, L8S 4J9, Canada
| | - Jennefer N Kohler
- Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, 94035, USA
| | - Jonathan A Bernstein
- Division of Medical Genetics, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94035, USA
| | | | | | | | - Amna Al Futaisi
- Department of Child Health, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Fathiya Al Murshedi
- Genetic and Developmental Medicine Clinic, Sultan Qaboos University Hospital, Muscat, Oman
| | - Renjith Mani
- Department of Child Health, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Faisal Al Azri
- Department of Radiology and Molecular Imaging, Sultan Qaboos University Hospital, Muscat, Oman
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Majid Mojarrad
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Medical Genetics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
- Genetic Center of Khorasan Razavi, Mashhad, Iran
| | - Atieh Eslahi
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | | | | | - Mohammad Doosti
- Department Medical Genetics, Next Generation Genetic Polyclinic, Mashhad, Iran
| | - Ehsan Ghayoor Karimiani
- Molecular and Clinical Sciences Institute, St. George's University of London, Cranmer Terrace, London, SW17 0RE, UK
- Innovative Medical Research Center, Mashhad Branch, Islamic Azad University, Mashhad, Iran
| | - Jana Vandrovcova
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Faisal Zafar
- Department of Paediatric Neurology, Children's Hospital and Institute of Child Health, Multan, 60000, Pakistan
| | - Nuzhat Rana
- Department of Paediatric Neurology, Children's Hospital and Institute of Child Health, Multan, 60000, Pakistan
| | | | - Jozef Hertecant
- Department of Pediatrics, Tawam Hospital, and College of Medicine and Health Sciences, UAE University, Al-Ain, UAE
| | | | - Mohammed A AlMuhaizea
- Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Mustafa A Salih
- Neurology Division, Department of Pediatrics, College of Medicine, King Saud University, Riyadh, 11461, Kingdom of Saudi Arabia
| | - Mazhor Aldosary
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Rawan Almass
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Laila Al-Quait
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Wafa Qubbaj
- Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Serdar Coskun
- Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Khaled O Alahmadi
- Radiology Department, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Muddathir H A Hamad
- Neurology Division, Department of Pediatrics, College of Medicine, King Saud University, Riyadh, 11461, Kingdom of Saudi Arabia
| | - Salem Alwadaee
- Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Khalid Awartani
- Obstetrics/Gynecology Department, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Anas M Dababo
- Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Futwan Almohanna
- Department of Cell Biology, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Dilek Colak
- Department of Biostatistics, Epidemiology and Scientific Computing, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Mohammadreza Dehghani
- Medical Genetics Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
- Yazd Reproductive Sciences Institute, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | | | - Murat Gunel
- Department of Neurosurgery, Program On Neurogenetics, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - A Gulhan Ercan-Sencicek
- Department of Neurosurgery, Program On Neurogenetics, Yale School of Medicine, Yale University, New Haven, CT, USA
- Masonic Medical Research Institute, Utica, NY, USA
| | - Gouri Rao Passi
- Department of Pediatrics, Pediatric Neurology Clinic, Choithram Hospital and Research Centre, Indore, Madhya Pradesh, India
| | - Huma Arshad Cheema
- Pediatric Gastroenterology Department, Children's Hospital and Institute of Child Health, Lahore, Pakistan
| | - Stephanie Efthymiou
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | | | - Alice S Brooks
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | - Reza Maroofian
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Namik Kaya
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Kingdom of Saudi Arabia
| | - Tjakko J van Ham
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.
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Abstract
Glucose is the long-established, obligatory fuel for brain that fulfills many critical functions, including ATP production, oxidative stress management, and synthesis of neurotransmitters, neuromodulators, and structural components. Neuronal glucose oxidation exceeds that in astrocytes, but both rates increase in direct proportion to excitatory neurotransmission; signaling and metabolism are closely coupled at the local level. Exact details of neuron-astrocyte glutamate-glutamine cycling remain to be established, and the specific roles of glucose and lactate in the cellular energetics of these processes are debated. Glycolysis is preferentially upregulated during brain activation even though oxygen availability is sufficient (aerobic glycolysis). Three major pathways, glycolysis, pentose phosphate shunt, and glycogen turnover, contribute to utilization of glucose in excess of oxygen, and adrenergic regulation of aerobic glycolysis draws attention to astrocytic metabolism, particularly glycogen turnover, which has a high impact on the oxygen-carbohydrate mismatch. Aerobic glycolysis is proposed to be predominant in young children and specific brain regions, but re-evaluation of data is necessary. Shuttling of glucose- and glycogen-derived lactate from astrocytes to neurons during activation, neurotransmission, and memory consolidation are controversial topics for which alternative mechanisms are proposed. Nutritional therapy and vagus nerve stimulation are translational bridges from metabolism to clinical treatment of diverse brain disorders.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences , Little Rock, Arkansas ; and Department of Cell Biology and Physiology, University of New Mexico , Albuquerque, New Mexico
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16
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Kilic K, Karatas H, Dönmez-Demir B, Eren-Kocak E, Gursoy-Ozdemir Y, Can A, Petit JM, Magistretti PJ, Dalkara T. Inadequate brain glycogen or sleep increases spreading depression susceptibility. Ann Neurol 2019; 83:61-73. [PMID: 29244233 DOI: 10.1002/ana.25122] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Revised: 11/23/2017] [Accepted: 12/12/2017] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Glycogen in astrocyte processes contributes to maintenance of low extracellular glutamate and K+ concentrations around excitatory synapses. Sleep deprivation (SD), a common migraine trigger, induces transcriptional changes in astrocytes, reducing glycogen breakdown. We hypothesize that when glycogen utilization cannot match synaptic energy demand, extracellular K+ can rise to levels that activate neuronal pannexin-1 channels and downstream inflammatory pathway, which might be one of the mechanisms initiating migraine headaches. METHODS We suppressed glycogen breakdown by inhibiting glycogen phosphorylation with 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) and by SD. RESULTS DAB caused neuronal pannexin-1 large pore opening and activation of the downstream inflammatory pathway as shown by procaspase-1 cleavage and HMGB1 release from neurons. Six-hour SD induced pannexin-1 mRNA. DAB and SD also lowered the cortical spreading depression (CSD) induction threshold, which was reversed by glucose or lactate supplement, suggesting that glycogen-derived energy substrates are needed to prevent CSD generation. Supporting this, knocking down the neuronal lactate transporter MCT2 with an antisense oligonucleotide or inhibiting glucose transport from vessels to astrocytes with intracerebroventricularly delivered phloretin reduced the CSD threshold. In vivo recordings with a K+ -sensitive/selective fluoroprobe, Asante Potassium Green-4, revealed that DAB treatment or SD caused a significant rise in extracellular K+ during whisker stimulation, illustrating the critical role of glycogen in extracellular K+ clearance. INTERPRETATION Synaptic metabolic stress caused by insufficient glycogen-derived energy substrate supply can activate neuronal pannexin-1 channels as well as lower the CSD threshold. Therefore, conditions that limit energy supply to synapses (eg, SD) may predispose to migraine attacks, as suggested by genetic studies associating glucose or lactate transporter deficiency with migraine. Ann Neurol 2018;83:61-73.
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Affiliation(s)
- Kivilcim Kilic
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Hulya Karatas
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Buket Dönmez-Demir
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Emine Eren-Kocak
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Yasemin Gursoy-Ozdemir
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey.,Current address for Dr Gursoy-Ozdemir: Department of Neurology, School of Medicine, Koç University, Istanbul, Turkey
| | - Alp Can
- Department of Histology and Embryology, School of Medicine, Ankara University, Ankara, Turkey
| | - Jean-Marie Petit
- Center for Psychiatric Neuroscience, Department of Psychiatry, University Hospital of the Canton of Vaud (CHUV), Prilly, Switzerland
| | - Pierre J Magistretti
- King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.,Brain Mind Institute, Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Turgay Dalkara
- Department of Neurology, Faculty of Medicine and Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
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17
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Ibrahim MMH, Alhamami HN, Briski KP. Norepinephrine regulation of ventromedial hypothalamic nucleus metabolic transmitter biomarker and astrocyte enzyme and receptor expression: Impact of 5' AMP-activated protein kinase. Brain Res 2019; 1711:48-57. [PMID: 30629946 DOI: 10.1016/j.brainres.2019.01.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 09/12/2018] [Accepted: 01/07/2019] [Indexed: 11/18/2022]
Abstract
The ventromedial hypothalamic energy sensor AMP-activated protein kinase (AMPK) maintains glucostasis via neurotransmitter signals that diminish [γ-aminobutyric acid] or enhance [nitric oxide] counter-regulation. Ventromedial hypothalamic nucleus (VMN) 'fuel-inhibited' neurons are sensitive to astrocyte-generated metabolic substrate stream. Norepinephrine (NE) regulates astrocyte glycogen metabolism in vitro, and hypoglycemia intensifies VMN NE activity in vivo. Current research investigated the premise that NE elicits AMPK-dependent adjustments in VMN astrocyte glycogen metabolic enzyme [glycogen synthase (GS); glycogen phosphorylase (GP)] and gluco-regulatory neuron biomarker [glutamate decarboxylase65/67 (GAD); neuronal nitric oxide synthase (nNOS); SF-1] protein expression in male rats. We also examined whether VMN astrocytes are directly receptive to NE and if noradrenergic input regulates cellular sensitivity to the neuro-protective steroid estradiol. Intra-VMN NE correspondingly augmented or reduced VMN tissue GAD and nNOS protein despite no change in circulating glucose, data that imply that short-term exposure to NE promotes persistent improvement in VMN nerve cell energy stability. The AMPK inhibitor Compound C (Cc) normalized VMN nNOS, GS, and GP expression in NE-treated animals. NE caused AMPK-independent down-regulation of alpha2-, alongside Cc-reversible augmentation of beta1-adrenergic receptor protein profiles in laser-microdissected astrocytes. NE elicited divergent adjustments in astrocyte estrogen receptor-beta (AMPK-unrelated reduction) and GPR-30 (Cc-revocable increase) proteins. Outcomes implicate AMPK in noradrenergic diminution of VMN nitrergic metabolic-deficit signaling and astrocyte glycogen shunt activity. Differentiating NE effects on VMN astrocyte adrenergic and estrogen receptor variant expression suggest that noradrenergic regulation of glycogen metabolism may be mediated, in part, by one or more receptors characterized here by sensitivity to this catecholamine.
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Affiliation(s)
- Mostafa M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, United States
| | - Hussain N Alhamami
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, United States
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, United States.
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18
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Hasan Mahmood ASM, Uddin MM, Ibrahim MMH, Mandal SK, Alhamami HN, Briski KP. Sex differences in forebrain estrogen receptor regulation of hypoglycemic patterns of counter-regulatory hormone secretion and ventromedial hypothalamic nucleus glucoregulatory neurotransmitter and astrocyte glycogen metabolic enzyme expression. Neuropeptides 2018; 72:65-74. [PMID: 30396594 PMCID: PMC6293983 DOI: 10.1016/j.npep.2018.10.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/24/2018] [Accepted: 10/24/2018] [Indexed: 12/13/2022]
Abstract
The female ventromedial hypothalamic nucleus (VMN) is a focal substrate for estradiol (E) regulation of energy balance, feeding, and body weight, but how E shapes VMN gluco-regulatory signaling in each sex is unclear. This study investigated the hypothesis that estrogen receptor-alpha (ERα) and/or -beta (ERβ) control VMN signals that inhibit [γ-aminobutyric acid] or stimulate [nitric oxide, steroidogenic factor-1 (SF-1)] counter-regulation in a sex-dependent manner. VMN nitrergic neurons monitor astrocyte fuel provision; here, we examined how these ER regulate astrocyte glycogen metabolic enzyme, monocarboxylate transporter, and adrenoreceptor protein responses to insulin-induced hypoglycemia (IIH) in each sex. Testes-intact male and E-replaced ovariectomized female rats were pretreated by intracerebroventricular ERα antagonist (MPP) or ERβ antagonist (PHTPP) administration before IIH. Data implicate both ER in hypoglycemic inhibition of neuronal nitric oxide synthase protein in each sex and up-regulation of glutamate decarboxylase65/67 and SF-1 expression in females. ERα and -β enhance astrocyte AMPK and glycogen synthase expression and inhibit glycogen phosphorylase in hypoglycemic females, while ERβ suppresses the same proteins in males. Differential VMN astrocyte protein responses to IIH may partially reflect ERα and -β augmentation of ERβ and down-regulation of alpha1, alpha2, and beta1 adrenoreceptor proteins in females, versus ERβ repression of GPER and alpha2 adrenoreceptor profiles in males. MPP or PHTPP pretreatment blunted counter-regulatory hormone secretion in hypoglycemic males only, suggesting that in males one or more VMN neurotransmitters exhibiting sensitivity to forebrain ER may passively regulate this endocrine outflow, whereas female forebrain ERα and -β are apparently uninvolved in these contra-regulatory responses.
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Affiliation(s)
- A S M Hasan Mahmood
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA 71201, USA
| | - M M Uddin
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA 71201, USA
| | - M M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA 71201, USA
| | - S K Mandal
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA 71201, USA
| | - H N Alhamami
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA 71201, USA
| | - K P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, 356 Bienville Building, 1800 Bienville Drive, Monroe, LA 71201, USA.
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Coggan JS, Keller D, Calì C, Lehväslaiho H, Markram H, Schürmann F, Magistretti PJ. Norepinephrine stimulates glycogenolysis in astrocytes to fuel neurons with lactate. PLoS Comput Biol 2018; 14:e1006392. [PMID: 30161133 PMCID: PMC6160207 DOI: 10.1371/journal.pcbi.1006392] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 09/27/2018] [Accepted: 07/24/2018] [Indexed: 12/20/2022] Open
Abstract
The mechanism of rapid energy supply to the brain, especially to accommodate the heightened metabolic activity of excited states, is not well-understood. We explored the role of glycogen as a fuel source for neuromodulation using the noradrenergic stimulation of glia in a computational model of the neural-glial-vasculature ensemble (NGV). The detection of norepinephrine (NE) by the astrocyte and the coupled cAMP signal are rapid and largely insensitive to the distance of the locus coeruleus projection release sites from the glia, implying a diminished impact for volume transmission in high affinity receptor transduction systems. Glucosyl-conjugated units liberated from glial glycogen by NE-elicited cAMP second messenger transduction winds sequentially through the glycolytic cascade, generating robust increases in NADH and ATP before pyruvate is finally transformed into lactate. This astrocytic lactate is rapidly exported by monocarboxylate transporters to the associated neuron, demonstrating that the astrocyte-to-neuron lactate shuttle activated by glycogenolysis is a likely fuel source for neuromodulation and enhanced neural activity. Altogether, the energy supply for both astrocytes and neurons can be supplied rapidly by glycogenolysis upon neuromodulatory stimulus. Although efficient compared to computers, the human brain utilizes energy at 10-fold the rate of other organs by mass. How the brain is supplied with sufficient on-demand energy to support its activity in the absence of neuronal storage capacity remains unknown. Neurons are not capable of meeting their own energy requirements, instead energy supply in the brain is managed by an oligocellular cartel composed of neurons, glia and the local vasculature (NGV), wherein glia can provide the ergogenic metabolite lactate to the neuron in a process called the astrocyte-to-neuron shuttle (ANLS). The only means of energy storage in the brain is glycogen, a polymerized form of glucose that is localized largely to astrocytes, but its exact role and conditions of use are not clear. In this computational model we show that neuromodulatory stimulation by norepinephrine induces astrocytes to recover glucosyl subunits from glycogen for use in a glycolytic process that favors the production of lactate. The ATP and NADH produced support metabolism in the astrocyte while the lactate is exported to feed the neuron. Thus, rapid energy demands by both neurons and glia in a stimulated brain can be met by glycogen mobilization.
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Affiliation(s)
- Jay S. Coggan
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
- * E-mail: (JSC); (PJM)
| | - Daniel Keller
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Corrado Calì
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Heikki Lehväslaiho
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Henry Markram
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Felix Schürmann
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Pierre J. Magistretti
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Geneva, Switzerland
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
- * E-mail: (JSC); (PJM)
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20
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Alhamami HN, Alshamrani A, Briski KP. Inhibition of glycogen phosphorylase stimulates ventromedial hypothalamic nucleus AMP-activated protein kinase: Activity and neuronal nitric oxide synthase protein expression in male rats. Physiol Rep 2018; 5. [PMID: 29199177 PMCID: PMC5727266 DOI: 10.14814/phy2.13484] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/28/2017] [Accepted: 10/02/2017] [Indexed: 11/24/2022] Open
Abstract
The glucose polymer glycogen is a vital fuel reserve in the brain. The mediobasal hypothalamic energy sensor AMP‐activated protein kinase (AMPK) maintains glucostasis via neurotransmitter mechanisms that suppress [γ‐aminobutyric acid; GABA] or stimulate [nitric oxide; steroidogenic factor‐1 (SF1)] counter‐regulatory outflow. This study investigated whether glycogen‐derived fuel supply is a critical screened variable in ventromedial hypothalamic nucleus (VMN) monitoring of neuro‐metabolic stability during glucostasis and/or insulin (I)‐induced hypoglycemia. Adult male rats were pretreated by intra‐VMN infusion of the glycogen phosphorylase inhibitor 1,4‐dideoxy‐1,4‐imino‐D‐arabinitol (DAB) before sc vehicle or I injection. Western blot analyses of micropunch‐dissected VMN tissue from euglycemic animals showed DAB augmentation of phosphoAMPK (pAMPK), neuronal nitric oxide synthase (nNOS), and SF‐1, but not glutamate decarboxylase65/67 (GAD) protein. Combinatory DAB/I treatment did not further enhance AMPK activity but significantly amplified nNOS expression relative to DAB alone. Hypoglycemic stimulation of corticosterone, but not glucagon release was prevented by DAB. Results imply that glycogen‐derived substrate fuel provision represses VMN AMPK activity and neurotransmitter signals of metabolic deficiency. Progressive augmentation of nNOS protein by DAB/I versus DAB/V intimates that “fuel‐inhibited” nitrergic neurons may exhibit increasing sensitivity to disrupted glycogen breakdown during glucoprivation versus glucostasis. nNOS and GAD reactivity to DAB/I, but not I implies that acute glycogen utilization during hypoglycemia may be sufficiently robust to avert effects on local metabolic sensory signaling. DAB/I upregulation of GAD alongside prevention of hypercorticosteronemia suggests that indicators of metabolic sufficiency may occur secondary to local compensatory adaptations to severe restriction of glucose‐derived energy.
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Affiliation(s)
- Hussain N Alhamami
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, College of Health and Pharmaceutical Sciences, University of Louisiana at Monroe, Monroe, Louisiana
| | - Ayed Alshamrani
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, College of Health and Pharmaceutical Sciences, University of Louisiana at Monroe, Monroe, Louisiana
| | - Karen P Briski
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, College of Health and Pharmaceutical Sciences, University of Louisiana at Monroe, Monroe, Louisiana
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21
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Gentry MS, Guinovart JJ, Minassian BA, Roach PJ, Serratosa JM. Lafora disease offers a unique window into neuronal glycogen metabolism. J Biol Chem 2018; 293:7117-7125. [PMID: 29483193 DOI: 10.1074/jbc.r117.803064] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Lafora disease (LD) is a fatal, autosomal recessive, glycogen-storage disorder that manifests as severe epilepsy. LD results from mutations in the gene encoding either the glycogen phosphatase laforin or the E3 ubiquitin ligase malin. Individuals with LD develop cytoplasmic, aberrant glycogen inclusions in nearly all tissues that more closely resemble plant starch than human glycogen. This Minireview discusses the unique window into glycogen metabolism that LD research offers. It also highlights recent discoveries, including that glycogen contains covalently bound phosphate and that neurons synthesize glycogen and express both glycogen synthase and glycogen phosphorylase.
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Affiliation(s)
- Matthew S Gentry
- Lafora Epilepsy Cure Initiative, Lexington, Kentucky 40503; Department of Biochemistry and Molecular Biology, Lexington, Kentucky 40503; University of Kentucky Epilepsy Research Center (EpiC), University of Kentucky, Lexington, Kentucky 40503.
| | - Joan J Guinovart
- Lafora Epilepsy Cure Initiative, Lexington, Kentucky 40503; Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; Biomedical Research Networking Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), 28029 Madrid, Spain; Department of Biochemistry and Molecular Biomedicine, University of Barcelona, 08028 Barcelona, Spain
| | - Berge A Minassian
- Lafora Epilepsy Cure Initiative, Lexington, Kentucky 40503; Department of Pediatrics and Dallas Children's Medical Center, University of Texas Southwestern, Dallas, Texas 75390-9063; Department of Pediatrics, The Hospital for Sick Children Research Institute, University of Toronto, Toronto, Ontario M5G 0A4, Canada
| | - Peter J Roach
- Lafora Epilepsy Cure Initiative, Lexington, Kentucky 40503; Department of Biochemistry and Molecular Biology, Center for Diabetes and Metabolic Diseases and Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Jose M Serratosa
- Lafora Epilepsy Cure Initiative, Lexington, Kentucky 40503; Laboratory of Neurology, IIS-Jimenez Diaz Foundation, UAM, 28045 Madrid, Spain; Biomedical Research Networking Center on Rare Diseases (CIBERER), 28029 Madrid, Spain
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22
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Anandhan A, Jacome MS, Lei S, Hernandez-Franco P, Pappa A, Panayiotidis MI, Powers R, Franco R. Metabolic Dysfunction in Parkinson's Disease: Bioenergetics, Redox Homeostasis and Central Carbon Metabolism. Brain Res Bull 2017; 133:12-30. [PMID: 28341600 PMCID: PMC5555796 DOI: 10.1016/j.brainresbull.2017.03.009] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 03/19/2017] [Accepted: 03/20/2017] [Indexed: 12/24/2022]
Abstract
The loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the accumulation of protein inclusions (Lewy bodies) are the pathological hallmarks of Parkinson's disease (PD). PD is triggered by genetic alterations, environmental/occupational exposures and aging. However, the exact molecular mechanisms linking these PD risk factors to neuronal dysfunction are still unclear. Alterations in redox homeostasis and bioenergetics (energy failure) are thought to be central components of neurodegeneration that contribute to the impairment of important homeostatic processes in dopaminergic cells such as protein quality control mechanisms, neurotransmitter release/metabolism, axonal transport of vesicles and cell survival. Importantly, both bioenergetics and redox homeostasis are coupled to neuro-glial central carbon metabolism. We and others have recently established a link between the alterations in central carbon metabolism induced by PD risk factors, redox homeostasis and bioenergetics and their contribution to the survival/death of dopaminergic cells. In this review, we focus on the link between metabolic dysfunction, energy failure and redox imbalance in PD, making an emphasis in the contribution of central carbon (glucose) metabolism. The evidence summarized here strongly supports the consideration of PD as a disorder of cell metabolism.
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Affiliation(s)
- Annadurai Anandhan
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68516, United States; Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68503, United States
| | - Maria S Jacome
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68516, United States
| | - Shulei Lei
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68503, United States
| | - Pablo Hernandez-Franco
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68516, United States; Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68503, United States
| | - Aglaia Pappa
- Department of Molecular Biology and Genetics, Democritus University of Thrace, University Campus, Dragana, 68100 Alexandroupolis, Greece
| | | | - Robert Powers
- Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68503, United States; Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68503, United States
| | - Rodrigo Franco
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68516, United States; Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68503, United States.
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Impaired Hippocampal Glutamate and Glutamine Metabolism in the db/db Mouse Model of Type 2 Diabetes Mellitus. Neural Plast 2017; 2017:2107084. [PMID: 28695014 PMCID: PMC5488168 DOI: 10.1155/2017/2107084] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/10/2017] [Indexed: 12/16/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a risk factor for the development of Alzheimer's disease, and changes in brain energy metabolism have been suggested as a causative mechanism. The aim of this study was to investigate the cerebral metabolism of the important amino acids glutamate and glutamine in the db/db mouse model of T2DM. Glutamate and glutamine are both substrates for mitochondrial oxidation, and oxygen consumption was assessed in isolated brain mitochondria by Seahorse XFe96 analysis. In addition, acutely isolated cerebral cortical and hippocampal slices were incubated with [U-13C]glutamate and [U-13C]glutamine, and tissue extracts were analyzed by gas chromatography-mass spectrometry. The oxygen consumption rate using glutamate and glutamine as substrates was not different in isolated cerebral mitochondria of db/db mice compared to controls. Hippocampal slices of db/db mice exhibited significantly reduced 13C labeling in glutamate, glutamine, GABA, citrate, and aspartate from metabolism of [U-13C]glutamate. Additionally, reduced 13C labeling were observed in GABA, citrate, and aspartate from [U-13C]glutamine metabolism in hippocampal slices of db/db mice when compared to controls. None of these changes were observed in cerebral cortical slices. The results suggest specific hippocampal impairments in glutamate and glutamine metabolism, without affecting mitochondrial oxidation of these substrates, in the db/db mouse.
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24
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Astroglial glutamate transporters coordinate excitatory signaling and brain energetics. Neurochem Int 2016; 98:56-71. [PMID: 27013346 DOI: 10.1016/j.neuint.2016.03.014] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 03/15/2016] [Accepted: 03/17/2016] [Indexed: 12/22/2022]
Abstract
In the mammalian brain, a family of sodium-dependent transporters maintains low extracellular glutamate and shapes excitatory signaling. The bulk of this activity is mediated by the astroglial glutamate transporters GLT-1 and GLAST (also called EAAT2 and EAAT1). In this review, we will discuss evidence that these transporters co-localize with, form physical (co-immunoprecipitable) interactions with, and functionally couple to various 'energy-generating' systems, including the Na(+)/K(+)-ATPase, the Na(+)/Ca(2+) exchanger, glycogen metabolizing enzymes, glycolytic enzymes, and mitochondria/mitochondrial proteins. This functional coupling is bi-directional with many of these systems both being regulated by glutamate transport and providing the 'fuel' to support glutamate uptake. Given the importance of glutamate uptake to maintaining synaptic signaling and preventing excitotoxicity, it should not be surprising that some of these systems appear to 'redundantly' support the energetic costs of glutamate uptake. Although the glutamate-glutamine cycle contributes to recycling of neurotransmitter pools of glutamate, this is an over-simplification. The ramifications of co-compartmentalization of glutamate transporters with mitochondria for glutamate metabolism are discussed. Energy consumption in the brain accounts for ∼20% of the basal metabolic rate and relies almost exclusively on glucose for the production of ATP. However, the brain does not possess substantial reserves of glucose or other fuels. To ensure adequate energetic supply, increases in neuronal activity are matched by increases in cerebral blood flow via a process known as 'neurovascular coupling'. While the mechanisms for this coupling are not completely resolved, it is generally agreed that astrocytes, with processes that extend to synapses and endfeet that surround blood vessels, mediate at least some of the signal that causes vasodilation. Several studies have shown that either genetic deletion or pharmacologic inhibition of glutamate transport impairs neurovascular coupling. Together these studies strongly suggest that glutamate transport not only coordinates excitatory signaling, but also plays a pivotal role in regulating brain energetics.
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25
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López-Ramos JC, Duran J, Gruart A, Guinovart JJ, Delgado-García JM. Role of brain glycogen in the response to hypoxia and in susceptibility to epilepsy. Front Cell Neurosci 2015; 9:431. [PMID: 26578889 PMCID: PMC4621300 DOI: 10.3389/fncel.2015.00431] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/13/2015] [Indexed: 12/23/2022] Open
Abstract
Although glycogen is the only carbohydrate reserve of the brain, its overall contribution to brain functions remains unclear. It has been proposed that glycogen participates in the preservation of such functions during hypoxia. Several reports also describe a relationship between brain glycogen and susceptibility to epilepsy. To address these issues, we used our brain-specific Glycogen Synthase knockout (GYS1Nestin-KO) mouse to study the functional consequences of glycogen depletion in the brain under hypoxic conditions and susceptibility to epilepsy. GYS1Nestin-KO mice presented significantly different power spectra of hippocampal local field potentials (LFPs) than controls under hypoxic conditions. In addition, they showed greater excitability than controls for paired-pulse facilitation evoked at the hippocampal CA3–CA1 synapse during experimentally induced hypoxia, thereby suggesting a compensatory switch to presynaptic mechanisms. Furthermore, GYS1Nestin-KO mice showed greater susceptibility to hippocampal seizures and myoclonus following the administration of kainate and/or a brief train stimulation of Schaffer collaterals. We conclude that brain glycogen could play a protective role both in hypoxic situations and in the prevention of brain seizures.
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Affiliation(s)
| | - Jordi Duran
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology Barcelona, Spain ; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) Barcelona, Spain
| | - Agnès Gruart
- Division of Neurosciences, Pablo de Olavide University Seville, Spain
| | - Joan J Guinovart
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology Barcelona, Spain ; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) Barcelona, Spain ; Department of Biochemistry and Molecular Biology, University of Barcelona Barcelona, Spain
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26
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Dienel GA, Cruz NF. Contributions of glycogen to astrocytic energetics during brain activation. Metab Brain Dis 2015; 30:281-98. [PMID: 24515302 PMCID: PMC4130810 DOI: 10.1007/s11011-014-9493-8] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 01/21/2014] [Indexed: 12/11/2022]
Abstract
Glycogen is the major store of glucose in brain and is mainly in astrocytes. Brain glycogen levels in unstimulated, carefully-handled rats are 10-12 μmol/g, and assuming that astrocytes account for half the brain mass, astrocytic glycogen content is twice as high. Glycogen turnover is slow under basal conditions, but it is mobilized during activation. There is no net increase in incorporation of label from glucose during activation, whereas label release from pre-labeled glycogen exceeds net glycogen consumption, which increases during stronger stimuli. Because glycogen level is restored by non-oxidative metabolism, astrocytes can influence the global ratio of oxygen to glucose utilization. Compensatory increases in utilization of blood glucose during inhibition of glycogen phosphorylase are large and approximate glycogenolysis rates during sensory stimulation. In contrast, glycogenolysis rates during hypoglycemia are low due to continued glucose delivery and oxidation of endogenous substrates; rates that preserve neuronal function in the absence of glucose are also low, probably due to metabolite oxidation. Modeling studies predict that glycogenolysis maintains a high level of glucose-6-phosphate in astrocytes to maintain feedback inhibition of hexokinase, thereby diverting glucose for use by neurons. The fate of glycogen carbon in vivo is not known, but lactate efflux from brain best accounts for the major metabolic characteristics during activation of living brain. Substantial shuttling coupled with oxidation of glycogen-derived lactate is inconsistent with available evidence. Glycogen has important roles in astrocytic energetics, including glucose sparing, control of extracellular K(+) level, oxidative stress management, and memory consolidation; it is a multi-functional compound.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Slot 500, 4301 W. Markham St., Little Rock, AR, 72205, USA,
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27
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Laureys G, Valentino M, Demol F, Zammit C, Muscat R, Cambron M, Kooijman R, De Keyser J. β₂-adrenergic receptors protect axons during energetic stress but do not influence basal glio-axonal lactate shuttling in mouse white matter. Neuroscience 2014; 277:367-74. [PMID: 25064060 DOI: 10.1016/j.neuroscience.2014.07.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/30/2014] [Accepted: 07/16/2014] [Indexed: 10/25/2022]
Abstract
In vitro studies have demonstrated that β2-adrenergic receptor activation stimulates glycogen degradation in astrocytes, generating lactate as a potential energy source for neurons. Using in vivo microdialysis in mouse cerebellar white matter we demonstrate continuous axonal lactate uptake and glial-axonal metabolic coupling of glutamate/lactate exchange. However, this physiological lactate production was not influenced by activation (clenbuterol) or blocking (ICI 118551) of β2-adrenergic receptors. In two-photon imaging experiments on ex vivo mouse corpus callosum subjected to aglycemia, β2-adrenergic activation rescued axons, whereas inhibition of axonal lactate uptake by α-cyano-4-hydroxycinnamic acid (4-CIN) was associated with severe axonal loss. Our results suggest that axonal protective effects of glial β2-adrenergic receptor activation are not mediated by enhanced lactate production.
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Affiliation(s)
- G Laureys
- Department of Neurology, University Hospital Brussels, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium.
| | - M Valentino
- Department of Physiology and Biochemistry, Faculty of Medicine & Surgery, University of Malta, Msida MSD 2080, Malta
| | - F Demol
- Department of Neurology, University Hospital Brussels, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
| | - C Zammit
- Department of Anatomy, Faculty of Medicine & Surgery, University of Malta, Msida MSD 2080, Malta
| | - R Muscat
- Department of Physiology and Biochemistry, Faculty of Medicine & Surgery, University of Malta, Msida MSD 2080, Malta
| | - M Cambron
- Department of Neurology, University Hospital Brussels, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
| | - R Kooijman
- Experimental Pharmacology, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - J De Keyser
- Department of Neurology, University Hospital Brussels, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium; Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands
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29
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Bosier B, Bellocchio L, Metna-Laurent M, Soria-Gomez E, Matias I, Hebert-Chatelain E, Cannich A, Maitre M, Leste-Lasserre T, Cardinal P, Mendizabal-Zubiaga J, Canduela MJ, Reguero L, Hermans E, Grandes P, Cota D, Marsicano G. Astroglial CB1 cannabinoid receptors regulate leptin signaling in mouse brain astrocytes. Mol Metab 2013; 2:393-404. [PMID: 24327955 DOI: 10.1016/j.molmet.2013.08.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 07/29/2013] [Accepted: 08/02/2013] [Indexed: 01/22/2023] Open
Abstract
Type-1 cannabinoid (CB1) and leptin (ObR) receptors regulate metabolic and astroglial functions, but the potential links between the two systems in astrocytes were not investigated so far. Genetic and pharmacological manipulations of CB1 receptor expression and activity in cultured cortical and hypothalamic astrocytes demonstrated that cannabinoid signaling controls the levels of ObR expression. Lack of CB1 receptors also markedly impaired leptin-mediated activation of signal transducers and activators of transcription 3 and 5 (STAT3 and STAT5) in astrocytes. In particular, CB1 deletion determined a basal overactivation of STAT5, thereby leading to the downregulation of ObR expression, and leptin failed to regulate STAT5-dependent glycogen storage in the absence of CB1 receptors. These results show that CB1 receptors directly interfere with leptin signaling and its ability to regulate glycogen storage, thereby representing a novel mechanism linking endocannabinoid and leptin signaling in the regulation of brain energy storage and neuronal functions.
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Key Words
- Astroglial CB1 receptors
- Astroglial leptin receptor
- CB1, type-1 cannabinoid receptor
- Cannabinoid
- Cx, cerebral cortex
- FAAH, fatty acid amide hydrolase
- GFAP, glial fibrillary acidic protein
- Glycogen
- Leptin signaling
- MGL, monoacylglycerol lipase
- ObR, leptin receptor
- ObRb, long-isoform leptin receptor
- P-STAT3, Tyr705-phosphorylated form of STAT3
- P-STAT5, Tyr694-phosphorylated form of STAT5
- STAT3 and 5
- STAT3, transducers and activators of transcription 3
- STAT5, transducers and activators of transcription 5
- VMH, ventromedial hypothalamus
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Affiliation(s)
- Barbara Bosier
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France ; University of Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France ; Neuropharmacology, Institute of Neurosciences, Université Catholique de Louvain, Av. Hippocrate 54, B1.54.10-10, 1200 Bruxelles, Belgium
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30
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Stobart JL, Anderson CM. Multifunctional role of astrocytes as gatekeepers of neuronal energy supply. Front Cell Neurosci 2013; 7:38. [PMID: 23596393 PMCID: PMC3622037 DOI: 10.3389/fncel.2013.00038] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 03/26/2013] [Indexed: 01/01/2023] Open
Abstract
Dynamic adjustments to neuronal energy supply in response to synaptic activity are critical for neuronal function. Glial cells known as astrocytes have processes that ensheath most central synapses and express G-protein-coupled neurotransmitter receptors and transporters that respond to neuronal activity. Astrocytes also release substrates for neuronal oxidative phosphorylation and have processes that terminate on the surface of brain arterioles and can influence vascular smooth muscle tone and local blood flow. Membrane receptor or transporter-mediated effects of glutamate represent a convergence point of astrocyte influence on neuronal bioenergetics. Astrocytic glutamate uptake drives glycolysis and subsequent shuttling of lactate from astrocytes to neurons for oxidative metabolism. Astrocytes also convert synaptically reclaimed glutamate to glutamine, which is returned to neurons for glutamate salvage or oxidation. Finally, astrocytes store brain energy currency in the form of glycogen, which can be mobilized to produce lactate for neuronal oxidative phosphorylation in response to glutamatergic neurotransmission. These mechanisms couple synaptically driven astrocytic responses to glutamate with release of energy substrates back to neurons to match demand with supply. In addition, astrocytes directly influence the tone of penetrating brain arterioles in response to glutamatergic neurotransmission, coordinating dynamic regulation of local blood flow. We will describe the role of astrocytes in neurometabolic and neurovascular coupling in detail and discuss, in turn, how astrocyte dysfunction may contribute to neuronal bioenergetic deficit and neurodegeneration. Understanding the role of astrocytes as a hub for neurometabolic and neurovascular coupling mechanisms is a critical underpinning for therapeutic development in a broad range of neurodegenerative disorders characterized by chronic generalized brain ischemia and brain microvascular dysfunction.
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Affiliation(s)
- Jillian L Stobart
- Division of Neurodegenerative Disorders, Department of Pharmacology and Therapeutics, St. Boniface Hospital Research, University of Manitoba Winnipeg, MB, Canada ; Department of Nuclear Medicine, Institute of Pharmacology and Toxicology, University of Zürich Zürich, Switzerland
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Lange SC, Bak LK, Waagepetersen HS, Schousboe A, Norenberg MD. Primary cultures of astrocytes: their value in understanding astrocytes in health and disease. Neurochem Res 2012; 37:2569-88. [PMID: 22926576 DOI: 10.1007/s11064-012-0868-0] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 08/01/2012] [Accepted: 08/01/2012] [Indexed: 12/26/2022]
Abstract
During the past few decades of astrocyte research it has become increasingly clear that astrocytes have taken a central position in all central nervous system activities. Much of our new understanding of astrocytes has been derived from studies conducted with primary cultures of astrocytes. Such cultures have been an invaluable tool for studying roles of astrocytes in physiological and pathological states. Many central astrocytic functions in metabolism, amino acid neurotransmission and calcium signaling were discovered using this tissue culture preparation and most of these observations were subsequently found in vivo. Nevertheless, primary cultures of astrocytes are an in vitro model that does not fully mimic the complex events occurring in vivo. Here we present an overview of the numerous contributions generated by the use of primary astrocyte cultures to uncover the diverse functions of astrocytes. Many of these discoveries would not have been possible to achieve without the use of astrocyte cultures. Additionally, we address and discuss the concerns that have been raised regarding the use of primary cultures of astrocytes as an experimental model system.
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Affiliation(s)
- Sofie C Lange
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
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Obel LF, Müller MS, Walls AB, Sickmann HM, Bak LK, Waagepetersen HS, Schousboe A. Brain glycogen-new perspectives on its metabolic function and regulation at the subcellular level. FRONTIERS IN NEUROENERGETICS 2012; 4:3. [PMID: 22403540 PMCID: PMC3291878 DOI: 10.3389/fnene.2012.00003] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 02/13/2012] [Indexed: 11/14/2022]
Abstract
Glycogen is a complex glucose polymer found in a variety of tissues, including brain, where it is localized primarily in astrocytes. The small quantity found in brain compared to e.g., liver has led to the understanding that brain glycogen is merely used during hypoglycemia or ischemia. In this review evidence is brought forward highlighting what has been an emerging understanding in brain energy metabolism: that glycogen is more than just a convenient way to store energy for use in emergencies—it is a highly dynamic molecule with versatile implications in brain function, i.e., synaptic activity and memory formation. In line with the great spatiotemporal complexity of the brain and thereof derived focus on the basis for ensuring the availability of the right amount of energy at the right time and place, we here encourage a closer look into the molecular and subcellular mechanisms underlying glycogen metabolism. Based on (1) the compartmentation of the interconnected second messenger pathways controlling glycogen metabolism (calcium and cAMP), (2) alterations in the subcellular location of glycogen-associated enzymes and proteins induced by the metabolic status and (3) a sequential component in the intermolecular mechanisms of glycogen metabolism, we suggest that glycogen metabolism in astrocytes is compartmentalized at the subcellular level. As a consequence, the meaning and importance of conventional terms used to describe glycogen metabolism (e.g., turnover) is challenged. Overall, this review represents an overview of contemporary knowledge about brain glycogen and its metabolism and function. However, it also has a sharp focus on what we do not know, which is perhaps even more important for the future quest of uncovering the roles of glycogen in brain physiology and pathology.
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Affiliation(s)
- Linea F Obel
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen Copenhagen, Denmark
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Parpura V, Heneka MT, Montana V, Oliet SHR, Schousboe A, Haydon PG, Stout RF, Spray DC, Reichenbach A, Pannicke T, Pekny M, Pekna M, Zorec R, Verkhratsky A. Glial cells in (patho)physiology. J Neurochem 2012; 121:4-27. [PMID: 22251135 DOI: 10.1111/j.1471-4159.2012.07664.x] [Citation(s) in RCA: 402] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neuroglial cells define brain homeostasis and mount defense against pathological insults. Astroglia regulate neurogenesis and development of brain circuits. In the adult brain, astrocytes enter into intimate dynamic relationship with neurons, especially at synaptic sites where they functionally form the tripartite synapse. At these sites, astrocytes regulate ion and neurotransmitter homeostasis, metabolically support neurons and monitor synaptic activity; one of the readouts of the latter manifests in astrocytic intracellular Ca(2+) signals. This form of astrocytic excitability can lead to release of chemical transmitters via Ca(2+) -dependent exocytosis. Once in the extracellular space, gliotransmitters can modulate synaptic plasticity and cause changes in behavior. Besides these physiological tasks, astrocytes are fundamental for progression and outcome of neurological diseases. In Alzheimer's disease, for example, astrocytes may contribute to the etiology of this disorder. Highly lethal glial-derived tumors use signaling trickery to coerce normal brain cells to assist tumor invasiveness. This review not only sheds new light on the brain operation in health and disease, but also points to many unknowns.
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Affiliation(s)
- Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy & Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, Alabama, USA.
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Schousboe A. Studies of Brain Metabolism: A Historical Perspective. NEURAL METABOLISM IN VIVO 2012. [DOI: 10.1007/978-1-4614-1788-0_31] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Obel LF, Andersen KMH, Bak LK, Schousboe A, Waagepetersen HS. Effects of adrenergic agents on intracellular Ca2+ homeostasis and metabolism of glucose in astrocytes with an emphasis on pyruvate carboxylation, oxidative decarboxylation and recycling: implications for glutamate neurotransmission and excitotoxicity. Neurotox Res 2011; 21:405-17. [PMID: 22194159 DOI: 10.1007/s12640-011-9296-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 11/17/2011] [Accepted: 11/29/2011] [Indexed: 12/26/2022]
Abstract
Glucose and glycogen are essential sources of energy for maintaining glutamate homeostasis as well as glutamatergic neurotransmission. The metabolism of glycogen, the location of which is confined to astrocytes, is affected by norepinephrine (NE), and hence, adrenergic signaling in the astrocyte might affect glutamate homeostasis with implications for excitatory neurotransmission and possibly excitotoxic neurodegeneration. In order to study this putative correlation, cultured astrocytes were incubated with 2.5 mM [U-(13)C]glucose in the presence and absence of NE as a time course for 1 h. Employing mass spectrometry, labeling in intracellular metabolites was determined. Moreover, the involvement of Ca(2+) in the noradrenergic response was studied. In unstimulated astrocytes, the labeling pattern of glutamate, aspartate, malate and citrate confirmed important roles for pyruvate carboxylation and oxidative decarboxylation in astrocytic glucose metabolism. Importantly, pyruvate carboxylation was best visualized at 10 min of incubation. The abundance and pattern of labeling in lactate and alanine indicated not only an extensive activity of malic enzyme (initial step for pyruvate recycling) but also a high degree of compartmentalization of the pyruvate pool. Stimulating with 1 μM NE had no effect on labeling patterns and glycogen metabolism, whereas 100 μM NE increased glutamate labeling and decreased labeling in alanine, the latter supposedly due to dilution from degradation of non-labeled glycogen. It is suggested that further experiments uncovering the correlation between adrenergic and glutamatergic pathways should be performed in order to gain further insight into the role of astrocytes in brain function and dysfunction, the latter including excitotoxicity.
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Affiliation(s)
- Linea F Obel
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark
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Schousboe A, Sickmann HM, Bak LK, Schousboe I, Jajo FS, Faek SAA, Waagepetersen HS. Neuron-glia interactions in glutamatergic neurotransmission: roles of oxidative and glycolytic adenosine triphosphate as energy source. J Neurosci Res 2011; 89:1926-34. [PMID: 21919035 DOI: 10.1002/jnr.22746] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 06/16/2011] [Accepted: 06/20/2011] [Indexed: 02/01/2023]
Abstract
Glutamatergic neurotransmission accounts for a considerable part of energy consumption related to signaling in the brain. Chemical energy is provided by adenosine triphosphate (ATP) formed in glycolysis and tricarboxylic acid (TCA) cycle combined with oxidative phosphorylation. It is not clear whether ATP generated in these pathways is equivalent in relation to fueling of the energy-requiring processes, i.e., vesicle filling, transport, and enzymatic processing in the glutamatergic tripartite synapse (the astrocyte and pre- and postsynapse). The role of astrocytic glycogenolysis in maintaining theses processes also has not been fully elucidated. Cultured astrocytes and neurons were utilized to monitor these processes related to glutamatergic neurotransmission. Inhibitors of glycolysis and TCA cycle in combination with pathway-selective substrates were used to study glutamate uptake and release monitored with D-aspartate. Western blotting of glyceraldehyde-3-P dehydrogenase (GAPDH) and phosphoglycerate kinase (PGK) was performed to determine whether these enzymes are associated with the cell membrane. We show that ATP formed in glycolysis is superior to that generated by oxidative phosphorylation in providing energy for glutamate uptake both in astrocytes and in neurons. The neuronal vesicular glutamate release was less dependent on glycolytic ATP. Dependence of glutamate uptake on glycolytic ATP may be at least partially explained by a close association in the membrane of GAPDH and PGK and the glutamate transporters. It may be suggested that these enzymes form a complex with the transporters and the Na(+) /K(+) -ATPase, the latter providing the sodium gradient required for the transport process.
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Affiliation(s)
- A Schousboe
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark
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