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Barbaresi P, Fabri M, Lorenzi T, Sagrati A, Morroni M. Intrinsic organization of the corpus callosum. Front Physiol 2024; 15:1393000. [PMID: 39035452 PMCID: PMC11259024 DOI: 10.3389/fphys.2024.1393000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 05/16/2024] [Indexed: 07/23/2024] Open
Abstract
The corpus callosum-the largest commissural fiber system connecting the two cerebral hemispheres-is considered essential for bilateral sensory integration and higher cognitive functions. Most studies exploring the corpus callosum have examined either the anatomical, physiological, and neurochemical organization of callosal projections or the functional and/or behavioral aspects of the callosal connections after complete/partial callosotomy or callosal lesion. There are no works that address the intrinsic organization of the corpus callosum. We review the existing information on the activities that take place in the commissure in three sections: I) the topographical and neurochemical organization of the intracallosal fibers, II) the role of glia in the corpus callosum, and III) the role of the intracallosal neurons.
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Affiliation(s)
- Paolo Barbaresi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Ancona, Italy
| | - Mara Fabri
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Teresa Lorenzi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Ancona, Italy
| | - Andrea Sagrati
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Manrico Morroni
- Electron Microscopy Unit, Azienda Ospedaliero-Universitaria, Ancona, Italy
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2
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Cognitive control affects motor learning through local variations in GABA within the primary motor cortex. Sci Rep 2021; 11:18566. [PMID: 34535725 PMCID: PMC8448760 DOI: 10.1038/s41598-021-97974-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 08/27/2021] [Indexed: 02/08/2023] Open
Abstract
The primary motor cortex (M1) is crucial for motor learning; however, its interaction with other brain areas during motor learning remains unclear. We hypothesized that the fronto-parietal execution network (FPN) provides learning-related information critical for the flexible cognitive control that is required for practice. We assessed network-level changes during sequential finger tapping learning under speed pressure by combining magnetic resonance spectroscopy and task and resting-state functional magnetic resonance imaging. There was a motor learning-related increase in preparatory activity in the fronto-parietal regions, including the right M1, overlapping the FPN and sensorimotor network (SMN). Learning-related increases in M1-seeded functional connectivity with the FPN, but not the SMN, were associated with decreased GABA/glutamate ratio in the M1, which were more prominent in the parietal than the frontal region. A decrease in the GABA/glutamate ratio in the right M1 was positively correlated with improvements in task performance (p = 0.042). Our findings indicate that motor learning driven by cognitive control is associated with local variations in the GABA/glutamate ratio in the M1 that reflects remote connectivity with the FPN, representing network-level motor sequence learning formations.
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Onaolapo AY, Onaolapo OJ. Dietary glutamate and the brain: In the footprints of a Jekyll and Hyde molecule. Neurotoxicology 2020; 80:93-104. [PMID: 32687843 DOI: 10.1016/j.neuro.2020.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/29/2020] [Accepted: 07/14/2020] [Indexed: 12/15/2022]
Abstract
Glutamate is a crucial neurotransmitter of the mammalian central nervous system, a molecular component of our diet, and a popular food-additive. However, for decades, concerns have been raised about the issue of glutamate's safety as a food additive; especially, with regards to its ability (or otherwise) to cross the blood-brain barrier, cause excitotoxicity, or lead to neuron death. Results of animal studies following glutamate administration via different routes suggest that an array of effects can be observed. While some of the changes appear deleterious, some are not fully-understood, and the impact of others might even be beneficial. These observations suggest that with regards to the mammalian brain, exogenous glutamate might exert a double-sided effect, and in essence be a two-faced molecule whose effects may be dependent on several factors. This review draws from the research experiences of the authors and other researchers regarding the effects of exogenous glutamate on the brain of rodents. We also highlight the possible implications of such effects on the brain, in health and disease. Finally, we deduce that beyond the culinary effects of exogenous glutamate, there is the possibility of a beneficial role in the understanding and management of brain disorders.
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Affiliation(s)
- Adejoke Y Onaolapo
- Behavioural Neuroscience/Neurobiology Unit, Department of Anatomy, Ladoke Akintola University of Technology, Ogbomosho, Oyo State, Nigeria.
| | - Olakunle J Onaolapo
- Behavioural Neuroscience/Neuropharmacology Unit, Department of Pharmacology, Ladoke Akintola University of Technology, Osogbo, Osun State, Nigeria.
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Sun JY, Yang JY, Wang F, Wang JY, Song W, Su GY, Dong YX, Wu CF. Lesions of nucleus accumbens affect morphine-induced release of ascorbic acid and GABA but not of glutamate in rats. Addict Biol 2011; 16:540-50. [PMID: 20731632 DOI: 10.1111/j.1369-1600.2010.00244.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Our previous studies have shown that local perfusion of morphine causes an increase of extracellular ascorbic acid (AA) levels in nucleus accumbens (NAc) of freely moving rats. Lines of evidence showed that glutamatergic and GABAergic were associated with morphine-induced effects on the neurotransmission of the brain, especially on the release of AA. In the present study, the effects of morphine on the release of extracellular AA, γ-aminobutyric acid (GABA) and glutamate (Glu) in the NAc following bilateral NAc lesions induced by kainic acid (KA) were studied by using the microdialysis technique, coupled to high performance liquid chromatography with electrochemical detection (HPLC-ECD) and fluorescent detection (HPLC-FD). The results showed that local perfusion of morphine (100 µM, 1 mM) in NAc dose-dependently increased AA and GABA release, while attenuated Glu release in the NAc. Naloxone (0.4 mM) pretreated by local perfusion to the NAc, significantly blocked the effects of morphine. After NAc lesion by KA (1 µg), morphine-induced increase in AA and GABA were markedly eliminated, while decrease in Glu was not affected. The loss effect of morphine on AA and GABA release after KA lesion could be recovered by GABA agonist, musimol. These results indicate that morphine-induced AA release may be mediated at least by µ-opioid receptor. Moreover, this effect of morphine possibly depend less on the glutamatergic afferents, but more on the GABAergic circuits within this nucleus. Finally, AA release induced by local perfusion of morphine may be GABA-receptor mediated and synaptically localized in the NAc.
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Affiliation(s)
- Ji Y Sun
- Department of Pharmacology, Shenyang Pharmaceutical University, PR China
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5
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Neurotransmitters and prefrontal cortex–limbic system interactions: implications for plasticity and psychiatric disorders. J Neural Transm (Vienna) 2009; 116:941-52. [DOI: 10.1007/s00702-009-0243-8] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Accepted: 05/11/2009] [Indexed: 12/30/2022]
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Prefrontal cortex-nucleus accumbens interaction: in vivo modulation by dopamine and glutamate in the prefrontal cortex. Pharmacol Biochem Behav 2008; 90:226-35. [PMID: 18508116 DOI: 10.1016/j.pbb.2008.04.011] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2007] [Revised: 04/09/2008] [Accepted: 04/14/2008] [Indexed: 11/24/2022]
Abstract
Previous experimental studies have shown that the prefrontal cortex (PFC) regulates the activity of the nucleus accumbens (NAc), and in particular the release of dopamine in this area of the brain. In the present report we review recent microinjections/microdialysis studies from our laboratory on the effects of stimulation/blockade of dopamine and glutamate receptors in the PFC that modulate dopamine, and also acetylcholine release in the NAc. Stimulation of prefrontal D2 dopamine receptors, but not group I mGlu glutamate receptors, reduces the release of dopamine and acetylcholine in the NAc and spontaneous motor activity. This inhibitory role of prefrontal D2 receptors is not changed by acute systemic injections of the NMDA antagonist phencyclidine. On the other hand, the blockade of NMDA receptors in the PFC increases the release of dopamine and acetylcholine in the NAc as well as motor activity which suggests that the hypofunction of prefrontal NMDA receptors is able to produce the neurochemical and behavioural changes associated with a dysfunction of the corticolimbic circuit. We suggest here that dopamine and glutamate receptors are, in part, segregated in specific cellular circuits in the PFC. Thus, the stimulation/blockade of these receptors would have a different net impact on PFC output projections to regulate dopamine and acetylcholine release in the NAc and in guided behaviour. Finally, it is speculated that environmental enrichment might produce plastic changes that modify the functional interaction between the PFC and the NAc in both physiological and pathological conditions.
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Villa AEP, Asai Y, Segundo JP. Influence of the temporal distribution of electric pulses on transcallosal single unit responses. Biosystems 2007; 89:143-53. [PMID: 17275171 DOI: 10.1016/j.biosystems.2006.04.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Accepted: 04/26/2006] [Indexed: 11/27/2022]
Abstract
We examined how differently timed stimuli to one auditory cortex affect the spike trains they drive in the controlateral homotopic field of anesthetized rats. Bipolar electrical stimulations consisted of trains of pulses (100 micro s, <500 micro A) at rates of 25, 50 or 125 pulses/s and with different stimulus patterns (i.e., dispersions, sequences), called "pacemaker", "accelerando" or "decelerando". Trains lasted for 342 ms and were separated by 4 s. When trains were evaluated over times comparable to the stimulus duration changes characteristically involved an initial slowing followed by recovery and several discharges both stimulus- and neuron-dependent. When evaluated by cross-correlations between cortical cell pairs, the changes extended far beyond the stimulus end. Results suggest that interhemispheric projections, by way of their averages and patterns, play key, long duration roles in the spike-dependent properties of cortical synapses (e.g., potentiation, depression) and thus of cortical circuit operations.
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Segovia G, Mora F. Effects of the metabotropic glutamate receptor agonist, ACPD, on the extracellular concentrations of GABA and acetylcholine in the prefrontal cortex of the rat during the normal process of aging. Brain Res Bull 2005; 65:11-6. [PMID: 15680540 DOI: 10.1016/j.brainresbull.2004.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Revised: 10/01/2004] [Accepted: 10/08/2004] [Indexed: 11/25/2022]
Abstract
The aim of the present study was to investigate the effects of activation of metabotropic glutamate receptors (mGluR) on the extracellular concentrations of GABA and acetylcholine in the prefrontal cortex of freely moving rats of different groups of age. Perfusion, through the microdialysis probe, of the agonist of mGluR, (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD; 100, 500 and 1000 microM), in the prefrontal cortex of young rats produced a dose-related increase of the dialysate concentrations of GABA. The effects of perfusion of ACPD on the concentrations of GABA were attenuated in middle-aged rats. In the prefrontal cortex of aged rats, perfusion of ACPD produced no changes in dialysate concentrations of GABA at any of the doses used. Conversely, perfusion of ACPD (100, 500 and 1000 microM) in the prefrontal cortex of young, middle-aged and aged rats did not modify the dialysate concentrations of acetylcholine. Basal concentrations of acetylcholine in the prefrontal cortex of middle-aged and aged rats were significantly lower than those in young rats. In contrast, basal dialysate concentrations of GABA were not significantly different in young, middle-aged and aged rats. These results suggest that the interaction GABA-glutamate in the prefrontal cortex, mediated by mGluRs, changes with age.
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Affiliation(s)
- Gregorio Segovia
- Department of Physiology, Faculty of Medicine, Universidad Complutense, Ciudad Universitaria, 28040 Madrid, Spain.
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Gu PF, Yang JY, Wu CF, Li W, Shang Y. Frontal decortication eliminates drug-induced ascorbic acid release in the striatum but not the nucleus accumbens of freely moving rats. Brain Res 2005; 1033:194-201. [PMID: 15694924 DOI: 10.1016/j.brainres.2004.11.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2004] [Indexed: 11/28/2022]
Abstract
The mechanism of morphine-, methamphetamine-, and nicotine-induced ascorbic acid (AA) release in the striatum and nucleus accumbens (NAc) is not well understood. In the present study, the roles of the corticostriatal and corticoaccumbens pathways in drug-induced AA release were studied by using microdialysis coupled to high performance liquid chromatography with electrochemical detection (HPLC-ECD). The results showed that morphine (20 mg/kg), methamphetamine (3.0 mg/kg), or nicotine (1.5 mg/kg) intraperitoneally (i.p.) significantly stimulated AA release in the striatum to more than 180%, 190%, and 140% compared with saline groups, respectively. These effects could be completely eliminated by frontal decortication, or antagonized by MK-801 (1.0 mg/kg). Moreover, methamphetamine or nicotine also significantly induced AA release in the NAc to more than 180% and 150% compared with saline groups, respectively. However, these effects could not be eliminated by frontal decortication. Although the effects of methamphetamine or nicotine in the NAc could be antagonized by MK-801, two-way ANOVA analysis did not show a significantly interaction between MK-801 and methamphetamine, or nicotine. The results indicates that the corticostriatal glutamatergic pathway may be a common and necessary pathway in drug-induced AA release in the striatum, but the corticoaccumbens glutamatergic pathway may not be crucial in drug-induced AA release in the NAc. The present study implies that different mechanisms might be involved in drug-induced AA release in the striatum and the NAc in rats.
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Affiliation(s)
- Pei Fei Gu
- Department of Pharmacology, Shenyang Pharmaceutical University, Wenhau Road 103, 110016 Shenyang, P. R. China
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Segovia G, Porras A, Del Arco A, Mora F. Glutamatergic neurotransmission in aging: a critical perspective. Mech Ageing Dev 2001; 122:1-29. [PMID: 11163621 DOI: 10.1016/s0047-6374(00)00225-6] [Citation(s) in RCA: 254] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The effects of aging on glutamate neurotransmission in the brain is reviewed and evaluated. Glutamate is the neurotransmitter in most of the excitatory synapses and appears to be involved in functions such as motor behaviour, cognition and emotion, which alter with age. However, relatively few studies have been conducted to study the relationship between glutamate and aging of the brain. The studies presented here indicate the existence of a number of changes in the glutamatergic system during the normal process of aging. First, an age-related decrease of glutamate content in tissue from cerebral cortex and hippocampus has been reported, although it may be mainly a consequence of changes in metabolic activity rather than glutamatergic neurotransmission. On the other hand, studies in vitro and in vivo have shown no changes in glutamate release during aging. Since glutamate sampled in most of these studies is the result of a balance between release and uptake processes, the lack of changes in glutamate release may be due to compensatory changes in glutamate uptake. In fact, a reduced glutamate uptake capacity, as well as a loss in the number of high affinity glutamate transporters in glutamatergic terminals of aged rats, have been described. However, the most significant and consistent finding is the decrease in the density of glutamatergic NMDA receptors with age. A new perspective, in which glutamate interacts with other neurotransmitters to conform the substrates of specific circuits of the brain and its relevance to aging, is included in this review. In particular, studies from our laboratory suggest the existence of age-related changes in the interaction between glutamate and other neurotransmitters, e.g. dopamine and GABA, which are regionally specific.
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Affiliation(s)
- G Segovia
- Department of Physiology, Faculty of Medicine, Complutense University of Madrid, Av. Complutense s/n, 28040, Madrid, Spain
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11
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Del Arco A, Mora F. Effects of endogenous glutamate on extracellular concentrations of GABA, dopamine, and dopamine metabolites in the prefrontal cortex of the freely moving rat: involvement of NMDA and AMPA/KA receptors. Neurochem Res 1999; 24:1027-35. [PMID: 10478942 DOI: 10.1023/a:1021056826829] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Using microdialysis, interactions between endogenous glutamate, dopamine, and GABA were investigated in the medial prefrontal cortex of the freely moving rat. Interactions between glutamate and other neurotransmitters in the prefrontal cortex had already been studied using pharmacological agonists or antagonists of glutamate receptors. This research investigated whether glutamate itself, through the increase of its endogenous extracellular concentration, is able to modulate the extracellular concentrations of GABA and dopamine in the prefrontal cortex. Intracortical infusions of the selective glutamate uptake inhibitor L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC) were used to increase the endogenous extracellular glutamate. PDC (0.5, 2, 8, 16 and 32 mM) produced a dose-related increase in dialysate glutamate in a range of 1-36 microM. At the dose of 16 mM, PDC increased dialysate glutamate from 1.25 to 28 microM. PDC also increased extracellular GABA and taurine, but not dopamine; and decreased extracellular concentrations of the dopamine metabolites DOPAC and HVA. NMDA and AMPA/KA receptor antagonists were used to investigate whether the increases of extracellular glutamate were responsible for the changes in the release of GABA, and dopamine metabolites. The NMDA antagonist had no effect on the increase of extracellular GABA, but blocked the decreases of extracellular DOPAC and HVA, produced by PDC. In contrast, the AMPA/KA antagonist blocked the increases of extracellular GABA without affecting the decreases of extracellular DOPAC and HVA produced by PDC. These results suggest that endogenous glutamate acts preferentially through NMDA receptors to decrease dopamine metabolism, and through AMPA/KA receptors to increase GABAergic activity in the medial prefrontal cortex of the awake rat.
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Affiliation(s)
- A Del Arco
- Department of Physiology, Faculty of Medicine, University Complutense, Madrid, Spain
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Del Arco A, Martínez R, Mora F. Amphetamine increases extracellular concentrations of glutamate in the prefrontal cortex of the awake rat: a microdialysis study. Neurochem Res 1998; 23:1153-8. [PMID: 9712184 DOI: 10.1023/a:1020769816332] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Using microdialysis, the effect was investigated of intracerebral infusions of different doses of amphetamine (1.25, 2.5, 5, 10, and 20 microg/microl) on the extracellular concentrations of glutamate in the medial prefrontal cortex of the rat. Amphetamine produced a dose-related increase in extracellular concentrations of glutamate. At the highest dose, amphetamine increased extracellular glutamate by 445% of baseline as well as extracellular concentrations of taurine, and reduced extracellular concentrations of glutamine. Amphetamine did not modify other amino acids such as arginine. Increases in extracellular concentrations of glutamate and taurine were independent of calcium in the perfusion medium. This is the first study showing that amphetamine produces a calcium-independent increase in extracellular concentrations of glutamate and taurine in the medial prefrontal cortex of the rat.
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Affiliation(s)
- A Del Arco
- Department of Physiology, Faculty of Medicine, Universidad Complutense, Ciudad Universitaria, Madrid, Spain
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Abstract
The callosal projections of the cerebral cortex play an important role in the functional integration of the two hemispheres, and the anatomy of these connections has been extensively studied in primary sensory and motor regions. In the present investigation, we examined the synaptic targets of callosal terminals in a limbic association area, the prefrontal cortex (PFC) in the rat. In addition, we examined the relationship of callosal afferents to GABA local circuit neurons within the PFC. Callosal terminals were labeled by either anterograde transport of Phaseolus vulgaris leucoagglutinin from superficial or deep layers or by anterograde degeneration following electrolytic lesion of the contralateral PFC. Callosal terminals in either the superficial or deep layers labeled by either method formed primarily asymmetric axo-spinous synapses (approximately 95%), while the remainder formed axo-dendritic synapses. Some of the dendrites postsynaptic to callosal terminals exhibited a morphology characteristic of local circuit neurons. This observation was confirmed in tissue immunolabeled for GABA, in which degenerating callosal terminals sometimes formed asymmetric synapses on GABA-labeled dendrites. In addition, GABA-labeled terminals and callosal afferents were sometimes observed to converge onto common postsynaptic dendritic shafts or spines within the PFC. These results indicate that callosal terminals in limbic association cortex, consistent with sensory and motor cortices, primarily target the spines of pyramidal neurons. In addition, the results suggest that callosal afferents to the PFC interact with GABA local circuit neurons at multiple levels. Specifically, a proportion of callosal terminals appear to provide excitatory drive to GABA cells, while GABA terminals may modulate the excitation from callosal inputs to the distal dendrites and spines of PFC pyramidal neurons.
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Affiliation(s)
- D B Carr
- Department of Neuroscience, University of Pittsburgh, Pennsylvania 15260, USA
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Francis PT, Bowen DM. Neuronal pathology in relation to molecular biology and treatment of Alzheimer's disease. MOLECULAR AND CELL BIOLOGY OF HUMAN DISEASES SERIES 1998; 4:25-54. [PMID: 9439743 DOI: 10.1007/978-94-011-0709-9_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- P T Francis
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London, UK
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Owen F, Simpson M. The neurochemistry of schizophrenia. MOLECULAR AND CELL BIOLOGY OF HUMAN DISEASES SERIES 1998; 4:133-59. [PMID: 9439747 DOI: 10.1007/978-94-011-0709-9_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- F Owen
- Department of Physiological Sciences, University of Manchester, UK
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Segovia G, Porras A, Mora F. Effects of 4-aminopyridine on extracellular concentrations of glutamate in striatum of the freely moving rat. Neurochem Res 1997; 22:1491-7. [PMID: 9357015 DOI: 10.1023/a:1021958613125] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
4-aminopyridine (4-AP) is a voltage-sensitive K(+)-channel blocker extensively used in in vitro experiments as a depolarizing agent for the release of glutamate (GLU). This research investigated whether 4-AP could be used in in vivo experiments using microdialysis. For that, the effects of 4-AP on the extracellular concentrations of glutamate (GLU), glutamine (GLN), taurine (TAU) and citrulline (CIT) in striatum of the freely moving rat were investigated. The effects of 4-AP were compared with those produced by perfusion with a high K+ (100 mM) medium. Intrastriatal perfusion with 4-AP (1, 5 and 10 mM) produced no effects on extracellular [GLU], [TAU] and [CIT], but decreased extracellular [GLN]. Perfusion with a high K+ (100 mM) medium increased extracellular [GLU] and [TAU], decreased extracellular [GLN], and had no effects on [CIT]. To test whether the lack of effects of 4-AP on extracellular [GLU] was due to GLU uptake mechanisms, 4-AP was perfused after a previous inhibition of GLU uptake with L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC). Under the effects of PDC (1 mM), 4-AP (1 mM) had no effects on extracellular [GLU], [TAU] and [CIT], but decreased extracellular [GLN]. These results show that 4-AP decreased extracellular [GLN] but failed to produce a significant release of GLU in striatum of the freely moving rat. Thus, 4-AP can not be used as a depolarizing agent for stimulating the release of GLU in in vivo studies using microdialysis.
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Affiliation(s)
- G Segovia
- Department of Physiology, Faculty of Medicine, University Complutense, Madrid, Spain
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17
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Minoshima S, Giordani B, Berent S, Frey KA, Foster NL, Kuhl DE. Metabolic reduction in the posterior cingulate cortex in very early Alzheimer's disease. Ann Neurol 1997; 42:85-94. [PMID: 9225689 DOI: 10.1002/ana.410420114] [Citation(s) in RCA: 1150] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This study investigated cerebral glucose metabolism in very early Alzheimer's disease, before a clinical diagnosis of probable Alzheimer's disease is possible, using [18F]fluorodeoxyglucose positron emission tomography. First, 66 patients with probable Alzheimer's disease with a spectrum of dementia severity (Mini-Mental State Examination score, 0-23) were recruited and studied. Cortical metabolic activity was analyzed topographically using three-dimensional stereotactic surface projections. Regression analysis was performed for each brain pixel to predict metabolic patterns of very early disease. Predictions were tested prospectively in a group of 8 patients who complained only of memory impairment without general cognitive decline (Mini-Mental State Examination score, 25 +/- 1) at the time of scanning but whose condition later progressed to probable Alzheimer's disease. Both results were compared to cerebral metabolic activity in 22 age-similar normal control subjects. Prediction and analysis of actual patients consistently indicated marked metabolic reduction (21-22%) in the posterior cingulate cortex and cinguloparietal transitional area in patients with very early Alzheimer's disease. Mean metabolic reduction in the posterior cingulate cortex was significantly greater than that in the lateral neocortices or parahippocampal cortex. The result suggests a functional importance for the posterior cingulate cortex in impairment of learning and memory, which is a feature of very early Alzheimer's disease.
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Affiliation(s)
- S Minoshima
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109-0028, USA
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18
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Sanz B, Exposito I, Mora F. M1 acetylcholine receptor stimulation increases the extracellular concentrations of glutamate and GABA in the medial prefrontal cortex of the rat. Neurochem Res 1997; 22:281-6. [PMID: 9051662 DOI: 10.1023/a:1022486721267] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The present study was undertaken to examine the effects of different muscarinic receptor agonists on glutamate and GABA concentrations in the medial prefrontal cortex of the rat. In vivo perfusions were made in the conscious rat using a concentric push-pull cannulae system. Amino acid concentrations in samples were determined by HPLC with fluorometric detection. The intracortical perfusion of arecoline, a M1-M2 muscarinic receptor agonist, produced a significant increase in extracellular [GLU] and [GABA]. McN-A-343, a M1 muscarinic receptor agonist, but not the M2 muscarinic receptor agonist, oxotremorine, produced a significant increase in extracellular [GLU] and [GABA]. The effects of McN-A-343 on extracellular [GLU] and [GABA] were blocked by pirenzepine, a M1 muscarinic receptor antagonist. These results suggest that M1 muscarinic receptor stimulation increases the extracellular concentrations of GLU and GABA in the medial prefrontal cortex of the rat.
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Affiliation(s)
- B Sanz
- Department of Physiology, Faculty of Medicine, Complutense University, Madrid, Spain
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Chessell IP, Humphrey PP. Nicotinic and muscarinic receptor-evoked depolarizations recorded from a novel cortical brain slice preparation. Neuropharmacology 1995; 34:1289-96. [PMID: 8570026 DOI: 10.1016/0028-3908(95)00096-o] [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: 01/31/2023]
Abstract
We have developed a novel cortical brain slice preparation for extracellular field-potential recording using the grease-gap barrier technique. This preparation allows the study of cholinergic and glutamatergic depolarization responses of neocortical pyramidal neurones whose axons pass through the corpus callosum to contralateral cortical areas. Concentration-effect curves to carbachol, 1,1-dimethyl-4-phenyl piperazinium (DMPP) and muscarine yielded mean EC50 values of 29.5, 13.2 and 17.7 microM, respectively. Carbachol-induced responses were antagonized by both atropine and mecamylamine in a manner consistent with agonist effects of carbachol at both nicotinic and muscarinic sites, while concentration-effect curves to DMPP and muscarine were shifted rightward in a parallel manner by mecamylamine (10 microM) and atropine (5 nM), with antagonist pKB estimates of 6.4 and 9.0, respectively. Depolarization responses to glutamate were reversibly antagonized by D-2-amino-5-phosphonopentanoic acid and 6-cyano-7-nitroquinoxaline-2,3-dione; these antagonists had no effect on carbachol or DMPP-induced responses. This preparation allows reproducible quantification of depolarization responses of pyramidal neurones forming the corticocortical pathway, and indicates the presence of functional nicotinic and muscarinic receptors. We conclude that the preparation is a convenient model with which to test the efficacy of cholinomimetic agents in an intact neocortical system, and may be useful in the development of novel drugs for the treatment of the cognitive symptoms of Alzheimer's disease.
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Affiliation(s)
- I P Chessell
- Glaxo Institute of Applied Pharmacology, Department of Pharmacology, University of Cambridge, England
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20
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Conti F, Manzoni T. The neurotransmitters and postsynaptic actions of callosally projecting neurons. Behav Brain Res 1994; 64:37-53. [PMID: 7840891 DOI: 10.1016/0166-4328(94)90117-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- F Conti
- Istituto di Fisiologia Umana, Università di Ancona, Italy
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21
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Abstract
The inhibitory effects of 5-hydroxytryptamine (5-HT) on interhemispheric and intracortical synaptic potentials in layer V neurons of the rat medial prefrontal (MFC) cortex were examined. Low concentrations (1-3 microM) of 5-HT selectively attenuated polysynaptic potentials that were similarly evoked by callosal or white matter stimulation. Maximally effective concentrations of 5-HT blocked interhemispheric transmission by 50-90%, as evidenced by an attention of the short latency callosal depolarizing synaptic potential (e-DPSP). These effects of 5-HT were not associated with a change in membrane potential or input resistance. The e-DPSP was characterized as having an N-methyl-D-aspartate (NMDA) and a non-NMDA component; the non-NMDA component was attenuated by 5-HT. Attenuation of the synaptic potential was accompanied by an attenuation of a postsynaptic glutamate potential. Suppression of both the e-DPSP and the glutamate potential was concentration dependent with 10-100 microM being maximally effective. The 5-HT1A/2 antagonist, spiperone, antagonized the effects of 5-HT on synaptic and glutamate potentials. Spiperone (1 microM) shifted the concentration-effect curves for suppression of the e-DPSP and the glutamate potential to the right; however, the Kb for the glutamate potential concentration-effect curve was 10 times that for the e-DPSP curve. The differential antagonist sensitivity of synaptic and glutamate potentials was an indication that serotonin acted on more than one receptor subtype to reduce interhemispheric transmission.
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Affiliation(s)
- H L Read
- Department of Pharmacology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153
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22
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Sánchez-Prieto J, Herrero I, Miras-Portugal MT, Mora F. Unchanged exocytotic release of glutamic acid in cortex and neostriatum of the rat during aging. Brain Res Bull 1994; 33:357-9. [PMID: 7904891 DOI: 10.1016/0361-9230(94)90206-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The Ca(2+)-dependent release of glutamate induced by 4-aminopyridine in synaptosomes prepared both from the cerebral cortex and basal ganglia was unchanged in aged rats (27-30 months) when compared to adults rats (3 months). Consistent with the absence of changes in glutamate exocytosis during aging, the rise in the cytosolic free Ca2+ concentration, [Ca2+]c, induced by depolarization in synaptosomes from aged rats was similar to that found in control adult rats. The results suggest that during aging the nerve terminals from the cerebral cortex and basal ganglia maintain an intact ability to release glutamate by exocytosis.
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Affiliation(s)
- J Sánchez-Prieto
- Departamento de Bioquímica, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain
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23
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Francis PT, Sims NR, Procter AW, Bowen DM. Cortical pyramidal neurone loss may cause glutamatergic hypoactivity and cognitive impairment in Alzheimer's disease: investigative and therapeutic perspectives. J Neurochem 1993; 60:1589-604. [PMID: 8473885 DOI: 10.1111/j.1471-4159.1993.tb13381.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- P T Francis
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London, England
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24
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Francis PT, Pangalos MN, Bowen DM. Animal and drug modelling for Alzheimer synaptic pathology. Prog Neurobiol 1992; 39:517-45. [PMID: 1529103 DOI: 10.1016/0301-0082(92)90005-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- P T Francis
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London, U.K
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25
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Pangalos MN, Francis PT, Foster AC, Pearson RC, Middlemiss DN, Bowen DM. NMDA receptors assessed by autoradiography with [3H]L-689,560 are present but not enriched on corticofugal-projecting pyramidal neurones. Brain Res 1992; 596:223-30. [PMID: 1361417 DOI: 10.1016/0006-8993(92)91551-o] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Experimental lesions followed by binding of [3H]4-trans-2-carboxy-5,7-dichloro-4-phenylamino-carbonylamino-1,2 ,3,4- tetrahydroquinoline ([3H]L-689,560, a novel ligand that binds to the glycine modulatory site), [3H]glycine and [3H]glutamate (N-methyl-D-aspartate (NMDA) sensitive) to cryostat sections and quantitative autoradiography were used to investigate the cellular localization of the NMDA receptor complex in the neocortex of the rat. The lesions were produced by intrastriatal injections of either volkensin (2 and 6 ng) or ricin (10 ng): both are suicide transport agents but only the former is retrogradely transported in the CNS. The binding of [3H]L-689,560 was significantly reduced in rats receiving 2 or 6 ng volkensin in deep cortical layers of Fr1/Fr2 ipsilateral to the striatal lesion. Similar reductions were also seen in [3H]glycine and [3H]glutamate binding, but only in rats receiving 6 ng volkensin. Quantitative histological analysis had previously revealed a loss of large infragranular pyramidal neurones with sparing of both interneurones and supragranular pyramidal neurones. There were no significant reductions in binding of any ligand in the superficial layers. In cortical areas Par1/Par2, [3H]L-689,560 was also significantly reduced in deep layers but only in rats receiving 6 ng volkensin. Binding was also reduced in the superficial layers by contrast to Fr1/Fr2. [3H]Glycine and [3H]glutamate binding were unaffected in this area. Binding of [3H]L-689,560 was unaffected in any area following intrastriatal ricin injection. The present study indicates that the NMDA receptor complex is present on pyramidal cells forming the corticofugal pathways. This is discussed in terms of the 5-HT1A receptor which is enriched on these cells.
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Affiliation(s)
- M N Pangalos
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London, UK
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26
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Storey E, Kowall NW, Finn SF, Mazurek MF, Beal MF. The cortical lesion of Huntington's disease: further neurochemical characterization, and reproduction of some of the histological and neurochemical features by N-methyl-D-aspartate lesions of rat cortex. Ann Neurol 1992; 32:526-34. [PMID: 1280937 DOI: 10.1002/ana.410320408] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Huntington's disease is a progressive neurodegenerative disease in which the basal ganglia are preferentially affected. Recent evidence, however, suggests involvement of the cerebral cortex as well, with sparing of neurochemically defined subsets of gamma-aminobutyric acid (GABA)-ergic interneurons. In the present study, we examined changes in concentrations of the amino acid neurotransmitters GABA, glutamate, and aspartate in nine cortical regions from 23 patients with advanced Huntington's disease and 12 control brains. GABA concentrations were significantly increased in eight of the nine regions, consistent with a sparing of GABAergic local circuit neurons in the context of progressive cortical atrophy. Small but significant increases in glutamate were found in six of the nine regions, while aspartate levels were generally unaffected. Striate cortex (Brodmann's area 17) showed the most profound increases in GABA and glutamate. We also investigated the effects of powdering the excitotoxins N-methyl-D-aspartate (NMDA) or kainic acid onto the dura of rats. The resulting lesions were examined at 1 week and 6 months. The NMDA-induced lesions showed striking sparing of parvalbumin-positive neurons (a subset of GABAergic interneurons), and this sparing was reflected in neurochemical measurements of GABA; kainic acid lesions failed to display this selectivity. Somatostatin, cholecystokinin, and vasoactive intestinal polypeptide concentrations were spared by the NMDA-induced lesions, and substance P levels were significantly increased. These results provide evidence that NMDA excitotoxic lesions of cerebral cortex can produce a selective pattern of neuronal damage similar to that which occurs in Huntington's disease.
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Affiliation(s)
- E Storey
- Neurochemistry Laboratory, Massachusetts General Hospital, Boston 02114
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27
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Slater P, McConnell S, D'Souza SW, Barson AJ, Simpson MD, Gilchrist AC. Age-related changes in binding to excitatory amino acid uptake site in temporal cortex of human brain. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1992; 65:157-60. [PMID: 1315225 DOI: 10.1016/0165-3806(92)90174-u] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The binding of D-[3H]aspartate to the specific uptake site for the excitatory amino acids glutamate and aspartate was measured in homogenates of temporal lobe cortex taken at postmortem from 76 human infant and adult brains. Binding levels were very low in brains of preterm and term infants but increased rapidly during the first 20 postnatal weeks to reach levels which exceeded those in adult brains. Linear regression analysis which compared the amount of D-[3H]aspartate binding with the age of the infant, showed a positive correlation up to 25 postnatal weeks. Saturation analysis showed that the maximum number of D-[3H]aspartate binding sites (Bmax) in temporal cortex from infants aged 20 postnatal weeks was 3 times greater than the number of sites in adult brain. The findings show that the number of excitatory amino acid uptake sites, which may be associated in part with presynaptic terminals, increase in number rapidly after birth. Furthermore, the data may indicate that a slow regression of excitatory amino acid terminals occurs during the later stages of brain development.
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Affiliation(s)
- P Slater
- Department of Physiological Sciences, Manchester University Medical School, U.K
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28
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Chessell IP, Procter AW, Francis PT, Bowen DM. D-cycloserine, a putative cognitive enhancer, facilitates activation of the N-methyl-D-aspartate receptor-ionophore complex in Alzheimer brain. Brain Res 1991; 565:345-8. [PMID: 1842701 DOI: 10.1016/0006-8993(91)91668-q] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The action of D-Cycloserine (DCS) at the strychnine-insensitive glycine recognition site of the NMDA receptor-ionophore complex has been studied with membranes from inferior parietal cortex of patients with Alzheimer's disease. The maximal response of the site, measured using [3H]MK-801 binding, was 64% of that observed with glycine. Stimulation of binding induced by DCS in the presence of fixed concentrations of glycine resulted in a family of dose-response curves, consistent with the antibiotic having the property of a partial agonist at this glycine site. It is proposed that because of circumscribed glutamatergic pyramidal cell pathology DCS will have benefit for Alzheimer's patients over and above all other types of cognitive impairment.
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Affiliation(s)
- I P Chessell
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London, U.K
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29
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Clow DW, Lee SJ, Hammer RP. Competitive (AP7) and non-competitive (MK-801) NMDA receptor antagonists differentially alter glucose utilization in rat cortex. Synapse 1991; 7:260-8. [PMID: 1828310 DOI: 10.1002/syn.890070403] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The effects of D,L-2-amino-7-phosphonoheptanoic acid (AP7), a competitive N-methyl-D-aspartate (NMDA) receptor antagonist, and MK-801, a non-competitive NMDA receptor antagonist, on regional brain metabolism were studied in unanesthetized, freely moving rats by using the quantitative [14C]2-deoxyglucose autoradiographic procedure. AP7 (338 or 901 mg/kg) produced a dose-dependent decrease of metabolic activity throughout most of the regions studied including sensory, motor, and limbic cortices. In contrast, MK-801 (0.1 or 1.0 mg/kg) resulted in a dose-dependent decrease of metabolic activity in sensory cortices, and an increase in limbic regions such as the hippocampal stratum lacunosum moleculare and entorhinal cortex. MK-801 also produced a biphasic response in agranular motor cortex, whereby the low dose increased while the high dose decreased labeling. In addition, MK-801 produced heterogeneous effects on regional cerebral metabolism in sensory cortices. Metabolic activity decreased in layer IV relative to layer Va following MK-801 treatment in primary somatosensory (SI) and visual (VI) cortices, suggesting a shift in activity from afferent fibers innervating layer IV to those innervating layer Va. MK-801 administration also decreased metabolic activity in granular SI relative to dysgranular SI, and in VI relative to secondary visual cortex (VII), thus providing a relative sparing of activity in dysgranular SI and VII. Thus, the non-competitive NMDA receptor antagonist suppressed activity from extrinsic neocortical sources, enhancing relative intracortical activity and stimulating limbic regions, while the competitive NMDA antagonist depressed metabolic activity in all cortical regions.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D W Clow
- Department of Anatomy and Reproductive Biology, School of Medicine, University of Hawaii, Honolulu 96822
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30
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Mora F, Cobo M. The neurobiological basis of prefrontal cortex self-stimulation: a review and an integrative hypothesis. PROGRESS IN BRAIN RESEARCH 1991; 85:419-31. [PMID: 2094908 DOI: 10.1016/s0079-6123(08)62693-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- F Mora
- Department of Physiology, Faculty of Medicine, University Complutense of Madrid, Spain
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31
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Bowen DM. Treatment of Alzheimer's disease. Molecular pathology versus neurotransmitter-based therapy. Br J Psychiatry 1990; 157:327-30. [PMID: 1978786 DOI: 10.1192/bjp.157.3.327] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cortical inhibitory neurotransmitters, neuropeptides, dopamine and noradrenaline are probably either not selectively or not critically affected in AD. It is, however, likely that a key change is shrinkage or loss of corticocortical pyramidal neurones, which probably use glutamate as their transmitter. This depletion appears to be circumscribed and clinically relevant.
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Affiliation(s)
- D M Bowen
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London
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32
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Uemura Y, Kowall NW, Beal MF. Selective sparing of NADPH-diaphorase-somatostatin-neuropeptide Y neurons in ischemic gerbil striatum. Ann Neurol 1990; 27:620-5. [PMID: 1972876 DOI: 10.1002/ana.410270606] [Citation(s) in RCA: 179] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the present study we investigated the relative vulnerability of neuronal subsets in the striatum to ischemia that was induced by bilateral transient ligation of the common carotid arteries in gerbils. After 4 days of survival, brains were evaluated using histochemical methods (NADPH-diaphorase and silver degeneration procedures) and neurochemical methods with radioimmunoassays for somatostatin-, neuropeptide Y-, and substance P-like immunoreactivity and measurements of amino acids using high-pressure liquid chromatography with electrochemical detection. NADPH-diaphorase-positive neurons were strikingly preserved in the ischemic dorsolateral portion of the striatum, in which there was severe neuronal loss. There was no significant depletion of NADPH-diaphorase-positive neurons in the striatum or cerebral cortex. Concentrations of neuropeptide Y-like and somatostatin-like immunoreactivity were unchanged despite a significant 25% depletion of substance P-like immunoreactivity and gamma-aminobutyric acid. Ischemic brain damage may be mediated by a neurotoxic effect of glutamate acting at the N-methyl-D-aspartate (NMDA) receptor. Previous studies of NMDA excitotoxin lesions in rat striatum have shown a sparing of neurons containing NADPH-diaphorase, somatostatin, and neuropeptide Y. The similar sparing of these neurons following ischemic lesions in gerbil striatum provides further evidence that NMDA receptor activation may play a role in ischemic injury.
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Affiliation(s)
- Y Uemura
- Department of Neurosurgery, Massachusetts General Hospital, Boston 02114
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33
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Excitatory dicarboxylic amino acid and pyramidal neurone neurotransmission of the cerebral cortex in Alzheimer’s disease. ACTA ACUST UNITED AC 1990. [DOI: 10.1007/978-3-7091-3396-5_28] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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34
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Kurumaji A, Nehls DG, Park CK, McCulloch J. Effects of NMDA antagonists, MK-801 and CPP, upon local cerebral glucose use. Brain Res 1989; 496:268-84. [PMID: 2553203 DOI: 10.1016/0006-8993(89)91074-3] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effects upon cerebral glucose utilisation of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801, a non-competitive N-methyl-D-aspartate (NMDA, receptor antagonist) and 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP, a competitive NMDA receptor antagonist) were examined in conscious, lightly restrained rats. Cerebral glucose utilisation was assessed quantitatively in 74 brain regions with [14C]2-deoxyglucose autoradiography. The intravenous (i.v.) administration of MK-801 (0.05-5 mg/kg) induced heterogeneous patterns of altered cerebral glucose utilisation with statistically significant increases being observed in 21 brain areas and statistically significant decrease in 8 brain regions. Pronounced dose-related increases in glucose use were observed after MK-801 in the subicular complex, hippocampus molecular layer, dentate gyrus, limbic system (posterior cingulate cortex; mamillary body; anteroventral thalamic nucleus), olfactory areas and substantia nigra (pars reticulata). Glucose use in the neocortex and inferior colliculus was particularly sensitive to reduction by MK-801 administration. The pattern of altered glucose use after administration of CPP (3-30 mg/kg, i.v.) differed markedly from that observed after MK-801 treatment. Statistically significant increases in glucose use after CPP were noted in 11 brain areas and statistically significant decreases in 5 of the regions examined. Regions in which increases were noted after CPP included hippocampus molecular layer, olfactory areas, cochlear nucleus, vestibular nucleus, cerebellar nucleus, superior olives and substantia nigra (pars reticulata). These data indicate that widespread, anatomically organised alterations in cerebral function are associated with the administration of NMDA receptor antagonists despite the minor role normally ascribed to these receptors in conventional fast synaptic transmission. The distinct patterns of response to competitive and non-competitive antagonists may be a reflection of the differential responses of the two modes of receptor blockade to increased glutaminergic transmission.
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Affiliation(s)
- A Kurumaji
- Wellcome Surgical Institute, University of Glasgow, U.K
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35
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Francis PT, Poynton A, Lowe SL, Najlerahim A, Bridges PK, Bartlett JR, Procter AW, Bruton CJ, Bowen DM. Brain amino acid concentrations and Ca2+-dependent release in intractable depression assessed antemortem. Brain Res 1989; 494:315-24. [PMID: 2570624 DOI: 10.1016/0006-8993(89)90600-8] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The concentrations of 3 putative neurotransmitters (glutamate, aspartate and gamma-aminobutyrate), 4 related amino acids and 5 non-transmitter-related amino acids have been measured in neurosurgical samples (frontal cortex) from patients with intractable depression and controls. In addition, the glutamate receptor agonist 2-amino-4-sulpho-butanoic acid (homocysteic acid) has been identified in human brain and measured in these samples. There were no changes in the concentrations of amino acids in depressed patients compared to control with the exception of aspartic and homocysteic acids which were elevated in a sub-group of patients with depression compared to control. The Ca2+-dependent release (K+-stimulated) of putative neurotransmitters has been demonstrated for the first time from brain tissue of depressed patients. Glutamate release was unaltered from the control value. Aspartate values showed unexplained variability but it's release and that of gamma-aminobutyrate were elevated in some depressed subjects. These results do not support the hypothesis of reduced amino acid function in depressive illness.
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Affiliation(s)
- P T Francis
- Miriam Marks Department of Neurochemistry, Institute of Neurology, London, U.K
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36
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Romijn HJ, de Jong BM. Unlike hypoxia, hypoglycemia does not preferentially destroy GABAergic neurons in developing rat neocortex explants in culture. Brain Res 1989; 480:58-64. [PMID: 2713668 DOI: 10.1016/0006-8993(89)91566-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We tested whether hypoglycemia, like hypoxia, would preferentially destroy GABAergic nerve cells in the neocortex. To this end, rat neocortex explants dissected from 6-day-old rat pups and cultured up to a developmental stage approximately comparable to that of the newborn human neocortex, were exposed to hypoglycemia for different periods. Quantitative light microscopic and immunocytochemical evaluation of the cultures demonstrated that hypoglycemia does not preferentially destroy GABAergic but rather non-GABAergic neurons, a finding quite opposite to what was found after hypoxia. Recent biochemical data from other laboratories which seem to support this difference in neuronal vulnerability are discussed. It is concluded that perinatal hypoglycemia may not form such a serious threat with respect to the genesis of epilepsy as does hypoxia.
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Affiliation(s)
- H J Romijn
- Netherlands Institute for Brain Research, Amsterdam
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37
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Finkbeiner S, Stevens CF. Applications of quantitative measurements for assessing glutamate neurotoxicity. Proc Natl Acad Sci U S A 1988; 85:4071-4. [PMID: 2453886 PMCID: PMC280363 DOI: 10.1073/pnas.85.11.4071] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The role of the N-methyl-D-aspartate receptor channel in glutamate neurotoxicity was investigated in cultured hippocampal neurons of the CA1 region. An equation, the survival function, was developed to quantify the effects of putative modulators of neurotoxicity. 2-Amino-5-phosphonovaleric acid (30 microM) reduced the neuronal sensitivity to glutamate by a factor greater than 20, whereas glycine (1 microM) enhanced it by a factor of 7.5 +/- 2.5. Neurons were protected by increasing Mg2+ concentrations in a predictable way based on the ion's ability to block the N-methyl-D-aspartate channel. These findings provide a quantitative basis for the assessment of various neuroprotective agents and add further support to the hypothesis that the N-methyl-D-aspartate channel is central to glutamate neurotoxicity.
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Affiliation(s)
- S Finkbeiner
- Section of Molecular Neurobiology, Yale University School of Medicine, New Haven, CT 06510
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38
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Peinado JM, Myers RD. In vivo analysis of cortical amino acid neurotransmitters collected in the rat by a new double lumen push-pull catheter system. Neuroscience 1988; 24:1027-34. [PMID: 2898108 DOI: 10.1016/0306-4522(88)90084-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The release of both endogenous and newly synthesized amino acid neurotransmitters was examined simultaneously in different areas of the cerebral cortex in the freely moving rat. An array of push-pull guide tubes was implanted permanently to rest above the frontal, parietal, temporal and occipital areas of the cortex of each rat. Then a new double-lumen catheter system, specially adapted for localized push-pull perfusion of the conscious animal, was used to perfuse an artificial cerebrospinal fluid at each cortical site. For the new synthesis experiments, 0.5 microCi of [14C]glucose in a volume of 2.0 microliter was first microinjected into the perfusion site as a precursor to label amino acids. After the site was perfused at a rate of 12.0 microliter/min, each of the samples was assayed by two-dimensional thin-layer chromatography. In a second analysis, the content of six endogenous amino acids present in unlabeled samples of push-pull perfusate was quantified by high-performance liquid chromatography analysis with electrochemical detection. The results showed a notable homogeneity among each of the four cortical areas in the content of four of the six amino acids examined. Endogenous glutamine exhibited the highest proportional content in the cortical perfusates, whereas glutamic acid was proportionally higher in terms of new synthesis. An anatomical analysis revealed that the level of endogenous glutamic acid in the frontal area was significantly lower than that found in the occipital or temporal regions of the rat's cortex. An opposite result was obtained when the proportional synthesis of glutamic acid from [14C] glucose was compared in different cortical regions in that a statistically higher release occurred in the frontal than in the occipital cortex.
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Affiliation(s)
- J M Peinado
- Department of Pharmacology, East Carolina University School of Medicine, Greenville, NC 27858
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39
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Peinado JM, Iribar MC, Myers RD. Hemidecortication selectively alters release of glutamate in perfusates collected from cerebral cortex of unrestrained rats. Neurochem Res 1987; 12:629-34. [PMID: 3614513 DOI: 10.1007/bf00971012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effect of hemidecortication on the in vivo release of amino acids was examined in different areas of the cerebral cortex of the freely-moving rat. After one side of the cortex was lesioned by aspiration, four guide tubes for push-pull perfusion were implanted chronically on the contralateral side so as to rest above the frontal, parietal, temporal and occipital areas of the cortex. After 10-14 days elapsed, each of these regions was perfused with an artificial cerebrospinal fluid (CSF) at a rate of 25.0 microliter/min. Two types of assays were undertaken to determine the release of either newly synthesized amino acids from [14C]glucose precursor or the actual endogenous content in samples of perfusate. The separation of the [14C]amino acids was performed by thin layer chromatography, whereas endogenous amino acids were separated by HPLC with electrochemical detection and quantitated in the range of 1.0-10.0 picomoles. When compared to the control group, samples collected in the hemidecorticate rat showed no significant differences in the new synthesis of glutamate, aspartate, glutamine, glycine, and GABA from the precursor. On the other hand, the analysis of the endogenous amino acid neurotransmitters revealed that the levels of glutamic acid and glutamine declined in samples obtained from the parietal and frontal cortex, respectively. These results implicate further the potential role of glutamic acid as a neurotransmitter of interhemispheric connections in the cerebral cortex.
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Mora F, Peinado JM, Myers RD. Amino acid profiles in cortex of conscious rat: recent studies and future perspectives. Ann N Y Acad Sci 1986; 473:461-74. [PMID: 2879495 DOI: 10.1111/j.1749-6632.1986.tb23636.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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