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de Bartolomeis A, De Simone G, De Prisco M, Barone A, Napoli R, Beguinot F, Billeci M, Fornaro M. Insulin effects on core neurotransmitter pathways involved in schizophrenia neurobiology: a meta-analysis of preclinical studies. Implications for the treatment. Mol Psychiatry 2023; 28:2811-2825. [PMID: 37085712 PMCID: PMC10615753 DOI: 10.1038/s41380-023-02065-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 03/28/2023] [Accepted: 03/31/2023] [Indexed: 04/23/2023]
Abstract
Impairment of insulin action and metabolic dysregulation have traditionally been associated with schizophrenia, although the molecular basis of such association remains still elusive. The present meta-analysis aims to assess the impact of insulin action manipulations (i.e., hyperinsulinemia, hypoinsulinemia, systemic or brain insulin resistance) on glutamatergic, dopaminergic, γ-aminobutyric acid (GABA)ergic, and serotonergic pathways in the central nervous system. More than one hundred outcomes, including transcript or protein levels, kinetic parameters, and other components of the neurotransmitter pathways, were collected from cultured cells, animals, or humans, and meta-analyzed by applying a random-effects model and adopting Hedges'g to compare means. Two hundred fifteen studies met the inclusion criteria, of which 180 entered the quantitative synthesis. Significant impairments in key regulators of synaptic plasticity processes were detected as the result of insulin handlings. Specifically, protein levels of N-methyl-D-aspartate receptor (NMDAR) subunits including type 2A (NR2A) (Hedges' g = -0.95, 95%C.I. = -1.50, -0.39; p = 0.001; I2 = 47.46%) and 2B (NR2B) (Hedges'g = -0.69, 95%C.I. = -1.35, -0.02; p = 0.043; I2 = 62.09%), and Postsynaptic density protein 95 (PSD-95) (Hedges'g = -0.91, 95%C.I. = -1.51, -0.32; p = 0.003; I2 = 77.81%) were found reduced in insulin-resistant animal models. Moreover, insulin-resistant animals showed significantly impaired dopamine transporter activity, whereas the dopamine D2 receptor mRNA expression (Hedges'g = 3.259; 95%C.I. = 0.497, 6.020; p = 0.021; I2 = 90.61%) increased under insulin deficiency conditions. Insulin action modulated glutamate and GABA release, as well as several enzymes involved in GABA and serotonin synthesis. These results suggest that brain neurotransmitter systems are susceptible to insulin signaling abnormalities, resembling the discrete psychotic disorders' neurobiology and possibly contributing to the development of neurobiological hallmarks of treatment-resistant schizophrenia.
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Affiliation(s)
- Andrea de Bartolomeis
- Section of Psychiatry, Laboratory of Molecular and Translational Psychiatry, Unit of Treatment-Resistant Psychiatric Disorders, Department of Neuroscience, Reproductive Sciences and Odontostomatology University of Naples "Federico II", School of Medicine, Via Pansini 5, 80131, Naples, Italy.
| | - Giuseppe De Simone
- Section of Psychiatry, Laboratory of Molecular and Translational Psychiatry, Unit of Treatment-Resistant Psychiatric Disorders, Department of Neuroscience, Reproductive Sciences and Odontostomatology University of Naples "Federico II", School of Medicine, Via Pansini 5, 80131, Naples, Italy
| | - Michele De Prisco
- Section of Psychiatry, Laboratory of Molecular and Translational Psychiatry, Unit of Treatment-Resistant Psychiatric Disorders, Department of Neuroscience, Reproductive Sciences and Odontostomatology University of Naples "Federico II", School of Medicine, Via Pansini 5, 80131, Naples, Italy
- Bipolar and Depressive Disorders Unit, Institute of Neuroscience, Hospital Clinic, University of Barcelona, IDIBAPS, CIBERSAM, 170 Villarroel st, 12-0, 08036, Barcelona, Catalonia, Spain
| | - Annarita Barone
- Section of Psychiatry, Laboratory of Molecular and Translational Psychiatry, Unit of Treatment-Resistant Psychiatric Disorders, Department of Neuroscience, Reproductive Sciences and Odontostomatology University of Naples "Federico II", School of Medicine, Via Pansini 5, 80131, Naples, Italy
| | - Raffaele Napoli
- Department of Translational Medical Sciences, University of Naples "Federico II", Via S. Pansini 5, 80131, Naples, Italy
- URT Genomic of Diabetes, Institute of Experimental Endocrinology and Oncology, National Research Council, Naples, Italy
| | - Francesco Beguinot
- Department of Translational Medical Sciences, University of Naples "Federico II", Via S. Pansini 5, 80131, Naples, Italy
- URT Genomic of Diabetes, Institute of Experimental Endocrinology and Oncology, National Research Council, Naples, Italy
| | - Martina Billeci
- Section of Psychiatry, Laboratory of Molecular and Translational Psychiatry, Unit of Treatment-Resistant Psychiatric Disorders, Department of Neuroscience, Reproductive Sciences and Odontostomatology University of Naples "Federico II", School of Medicine, Via Pansini 5, 80131, Naples, Italy
| | - Michele Fornaro
- Section of Psychiatry, Laboratory of Molecular and Translational Psychiatry, Unit of Treatment-Resistant Psychiatric Disorders, Department of Neuroscience, Reproductive Sciences and Odontostomatology University of Naples "Federico II", School of Medicine, Via Pansini 5, 80131, Naples, Italy
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Melanson B, Lapointe T, Leri F. Impact of impaired glucose metabolism on responses to a psychophysical stressor: modulation by ketamine. Psychopharmacology (Berl) 2021; 238:1005-1015. [PMID: 33404733 DOI: 10.1007/s00213-020-05748-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 12/08/2020] [Indexed: 12/11/2022]
Abstract
RATIONALE There is evidence that hypoglycemia, a metabolic stressor, can negatively impact mood and motivation, and can interact with other stressors to potentiate their effects on behavior and physiology. OBJECTIVES/METHODS The current study in male Sprague-Dawley rats explored the interaction between impaired glucose metabolism induced by 0, 200, or 300 mg/kg 2-deoxy-D-glucose (2-DG) and a psychophysical stressor induced by forced swimming stress (FSS; 6 sessions, 10 min/session). The endpoints of interest were blood glucose levels, progressive behavioral immobility, and saccharin preference (2-bottle choice test). Furthermore, it was investigated whether pre-treatment with 0, 10, or 20 mg/kg ketamine could modify the interaction between 2-DG and FSS on these endpoints. RESULTS It was found that 2-DG increased blood glucose levels equally in all experimental groups, accelerated the immobile response to FSS, and suppressed saccharin preference 1 week following termination of stress exposure. As well, pre-treatment with ketamine blocked the effects of combined 2-DG and FSS on immobility and saccharin preference without affecting blood glucose levels and produced an anti-immobility effect that was observed during a drug-free test swim 1 week following administration. CONCLUSIONS Overall, these findings demonstrate that impaired glucose metabolism can potentiate the effects of a psychophysical stressor, and that this interaction can be modulated pharmacologically by ketamine.
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Affiliation(s)
- Brett Melanson
- Department of Psychology and Collaborative Neuroscience Program, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Thomas Lapointe
- Department of Psychology and Collaborative Neuroscience Program, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Francesco Leri
- Department of Psychology and Collaborative Neuroscience Program, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
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Matsui T, Soya M, Soya H. Endurance and Brain Glycogen: A Clue Toward Understanding Central Fatigue. ADVANCES IN NEUROBIOLOGY 2019; 23:331-346. [PMID: 31667814 DOI: 10.1007/978-3-030-27480-1_11] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Brain glycogen stored in astrocytes produces lactate as a neuronal energy source transported by monocarboxylate transporters (MCTs) to maintain neuronal functions, such as hippocampus-regulated memory formation. Although exercise activates brain neurons, the role of astrocytic glycogen in the brain during exercise remains unknown. Since muscle glycogen fuels active muscles during exercise, we hypothesized that astrocytic glycogen plays an energetic role in the brain during exercise to maintain endurance capacity through lactate transport. To explore this hypothesis, we have used a rat model of prolonged exercise, microwave irradiation for the accurate detection of brain glycogen, capillary electrophoresis-mass spectrometry-based metabolomics, and inhibitors of glycogenolysis (1,4-dideoxy-1,4-imino-D-arabinitol; DAB) and lactate transport (α-cyano-4-hydroxycinnamate; 4-CIN). During prolonged exhaustive exercise, muscle glycogen was depleted and brain glycogen decreased when associated with decreased blood glucose levels and increased serotonergic activity known as central fatigue factors, suggesting brain glycogen decrease as an integrative factor for central fatigue. Prolonged exhaustive exercise also increased MCT2 protein in the brain, which takes up lactate in neurons, just as muscle MCTs are increased. Metabolomics revealed that brain but not muscle adenosine triphosphate (ATP) was maintained with lactate and other glycogenolytic and glycolytic sources. Intracerebroventricular (icv) injection of DAB suppressed brain lactate production and decreased hippocampal ATP levels at exhaustion. An icv injection of 4-CIN also decreased hippocampal ATP, resulting in lower endurance capacity. Our findings provide direct evidence that astrocytic glycogen-derived lactate fuels the brain to maintain endurance capacity during exhaustive exercise. Brain ATP levels maintained by glycogen might serve as a possible defense mechanism for neurons in the exhausted state.
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Affiliation(s)
- Takashi Matsui
- Sport Neuroscience Division, Faculty of Health and Sport Sciences, Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Ibaraki, Japan.
| | - Mariko Soya
- Sport Neuroscience Division, Faculty of Health and Sport Sciences, Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Ibaraki, Japan
| | - Hideaki Soya
- Sport Neuroscience Division, Faculty of Health and Sport Sciences, Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Ibaraki, Japan.
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Astrocytic glycogen-derived lactate fuels the brain during exhaustive exercise to maintain endurance capacity. Proc Natl Acad Sci U S A 2017; 114:6358-6363. [PMID: 28515312 DOI: 10.1073/pnas.1702739114] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Brain glycogen stored in astrocytes provides lactate as an energy source to neurons through monocarboxylate transporters (MCTs) to maintain neuronal functions such as hippocampus-regulated memory formation. Although prolonged exhaustive exercise decreases brain glycogen, the role of this decrease and lactate transport in the exercising brain remains less clear. Because muscle glycogen fuels exercising muscles, we hypothesized that astrocytic glycogen plays an energetic role in the prolonged-exercising brain to maintain endurance capacity through lactate transport. To test this hypothesis, we used a rat model of exhaustive exercise and capillary electrophoresis-mass spectrometry-based metabolomics to observe comprehensive energetics of the brain (cortex and hippocampus) and muscle (plantaris). At exhaustion, muscle glycogen was depleted but brain glycogen was only decreased. The levels of MCT2, which takes up lactate in neurons, increased in the brain, as did muscle MCTs. Metabolomics revealed that brain, but not muscle, ATP was maintained with lactate and other glycogenolytic/glycolytic sources. Intracerebroventricular injection of the glycogen phosphorylase inhibitor 1,4-dideoxy-1,4-imino-d-arabinitol did not affect peripheral glycemic conditions but suppressed brain lactate production and decreased hippocampal ATP levels at exhaustion. An MCT2 inhibitor, α-cyano-4-hydroxy-cinnamate, triggered a similar response that resulted in lower endurance capacity. These findings provide direct evidence for the energetic role of astrocytic glycogen-derived lactate in the exhaustive-exercising brain, implicating the significance of brain glycogen level in endurance capacity. Glycogen-maintained ATP in the brain is a possible defense mechanism for neurons in the exhausted brain.
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Isaev NK, Stel'mashuk EV, Zorov DB. Cellular mechanisms of brain hypoglycemia. BIOCHEMISTRY (MOSCOW) 2007; 72:471-8. [PMID: 17573700 DOI: 10.1134/s0006297907050021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Data on intracellular processes induced by a low glucose level in nerve tissue are presented. The involvement of glutamate and adenosine receptors, mitochondria, reactive oxygen species (ROS), and calcium ions in the development of hypoglycemia-induced damage of neurons is considered. Hypoglycemia-induced calcium overload of neuronal mitochondria is suggested to be responsible for the increased ROS production by mitochondria.
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Affiliation(s)
- N K Isaev
- Belozersky Institute of Physico-Nhemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
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Bjugstad KB, Zawada WM, Goodman S, Freed CR. IGF-1 and bFGF reduce glutaric acid and 3-hydroxyglutaric acid toxicity in striatal cultures. J Inherit Metab Dis 2001; 24:631-47. [PMID: 11768583 DOI: 10.1023/a:1012706908779] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Glutaric acid (GA) and 3-hydroxyglutaric acid (3GA) are thought to contribute to the degeneration of the caudate and putamen that is seen in some children with glutaric acidaemia type I, a metabolic disorder caused by a glutaryl-CoA dehydrogenase deficiency. This study assessed the neurotoxicity of GA and 3GA (0-50 mmol/L) compared to quinolinic acid (QUIN) in striatal and cortical cultures. All three acids were neurotoxic in a dose-dependent manner; however, GA and 3GA were both more toxic than QUIN. The neurotoxic effects of low concentrations of GA or 3GA were additive to QUIN toxicity. A series of hormones and growth factors were tested for protection against GA and 3GA toxicity. Insulin (5-500 microU /ml), basic fibroblast growth factor (bFGF; 10 ng/ml), insulin-like growth factor (IGF-1; 50 ng/ml), brain-derived neurotrophic factor (BDNF; 10 ng/ml), glial-derived neurotrophic factor (GDNF; 10 ng/ml), and two glutamate antagonists were evaluated in brain cultures to which 7 mmol/L GA or 3GA were added. GA and 3GA neurotoxicities were prevented by bFGF. Attenuation of 3GA-induced neurotoxicity was seen with insulin (5 microU/ml) and IGF-1. BDNF and GDNF had no effects on neuronal survival. Glutamate antagonists MK801 (10 micromol/L) and NBQX (10 micromol/L) failed to prevent GA or 3GA neurotoxicity. We conclude that GA and 3GA are neurotoxic in cultures of embryonic rat striatum and cortex. Striatal neurons were rescued from death by bFGF and IGF-1 but not by glutamate antagonist, suggesting that toxicity in this embryonic system is not necessarily mediated by glutamate receptors.
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Affiliation(s)
- K B Bjugstad
- Division of Clinical Pharmacology and Toxicology, University of Colorado Health Science Center, Denver, Colorado, USA
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Abstract
In just under 20 years the kynurenine family of compounds has developed from a group of obscure metabolites of the essential amino acid tryptophan into a source of intensive research, with postulated roles for quinolinic acid in neurodegenerative disorders, most especially the AIDS-dementia complex and Huntington's disease. One of the kynurenines, kynurenic acid, has become a standard tool for use in the identification of glutamate-releasing synapses, and has been used as the parent for several groups of compounds now being developed as drugs for the treatment of epilepsy and stroke. The kynurenines represent a major success in translating a basic discovery into a source of clinical understanding and therapeutic application, with around 3000 papers published on quinolinic acid or kynurenic acid since the discovery of their effects in 1981 and 1982. This review concentrates on some of the recent work most directly relevant to the understanding and applications of kynurenines in medicine.
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Affiliation(s)
- T W Stone
- Institute of Biomedical and Life Sciences, University West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
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Maeda K, Kaneda H, Whetsell WO, Tamminga CA. Neurochemical and metabolic consequences of elevated cerebrospinal fluid quinolinic acid concentrations in rat brain. Neurosci Res 1997; 29:303-9. [PMID: 9527621 DOI: 10.1016/s0168-0102(97)00102-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Quinolinic acid (QUIN) is an endogenous excitatory amino acid, which is elevated in brain tissues or cerebrospinal fluid (CSF) in several acute and chronic inflammatory central nervous system (CNS) diseases. The functional significance of this elevation is unknown but speculations of excitotoxicity have been raised. We have begun to address the pathologic consequences of elevated CSF QUIN by studying the effects of intracerebroventricular (i.cv) administration of QUIN on regional choline acetyltransferase (ChAT) activity, somatostatin content and glucose metabolism in the rat brain. QUIN (12 and 60 nmol) i.cv administration once a day for 7 days (total dose; 84 and 420 nmol, respectively) had minimal effect on somatostatin content and no effect on ChAT activity. In contrast, following continuous i.cv infusion of QUIN for 14 days using an osmotic minipump (480 nmol), ChAT activity dropped in the hippocampus and the striatum and somatostatin content was reduced in the frontal cortex, hippocampus, striatum and amygdala. Moreover, following the QUIN infusion, glucose utilization decreased in the basal nucleus of Meynert, frontal cortex, and portions of the basal ganglia and the limbic system. These results indicate that subchronic i.cv infusion of QUIN to rats results in selective regional neurochemical and metabolic changes distributed throughout the CNS. These results suggest target brain areas and transmitter systems which may be associated with neurologic syndromes characterized by elevated CSF QUIN levels.
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Affiliation(s)
- K Maeda
- Maryland Psychiatric Research Center, University of Maryland, Baltimore 21228, USA.
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Holden RJ, Mooney PA. Interleukin-1 beta: a common cause of Alzheimer's disease and diabetes mellitus. Med Hypotheses 1995; 45:559-71. [PMID: 8771051 DOI: 10.1016/0306-9877(95)90240-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Alzheimer disease is characterized by the presence of beta-amyloid protein deposits, neurofibrillary tangles and cholinergic dysfunction throughout the hippocampal region. In addition, the hippocampus, hypothalamus and olfactory bulb--the three areas where the insulin receptors are most dense--are also subject to neurodegeneration. The exact cause of the beta-amyloid deposits and NFTs is unknown. However, it is our intention to explicate the various pathogenic pathways through which Alzheimer disease arises. Fundamentally, the structural and metabolic damage found in Alzheimer disease is due to sustained elevation of interleukin-1 beta, a feature which is also found in insulin-dependent diabetes mellitus. Similarly, the beta-AP deposits found in the Alzheimer brain share the same molecular structure as the amylin deposits found in the pancreatic beta-cells in non-insulin-dependent diabetes mellitus (NIDDM), and are equally neurotoxic. These, and other pathophysiological parallels, afford some insight into the probably cause of Alzheimer disease and, as such, forms the basis of the causal hypothesis advanced in this paper.
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Affiliation(s)
- R J Holden
- Medical Research Unit, University of Wollongong, NWS, Australia
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Holden RJ. The estrogen connection: the etiological relationship between diabetes, cancer, rheumatoid arthritis and psychiatric disorders. Med Hypotheses 1995; 45:169-89. [PMID: 8531840 DOI: 10.1016/0306-9877(95)90066-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
For some considerable time, there has been a growing awareness that defective essential fatty acid metabolism plays a causal role in the pathogenesis of both schizophrenia and non-insulin-dependent diabetes mellitus (NIDDM) but the influence of defective essential fatty acid metabolism in the pathogenesis of rheumatoid arthritis and cancer is less well appreciated. An EFA deficiency, or defective EFA metabolism, negatively influences prostaglandin synthesis and glucose regulation and transport. Moreover, defective EFA metabolism negatively influences estrogen availability which contributes to the observed gender bias some of these illnesses manifest. While fluctuations of estrogen are known to contribute to the pathogenesis of these conditions, so also do fluctuations of IGF-II and there is some suggestion that IGF-II and insulin may well be inversely regulated. In addition, insulin-dependent diabetes mellitus (IDDM), rheumatoid arthritis, and schizophrenia are thought to be autoimmune disorders, while cancer is associated with immune system failure. Consequently, this paper aims to examine the pathophysiological similarities and differences between mental illness, diabetes, rheumatoid arthritis and cancer in respect of which the causal relationship that obtains between essential fatty acids, estrogen, IGF-II, glucose regulation and autoimmunity will be addressed.
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Affiliation(s)
- R J Holden
- Medical Research Unit, University of Wollongong, NSW, Australia
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Abstract
In this paper, the relationship between schizophrenia, suicide and serotonin will be examined. Throughout, it will be argued that the fundamental problem does not lie with the neurotransmitter per se, but rather with uncontrolled fluctuations of brain glycaemic levels acting in conjunction with insulin resistance. It will be shown that the area of dopaminergic and serotonergic activity in the brain is intimately tied to the relative distribution of the central glucose transporters and, hence, to glucose metabolism and insulin activity. It will be argued that mania and positive schizophrenia represent a continuum of liability associated with hyperglycaemia, hyperdopaminergia, and hyperserotonergia. In contrast, depression and negative schizophrenia represent another continuum of liability involving hypoglycaemia, hypodopaminergia, and hyposerotonergia. This serves as a useful distinction in drawing together a large number of seemingly unrelated, diverse facts concerning both schizophrenia and suicide and, in particular, the possible relationship that obtains between cholesterol-lowering drugs, low serotonin and suicide. Essentially, this paper reaffirms a previously stated contention that mental illness, in its many guises, is a general manifestation of a diabetic brain state which has been termed 'cerebral diabetes'.
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Affiliation(s)
- R J Holden
- Medical Research Unit, University of Wollongong, NSW, Australia
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Reinhard JF, Erickson JB, Flanagan EM. Quinolinic acid in neurological disease: opportunities for novel drug discovery. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1994; 30:85-127. [PMID: 7833298 DOI: 10.1016/s1054-3589(08)60173-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- J F Reinhard
- Department of Pharmacology, Wellcome Research Laboratories, Research Triangle Park, North Carolina 27709
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Saito K, Nowak TS, Suyama K, Quearry BJ, Saito M, Crowley JS, Markey SP, Heyes MP. Kynurenine pathway enzymes in brain: responses to ischemic brain injury versus systemic immune activation. J Neurochem 1993; 61:2061-70. [PMID: 8245962 DOI: 10.1111/j.1471-4159.1993.tb07443.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Accumulation of L-kynurenine and quinolinic acid (QUIN) in the brain occurs after either ischemic brain injury or after systemic administration of pokeweed mitogen. Although conversion of L-[13C6]tryptophan to [13C6]-QUIN has not been demonstrated in brain either from normal gerbils or from gerbils given pokeweed mitogen, direct conversion in brain tissue does occur 4 days after transient cerebral ischemia. Increased activities of enzymes distal to indoleamine-2,3-dioxygenase may determine whether L-kynurenine is converted to QUIN. One day after 10 min of cerebral ischemia, the activities of kynureninase and 3-hydroxy-3,4-dioxygenase were increased in the hippocampus, but local QUIN levels and the activities of the indoleamine-2,3-dioxygenase and kynurenine-3-hydroxylase were unchanged. By days 2 and 4 after ischemia, however, the activities of all these enzymes in the hippocampus as well as QUIN levels were significantly increased. Kynurenine aminotransferase activity in the hippocampus was unchanged on days 1 and 2 after ischemia but was decreased on day 4, at a time when local kynurenic acid levels were unchanged. A putative precursor of QUIN, [13C6]anthranilic acid, was not converted to [13C6]QUIN in the hippocampus of either normal or 4-day post-ischemic gerbils. Gerbil macrophages stimulated by endotoxin in vitro converted L-[13C6]tryptophan to [13C6]QUIN. Kinetic analysis of kynurenine-3-hydroxylase activity in the cerebral cortex of postischemic gerbils showed that Vmax increased, without changes in Km. Systemic administration of pokeweed mitogen increased indoleamine-2,3-dioxygenase and kynureninase activities in the brain without significant changes in kynurenine-3-hydroxylase or 3-hydroxyanthranilate-3,4-dioxygenase activities. Increases in kynurenine-3-hydroxylase activity, in conjunction with induction of indoleamine-2,3-dioxygenase, kynureninase, and 3-hydroxyanthranilate-3,4-dioxygenase in macrophage infiltrates at the site of brain injury, may explain the ability of postischemic hippocampus to convert L-[13C6]tryptophan to [13C6]QUIN.
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Affiliation(s)
- K Saito
- Section on Analytical Biochemistry, National Institute of Mental Health, Bethesda, Maryland 20892
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Auer RN, Siesjö BK. Hypoglycaemia: brain neurochemistry and neuropathology. BAILLIERE'S CLINICAL ENDOCRINOLOGY AND METABOLISM 1993; 7:611-25. [PMID: 8379907 DOI: 10.1016/s0950-351x(05)80210-1] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The widespread use of insulin and oral hypoglycaemic agents has increased the incidence of hypoglycaemic brain damage due to accidental, suicidal, or homicidal overdose. Hypoglycaemia is capable of damaging the brain in the face of intact cardiac function, but neuronal necrosis occurs only when the electroencephalogram (EEG) becomes isoelectric. Neurochemical changes are distinct from ischaemia, and cerebral blood flow is actually increased, in contrast to cerebral ischaemia. Salient neurochemical changes include an arrest of protein synthesis in many but not all brain regions, a shift of brain redox equilibria towards oxidation, incomplete energy failure, loss of ion homeostasis, cellular calcium influx, intracellular alkalosis, and a release of neuroactive amino acids, especially aspartate, into the extracellular space of the brain. The metabolic release of aspartate, and to a lesser extent glutamate, into the interstitial space of the brain produces histopathological patterns of neuronal death that can be distinguished from ischaemic brain damage in experimental brain tissue and, occasionally, in brains from human autopsies after hypoglycaemic brain damage. The excitatory amino acids released during profound hypoglycaemia bind to neuronal dendrites and perikarya, but not to other cell types in the nervous system, thus giving rise to selective neuronal death. The absence of acidosis, and an adequate blood supply during hypoglycaemia, protect the brain against pan-necrosis or infarction. However, the neurons die more quickly during hypoglycaemic brain damage than after cerebral ischaemia. Hypoglycaemic brain damage thus falls into the newly defined class of cerebral 'excitotoxic' neuropathologies, where neurons are selectively killed by an extracellular overflow of excitatory amino acids produced by the brain itself. The pathogenesis of hypoglycaemic brain damage is thus rather more novel and intriguing than was thought even a decade ago, when it was believed that glucose starvation and simple energy failure resulted directly in neuronal catabolism.
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Affiliation(s)
- R N Auer
- University of Calgary, Foothills Hospital, Alberta, Canada
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Nakano K, Asai H, Kitoh J. Abnormally high activity of 3-hydroxyanthranilate 3,4-dioxygenase in brain of epilepsy-prone El mice. Brain Res 1992; 572:1-4. [PMID: 1611505 DOI: 10.1016/0006-8993(92)90443-d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Quinolinic acid (QUI), a structural analogue of neurotransmitters such as L-glutamate and L-aspartate, may act as an 'excitotoxin' when it is abundant in the brain. The compound has been causally related to various neurodegenerative disorders, including epilepsy. We tested the capacity of the brains of epilepsy-prone El mice to synthesize QUI. The activity of 3-hydroxyanthranilate 3,4-dioxygenase in the cerebral cortex of El mice was about 17 times that of ddY mice, the parent strain of El mice. The activity of this enzyme was undetectable in brains of BALB/cA mice and C3H/HeN mice. In El mice the sexes had comparable enzyme activity. The enzyme activity increased gradually as the animals aged. An injection of endotoxin caused a further increase in the enzyme activity. The enzyme activity in the spleen of El mice did not differ from that of ddY mice, and endotoxin did not affect the enzyme activity in the spleen. No strain-difference was observed in the activity of quinolinate phosphoribosyltransferase, a QUI-degrading enzyme, in the cerebral cortex. These results suggest that an increase in the synthesis of QUI in the brain is involved in the pathogenesis of epileptic seizures in El mice.
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Affiliation(s)
- K Nakano
- Department of Nutritional Regulation, Nagoya University School of Agriculture, Japan
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Vezzani A, Forloni GL, Serafini R, Rizzi M, Samanin R. Neurodegenerative Effects Induced by Chronic Infusion of Quinolinic Acid in Rat Striatum and Hippocampus. Eur J Neurosci 1991; 3:40-46. [PMID: 12106267 DOI: 10.1111/j.1460-9568.1991.tb00809.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In this study we examined whether the potency of quinolinic acid (Quin) in inducing neurodegeneration in vivo was dependent on the exposure time of the tissue to the excitotoxin. The effect of chronic infusion of Quin into rat striatum and hippocampus was examined at the light microscopic level and by cell count on 40 microm Cresyl violet stained brain sections. Continuous infusion was at a constant speed (0.5 microl/h) for various times (15 h - 2 weeks) by osmotic minipumps (Alzet 2002). No build up of [3H]Quin occurred in the tissue during infusion; this was assessed by measuring the radioactivity 3 - 14 days after minipump placement. Intrastriatal infusion of 6 and 10 nmol/h Quin, but not of nicotinic acid, for 1 week induced a dose-dependent neurodegeneration (70 and 90% loss of neurons, respectively, compared to the contralateral striatum) extending 1.2 - 2 mm from the centre of the injection. The onset of the neurotoxicity caused by 10 nmol/h Quin was >24 h. One week's infusion of 4 nmol/h Quin did not induce neurotoxicity, but a 40% drop of neurons, compared to the contralateral side, occurred after 2 weeks. One week's intrahippocampal infusion of 2.4 and 6 nmol/h Quin, but not of nicotinic acid, caused a dose-dependent neurodegeneration with a radius of approximately 1 - 1.5 mm around the injection track. The onset of the neurotoxicity induced by 2.4 nmol/h Quin was < 15 h. The pattern of nerve cell loss induced by 1.2 nmol/h Quin after 1 week (CA4 cells lost in 50% of the rats) did not differ from that observed after 2 weeks of infusion. Nerve cell loss caused by Quin in the striatum and in the hippocampus was restricted to the injected area and antagonized by coinfusion with d(-)-2-amino-7-phosphonoheptanoic and kynurenic acids in molar ratios of 1:0.1 and 1:3, respectively. These data show that Quin's potency in inducing neurodegeneration in the striatum, but not in the hippocampus, depends on the exposure time of the tissue to the excitotoxin. In addition, neurodegeneration is induced faster by Quin in the hippocampus than in the striatum. The usefulness of this model to study the sequelae of the neurotoxic process in vivo will be discussed.
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Heyes MP, Swartz KJ, Markey SP, Beal MF. Regional brain and cerebrospinal fluid quinolinic acid concentrations in Huntington's disease. Neurosci Lett 1991; 122:265-9. [PMID: 1827518 DOI: 10.1016/0304-3940(91)90874-s] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Many of the characteristics neuroanatomical and neurochemical features of Huntington's disease (HD) are produced in experimental animals by an intrastriatal injection of the endogenous N-methyl-D-aspartate receptor agonist quinolinic acid (QUIN). Conceivably, a chronic over-production of QUIN in brain could be involved in the pathogenesis of HD. To investigate this hypothesis, concentrations of QUIN were measured both in cerebrospinal fluid (CSF) and postmortem tissue from patients with HD and neurologically normal age-matched controls. CSF QUIN concentrations were slightly lower in patients with HD, however the changes were not significant. Mean concentrations of QUIN tended to be lower in HD putamen, dentate nucleus and several cortical regions, although significant reductions were found only in Brodmann areas 17, 20 and 28. The mechanisms responsible for these small reductions in brain QUIN concentrations remain to be determined. These results do not support the hypothesis that a chronic increase of QUIN production is responsible for neurodengeneration in HD.
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Affiliation(s)
- M P Heyes
- Section of Analytical Biochemistry, Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, MD 20892
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Schwarcz R, Du F. Quinolinic acid and kynurenic acid in the mammalian brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1991; 294:185-99. [PMID: 1685291 DOI: 10.1007/978-1-4684-5952-4_17] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- R Schwarcz
- Maryland Psychiatric Research Center, Baltimore 21228
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19
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Heyes MP, Gravell M, London WT, Eckhaus M, Vickers JH, Yergey JA, April M, Blackmore D, Markey SP. Sustained increases in cerebrospinal fluid quinolinic acid concentrations in rhesus macaques (Macaca mulatta) naturally infected with simian retrovirus type-D. Brain Res 1990; 531:148-58. [PMID: 1963097 DOI: 10.1016/0006-8993(90)90768-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Sustained increases in CSF concentrations of the excitotoxin quinolinic acid (QUIN) occur in patients with AIDS and have been implicated in the pathogenesis of the AIDS dementia complex. Macaques in captivity may also develop immunodeficiency syndromes caused by retrovirus infection, including simian retrovirus type-D. In the present study, CSF QUIN concentrations were moderately increased in retrovirus type-D-positive/antibody-negative macaques (163.8 +/- 35.1 nmol/l; P less than 0.0001, n = 21) but not virus-negative/antibody-positive macaques (27.4 +/- 9.4 nmol/l, n = 8) compared to uninfected control macaques (23.0 +/- 1.6 nmol/l; n = 22). CSF QUIN concentrations in virus-positive/antibody-negative macaques tended to remain elevated over a 4-20 month period. Post-mortem studies of 9 virus-positive/antibody-negative macaques and 6 virus-negative/antibody-positive macaques revealed inflammatory responses in the brains of 6 of 9 virus-positive/antibody negative macaques, including lymphocytic infiltrates of the choroid plexus in 3 macaques, glial nodules in 3 macaques and perivascular infiltrates in 1 macaque. These lesions were not extensive and no evidence of brain atrophy was observed. No lesions were observed in the 6 antibody-positive/virus-negative macaques. Small increases in plasma L-kynurenine in virus-positive/antibody-negative macaques are consistent with activation of indoleamine-2,3-dioxygenase, the first enzyme in the kynurenine pathway. We conclude that sustained moderate increases in CSF QUIN occur in viremic simian retrovirus type-D macaques. The increases in CSF QUIN may reflect inflammatory responses within the brain or synthesis of QUIN precursors in systemic tissues, their entry into brain and subsequent conversion to QUIN. The neuropathologic significance of these increases in CSF QUIN remains to be determined.
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Affiliation(s)
- M P Heyes
- Section on Analytical Biochemistry, NIMH, Bethesda, MD 20892
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Heyes MP, Nowak TS. Delayed increases in regional brain quinolinic acid follow transient ischemia in the gerbil. J Cereb Blood Flow Metab 1990; 10:660-7. [PMID: 1696582 DOI: 10.1038/jcbfm.1990.119] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Excessive activity or release of excitatory amino acids has been implicated in the neuronal injury that follows transient cerebral ischemia. To investigate the metabolism of the endogenous excitotoxin, quinolinic acid, and its potential for mediating cell loss following ischemia, the concentrations of quinolinic acid, L-tryptophan, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid were quantified in gerbil brain regions at different times after 5 or 15 min of ischemia induced by bilateral carotid artery occlusion. Significant elevation of brain tryptophan levels, accompanied by increased 5-hydroxyindoleacetic acid concentrations, occurred during the first several hours of recirculation, but regional brain quinolinic acid concentrations were found either to decrease or remain unchanged during the first 24 h after the ischemic insult. However, significant increases in quinolinic acid concentrations occurred in striatum and hippocampus at 2 days of recirculation after 5 min of ischemia. After a further 4 and 7 days, strikingly large increases in quinolinic acid concentrations were observed in all regions examined, with the highest levels observed in the hippocampus and striatum, regions that also show the most severe ischemic injury. These delayed increases in brain quinolinic acid concentrations are suggested to reflect the presence of activated macrophages, reactive astrocytes, and/or microglia in vulnerable regions during and subsequent to ischemic injury. While the results do not support a role for increased quinolinic acid concentrations in early excitotoxic neuronal damage, the role of the delayed increases in brain quinolinic acid in the progression of postischemic injury and its relevance to postischemic brain function remain to be established.
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Affiliation(s)
- M P Heyes
- Section on Analytical Biochemistry, National Institute of Mental Health, Bethesda, Maryland 20892
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Heyes MP, Lackner A. Increased cerebrospinal fluid quinolinic acid, kynurenic acid, and L-kynurenine in acute septicemia. J Neurochem 1990; 55:338-41. [PMID: 2141357 DOI: 10.1111/j.1471-4159.1990.tb08857.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Increases in brain quinolinic acid have been implicated in neurodegeneration and convulsions that may accompany infectious diseases. In three rhesus macaques (Macaca mulatta) with septicemia, both CSF and serum quinolinic acid concentrations were markedly elevated and were accompanied by increases in CSF kynurenic acid levels that were of a smaller magnitude. Elevated serum and CSF L-kynurenine concentrations also occurred and are consistent with activation of indoleamine-2,3-dioxygenase and increased substrate flux through the kynurenine pathway. Although it is probable that the marked increases in CSF quinolinic acid and kynurenic acid concentrations are reflected in the extracellular fluid space of brain, it remains to be determined whether the magnitude of such increases influences the activity of excitatory amino acid receptors in brain to produce excitotoxic pathology or noncytolytic disruption of functions mediated by excitatory amino acid receptors.
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Affiliation(s)
- M P Heyes
- Section on Analytical Biochemistry, National Institute of Mental Health, Bethesda, MD 20892
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