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Zhao W, Ng KT, Sedman GL. Passive avoidance learning induced change in GAP43 phosphorylation in day-old chicks. Brain Res Bull 1995; 36:11-7. [PMID: 7882044 DOI: 10.1016/0361-9230(94)00122-h] [Citation(s) in RCA: 13] [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
Day-old chicks trained on a single trial passive discriminated avoidance task demonstrated a significant increase in in vitro phosphorylation of a 50 kDa protein in P2M fractions of total forebrain. The increase occurred 30 min posttraining, at a time when previous reports suggest that mechanisms for triggering protein synthesis-dependent long-term memory consolidation are activated. These changes in phosphorylation rates were accompanied by a substantial enhancement of total kinase activity. Immunoblotting studies with monoclonal anti-GAP43 antibody indicate that this protein is GAP43. These results contradict previous reports of a decrease in in vitro GAP43 phosphorylation following the same learning paradigm. A number of procedural differences may account for this discrepancy. The results suggest that changes in the phosphorylation state may be associated with mechanisms triggering long-term memory consolidation.
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Affiliation(s)
- W Zhao
- Department of Psychology, La Trobe University, Bundoora, Victoria, Australia
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2
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Lester DS, Bramham CR. Persistent, membrane-associated protein kinase C: from model membranes to synaptic long-term potentiation. Cell Signal 1993; 5:695-708. [PMID: 8130074 DOI: 10.1016/0898-6568(93)90031-g] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- D S Lester
- Neural Systems Section, NINDS, NIH, Bethesda, MD 20892
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3
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Robinson PJ, Noronha J, DeGeorge JJ, Freed LM, Nariai T, Rapoport SI. A quantitative method for measuring regional in vivo fatty-acid incorporation into and turnover within brain phospholipids: review and critical analysis. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1992; 17:187-214. [PMID: 1467810 DOI: 10.1016/0165-0173(92)90016-f] [Citation(s) in RCA: 213] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An experimental method and its associated mathematical model are described to quantitate in vivo incorporation rates into and turnovers of fatty acids (FAs) within stable brain metabolic compartments, particularly phospholipids. A radiolabeled FA is injected i.v. in a rat, and arterial plasma unacylated FA radioactivities and unlabeled concentrations are sampled until the animal is killed after 15 min, when the brain is analyzed biochemically or with quantitative autoradiography. Unbound unacylated label in blood easily crosses the blood-brain barrier; rapidly equilibrates in the unacylated FA, acyl-CoA and phosphatidate-diacylglycerol brain pools; then is incorporated into phospholipids and other stable metabolic compartments. Uptake and incorporation of labeled FAs are independent of cerebral blood flow at constant brain blood volume. Different labeled FAs enter specific sn positions of different brain phospholipids, suggesting that a combination of probes can be used to investigate metabolism of these phospholipids. Thus, [9,10-3-H]palmitate preferentially labels the sn1 position of phosphatidylcholine; [1-14C]arachidonate the sn2 positions of phosphatidylinositol and phosphatidylcholine; and [1-14C]docosahexaenoate the sn2 positions of phosphatidylethanolamine and phosphatidylcholine. The FA model provides an operational equation for rates of incorporation of FAs into brain phospholipids, taking into account intracerebral recycling and de novo synthesis of the FA, as well as entry into brain of FA from acylated blood sources. The equation is essentially independent of specific details of the proposed model, and can be used to calculate turnovers and half-lives of FAs within different phospholipid classes. For the model to be most applicable, experiments should satisfy conditions for pulse-labeling of the phospholipids, with brain sampling times short enough to minimize exchange of label between stable metabolic compartments. A 15-20 min sampling time satisfies these criteria. The FA method has been used to elucidate the dynamics of brain phospholipids metabolism in relation to brain development, brain tumor, chronically reduced auditory input, transient ischemic insult, axotomy with and without nerve regeneration, and cholinergic stimulation in animals with or without a chronic unilateral lesion of the nucleus basalis magnocellularis.
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Affiliation(s)
- P J Robinson
- Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892
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4
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Kumagai C, Tohda M, Isobe M, Nomura Y. Involvement of growth-associated protein-43 with irreversible neurite outgrowth by dibutyryl cyclic AMP and phorbol ester in NG108-15 cells. J Neurochem 1992; 59:41-7. [PMID: 1319472 DOI: 10.1111/j.1471-4159.1992.tb08873.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Simultaneous treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) and dibutyryl cyclic AMP (diBu-cAMP) for 72 h induced neurites in NG108-15 cells significantly longer than treatment with each alone. Treatment for 72 h with both drugs induced irreversible neurite extension and a decline in protein kinase C activity, although neurites extended by diBu-cAMP alone disappeared after the withdrawal of the drug. The expression of growth-associated protein-43 (GAP-43) mRNA was also observed by a combined application of TPA and diBu-cAMP. The increased level of GAP-43 mRNA induced by treatment with both drugs for 72 h was maintained at least 24 h after withdrawal of the drugs. In cells transfected with GAP-43 cDNA, neurites induced by treatment with diBu-cAMP alone for 72 h were maintained at least 48 h after removal of the drugs. These results suggest that GAP-43 could be involved in the maintenance of elongated neurites and that a decline in protein kinase C activity may be involved in the accumulation of GAP-43.
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Affiliation(s)
- C Kumagai
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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5
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Kelso SR, Nelson TE, Leonard JP. Protein kinase C-mediated enhancement of NMDA currents by metabotropic glutamate receptors in Xenopus oocytes. J Physiol 1992; 449:705-18. [PMID: 1381753 PMCID: PMC1176103 DOI: 10.1113/jphysiol.1992.sp019110] [Citation(s) in RCA: 187] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
1. N-Methyl-D-aspartate (NMDA) receptors were expressed in Xenopus oocytes injected with rat brain RNA. The modulation of NMDA-induced currents was examined by activating protein kinase C (PKC) either directly (using phorbol esters) or indirectly (via metabotropic glutamate agonists). 2. Bath application of the PKC activator, 4-beta-phorbol-12,13-dibutyrate (PDBu) resulted in a two-fold increase in the NMDA-evoked current at all holding potentials examined (-80 to 0 mV). The inactive (alpha) stereoisomer of phorbol ester was ineffective. 3. The increase was observed under conditions that eliminate the oocyte's endogenous calcium-dependent chloride current, which often contributes to the NMDA response in oocytes. 4. The PDBu effect was specific to the NMDA subclass of glutamate receptors in that no increase was observed in the responses to two other glutamate agonists, kainate and AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid). 5. Stimulation of PKC by activation of metabotropic receptors via either quisqualate or trans-ACPD (trans-1-aminocyclopentane-1,3-dicarboxylic acid) also led to an increase in NMDA currents. 6. Both methods of enhancement induced transient effects. PDBu effects lasted 10-45 min, depending upon both dose and length of application. Quisqualate and trans-ACPD effects were shorter, lasting less than 10 min under these conditions of application. 7. Both methods of enhancement were blocked by the PKC inhibitor, staurosporine. In addition, the phorbol ester-induced enhancement of NMDA responses occluded further enhancement by quisqualate. 8. The results suggest a role for metabotropic glutamate receptors in modulation of NMDA-mediated processes.
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Affiliation(s)
- S R Kelso
- Department of Biological Sciences and Committee on Neuroscience, University of Illinois, Chicago 60680
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6
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Abstract
The neuronal cell line PC12 undergoes a well-documented morphological and biochemical differentiation when treated with NGF and other growth factors. A hallmark of this growth factor-mediated differentiation is the induction of the growth-associated protein, GAP-43. Here we show that a PC12 cell line which is capable of NGF-, bFGF-, and cAMP-mediated neurite outgrowth is deficient in GAP-43 protein and full-length mRNA, as measured by immunocytochemistry, Western blot, Northern blot, and PCR analyses, respectively. We propose that the GAP-43 protein may not be essential for the initial extension and maintenance of neurites induced by these neuritogenic factors; rather, its role may lie predominantly in growth cone function and in the operation of the presynaptic terminal.
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Affiliation(s)
- E E Baetge
- Bristol-Myers Squibb Company, CNS Molecular Biology, Wallingford, Connecticut 06492
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7
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Kirschenbaum B, Pulsinelli WA. Posthoc phosphorylation of proteins derived from ischemic rat hippocampus, striatum and neocortex. Brain Res 1990; 511:21-9. [PMID: 2331616 DOI: 10.1016/0006-8993(90)90221-v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Disruption of the brain's protein phosphorylation system by ischemia may cause irreversible metabolic and structural alterations leading eventually to cell death. To examine the effect of ischemia on the phosphorylation state of brain proteins, tissue homogenates derived from the hippocampus, striatum and neocortex of normal rats and rats subjected to severe forebrain ischemia were phosphorylated with [gamma-32P]ATP. The phosphorylated proteins were separated by two-dimensional polyacrylamide gel electrophoresis and changes were assessed by autoradiography. Cerebral ischemia caused marked alterations of the phosphorylation state of many brain proteins; phosphorylation of some proteins was increased while phosphorylation of others was decreased. Despite differences in the sensitivity of the hippocampus, striatum and neocortex to ischemic injury the direction and approximate magnitude of protein phosphorylation changes caused by ischemia were similar in all three regions. Since the pattern of protein phosphorylation in the ischemia-vulnerable hippocampus was identical to that in the ischemia-resistant paramedian neocortex we conclude that abnormalities of protein phosphorylation may be necessary for ischemic injury to neurons but none are sufficient to explain the selective vulnerability of certain brain regions to ischemic damage.
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Affiliation(s)
- B Kirschenbaum
- Cerebrovascular Disease Research Center, Cornell University Medical College, New York, NY 10021
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8
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Heemskerk FM, Schrama LH, Gianotti C, Spierenburg H, Versteeg DH, De Graan PN, Gispen WH. 4-Aminopyridine stimulates B-50 (GAP43) phosphorylation and [3H]noradrenaline release in rat hippocampal slices. J Neurochem 1990; 54:863-9. [PMID: 2137530 DOI: 10.1111/j.1471-4159.1990.tb02331.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In situ phosphorylation of the presynaptic protein kinase C substrate B-50 was investigated in rat hippocampal slices incubated with the convulsant drug 4-aminopyridine (4-AP). Phosphorylation of B-50 was significantly enhanced 1 min after the addition of 4-AP (100 microM). This increase by 4-AP was concentration dependent (estimated EC50 30-50 microM). Concomitant with the changes in B-50 phosphorylation, 4-AP also dose-dependently stimulated [3H]noradrenaline [( 3H]NA) release from the slices. 4-AP stimulated [3H]NA release within 5 min to seven times the control level. The B-50 phosphorylation induced by 4-AP remained elevated after removal of the convulsant, this is contrast to B-50 phosphorylation induced by depolarization with K+. A similar persistent increase was observed for [3H]NA release after a 5-min incubation period with 4-AP. These results give more insight into the molecular mechanisms underlying 4-AP-induced epileptogenesis and provide further evidence for the correlation between B-50 phosphorylation and neurotransmitter release in the hippocampal slice.
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Affiliation(s)
- F M Heemskerk
- Division of Molecular Neurobiology, Rudolf Magnus Institute, University of Utrecht, The Netherlands
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9
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Dokas LA, Pisano MR, Schrama LH, Zwiers H, Gispen WH. Dephosphorylation of B-50 in synaptic plasma membranes. Brain Res Bull 1990; 24:321-9. [PMID: 2159832 DOI: 10.1016/0361-9230(90)90086-f] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Synaptic plasma membranes from rat brain cortex possess intrinsic ability to dephosphorylate the endogenous protein B-50. At low concentrations of [gamma-32P]ATP, B-50 phosphorylation in synaptic membranes is maximal at 30 seconds, followed by dephosphorylation for an additional 60 minutes. The dephosphorylation of 32P-labeled B-50 is not sensitive to the protease inhibitor leupeptin and not correlated with a loss of the B-50 content of synaptic membranes as measured with immunoblot analysis. Dephosphorylation of membrane-associated B-50 is stimulated to a small extent by Mg2+ but not by Ca2+. Heat-stable protein phosphatase inhibitors prevent dephosphorylation of 32P-labeled B-50. Dephosphorylation of B-50 in synaptic membranes is stimulated by ATP, ADP, or adenosine 5'-O-thiotriphosphate, but not by adenine, adenosine, other adenine or guanine nucleotides, nonhydrolyzable analogs of ATP or GTP, nor by adenosine 5'-O-(2-thiodiphosphate). B-50, phosphorylated by exogenous protein kinase C and purified to homogeneity, has been used as a substrate to follow the purification of B-50 phosphatase activity. B-50 phosphatase activity can be solubilized from synaptic membranes with 0.5% Triton X-100 and 75 mM KCl. Chromatography of the extract on DEAE-cellulose yields enhanced B-50 phosphatase activity.
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Affiliation(s)
- L A Dokas
- Department of Neurology, Medical College of Ohio, Toledo 43699
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10
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De Graan PN, Schrama LH, Heemskerk FM, Dekker LV, Gispen WH. The role of protein kinase C substrate B-50 (GAP-43) in neurotransmitter release and long-term potentiation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1990; 268:347-58. [PMID: 1981651 DOI: 10.1007/978-1-4684-5769-8_38] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- P N De Graan
- Division of Molecular Neurobiology, Rudolf Magnus Institute, Utrecht, NL
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11
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Mattson MP. Cellular signaling mechanisms common to the development and degeneration of neuroarchitecture. A review. Mech Ageing Dev 1989; 50:103-57. [PMID: 2557497 DOI: 10.1016/0047-6374(89)90010-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The present review examines the hypothesis that similar cellular signaling mechanisms are involved in neural development and in age- or disease-associated degeneration. It is hoped that approaching the problem of the regulation of brain structure from this perspective will spur future studies on the links between development, aging and disease. In order for functional neural circuitry to form, the component neurons must interact in highly specific ways. Growth factors and neurotransmitters constitute two major classes of intercellular signals that sculpt neuroarchitecture. These signals influence the neuronal growth cone behaviors which ultimately determine the details of neuritic form. In addition, growth factors and neurotransmitters can influence neuronal survival and synapse formation, and thereby determine both the presence of neurons within circuits and their specific connectivity patterns. Imbalances in growth factor and/or neurotransmitter systems may lead to neurodegeneration in aging and in specific neurodegenerative disorders such as Alzheimer's disease. Developmental, functional and pathological studies of excitatory amino acid neurotransmitters provide a compelling example of how a common intercellular signal can be involved in neuronal development, plasticity and degeneration. Intracellular signaling systems mediate neuroarchitectural responses to neurotransmitters and growth factors by altering the status of the cytoskeletal and vesicular substrates that are the basis of neuronal form. These signal transduction systems include ion channels and second messengers such as calcium, cyclic nucleotides and diacylglycerol. Cytoskeletal and vesicular substrates may be influenced directly by second messenger kinases, or indirectly via actions on the biosynthetic and degradative systems of the cell. Alterations in these various intracellular neuroarchitecture-regulating systems can lead to neurodegeneration. Taken together, the data presented here indicate that similar cellular and molecular mechanisms are involved in nervous system development, function, adaptive plasticity and degeneration.
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Affiliation(s)
- M P Mattson
- Sanders-Brown Center on Aging, University of Kentucky Medical Center, Lexington 40536-0230
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12
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Linden DJ, Routtenberg A. The role of protein kinase C in long-term potentiation: a testable model. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1989; 14:279-96. [PMID: 2679942 DOI: 10.1016/0165-0173(89)90004-0] [Citation(s) in RCA: 249] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
With the use of appropriate reagents, LTP may be divided into at least two stages, induction and maintenance. Induction of LTP is dependent upon the activation of the NMDA receptor, and the consequent influx of calcium into the postsynaptic cell. Both correlational evidence (measures of PKC activity, protein F1 phosphorylation, and PI turnover) and interventive evidence (application of PKC inhibitors and activators) indicate that PKC activation is necessary for maintenance of the LTP response. An important regulatory pathway for PKC activation is the liberation of c-FAs from membrane phospholipids by PLA2. In LTP, activation of this pathway may stabilize PKC in an activated state, and thus contribute to maintenance of the potentiated response. LTP maintenance could result from presynaptic alteration (increased neurotransmitter release), postsynaptic alteration (increases in receptor number or sensitivity, or alterations of postsynaptic morphology), synapse addition, or any of these processes in combination. If LTP maintenance is mediated by presynaptic alteration, as has been indicated by measurement of glutamate release, then one must posit a signal that travels from the postsynaptic to the presynaptic membrane to activate presynaptic PKC. Alternatively, if LTP maintenance is mediated by postsynaptic alteration, a signal contained within the dendritic spine would suffice to activate postsynaptic PKC-mediated maintenance processes. We suggest that the contributions of presynaptic and postsynaptic processes to LTP maintenance may be determined by the differential distribution of PKC subtypes and substrates among hippocampal synaptic zones.
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Affiliation(s)
- D J Linden
- Cresap Neuroscience Laboratory, Northwestern University, Evanston, IL 60208
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13
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Linden DJ, Wong KL, Sheu FS, Routtenberg A. NMDA receptor blockade prevents the increase in protein kinase C substrate (protein F1) phosphorylation produced by long-term potentiation. Brain Res 1988; 458:142-6. [PMID: 2905192 DOI: 10.1016/0006-8993(88)90506-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Recent evidence has implicated activation of the N-methyl-D-aspartate (NMDA) class of glutamate receptor in the initiation of hippocampal long-term potentiation (LTP), an electrophysiological model of information storage in the brain. A separate line of evidence has suggested that activation of protein kinase C (PKC) and the consequent phosphorylation of its substrates is necessary for the maintenance of the LTP response. To determine if PKC activation is a consequence of NMDA receptor activation during LTP, we applied the NMDA receptor antagonist drug, DL-aminophosphonovalerate (APV) both immediately prior to and following high frequency stimulation, resulting in successful and unsuccessful blockade of LTP initiation, respectively. We then measured the phosphorylation of a PKC substrate (protein F1) in hippocampal tissue dissected from these animals. Only successful blockade of LTP initiation by prior application of APV was seen to block the LTP-associated increase in protein F1 phosphorylation measured in vitro (P less than 0.001 by ANOVA). This suggests that NMDA receptor-mediated initiation triggers maintenance processes that are, at least in part, mediated by protein F1 phosphorylation. These data provide the first evidence linking two mechanisms associated with LTP, NMDA receptor activation and PKC substrate phosphorylation.
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Affiliation(s)
- D J Linden
- Cresap Neuroscience Laboratory, Northwestern University, Evanston, IL 60201
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14
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Lovinger DM, Routtenberg A. Synapse-specific protein kinase C activation enhances maintenance of long-term potentiation in rat hippocampus. J Physiol 1988; 400:321-33. [PMID: 3418528 PMCID: PMC1191809 DOI: 10.1113/jphysiol.1988.sp017122] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
1. Protein kinase C (PKC) stimulators, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or cis-unsaturated fatty acid (UFA), have been shown to prolong synaptic enhancement induced by long-term potentiation (LTP). This observation suggests a role for PKC in the biochemical mechanisms underlying maintained enhancement. 2. To determine if PKC stimulators prolong LTP by acting selectively at synapses given high-frequency stimulation or by actions that are not synapse-specific (e.g. increased postsynaptic excitability) we examined the effect of TPA or UFA on input-selective enhancement. Population EPSPs, evoked in the same granule cell population by either the medial (MPP) or lateral (LPP) perforant path, can be selectively enhanced leaving the other perforant path input which receives only low-frequency stimulation as an internal control for PKC stimulator effects not specific to enhanced synapses. 3. Synapse-specific effects were in fact observed, as UFA or TPA selectively prolonged MPP enhancement following two trains of high-frequency MPP stimulation, without affecting responses evoked by the LPP. A similar synapse selectivity of PKC stimulator action was seen following high-frequency LPP stimulation. 4. These findings suggest that PKC stimulators prolong enhancement by acting specifically at high-frequency-stimulated synapses. PKC stimulators do not appear to affect either postsynaptic neurone excitability or synapses given only low-frequency stimulation. This provides further evidence that PKC acts synergistically with the consequences of repetitive synaptic activation to maintain enhancement.
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Affiliation(s)
- D M Lovinger
- Cresap Neuroscience Laboratory, Northwestern University, Evanston, IL 60201
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15
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Bramham CR, Errington ML, Bliss TV. Naloxone blocks the induction of long-term potentiation in the lateral but not in the medial perforant pathway in the anesthetized rat. Brain Res 1988; 449:352-6. [PMID: 3395853 DOI: 10.1016/0006-8993(88)91052-9] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The possible importance of opioid peptides in the induction of long-term potentiation (LTP) was investigated in the perforant path-granule cell system. A high-frequency train (400 Hz) was delivered to the lateral or medial perforant path, during push-pull perfusion of the dentate molecular layer with artificial cerebrospinal fluid (CSF) alone, or with CSF containing naloxone (10(-4) M). Naloxone effectively blocked the induction, but not the maintenance of LTP in the lateral perforant path, a putative proenkephalin system. Naloxone did not affect the production of LTP in the medial pathway. These findings suggest that activation of naloxone-sensitive receptors is necessary for the full expression of LTP in the lateral perforant pathway.
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Affiliation(s)
- C R Bramham
- Department of Physiology, University of Bergen, Norway
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16
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Heemskerk FM, Schrama LH, de Graan PN, Gispen WH. 4-Aminopyridine inhibits synaptosomal plasma membrane protein phosphorylation in vitro: effect of the selective NMDA-antagonist 2-amino-5-phosphonovalerate. Biochem Biophys Res Commun 1987; 147:94-9. [PMID: 2443136 DOI: 10.1016/s0006-291x(87)80091-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Phosphorylation of synaptosomal plasma membranes from rat hippocampus in the presence of the convulsant drug 4-aminopyridine resulted in the inhibition of the phosphorylation of the nervous tissue specific protein kinase C substrate protein B-50 (48 kDa) and the alpha-subunit of calcium/calmodulin-dependent protein kinase II (50 kDa). Preincubation of SPM with 2-amino-5-phosphonovalerate prevents the inhibition of B-50 phosphorylation by 4-aminopyridine, but had no effect on the inhibition of 50 kDa phosphorylation. 2-Amino-5-phosphonovalerate is known to be a specific N-methyl-D-aspartate antagonist and has anti-epileptic activity in vitro and in vivo. Several other anti-epileptic drugs tested did not influence the 4-aminopyridine-induced inhibition of protein phosphorylation.
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17
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De Graan PN, Schrama LH, Brussaard AB, Jork R, Gispen WH. 4-Aminopyridine affects synaptosomal protein phosphorylation in rat hippocampal slices. Brain Res 1987; 404:345-9. [PMID: 3032338 DOI: 10.1016/0006-8993(87)91392-8] [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: 01/03/2023]
Abstract
Rat brain hippocampal slices were incubated with or without the convulsant 4-aminopyridine (4-AP). From these slices a crude mitochondrial/synaptosomal membrane fraction was prepared and analyzed for endogenous protein phosphorylation. 4-AP (10(-5) M) stimulated the phosphorylation of a 50 kDa protein by 86%. The phosphorylation of this 50 kDa protein is Ca2+/calmodulin-dependent and we suggest that this protein is the lower molecular weight subunit of Ca2+/calmodulin-dependent protein kinase II (CaMK II).
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18
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Schrama LH, De Graan PN, Oestreicher AB, Gispen WH. B-50 phosphorylation, protein kinase C and the induction of excessive grooming behavior in the rat. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1987; 221:393-408. [PMID: 2829585 DOI: 10.1007/978-1-4684-7618-7_29] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- L H Schrama
- Division of Molecular Neurobiology, University of Utrecht, The Netherlands
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