251
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Miller RR, Leanza CM, Phillips EE, Blacquire KD. Homocysteine-induced changes in brain membrane composition correlate with increased brain caspase-3 activities and reduced chick embryo viability. Comp Biochem Physiol B Biochem Mol Biol 2004; 136:521-32. [PMID: 14602160 DOI: 10.1016/s1096-4959(03)00277-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In adult systems, high homocysteine (HoCys) levels inhibit methylation reactions and can induce apoptosis in the central nervous system. In embryos, exogenous HoCys is teratogenic and is associated with neural tube defects. Because, methylation inhibitors and inducers of apoptosis can influence membrane composition, we have studied whether or not embryonic exposure to HoCys influenced membrane phospholipid levels, membrane fatty acid composition, and Caspase-3 activities in embryonic chick brains. Embryonic exposure to HoCys caused reduced brain phosphatidylcholine levels and increased levels of brain phosphatidylethanolamine. Exogenous HoCys also promoted decreased levels of long-chain, unsaturated membrane fatty acids and increased levels of saturated short-chain membrane fatty acids. These HoCys-induced brain membrane changes correlated with HoCys-induced increases in brain Caspase-3 activities, HoCys-induced reductions in brain mass, HoCys-induced reductions in embryo mass, and HoCys-induced reductions in the percentage of embryos that survived to 11 days of development (theoretical stage 37). Thus, HoCys-induced changes in brain membrane composition correlated with HoCys-induced apoptosis and reduced embryo viability.
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Affiliation(s)
- Robert R Miller
- Hillsdale College, Biology Department, 33 E College, Hillsdale, MI 49242-1205, USA.
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252
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Heider I, Lehmensiek V, Lenk T, Müller T, Storch A. Dopaminergic neurotoxicity of homocysteine and its derivatives in primary mesencephalic cultures. ACTA ACUST UNITED AC 2004:1-13. [PMID: 15354384 DOI: 10.1007/978-3-7091-0579-5_1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Levodopa and dopamine are metabolized to 3-O-methyldopa and 3-methoxytyramine, respectively, by the enzyme catechol-O-methyltransferase (COMT) leading to the production of the demethylated cofactor S-adenosylhomo-cysteine (SAH) and subsequently homocysteine (HC). Indeed, treatment of Parkinson's disease (PD) patients with levodopa leads to increased HC blood levels. Therefore, HC is discussed to be involved in the pathogenesis of PD as well as in enhanced progression of PD in patients treated with levodopa. Here we investigated the toxicity of HC and its derivatives SAH, homocysteic acid (HCA) and cysteic acid (CA) on tyrosine hydroxylase (TH)-positive neurons in primary mesencephalic cultures from rat in vitro. Furthermore, we evaluated the toxicity of HC on cultures stressed with the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium (MPP+). Incubation with HC or HCA did not result in significant effects on TH-positive neuron survival with concentrations up to 1 mM, but led to morphological changes of TH-positive cells with significantly fewer and shorter neurites at concentrations of > or = 100 microM after 48 h. In contrast, SAH and CA were toxic at concentrations of >100 microM after 48h. Furthermore, MPP+ showed strong toxicity towards TH-positive cells after 48 h (half-maximal toxic concentration: 20 microM), whereas co-incubation with HC for 24 or 48 h did not further alter TH-positive cell survival. Taken together, our results do not demonstrate relevant dopaminergic toxicity of HC in vitro, and therefore HC is most likely not involved in the pathogenesis of PD or in accelerating the progression of PD by levodopa.
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Affiliation(s)
- I Heider
- Department of Neurology, University of Ulm, Germany
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253
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Schelman WR, Andres RD, Sipe KJ, Kang E, Weyhenmeyer JA. Glutamate mediates cell death and increases the Bax to Bcl-2 ratio in a differentiated neuronal cell line. ACTA ACUST UNITED AC 2004; 128:160-9. [PMID: 15363891 DOI: 10.1016/j.molbrainres.2004.06.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2004] [Indexed: 10/26/2022]
Abstract
Excessive stimulation of the NMDA receptor by glutamate induces cell death and has been implicated in the development of several neurodegenerative diseases. While apoptosis plays a role in glutamate-mediated toxicity, the mechanisms underlying this process have yet to be completely determined. Recent evidence has shown that exposure to excitatory amino acids regulates the expression of the antiapoptotic protein, Bcl-2, and the proapoptotic protein, Bax, in neurons. Since it has been suggested that the ratio of Bax to Bcl-2 is an important determinant of neuronal survival, the reciprocal regulation of these Bcl-2 family proteins may play a role in the neurotoxicity mediated by glutamate. Here, we have used a differentiable neuronal cell line, N1E-115, to investigate the molecular properties of glutamate-induced cell death. Annexin V staining was used to determine apoptotic cell death between 0 and 5 days differentiation with DMSO/low serum. Immunoblot analysis was used to determine whether the expression of Bcl-2 or Bax was modulated during the differentiation process. Bcl-2 protein levels were increased during maturation while Bax expression remained unchanged. Maximum Bcl-2 expression was observed following 5 days of differentiation. Examination of Bcl-2 and Bax following glutamate treatment revealed that the expression of these proteins was inversely regulated. Exposure to glutamate (0.001-10 mM) for 20+/-2 h resulted in a dose-dependent decrease in cell survival (as measured by MTT analysis) that was maximal at 10 mM. These results further support the role of apoptosis in glutamate-mediated cell death. Furthermore, a significant decrease in Bcl-2 levels was observed at 1 mM and 10 mM glutamate (32.1%+/-4.8 and 33.7+/-12.8%, respectively) while a significant upregulation of Bax expression (88.2+/-17.9%) was observed at 10 mM glutamate. Interestingly, Bcl-2 and Bax levels in cells treated with glutamate from 12-24 h were not significantly different from those of control. Taken together, these findings provide additional evidence for the reciprocal regulation of Bcl-2 and Bax expression by glutamate and suggest that neuronal excitotoxicity may, in part, result from the inverse regulation of these proteins.
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Affiliation(s)
- William R Schelman
- Department of Cell and Structural Biology, University of Illinois, B107 CLSL, 601 South Goodwin Avenue, Urbana IL 61801, USA
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254
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Shea TB, Ashline D, Ortiz D, Milhalik S, Rogers E. The S-adenosyl homocysteine hydrolase inhibitor 3-deaza-adenosine prevents oxidative damage and cognitive impairment following folate and vitamin E deprivation in a murine model of age-related, oxidative stress-induced neurodegeneration. Neuromolecular Med 2004; 5:171-80. [PMID: 15075443 DOI: 10.1385/nmm:5:2:171] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Deficiencies in folate promote neurodegeneration and potentiate the influence of other risk factors for neurodegeneration. This is accomplished at least in part by increasing levels of the neurotoxin homocysteine (HC). The S-adenosyl homocysteine (SAH) hydrolase inhibitor 3-deaza-adenosine (DZA) prevents HC accumulation following folate deprivation. We tested the ability of dietary supplementation with DZA to counteract the deleterious influence of folate deprivation. Folate deficiency has previously been shown to potentiate the impact of apolipoprotein E (ApoE); ApoE-/- mice deprived of folate demonstrated increased oxidative damage in brain tissue and impaired cognitive performance as compared to normal mice or to ApoE-/- mice receiving folate. Herein, we demonstrate that dietary supplementation with DZA prevented both the increase in oxidative damage and impaired cognition characteristic of ApoE-/- mice following folate deprivation. These findings suggest that manipulation of the methionine cycle by DZA can counteract folate deficiency. Because folate deprivation, increased HC, and apolipoprotein E deficiency are all risk factors for Alzheimer's disease, these findings also underscore that DZA might be useful in a therapeutic approach to delay neurodegeneration in Alzheimer's disease.
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Affiliation(s)
- Thomas B Shea
- Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts-Lowell, Lowell, MA, USA.
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255
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Applebaum J, Shimon H, Sela BA, Belmaker RH, Levine J. Homocysteine levels in newly admitted schizophrenic patients. J Psychiatr Res 2004; 38:413-6. [PMID: 15203293 DOI: 10.1016/j.jpsychires.2004.01.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2003] [Revised: 01/06/2004] [Accepted: 01/07/2004] [Indexed: 11/15/2022]
Abstract
We previously found a marked elevation of plasma homocysteine in young male schizophrenic patients in hospital. It seemed important to determine if this finding is already present in newly admitted schizophrenic patients. Serum homocysteine levels were studied in 184 consecutively admitted schizophrenic patients and 305 control subjects from an employee screening program. Homocysteine levels were markedly increased in this population of newly admitted schizophrenic patients, especially in young males. Newly admitted male schizophrenic patients have elevated homocysteine levels that cannot be explained on the basis of poor hospital nutrition. Smoking may raise homocysteine by 1-2 microM/L but this is not a large enough effect to explain our findings.
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Affiliation(s)
- Julia Applebaum
- Beer-Sheba Mental Health Center, Stanley Research Center, Ben Gurion University of the Negev, Beersheva, Israel
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256
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Quinn CT, Griener JC, Bottiglieri T, Arning E, Winick NJ. Effects of intraventricular methotrexate on folate, adenosine, and homocysteine metabolism in cerebrospinal fluid. J Pediatr Hematol Oncol 2004; 26:386-8. [PMID: 15167354 DOI: 10.1097/00043426-200406000-00011] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Methotrexate (MTX) is an antifolate that affects many metabolic pathways. MTX may cause neurologic toxicity, but the biochemical effects of MTX on the central nervous system (CNS) are poorly characterized. The authors studied serial cerebrospinal fluid (CSF) samples from a child during two courses of intraventricular MTX and found a rapid and reproducible depletion in CSF of reduced folates and S-adenosylmethionine that was accompanied by marked increases in homocysteine and adenosine. No sulfur-containing excitatory amino acids were detected. This study demonstrates multiple profound effects of MTX on CNS metabolism and provides insight to the pathogenesis of MTX neurotoxicity.
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Affiliation(s)
- Charles T Quinn
- Department of Pediatrics, The University of Texas Southwestern Medical Center at Dallas, Texas 75390-9063, USA.
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257
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Bleich S, Degner D, Sperling W, Bönsch D, Thürauf N, Kornhuber J. Homocysteine as a neurotoxin in chronic alcoholism. Prog Neuropsychopharmacol Biol Psychiatry 2004; 28:453-64. [PMID: 15093951 DOI: 10.1016/j.pnpbp.2003.11.019] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/14/2003] [Indexed: 11/28/2022]
Abstract
There is evidence from in vitro and in vivo studies that homocysteine induces neuronal damage and cell loss by both excitotoxicity and different apoptotic processes. Clinical evidence suggest a strong relationship between higher plasma homocysteine levels and brain atrophy in healthy elderly subjects as well as in elderly at risk of and with Alzheimer's disease. Chronic alcoholism leads to elevated plasma homocysteine levels, as shown by clinical investigations and animal experiments. In addition, an association between brain atrophy and increased levels of homocysteine in chronic alcoholism was shown. This may have important implications for the pathogenesis of alcoholism-associated brain atrophy. Furthermore, taking into account that high plasma homocysteine levels are helpful in the prediction of alcohol withdrawal seizures, early anticonvulsive therapy could prevent this severe complication. Homocysteine plays a role in a shared biochemical cascade involving overstimulation of N-methyl-D-aspartate (NMDA) receptors, oxidative stress, activation of caspases, DNA damage, endoplasmic reticulum and mitochondrial dysfunction. These mechanisms are believed to be important in the pathogenesis of both excitotoxicity and apoptotic neurotoxicity. Prospective intervention studies may show whether the incidence of complications of alcohol withdrawal or alcoholism-associated disorders can be reduced by therapeutic measures with early lowering of elevated homocysteine levels (e.g. folate administration). The most important pathophysiological and pathobiochemical features of glutamatergic neurotransmission and of ethanol-induced hyperhomocysteinaemia are reviewed in relation to their excitotoxic and apoptotic potential.
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Affiliation(s)
- Stefan Bleich
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander University of Erlangen-Nuremberg, Schwabachanlage 6-10, Erlangen 91054, Germany.
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258
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Tchantchou F, Graves M, Ashline D, Morin A, Pimenta A, Ortiz D, Rogers E, Shea TB. Increased transcription and activity of glutathione synthase in response to deficiencies in folate, vitamin E, and apolipoprotein E. J Neurosci Res 2004; 75:508-15. [PMID: 14743434 DOI: 10.1002/jnr.10867] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Oxidative stress is a major contributing factor in neurodegeneration and can arise from dietary, environmental, and genetic sources. Here we examine the separate and combined impact of deprivation of folate and vitamin E, coupled with dietary iron as a prooxidant, on normal mice and transgenic mice lacking apolipoprotein E (ApoE-/- mice). Both mouse strains exhibited increased levels of glutathione when deprived of folate and vitamin E, but a substantial further increase was observed in ApoE-/- mice. To determine the mechanism(s) underlying this increase, we quantified transcription and activity of glutathione synthase (GS). Both normal and ApoE-/- mice demonstrated increased GS activity when deprived of folate and vitamin E. However, transcription was increased only in ApoE-/- mice deprived of folate and vitamin E. These findings demonstrate that deficiency in one gene can result in compensatory up-regulation in a second relevant gene and, furthermore, indicate that compensation for oxidative stress can occur in brain tissue at epigenetic and genetic levels depending on the nature and/or extent of oxidative stress.
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Affiliation(s)
- Flaubert Tchantchou
- Center for Cellular Neurobiology and Neurodegeneration Research, University of Massachusetts--Lowell, Massachusetts 01854, USA
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259
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Tjiattas L, Ortiz DO, Dhivant S, Mitton K, Rogers E, Shea TB. Folate deficiency and homocysteine induce toxicity in cultured dorsal root ganglion neurons via cytosolic calcium accumulation. Aging Cell 2004; 3:71-6. [PMID: 15038821 DOI: 10.1111/j.1474-9728.2004.00086.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Folate deficiency induces neurotoxicity by multiple routes, including increasing cytosolic calcium and oxidative stress via increasing levels of the neurotoxin homocysteine (HC), and inducing mitochondrial and DNA damage. Because some of these neurotoxic effects overlap with those observed in motor neuron disease, we examined the impact of folate deprivation on dorsal root ganglion (DRG) neurons in culture. Folate deprivation for 2 h increased cytosolic calcium and reactive oxygen species (ROS) and impaired mitochondrial function. Treatment with nimodipine [an L voltage-sensitive calcium channel (LVSCC) antagonist], MK-801 (an NMDA channel antagonist) and thapsigarin (an inhibitor of efflux of calcium from internal stores) indicated that folate deprivation initially induced calcium influx via the LVSCC, with subsequent additional calcium derived from NMDA channels and internal stores. These compounds also reduced ROS and mitochondrial degeneration, indicating that calcium influx contributed to these phenomena. Calcium influx was prevented by co-treatment with 3-deaza-adenosine, which inhibits HC formation, indicating that HC mediated increased cytosolic calcium following folate deprivation. Nimodipine, MK-801 and thapsigargin had similar effects following direct treatment with HC as they did following folate deprivation. These findings support the idea that folate deprivation and HC treatment can compromise the health of DRG neurons by perturbing calcium homeostasis.
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Affiliation(s)
- Lindsay Tjiattas
- Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA 01854, USA
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260
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Görtz P, Hoinkes A, Fleischer W, Otto F, Schwahn B, Wendel U, Siebler M. Implications for hyperhomocysteinemia: not homocysteine but its oxidized forms strongly inhibit neuronal network activity. J Neurol Sci 2004; 218:109-14. [PMID: 14759642 DOI: 10.1016/j.jns.2003.11.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2003] [Revised: 10/28/2003] [Accepted: 11/16/2003] [Indexed: 10/26/2022]
Abstract
Severe hyperhomocysteinemia (50-200 microM) often presents itself with acute neuronal dysfunction including seizures and psychosis. Its moderate form (15-50 microM) is associated with cognitive impairment and dementia. We investigated the neuropharmacological effects of homocysteine and its oxidized forms, homocysteinesulfinic acid (HCSA) and homocysteic acid (HCA), on neuronal network function utilizing dissociated cortical neurons from embryonic Wistar rats on microelectrode arrays. All substances inhibited dose-dependently and reversibly spontaneous neuronal network activity within seconds: L-HCSA and L-HCA blocked spontaneous spike rate (SSR) significantly at very low concentrations, with an IC50 of 1.9 and 1.3 microM, respectively; whereas the dose-response curve of D,L-homocysteine revealed an IC50 of 401 microM. These effects were antagonized by 2-amino-5-phosphonovaleric acid (APV) pointing to the NMDA receptor as mediator of this fast and reversible inhibition of network activity. We conclude that a neuronal dysfunction observed in hyperhomocysteinemia is likely due to HCSA and HCA since effective concentrations of homocysteine are not reached in patients.
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Affiliation(s)
- Philipp Görtz
- Department of Neurology, Heinrich-Heine University, Düsseldorf, Germany
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261
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Robert K, Santiard-Baron D, Chassé JF, Paly E, Aupetit J, Kamoun P, London J, Janel N. The neuronal SAPK/JNK pathway is altered in a murine model of hyperhomocysteinemia. J Neurochem 2004; 89:33-43. [PMID: 15030387 DOI: 10.1046/j.1471-4159.2003.02297.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Deficiency in cystathionine beta synthase (CBS) leads to high plasma homocysteine concentrations and causes hyperhomocysteinemia, a common risk factor for vascular disease, stroke and possibly neurodegenerative diseases. Various neuronal diseases have been associated with hyperhomocysteinemia, but the molecular mechanisms of homocysteine toxicity are unknown. We investigated the pathways involved in the pathological process, by analyzing differential gene expression in neuronal tissues. We used a combination of differential display and cDNA arrays to identify genes differentially expressed during hyperhomocysteinemia in brain of CBS-deficient mice. In this murine model of hyperhomocysteinemia, both plasma and brain homocysteine concentrations were high. Several genes were found to be differentially expressed in the brains of CBS-deficient mice, and the identities of some of these genes suggested that the SAPK/JNK pathway was altered in the brains of CBS-deficient mice. We therefore investigated the activation of proteins involved in the SAPK/JNK cascade. JNK and c-Jun were activated in the hippocampal neurones of CBS-deficient mice, suggesting that the SAPK/JNK pathway may play an important role in the development of neuronal defects associated with hyperhomocysteinemia.
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262
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Selley ML. Homocysteine increases the production of asymmetric dimethylarginine in cultured neurons. J Neurosci Res 2004; 77:90-3. [PMID: 15197741 DOI: 10.1002/jnr.20070] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Increased circulating concentrations of homocysteine may be a risk factor for Alzheimer's disease and cognitive dysfunction in normal aging. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide synthase (NOS). ADMA is metabolized in neurons by the enzyme dimethylarginine dimethylaminohydrolase (DDAH). Nitric oxide plays an important role in synaptic events involved in learning and memory. We determined the effect of L-homocysteine on ADMA accumulation and nitric oxide production in cultured rat neuronal granule cells. The incubation of neuronal granule cells with L-homocysteine for 24 hr caused a dose-dependent accumulation of ADMA and a dose-dependent decrease in nitric oxide production. The addition of the sulfhydryl antioxidant pyrrolidine dithiocarbamate (PDTC) attenuated the effect of homocysteine on ADMA accumulation and nitric oxide production. DDAH activity had a decreasing dose-response relationship with increasing L-homocysteine concentrations. The addition of PDTC caused a dose-dependent increase in DDAH activity. The addition of the N-methyl-D-aspartate receptor antagonists (+/-)-2-amino-5-phosphopentanoic acid and 7-chlorokynurenate had no effect on the inhibition of DDAH by homocysteine. It is concluded that L-homocysteine inhibits DDAH activity, thereby causing ADMA accumulation and decreasing nitric oxide production in cultured neurons. The protective effect of PDTC suggests that L-homocysteine inactivates DDAH in neurons by reacting with the cysteine residue in its active site. The preservation of DDAH activity and the reduction of ADMA accumulation in neurons may be a new strategy for the treatment of Alzheimer's disease and cognitive impairment in normal aging.
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Affiliation(s)
- Michael L Selley
- Angiogen Pharmaceuticals Pty. Ltd., Sydney, New South Wales, Australia.
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263
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Abstract
BACKGROUND A high circulating concentration of the amino acid homocysteine is an independent risk factor for stroke. Alzheimer's disease (AD) commonly co-occurs with stroke. Epidemiological studies found associations between hyperhomocysteinaemia and both histologically confirmed AD and disease progression and revealed that dementia in AD was associated with evidence of brain infarcts on autopsy. Thus, hyperhomocysteinaemia and AD could be linked by stroke or microvascular disease. However, given known relations between B-group-vitamin deficiency and both hyperhomocysteinaemia and neurological dysfunction, direct causal mechanisms are also plausible. RECENT DEVELOPMENTS A recent prospective study (S Seshadri and colleagues N Engl J Med; 2002 346: 476-83) showed hyperhomocysteinaemia to be a strong, independent risk factor for dementia and AD. The researchers found a graded increase in risk of both outcomes with rising plasma concentration of homocysteine after multivariate control for putative risk factors for AD. In conjunction with demonstration of a fall in homocysteine concentrations in response to increasing B-group-vitamin status, these findings give hope that mental decline, or AD itself, could be prevented by dietary modification or food fortification. WHERE NEXT? 25% of dementia cases are attributed to stroke. The possibility that some of the other 75% might be prevented by the lowering of homocysteine concentrations greatly increases the hope of maintaining self-sufficiency into old age. If homocysteine lowering can reduce the incidence of dementia or AD, decreased incidence of these disorders may be seen in Canada and the USA, where government-mandated folate-fortification programmes are in effect. Future research should focus on early detection of AD and on the possibility that the disease itself, or its primary symptom, could be prevented by folate supplementation.
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264
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Streck EL, Vieira PS, Wannmacher CMD, Dutra-Filho CS, Wajner M, Wyse ATS. In vitro effect of homocysteine on some parameters of oxidative stress in rat hippocampus. Metab Brain Dis 2003; 18:147-54. [PMID: 12822833 DOI: 10.1023/a:1023815119931] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Homocystinuria is an inherited metabolic disease characterized biochemically by increased blood and brain levels of homocysteine caused by severe deficiency of cystathionine beta-synthase activity. Affected patients present mental retardation, seizures, and atherosclerosis. Oxidative stress plays an important role in the pathogenesis of many neurodegenerative and vascular diseases, such Alzheimer's disease, stroke, and atherosclerosis. However, the mechanisms underlying the neurological damage characteristic of homocystinuria are still poorly understood. To evaluate the involvement of oxidative stress on the neurological dysfunction present in homocystinuria, we measured thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, and total radical-trapping antioxidant potential (TRAP) and antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase) in rat hippocampus in the absence (controls) or in the presence of homocysteine (10-500 microM) in vitro. We demonstrated that homocysteine significantly increases TBARS and decreases TRAP, both in a dose-dependent manner, but did not change antioxidant enzymes. Our results suggest that oxidative stress is involved in the neurological dysfunction of homocystinuria. However, further studies are necessary to confirm and extend our findings to the human condition and also to determine whether antioxidant therapy may be of benefit to these patients.
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Affiliation(s)
- Emilio L Streck
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, Porto Alegre, RS, Brazil
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265
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Leboeuf R. Homocysteine and Alzheimer's disease. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION 2003; 103:304-7. [PMID: 12616250 DOI: 10.1053/jada.2003.50083] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Renee Leboeuf
- School of Public Health at the University of Washington, Seattle, WA, USA
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266
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Mattson MP, Shea TB. Folate and homocysteine metabolism in neural plasticity and neurodegenerative disorders. Trends Neurosci 2003; 26:137-46. [PMID: 12591216 DOI: 10.1016/s0166-2236(03)00032-8] [Citation(s) in RCA: 587] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Folate is a cofactor in one-carbon metabolism, during which it promotes the remethylation of homocysteine -- a cytotoxic sulfur-containing amino acid that can induce DNA strand breakage, oxidative stress and apoptosis. Dietary folate is required for normal development of the nervous system, playing important roles regulating neurogenesis and programmed cell death. Recent epidemiological and experimental studies have linked folate deficiency and resultant increased homocysteine levels with several neurodegenerative conditions, including stroke, Alzheimer's disease and Parkinson's disease. Moreover, genetic and clinical data suggest roles for folate and homocysteine in the pathogenesis of psychiatric disorders. A better understanding of the roles of folate and homocysteine in neuronal homeostasis throughout life is revealing novel approaches for preventing and treating neurological disorders.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Gerontology Research Center, National Institutes of health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
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