1
|
Harders AR, Watermann P, Karger G, Denieffe SC, Weller A, Dannemann AC, Willker JE, Köhler Y, Arend C, Dringen R. Consequences of a 2-Deoxyglucose Exposure on the ATP Content and the Cytosolic Glucose Metabolism of Cultured Primary Rat Astrocytes. Neurochem Res 2024:10.1007/s11064-024-04192-y. [PMID: 38898248 DOI: 10.1007/s11064-024-04192-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 06/04/2024] [Accepted: 06/04/2024] [Indexed: 06/21/2024]
Abstract
The glucose analogue 2-deoxyglucose (2DG) has frequently been used as a tool to study cellular glucose uptake and to inhibit glycolysis. Exposure of primary cultured astrocytes to 2DG caused a time- and concentration-dependent cellular accumulation of 2-deoxyglucose-6-phosphate (2DG6P) that was accompanied by a rapid initial decline in cellular ATP content. Inhibitors of mitochondrial respiration as well as inhibitors of mitochondrial uptake of pyruvate and activated fatty acids accelerated the ATP loss, demonstrating that mitochondrial ATP regeneration contributes to the partial maintenance of the ATP content in 2DG-treated astrocytes. After a 30 min exposure to 10 mM 2DG the specific content of cellular 2DG6P had accumulated to around 150 nmol/mg, while cellular ATP was lowered by 50% to around 16 nmol/mg. Following such a 2DG6P-loading of astrocytes, glycolytic lactate production from applied glucose was severely impaired during the initial 60 min of incubation, but was reestablished during longer incubation concomitant with a loss in cellular 2DG6P content. In contrast to glycolysis, the glucose-dependent NADPH regeneration via the pentose phosphate pathway (PPP) was only weakly affected in 2DG6P-loaded astrocytes and in cells that were coincubated with glucose in the presence of an excess of 2DG. Additionally, in the presence of 2DG PPP-dependent WST1 reduction was found to have doubled compared to hexose-free control incubations, indicating that cellular 2DG6P can serve as substrate for NADPH regeneration by the astrocytic PPP. The data presented provide new insights on the metabolic consequences of a 2DG exposure on the energy and glucose metabolism of astrocytes and demonstrate the reversibility of the inhibitory potential of a 2DG-treatment on the glucose metabolism of cultured astrocytes.
Collapse
Affiliation(s)
- Antonia Regina Harders
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Patrick Watermann
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Gabriele Karger
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Sadhbh Cynth Denieffe
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Alina Weller
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Annika Carina Dannemann
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Johanna Elisabeth Willker
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Yvonne Köhler
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Christian Arend
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany.
| |
Collapse
|
2
|
Denker N, Dringen R. Modulation of Pyruvate Export and Extracellular Pyruvate Concentration in Primary Astrocyte Cultures. Neurochem Res 2024; 49:1331-1346. [PMID: 38376749 PMCID: PMC10991036 DOI: 10.1007/s11064-024-04120-0] [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: 11/10/2023] [Revised: 02/02/2024] [Accepted: 02/02/2024] [Indexed: 02/21/2024]
Abstract
Astrocyte-derived pyruvate is considered to have neuroprotective functions. In order to investigate the processes that are involved in astrocytic pyruvate release, we used primary rat astrocyte cultures as model system. Depending on the incubation conditions and medium composition, astrocyte cultures established extracellular steady state pyruvate concentrations in the range between 150 µM and 300 µM. During incubations for up to 2 weeks in DMEM culture medium, the extracellular pyruvate concentration remained almost constant for days, while the extracellular lactate concentration increased continuously during the incubation into the millimolar concentration range as long as glucose was present. In an amino acid-free incubation buffer, glucose-fed astrocytes released pyruvate with an initial rate of around 60 nmol/(h × mg) and after around 5 h an almost constant extracellular pyruvate concentration was established that was maintained for several hours. Extracellular pyruvate accumulation was also observed, if glucose had been replaced by mannose, fructose, lactate or alanine. Glucose-fed astrocyte cultures established similar extracellular steady state concentrations of pyruvate by releasing pyruvate into pyruvate-free media or by consuming excess of extracellular pyruvate. Inhibition of the monocarboxylate transporter MCT1 by AR-C155858 lowered extracellular pyruvate accumulation, while inhibition of mitochondrial pyruvate uptake by UK5099 increased the extracellular pyruvate concentration. Finally, the presence of the uncoupler BAM15 or of the respiratory chain inhibitor antimycin A almost completely abolished extracellular pyruvate accumulation. The data presented demonstrate that cultured astrocytes establish a transient extracellular steady state concentration of pyruvate which is strongly affected by modulation of the mitochondrial pyruvate metabolism.
Collapse
Affiliation(s)
- Nadine Denker
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry) and Centre for Environmental Research and Sustainable Technologies, University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry) and Centre for Environmental Research and Sustainable Technologies, University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.
| |
Collapse
|
3
|
Harders AR, Spellerberg P, Dringen R. Exogenous Substrates Prevent the Decline in the Cellular ATP Content of Primary Rat Astrocytes During Glucose Deprivation. Neurochem Res 2024; 49:1188-1199. [PMID: 38341839 PMCID: PMC10991069 DOI: 10.1007/s11064-024-04104-0] [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: 11/29/2023] [Revised: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 02/13/2024]
Abstract
Brain astrocytes are well known for their broad metabolic potential. After glucose deprivation, cultured primary astrocytes maintain a high cellular ATP content for many hours by mobilizing endogenous substrates, but within 24 h the specific cellular ATP content was lowered to around 30% of the initial ATP content. This experimental setting was used to test for the potential of various exogenous substrates to prevent a loss in cellular ATP in glucose deprived astrocytes. The presence of various extracellular monocarboxylates, purine nucleosides or fatty acids prevented the loss of ATP from glucose-deprived astrocytes. Of the 20 proteinogenic amino acids, only alanine, aspartate, glutamate, glutamine, lysine or proline maintained high ATP levels in starved astrocytes. Among these amino acids, proline was found to be the most potent one to prevent the ATP loss. The astrocytic consumption of proline as well as the ability of proline to maintain a high cellular ATP content was prevented in a concentration-dependent manner by the proline dehydrogenase inhibitor tetrahydro-2-furoic acid. Analysis of the concentration-dependencies obtained by considering the different carbon content of the applied substrates revealed that fatty acids and proline are more potent than glucose and monocarboxylates as exogenous substrates to prevent ATP depletion in glucose-deprived astrocytes. These data demonstrate that cultured astrocytes can utilise a wide range of extracellular substrates as fuels to support mitochondrial ATP regeneration and identify proline as potent exogenous substrate for the energy metabolism of starved astrocytes.
Collapse
Affiliation(s)
- Antonia Regina Harders
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Paul Spellerberg
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany.
| |
Collapse
|
4
|
Karger G, Berger J, Dringen R. Modulation of Cellular Levels of Adenosine Phosphates and Creatine Phosphate in Cultured Primary Astrocytes. Neurochem Res 2024; 49:402-414. [PMID: 37855866 PMCID: PMC10787699 DOI: 10.1007/s11064-023-04039-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/19/2023] [Accepted: 09/22/2023] [Indexed: 10/20/2023]
Abstract
Adenosine triphosphate (ATP) is the main energy currency of all cells, while creatine phosphate (CrP) is considered as a buffer of high energy-bond phosphate that facilitates rapid regeneration of ATP from adenosine diphosphate (ADP). Astrocyte-rich primary cultures contain ATP, ADP and adenosine monophosphate (AMP) in average specific contents of 36.0 ± 6.4 nmol/mg, 2.9 ± 2.1 nmol/mg and 1.7 ± 2.1 nmol/mg, respectively, which establish an adenylate energy charge of 0.92 ± 0.04. The average specific cellular CrP level was found to be 25.9 ± 10.8 nmol/mg and the CrP/ATP ratio was 0.74 ± 0.28. The specific cellular CrP content, but not the ATP content, declined with the age of the culture. Absence of fetal calf serum for 24 h caused a partial loss in the cellular contents of both CrP and ATP, while application of creatine for 24 h doubled the cellular CrP content and the CrP/ATP ratio, but did not affect ATP levels. In glucose-deprived astrocytes, the high cellular ATP and CrP contents were rapidly depleted within minutes after application of the glycolysis inhibitor 2-deoxyglucose and the respiratory chain inhibitor antimycin A. For those conditions, the decline in CrP levels always preceded that of ATP contents. In contrast, incubation of glucose-fed astrocytes for up to 30 min with antimycin A had little effect on the high cellular ATP content, while the CrP level was significantly lowered. These data demonstrate the importance of cellular CrP for maintaining a high cellular ATP content in astrocytes during episodes of impaired ATP regeneration.
Collapse
Affiliation(s)
- Gabriele Karger
- Faculty 2 (Biology/Chemistry), Centre for Biomolecular Interactions Bremen, University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Julius Berger
- Faculty 2 (Biology/Chemistry), Centre for Biomolecular Interactions Bremen, University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Ralf Dringen
- Faculty 2 (Biology/Chemistry), Centre for Biomolecular Interactions Bremen, University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.
- Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany.
| |
Collapse
|
5
|
Arend C, Grothaus IL, Waespy M, Ciacchi LC, Dringen R. Modulation of Multidrug Resistance Protein 1-mediated Transport Processes by the Antiviral Drug Ritonavir in Cultured Primary Astrocytes. Neurochem Res 2024; 49:66-84. [PMID: 37603214 PMCID: PMC10776481 DOI: 10.1007/s11064-023-04008-5] [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: 06/02/2023] [Revised: 07/25/2023] [Accepted: 08/01/2023] [Indexed: 08/22/2023]
Abstract
The Multidrug Resistance Protein 1 (Mrp1) is an ATP-dependent efflux transporter and a major facilitator of drug resistance in mammalian cells during cancer and HIV therapy. In brain, Mrp1-mediated GSH export from astrocytes is the first step in the supply of GSH precursors to neurons. To reveal potential mechanisms underlying the drug-induced modulation of Mrp1-mediated transport processes, we investigated the effects of the antiviral drug ritonavir on cultured rat primary astrocytes. Ritonavir strongly stimulated the Mrp1-mediated export of glutathione (GSH) by decreasing the Km value from 200 nmol/mg to 28 nmol/mg. In contrast, ritonavir decreased the export of the other Mrp1 substrates glutathione disulfide (GSSG) and bimane-glutathione. To give explanation for these apparently contradictory observations, we performed in silico docking analysis and molecular dynamics simulations using a homology model of rat Mrp1 to predict the binding modes of ritonavir, GSH and GSSG to Mrp1. The results suggest that ritonavir binds to the hydrophilic part of the bipartite binding site of Mrp1 and thereby differently affects the binding and transport of the Mrp1 substrates. These new insights into the modulation of Mrp1-mediated export processes by ritonavir provide a new model to better understand GSH-dependent detoxification processes in brain cells.
Collapse
Affiliation(s)
- Christian Arend
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28359, Bremen, Germany.
- Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany.
| | - Isabell L Grothaus
- Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
- Hybrid Materials Interfaces Group, Faculty of Production Engineering, Bremen Center for Computational Materials Science, MAPEX Center for Materials and Processes, University of Bremen, Am Fallturm 1, 28359, Bremen, Germany
| | - Mario Waespy
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28359, Bremen, Germany
| | - Lucio Colombi Ciacchi
- Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
- Hybrid Materials Interfaces Group, Faculty of Production Engineering, Bremen Center for Computational Materials Science, MAPEX Center for Materials and Processes, University of Bremen, Am Fallturm 1, 28359, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28359, Bremen, Germany
- Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
| |
Collapse
|
6
|
Irrsack E, Aydin S, Bleckmann K, Schuller J, Dringen R, Koch M. Local Administrations of Iron Oxide Nanoparticles in the Prefrontal Cortex and Caudate Putamen of Rats Do Not Compromise Working Memory and Motor Activity. Neurotox Res 2023; 42:6. [PMID: 38133743 PMCID: PMC10746586 DOI: 10.1007/s12640-023-00684-x] [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: 08/22/2023] [Revised: 11/10/2023] [Accepted: 12/12/2023] [Indexed: 12/23/2023]
Abstract
Iron oxide nanoparticles (IONPs) have come into focus for their use in medical applications although possible health risks for humans, especially in terms of brain functions, have not yet been fully clarified. The present study investigates the effects of IONPs on neurobehavioural functions in rats. For this purpose, we infused dimercaptosuccinic acid-coated IONPs into the medial prefrontal cortex (mPFC) and caudate putamen (CPu). Saline (VEH) and ferric ammonium citrate (FAC) were administered as controls. One- and 4-week post-surgery mPFC-infused animals were tested for their working memory performance in the delayed alternation T-maze task and in the open field (OF) for motor activity, and CPu-infused rats were tested for their motor activity in the OF. After completion of the experiments, the brains were examined histologically and immunohistochemically. We did not observe any behavioural or structural abnormalities in the rats after administration of IONPs in the mPFC and the CPu. In contrast, administration of FAC into the CPu resulted in decreased motor activity and increased the number of microglia in the mPFC. Perls' Prussian blue staining revealed that FAC- and IONP-treated rats had more iron-containing ramified cells than VEH-treated rats, indicating iron uptake by microglia. Our results demonstrate that local infusions of IONPs into selected brain regions have no adverse impact on locomotor behaviour and working memory.
Collapse
Affiliation(s)
- Ellen Irrsack
- Department of Neuropharmacology, Centre for Cognitive Sciences, University of Bremen, PO Box 330440, Bremen, 28334, Germany.
| | - Sidar Aydin
- Department of Neuropharmacology, Centre for Cognitive Sciences, University of Bremen, PO Box 330440, Bremen, 28334, Germany
| | - Katja Bleckmann
- Department of Neuropharmacology, Centre for Cognitive Sciences, University of Bremen, PO Box 330440, Bremen, 28334, Germany
| | - Julia Schuller
- Department of Neuropharmacology, Centre for Cognitive Sciences, University of Bremen, PO Box 330440, Bremen, 28334, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen (CBIB), and Centre for Environmental Research and Sustainable, Technology, University of Bremen, PO Box 330440, Bremen, 28334, Germany
| | - Michael Koch
- Department of Neuropharmacology, Centre for Cognitive Sciences, University of Bremen, PO Box 330440, Bremen, 28334, Germany
| |
Collapse
|
7
|
Harders AR, Arend C, Denieffe SC, Berger J, Dringen R. Endogenous Energy Stores Maintain a High ATP Concentration for Hours in Glucose-Depleted Cultured Primary Rat Astrocytes. Neurochem Res 2023; 48:2241-2252. [PMID: 36914795 PMCID: PMC10182151 DOI: 10.1007/s11064-023-03903-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/24/2023] [Accepted: 02/25/2023] [Indexed: 03/16/2023]
Abstract
Adenosine triphosphate (ATP) is the central energy currency of all cells. Cultured primary rat astrocytes contain a specific cellular ATP content of 27.9 ± 4.7 nmol/mg. During incubation in a glucose- and amino acid-free incubation buffer, this high cellular ATP content was maintained for at least 6 h, while within 24 h the levels of ATP declined to around 30% of the initial value without compromising cell viability. In contrast, cells exposed to 1 mM and 5 mM glucose maintained the initial high cellular ATP content for 24 and 72 h, respectively. The loss in cellular ATP content observed during a 24 h glucose-deprivation was fully prevented by the presence of glucose, fructose or mannose as well as by the mitochondrial substrates lactate, pyruvate, β-hydroxybutyrate or acetate. The high initial specific ATP content in glucose-starved astrocytes, was almost completely abolished within 30 min after application of the respiratory chain inhibitor antimycin A or the mitochondrial uncoupler BAM-15, while these inhibitors lowered in glucose-fed cells the ATP content only to 60% (BAM-15) and 40% (antimycin A) within 5 h. Inhibition of the mitochondrial pyruvate carrier by UK5099 alone or of mitochondrial fatty acid uptake by etomoxir alone hardly affected the high ATP content of glucose-deprived astrocytes during an incubation for 8 h, while the co-application of both inhibitors depleted cellular ATP levels almost completely within 5 h. These data underline the importance of mitochondrial metabolism for the ATP regeneration of astrocytes and demonstrate that the mitochondrial oxidation of pyruvate and fatty acids strongly contributes to the maintenance of a high ATP concentration in glucose-deprived astrocytes.
Collapse
Affiliation(s)
- Antonia Regina Harders
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Christian Arend
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany
| | - Sadhbh Cynth Denieffe
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Julius Berger
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany. .,Centre for Environmental Research and Sustainable Technologies, University of Bremen, Bremen, Germany.
| |
Collapse
|
8
|
Consumption and Metabolism of Extracellular Pyruvate by Cultured Rat Brain Astrocytes. Neurochem Res 2022; 48:1438-1454. [PMID: 36495387 PMCID: PMC10066139 DOI: 10.1007/s11064-022-03831-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022]
Abstract
AbstractBrain astrocytes are considered as glycolytic cell type, but these cells also produce ATP via mitochondrial oxidative phosphorylation. Exposure of cultured primary astrocytes in a glucose-free medium to extracellular substrates that are known to be metabolised by mitochondrial pathways, including pyruvate, lactate, beta-hydroxybutyrate, alanine and acetate, revealed that among the substrates investigated extracellular pyruvate was most efficiently consumed by astrocytes. Extracellular pyruvate was consumed by the cells almost proportional to time over hours in a concentration-dependent manner with apparent Michaelis–Menten kinetics [Km = 0.6 ± 0.1 mM, Vmax = 5.1 ± 0.8 nmol/(min × mg protein)]. The astrocytic consumption of pyruvate was strongly impaired in the presence of the monocarboxylate transporter 1 (MCT1) inhibitor AR-C155858 or by application of a 10-times excess of the MCT1 substrates lactate or beta-hydroxybutyrate. Pyruvate consumption by viable astrocytes was inhibited in the presence of UK5099, an inhibitor of the mitochondrial pyruvate carrier, or after application of the respiratory chain inhibitor antimycin A. In contrast, the mitochondrial uncoupler BAM15 strongly accelerated cellular pyruvate consumption. Lactate and alanine accounted after 3 h of incubation with pyruvate for around 60% and 10%, respectively, of the pyruvate consumed by the cells. These results demonstrate that consumption of extracellular pyruvate by astrocytes involves uptake via MCT1 and that the velocity of pyruvate consumption is strongly modified by substances that affect the entry of pyruvate into mitochondria or the activity of mitochondrial respiration.
Collapse
|
9
|
Fernández-Bertólez N, Costa C, Brandão F, Teixeira JP, Pásaro E, Valdiglesias V, Laffon B. Toxicological Aspects of Iron Oxide Nanoparticles. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1357:303-350. [DOI: 10.1007/978-3-030-88071-2_13] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
10
|
Irrsack E, Schuller J, Petters C, Willmann W, Dringen R, Koch M. Effects of Local Administration of Iron Oxide Nanoparticles in the Prefrontal Cortex, Striatum, and Hippocampus of Rats. Neurotox Res 2021; 39:2056-2071. [PMID: 34705254 PMCID: PMC8639550 DOI: 10.1007/s12640-021-00432-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 10/08/2021] [Accepted: 10/18/2021] [Indexed: 10/26/2022]
Abstract
Iron oxide nanoparticles (IONPs) are used for diverse medical approaches, although the potential health risks, for example adverse effects on brain functions, are not fully clarified. Several in vitro studies demonstrated that the different types of brain cells are able to accumulate IONPs and reported a toxic potential for IONPs, at least for microglia. However, little information is available for the in vivo effects of direct application of IONPs into the brain over time. Therefore, we examined the cellular responses and the distribution of iron in the rat brain at different time points after local infusion of IONPs into selected brain areas. Dispersed IONPs or an equivalent amount of low molecular weight iron complex ferric ammonium citrate or vehicle were infused into the medial prefrontal cortex (mPFC), the caudate putamen (CPu), or the dorsal hippocampus (dHip). Rats were sacrificed 1 day, 1 week, or 4 weeks post-infusion and brain sections were histologically examined for treatment effects on astrocytes, microglia, and neurons. Glial scar formation was observed in the mPFC and CPu 1 week post-infusion independent of the substance and probably resulted from the infusion procedure. Compared to vehicle, IONPs did not cause any obvious additional adverse effects and no additional tissue damage, while the infusion of ferric ammonium citrate enhanced neurodegeneration in the mPFC. Results of iron staining indicate that IONPs were mainly accumulated in microglia. Our results demonstrate that local infusions of IONPs in selected brain areas do not cause any additional adverse effects or neurodegeneration compared to vehicle.
Collapse
Affiliation(s)
- Ellen Irrsack
- Department of Neuropharmacology, Centre for Cognitive Sciences, University of Bremen, PO Box 330440, 28334, Bremen, Germany.
| | - Julia Schuller
- Department of Neuropharmacology, Centre for Cognitive Sciences, University of Bremen, PO Box 330440, 28334, Bremen, Germany
| | - Charlotte Petters
- Centre for Biomolecular Interactions Bremen (CBIB), and Centre for Environmental Research and Sustainable Technology, University of Bremen, PO Box 330440, 28334, Bremen, Germany
| | - Wiebke Willmann
- Centre for Biomolecular Interactions Bremen (CBIB), and Centre for Environmental Research and Sustainable Technology, University of Bremen, PO Box 330440, 28334, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen (CBIB), and Centre for Environmental Research and Sustainable Technology, University of Bremen, PO Box 330440, 28334, Bremen, Germany
| | - Michael Koch
- Department of Neuropharmacology, Centre for Cognitive Sciences, University of Bremen, PO Box 330440, 28334, Bremen, Germany
| |
Collapse
|
11
|
Elassy N, El-Dafrawy S, Abd El-Azim AO, El-Khawaga OAY, Negm A. Zinc oxide nanoparticles augment CD4, CD8, and GLUT-4 expression and restrict inflammation response in streptozotocin-induced diabetic rats. IET Nanobiotechnol 2021; 14:680-687. [PMID: 33108324 DOI: 10.1049/iet-nbt.2020.0079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
This study evaluated the biochemical, molecular, and histopathological mechanisms involved in the hypoglycaemic effect of zinc oxide nanoparticles (ZnONPs) in experimental diabetic rats. ZnONPs were prepared by the sol-gel method and characterised by scanning and transmission electron microscopy (SEM and TEM). To explore the possible hypoglycaemic and antioxidant effect of ZnONPs, rats were grouped as follows: control group, ZnONPs treated group, diabetic group, and diabetic + ZnONPs group. Upon treatment with ZnONPs, a significant alteration in the activities of superoxide dismutase, glutathione peroxidase, and the levels of insulin, haemoglobin A1c, and the expression of cluster of differentiation 4+ (CD4+), CD8+ T cells, glucose transporter type-4 (GLUT-4), tumour necrosis factor, and interleukin-6 when compared to diabetic and their control rats. ZnONPs administration to the diabetic group showed eminent blood glucose control and restoration of the biochemical profile. This raises their active role in controlling pancreas functions to improve glycaemic status as well as the inflammatory responses. Histopathological investigations showed the non-toxic and therapeutic effect of ZnONPs on the pancreas. TEM of pancreatic tissues displayed restoration of islets of Langerhans and increased insulin-secreting granules. This shows the therapeutic application of ZnONPs as a safe anti-diabetic agent and to have a potential for the control of diabetes.
Collapse
Affiliation(s)
- Norhan Elassy
- Chemistry Department, Faculty of Science, Mansoura University, 35516 Mansoura, Egypt
| | - Shady El-Dafrawy
- Chemistry Department, Faculty of Science, Mansoura University, 35516 Mansoura, Egypt
| | - Amira O Abd El-Azim
- Zoology Department, Faculty of Science, Mansoura University, 35516 Mansoura, Egypt
| | - Om Ali Y El-Khawaga
- Chemistry Department, Faculty of Science, Mansoura University, 35516 Mansoura, Egypt
| | - Amr Negm
- Department of Chemistry, College of Science, King Faisal University, Al-Ahsa, 31982 Saudi Arabia.
| |
Collapse
|
12
|
Methylmercury induces neuronal cell death by inducing TNF-α expression through the ASK1/p38 signaling pathway in microglia. Sci Rep 2021; 11:9832. [PMID: 33972601 PMCID: PMC8110582 DOI: 10.1038/s41598-021-89210-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/15/2021] [Indexed: 02/08/2023] Open
Abstract
We recently found that tumor necrosis factor-α (TNF-α) may be involved in neuronal cell death induced by methylmercury in the mouse brain. Here, we examined the cells involved in the induction of TNF-α expression by methylmercury in the mouse brain by in situ hybridization. TNF-α-expressing cells were found throughout the brain and were identified as microglia by immunostaining for ionized calcium binding adaptor molecule 1 (Iba1). Methylmercury induced TNF-α expression in mouse primary microglia and mouse microglial cell line BV2. Knockdown of apoptosis signal-regulating kinase 1 (ASK1), an inflammatory cytokine up-regulator that is responsible for reactive oxygen species (ROS), decreased methylmercury-induced TNF-α expression through decreased phosphorylation of p38 MAP kinase in BV2 cells. Suppression of methylmercury-induced reactive oxygen species (ROS) by antioxidant treatment largely abolished the induction of TNF-α expression and phosphorylation of p38 by methylmercury in BV2 cells. Finally, in mouse brain slices, the TNF-α antagonist (WP9QY) inhibited neuronal cell death induced by methylmercury, as did the p38 inhibitor SB203580 and liposomal clodronate (a microglia-depleting agent). These results indicate that methylmercury induces mitochondrial ROS that are involved in activation of the ASK1/p38 pathway in microglia and that this is associated with induction of TNF-α expression and neuronal cell death.
Collapse
|
13
|
Arend C, Ehrke E, Dringen R. Consequences of a Metabolic Glucose-Depletion on the Survival and the Metabolism of Cultured Rat Astrocytes. Neurochem Res 2019; 44:2288-2300. [PMID: 30788754 DOI: 10.1007/s11064-019-02752-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/08/2019] [Accepted: 02/12/2019] [Indexed: 11/29/2022]
Abstract
Brain astrocytes are considered to be highly glycolytic, but these cells also produce ATP via mitochondrial oxidative phosphorylation. To investigate how a metabolic depletion of glucose will affect the metabolism of astrocytes, we applied glucose at an initial concentration of 2 mM to cultured primary astrocytes and monitored the cell viability and various metabolic parameters during an incubation for up to 2 weeks. Already within 2 days of incubation the cells had completely consumed the applied glucose and lactate had accumulated in the medium to a concentration of around 3 mM. During the subsequent 10 days of incubation, the cell viability was not compromised while the extracellular lactate concentration declined to values of around 0.2 mM, before the cell viability was compromised. Application of known inhibitors of mitochondrial metabolism strongly accelerated glucose consumption and initial lactate production, while the lactate consumption was completely (antimycin A or 8-hydroxy efavirenz) and partially (efavirenz, metformin or tyrphostin 23) inhibited which caused rapid and delayed cell toxicity, respectively. The switch from glycolytic glucose metabolism to mitochondrial metabolism during the incubation was neither accompanied by alterations in the specific cytosolic lactate dehydrogenase activity or in the WST1 reduction capacity nor in the mitochondrial citrate synthase activity, but a cellular redistribution of mitochondria from a perinuclear to a more spread cytoplasmic localization was observed during the lactate consumption phase. These results demonstrate that cultured astrocytes survive a metabolism-induced glucose depletion very well by consuming lactate as fuel for mitochondrial ATP generation.
Collapse
Affiliation(s)
- Christian Arend
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
| | - Eric Ehrke
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany. .,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany.
| |
Collapse
|
14
|
Willmann W, Dringen R. Monitoring of the Cytoskeleton-Dependent Intracellular Trafficking of Fluorescent Iron Oxide Nanoparticles by Nanoparticle Pulse-Chase Experiments in C6 Glioma Cells. Neurochem Res 2018; 43:2055-2071. [PMID: 30196349 DOI: 10.1007/s11064-018-2627-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 08/21/2018] [Accepted: 08/31/2018] [Indexed: 12/12/2022]
Abstract
Iron oxide nanoparticles (IONPs) are used for various biomedical and therapeutic approaches. To investigate the uptake and the intracellular trafficking of IONPs in neural cells we have performed nanoparticle pulse-chase experiments to visualize the internalization and the fate of fluorescent IONPs in C6 glioma cells and astrocyte cultures. Already a short exposure to IONPs for 10 min at 4 °C (nanoparticle pulse) allowed binding of substantial amounts of nanoparticles to the cells, while internalization of IONPs into the cell was prevented. The uptake of bound IONPs and the intracellular trafficking was started by increasing the temperature to 37 °C (chase period). While hardly any cellular fluorescence nor any iron staining was detectable directly after the nanoparticle pulse, dotted cellular fluorescence and iron patterns appeared already within a few minutes after start of the chase incubation and became intensified in the perinuclear region during further incubation for up to 90 min. Longer chase incubations resulted in separation of the fluorescent coat from the core of the internalized IONPs. Disruption of actin filaments in C6 cells strongly impaired the internalization of IONPs, whereas destabilization of microtubules traped IONP-containing vesicles to the plasma membrane. In conclusion, nanoparticle pulse-chase experiments allowed to synchronize the cellular uptake of fluorescent IONPs and to identify for C6 cells an actin-dependent early and a microtubule-dependent later process in the intracellular trafficking of fluorescent IONPs.
Collapse
Affiliation(s)
- Wiebke Willmann
- Center for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, PO. Box 330440, 28334, Bremen, Germany
- Center for Environmental Research and Sustainable Technology, Leobener Strasse, 28359, Bremen, Germany
| | - Ralf Dringen
- Center for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, PO. Box 330440, 28334, Bremen, Germany.
- Center for Environmental Research and Sustainable Technology, Leobener Strasse, 28359, Bremen, Germany.
| |
Collapse
|
15
|
Willmann W, Dringen R. How to Study the Uptake and Toxicity of Nanoparticles in Cultured Brain Cells: The Dos and Don't Forgets. Neurochem Res 2018; 44:1330-1345. [PMID: 30088236 DOI: 10.1007/s11064-018-2598-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 07/09/2018] [Accepted: 07/18/2018] [Indexed: 12/16/2022]
Abstract
Due to their exciting properties, engineered nanoparticles have obtained substantial attention over the last two decades. As many types of nanoparticles are already used for technical and biomedical applications, the chances that cells in the brain will encounter nanoparticles have strongly increased. To test for potential consequences of an exposure of brain cells to engineered nanoparticles, cell culture models for different types of neural cells are frequently used. In this review article we will discuss experimental strategies and important controls that should be used to investigate the physicochemical properties of nanoparticles for the cell incubation conditions applied as well as for studies on the biocompatibility and the cellular uptake of nanoparticles in neural cells. The main focus of this article will be the interaction of cultured neural cells with iron oxide nanoparticles, but similar considerations are important for studying the consequences of an exposure of other types of cultured cells with other types of nanoparticles. Our article aims to improve the understanding of the special technical challenges of working with nanoparticles on cultured neural cells, to identify potential artifacts and to prevent misinterpretation of data on the potential adverse or beneficial consequences of a treatment of cultured cells with nanoparticles.
Collapse
Affiliation(s)
- Wiebke Willmann
- Center for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Center for Environmental Research and Sustainable Technology, Leobener Strasse, 28359, Bremen, Germany
| | - Ralf Dringen
- Center for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany. .,Center for Environmental Research and Sustainable Technology, Leobener Strasse, 28359, Bremen, Germany.
| |
Collapse
|
16
|
Hohnholt MC, Blumrich EM, Waagepetersen HS, Dringen R. The antidiabetic drug metformin decreases mitochondrial respiration and tricarboxylic acid cycle activity in cultured primary rat astrocytes. J Neurosci Res 2017; 95:2307-2320. [PMID: 28316081 DOI: 10.1002/jnr.24050] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 12/18/2022]
Abstract
Metformin is an antidiabetic drug that is used daily by millions of patients worldwide. Metformin is able to cross the blood-brain barrier and has recently been shown to increase glucose consumption and lactate release in cultured astrocytes. However, potential effects of metformin on mitochondrial tricarboxylic acid (TCA) cycle metabolism in astrocytes are unknown. We investigated this by mapping 13 C labeling in TCA cycle intermediates and corresponding amino acids after incubation of primary rat astrocytes with [U-13 C]glucose. The presence of metformin did not compromise the viability of cultured astrocytes during 4 hr of incubation, but almost doubled cellular glucose consumption and lactate release. Compared with control cells, the presence of metformin dramatically lowered the molecular 13 C carbon labeling (MCL) of the cellular TCA cycle intermediates citrate, α-ketoglutarate, succinate, fumarate, and malate, as well as the MCL of the TCA cycle intermediate-derived amino acids glutamate, glutamine, and aspartate. In addition to the total molecular 13 C labeling, analysis of the individual isotopomers of TCA cycle intermediates confirmed a severe decline in labeling and a significant lowering in TCA cycling ratio in metformin-treated astrocytes. Finally, the oxygen consumption of mitochondria isolated from metformin-treated astrocytes was drastically reduced in the presence of complex I substrates, but not of complex II substrates. These data demonstrate that exposure to metformin strongly impairs complex I-mediated mitochondrial respiration in astrocytes, which is likely to cause the observed decrease in labeling of mitochondrial TCA cycle intermediates and the stimulation of glycolytic lactate production. © 2017 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Michaela C Hohnholt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Eva-Maria Blumrich
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, Bremen, Germany
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, Bremen, Germany
| |
Collapse
|
17
|
Time-Dependent Lactate Production and Amino Acid Utilization in Cultured Astrocytes Under High Glucose Exposure. Mol Neurobiol 2017; 55:1112-1122. [DOI: 10.1007/s12035-016-0360-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 12/28/2016] [Indexed: 02/07/2023]
|
18
|
Hohnholt MC, Blumrich EM, Waagepetersen HS, Dringen R. The tricarboxylic acid cycle activity in cultured primary astrocytes is strongly accelerated by the protein tyrosine kinase inhibitor tyrphostin 23. Neurochem Int 2016; 102:13-21. [PMID: 27894844 DOI: 10.1016/j.neuint.2016.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 11/09/2016] [Accepted: 11/14/2016] [Indexed: 11/28/2022]
Abstract
Tyrphostin 23 (T23) is a well-known inhibitor of protein tyrosine kinases and has been considered as potential anti-cancer drug. T23 was recently reported to acutely stimulate the glycolytic flux in primary cultured astrocytes. To investigate whether T23 also affects the tricarboxylic acid (TCA) cycle, we incubated primary rat astrocyte cultures with [U-13C]glucose in the absence or the presence of 100 μM T23 for 2 h and analyzed the 13C metabolite pattern. These incubation conditions did not compromise cell viability and confirmed that the presence of T23 doubled glycolytic lactate production. In addition, T23-treatment strongly increased the molecular carbon labeling of the TCA cycle intermediates citrate, succinate, fumarate and malate, and significantly increased the incorporation of 13C-labelling into the amino acids glutamate, glutamine and aspartate. These results clearly demonstrate that, in addition to glycolysis, also the mitochondrial TCA cycle is strongly accelerated after exposure of astrocytes to T23, suggesting that a protein tyrosine kinase may be involved in the regulation of the TCA cycle in astrocytes.
Collapse
Affiliation(s)
- Michaela C Hohnholt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
| | - Eva-Maria Blumrich
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, PO. Box 330440, D-28334 Bremen, Germany; Centre for Environmental Research and Sustainable Technology, Leobener Strasse, D-28359 Bremen, Germany
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, PO. Box 330440, D-28334 Bremen, Germany; Centre for Environmental Research and Sustainable Technology, Leobener Strasse, D-28359 Bremen, Germany
| |
Collapse
|
19
|
Hagl S, Asseburg H, Heinrich M, Sus N, Blumrich EM, Dringen R, Frank J, Eckert GP. Effects of Long-Term Rice Bran Extract Supplementation on Survival, Cognition and Brain Mitochondrial Function in Aged NMRI Mice. Neuromolecular Med 2016; 18:347-63. [PMID: 27350374 DOI: 10.1007/s12017-016-8420-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 06/14/2016] [Indexed: 11/27/2022]
Abstract
Aging represents a major risk factor for the development of neurodegenerative diseases like Alzheimer's disease (AD). As mitochondrial dysfunction plays an important role in brain aging and occurs early in the development of AD, the prevention of mitochondrial dysfunction might help to slow brain aging and the development of neurodegenerative diseases. Rice bran extract (RBE) contains high concentrations of vitamin E congeners and γ-oryzanol. We have previously shown that RBE increased mitochondrial function and protected from mitochondrial dysfunction in vitro and in short-term in vivo feeding studies. To mimic the use of RBE as food additive, we have now investigated the effects of a long-term (6 months) feeding of RBE on survival, behavior and brain mitochondrial function in aged NMRI mice. RBE administration significantly increased survival and performance of aged NMRI mice in the passive avoidance and Y-maze test. Brain mitochondrial dysfunction found in aged mice was ameliorated after RBE administration. Furthermore, data from mRNA and protein expression studies revealed an up-regulation of mitochondrial proteins in RBE-fed mice, suggesting an increase in mitochondrial content which is mediated by a peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α)-dependent mechanism. Our findings suggest that a long-term treatment with a nutraceutical containing RBE could be useful for slowing down brain aging and thereby delaying or even preventing AD.
Collapse
Affiliation(s)
- Stephanie Hagl
- Department of Pharmacology, Goethe-University, Biozentrum Niederursel, Max-von-Laue-Straße 9, 60438, Frankfurt, Germany
| | - Heike Asseburg
- Department of Pharmacology, Goethe-University, Biozentrum Niederursel, Max-von-Laue-Straße 9, 60438, Frankfurt, Germany
| | - Martina Heinrich
- Department of Pharmacology, Goethe-University, Biozentrum Niederursel, Max-von-Laue-Straße 9, 60438, Frankfurt, Germany
| | - Nadine Sus
- Institute of Biological Chemistry and Nutrition, University of Hohenheim, Garbenstraße 28, 70599, Stuttgart, Germany
| | - Eva-Maria Blumrich
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
| | - Jan Frank
- Institute of Biological Chemistry and Nutrition, University of Hohenheim, Garbenstraße 28, 70599, Stuttgart, Germany
| | - Gunter P Eckert
- Department of Pharmacology, Goethe-University, Biozentrum Niederursel, Max-von-Laue-Straße 9, 60438, Frankfurt, Germany. .,Institute of Nutritional Sciences, University of Giessen, Wilhelmstrasse 20, 35392, Giessen, Germany.
| |
Collapse
|
20
|
The Protein Tyrosine Kinase Inhibitor Tyrphostin 23 Strongly Accelerates Glycolytic Lactate Production in Cultured Primary Astrocytes. Neurochem Res 2016; 41:2607-2618. [PMID: 27278759 DOI: 10.1007/s11064-016-1972-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/29/2016] [Accepted: 06/01/2016] [Indexed: 02/07/2023]
Abstract
Tyrphostin 23 (T23) is a well-known inhibitor of protein tyrosine kinases. To investigate potential acute effects of T23 on the viability and the glucose metabolism of brain cells, we exposed cultured primary rat astrocytes to T23 for up to 4 h. While the viability and the morphology of the cultured astrocytes were not acutely affected by the presence of T23 in concentrations of up to 300 µM, this compound caused a rapid, time- and concentration-dependent increase in glucose consumption and lactate release. Maximal effects on glycolytic flux were found for incubations with 100 µM T23 for 2 h which doubled both glucose consumption and lactate production. The stimulation of glycolytic flux by T23 was reversible, completely abolished upon removal of the compound and not found in presence of other known inhibitors of endocytosis. Structurally related compounds such as tyrphostin 25 and catechol or modulators of AMP kinase activity did neither affect the basal nor the T23-stimulated lactate production by astrocytes. In contrast, the presence of the phosphatase inhibitor vanadate completely abolished the stimulation by T23 of astrocytic lactate production in a concentration-dependent manner. These data suggest that T23-sensitive phosphorylation/dephosphorylation events are involved in the regulation of astrocytic glycolysis.
Collapse
|
21
|
Westhaus A, Blumrich EM, Dringen R. The Antidiabetic Drug Metformin Stimulates Glycolytic Lactate Production in Cultured Primary Rat Astrocytes. Neurochem Res 2015; 42:294-305. [PMID: 26433380 DOI: 10.1007/s11064-015-1733-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 09/25/2015] [Accepted: 09/26/2015] [Indexed: 12/11/2022]
Abstract
Metformin is the most frequently used drug for the treatment of type 2 diabetes in humans. However, only little is known about effects of metformin on brain metabolism. To investigate potential metabolic consequences of an exposure of brain cells to metformin, we incubated rat astrocyte-rich primary cultures with this compound. Metformin in concentrations of up to 30 mM did not acutely compromise the viability of astrocytes, but caused a time- and concentration-dependent increase in cellular glucose consumption and lactate production. For acute incubations in the hour range, the presence of 10 mM metformin doubled the glycolytic flux, while already 1 mM metformin doubled glycolytic flux during incubation for 24 h. In addition to metformin, also other guanidino compounds increased astrocytic lactate production. After 4 h of incubation, half-maximal stimulation of glycolysis was observed for metformin, guanidine and phenformin at concentrations of around 3 mM, 3 mM and 30 µM, respectively. The acute stimulation of glycolytic lactate production by metformin was persistent after removal of extracellular metformin and was also observed, if glucose was absent from the incubation medium or replaced by other hexoses. The metformin-induced stimulation of glycolytic flux was not prevented by compound C, an inhibitor of AMP-dependent protein kinase, nor was it additive to the stimulation of glycolytic flux caused by respiratory chain inhibitors. These data demonstrate that the antidiabetic drug metformin has the potential to strongly activate glycolytic lactate production in brain astrocytes.
Collapse
Affiliation(s)
- Adrian Westhaus
- Centre for Biomolecular Interactions Bremen, University of Bremen, PO. Box 330440, 28334, Bremen, Germany
| | - Eva Maria Blumrich
- Centre for Biomolecular Interactions Bremen, University of Bremen, PO. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, Leobener Strasse, 28359, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, University of Bremen, PO. Box 330440, 28334, Bremen, Germany. .,Centre for Environmental Research and Sustainable Technology, Leobener Strasse, 28359, Bremen, Germany.
| |
Collapse
|
22
|
Bulcke F, Santofimia-Castaño P, Gonzalez-Mateos A, Dringen R. Modulation of copper accumulation and copper-induced toxicity by antioxidants and copper chelators in cultured primary brain astrocytes. J Trace Elem Med Biol 2015; 32:168-76. [PMID: 26302925 DOI: 10.1016/j.jtemb.2015.07.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 06/30/2015] [Accepted: 07/03/2015] [Indexed: 12/22/2022]
Abstract
Copper is essential for several important cellular processes, but an excess of copper can also lead to oxidative damage. In brain, astrocytes are considered to play a pivotal role in the copper homeostasis and antioxidative defence. To investigate whether antioxidants and copper chelators can modulate the uptake and the toxicity of copper ions in brain astrocytes, we used primary astrocytes as cell culture model. These cells accumulated substantial amounts of copper during exposure to copper chloride. Copper accumulation was accompanied by a time- and concentration-dependent loss in cell viability, as demonstrated by a lowering in cellular MTT reduction capacity and by an increase in membrane permeability for propidium iodide. During incubations in the presence of the antioxidants ascorbate, trolox or ebselen, the specific cellular copper content and the toxicity in copper chloride-treated astrocyte cultures were strongly increased. In contrast, the presence of the copper chelators bathocuproine disulfonate or tetrathiomolybdate lowered the cellular copper accumulation and the copper-induced as well as the ascorbate-accelerated copper toxicity was fully prevented. These data suggest that predominantly the cellular content of copper determines copper-induced toxicity in brain astrocytes.
Collapse
Affiliation(s)
- Felix Bulcke
- Center for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, PO Box 330440, D-28334 Bremen, Germany; Center for Environmental Research and Sustainable Technology, Leobener Strasse, D-28359 Bremen, Germany
| | - Patricia Santofimia-Castaño
- Department of Physiology (Cell Physiology Research Group), University of Extremadura, E-10003 Caceres, Spain
| | - Antonio Gonzalez-Mateos
- Department of Physiology (Cell Physiology Research Group), University of Extremadura, E-10003 Caceres, Spain
| | - Ralf Dringen
- Center for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, PO Box 330440, D-28334 Bremen, Germany; Center for Environmental Research and Sustainable Technology, Leobener Strasse, D-28359 Bremen, Germany.
| |
Collapse
|
23
|
Petters C, Thiel K, Dringen R. Lysosomal iron liberation is responsible for the vulnerability of brain microglial cells to iron oxide nanoparticles: comparison with neurons and astrocytes. Nanotoxicology 2015; 10:332-42. [DOI: 10.3109/17435390.2015.1071445] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Charlotte Petters
- Center for Biomedical Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany,
- Center for Environmental Research and Sustainable Technology, Bremen, Germany, and
| | - Karsten Thiel
- Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Bremen, Germany
| | - Ralf Dringen
- Center for Biomedical Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany,
- Center for Environmental Research and Sustainable Technology, Bremen, Germany, and
| |
Collapse
|
24
|
Petters C, Dringen R. Accumulation of iron oxide nanoparticles by cultured primary neurons. Neurochem Int 2015; 81:1-9. [DOI: 10.1016/j.neuint.2014.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 12/03/2014] [Accepted: 12/09/2014] [Indexed: 01/13/2023]
|
25
|
Glutathione-Dependent Detoxification Processes in Astrocytes. Neurochem Res 2014; 40:2570-82. [PMID: 25428182 DOI: 10.1007/s11064-014-1481-1] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 11/10/2014] [Accepted: 11/15/2014] [Indexed: 01/17/2023]
Abstract
Astrocytes have a pivotal role in brain as partners of neurons in homeostatic and metabolic processes. Astrocytes also protect other types of brain cells against the toxicity of reactive oxygen species and are considered as first line of defence against the toxic potential of xenobiotics. A key component in many of the astrocytic detoxification processes is the tripeptide glutathione (GSH) which serves as electron donor in the GSH peroxidase-catalyzed reduction of peroxides. In addition, GSH is substrate in the detoxification of xenobiotics and endogenous compounds by GSH-S-transferases which generate GSH conjugates that are efficiently exported from the cells by multidrug resistance proteins. Moreover, GSH reacts with the reactive endogenous carbonyls methylglyoxal and formaldehyde to intermediates which are substrates of detoxifying enzymes. In this article we will review the current knowledge on the GSH metabolism of astrocytes with a special emphasis on GSH-dependent detoxification processes.
Collapse
|
26
|
Copper Oxide Nanoparticles Stimulate Glycolytic Flux and Increase the Cellular Contents of Glutathione and Metallothioneins in Cultured Astrocytes. Neurochem Res 2014; 40:15-26. [DOI: 10.1007/s11064-014-1458-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/13/2014] [Accepted: 10/17/2014] [Indexed: 11/26/2022]
|