1
|
McClain JL, Gulbransen BD. The acute inhibition of enteric glial metabolism with fluoroacetate alters calcium signaling, hemichannel function, and the expression of key proteins. J Neurophysiol 2016; 117:365-375. [PMID: 27784805 DOI: 10.1152/jn.00507.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/25/2016] [Indexed: 11/22/2022] Open
Abstract
Glia play key roles in the regulation of neurotransmission in the nervous system. Fluoroacetate (FA) is a metabolic poison widely used to study glial functions by disrupting the tricarboxylic acid cycle enzyme aconitase. Despite the widespread use of FA, the effects of FA on essential glial functions such as calcium (Ca2+) signaling and hemichannel function remain unknown. Therefore, our goal was to assess specifically the impact of FA on essential glial cell functions that are involved with neurotransmission in the enteric nervous system. To this end, we generated a new optogenetic mouse model to study specifically the effects of FA on enteric glial Ca2+ signaling by crossing PC::G5-tdTomato mice with Sox10::creERT2 mice. FA did not change the peak glial Ca2+ response when averaged across all glia within a ganglion. However, FA decreased the percent of responding glia by 30% (P < 0.05) and increased the peak Ca2+ response of the glial cells that still exhibited a response by 26% (P < 0.01). Disruption of Ca2+ signaling with FA impaired the activity-dependent uptake of ethidium bromide through connexin-43 (Cx43) hemichannels (P < 0.05) but did not affect baseline Cx43-dependent dye uptake. FA did not cause overt glial or neurodegeneration, but glial cells significantly increased glial fibrillary acid protein by 56% (P < 0.05) following treatment with FA. Together, these data show that the acute impairment of glial metabolism with FA causes key changes in glial functions associated with their roles in neurotransmission and phenotypic changes indicative of reactive gliosis. NEW & NOTEWORTHY Our study shows that the acute impairment of enteric glial metabolism with fluoroacetate (FA) alters specific glial functions that are associated with the modification of neurotransmission in the gut. These include subtle changes to glial agonist-evoked calcium signaling, the subsequent disruption of connexin-43 hemichannels, and changes in protein expression that are consistent with a transition to reactive glia. These changes in glial function offer a mechanistic explanation for the effects of FA on peripheral neuronal networks.
Collapse
Affiliation(s)
- Jonathon L McClain
- Department of Physiology, Michigan State University, East Lansing, Michigan; and
| | - Brian D Gulbransen
- Department of Physiology, Michigan State University, East Lansing, Michigan; and .,Neuroscience Program, Michigan State University, East Lansing, Michigan
| |
Collapse
|
2
|
Prior M, Chiruta C, Currais A, Goldberg J, Ramsey J, Dargusch R, Maher PA, Schubert D. Back to the future with phenotypic screening. ACS Chem Neurosci 2014; 5:503-13. [PMID: 24902068 DOI: 10.1021/cn500051h] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
There are no disease-modifying drugs for any old age associated neurodegenerative disease or stroke. This is at least in part due to the failure of drug developers to recognize that the vast majority of neurodegenerative diseases arise from a confluence of multiple toxic insults that accumulate during normal aging and interact with genetic and environmental risk factors. Thus, it is unlikely that the current single target approach based upon rare dominant mutations or even a few preselected targets is going to yield useful drugs for these conditions. Therefore, the identification of drug candidates for neurodegeneration should be based upon their efficacy in phenotypic screening assays that reflect the biology of the aging brain, not a single, preselected target. It is argued here that this approach to drug discovery is the most likely to produce safe and effective drugs for neurodegenerative diseases.
Collapse
Affiliation(s)
- Marguerite Prior
- Cellular
Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037-1002, United States
| | - Chandramouli Chiruta
- Cellular
Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037-1002, United States
| | - Antonio Currais
- Cellular
Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037-1002, United States
| | - Josh Goldberg
- Cellular
Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037-1002, United States
| | - Justin Ramsey
- Cellular
Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037-1002, United States
| | - Richard Dargusch
- Cellular
Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037-1002, United States
| | - Pamela A. Maher
- Cellular
Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037-1002, United States
| | - David Schubert
- Cellular
Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037-1002, United States
| |
Collapse
|
3
|
Poteet E, Winters A, Yan LJ, Shufelt K, Green KN, Simpkins JW, Wen Y, Yang SH. Neuroprotective actions of methylene blue and its derivatives. PLoS One 2012; 7:e48279. [PMID: 23118969 PMCID: PMC3485214 DOI: 10.1371/journal.pone.0048279] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 09/21/2012] [Indexed: 01/08/2023] Open
Abstract
Methylene blue (MB), the first lead chemical structure of phenothiazine and other derivatives, is commonly used in diagnostic procedures and as a treatment for methemoglobinemia. We have previously demonstrated that MB could function as an alternative mitochondrial electron transfer carrier, enhance cellular oxygen consumption, and provide protection in vitro and in rodent models of Parkinson's disease and stroke. In the present study, we investigated the structure-activity relationships of MB in vitro using MB and six structurally related compounds. MB reduces mitochondrial superoxide production via alternative electron transfer that bypasses mitochondrial complexes I-III. MB mitigates reactive free radical production and provides neuroprotection in HT-22 cells against glutamate, IAA and rotenone toxicity. Distinctly, MB provides no protection against direct oxidative stress induced by glucose oxidase. Substitution of a side chain at MB's 10-nitrogen rendered a 1000-fold reduction of the protective potency against glutamate neurototoxicity. Compounds without side chains at positions 3 and 7, chlorophenothiazine and phenothiazine, have distinct redox potentials compared to MB and are incapable of enhancing mitochondrial electron transfer, while obtaining direct antioxidant actions against glutamate, IAA, and rotenone insults. Chlorophenothiazine exhibited direct antioxidant actions in mitochondria lysate assay compared to MB, which required reduction by NADH and mitochondria. MB increased complex IV expression and activity, while 2-chlorphenothiazine had no effect. Our study indicated that MB could attenuate superoxide production by functioning as an alternative mitochondrial electron transfer carrier and as a regenerable anti-oxidant in mitochondria.
Collapse
Affiliation(s)
- Ethan Poteet
- Department of Pharmacology and Neuroscience, Institute for Alzheimer’s Disease and Aging Research, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States of America
| | - Ali Winters
- Department of Pharmacology and Neuroscience, Institute for Alzheimer’s Disease and Aging Research, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States of America
| | - Liang-Jun Yan
- Department of Pharmacology and Neuroscience, Institute for Alzheimer’s Disease and Aging Research, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States of America
| | - Kyle Shufelt
- Department of Chemistry, Texas Christian University, Fort Worth, Texas, United States of America
| | - Kayla N. Green
- Department of Chemistry, Texas Christian University, Fort Worth, Texas, United States of America
| | - James W. Simpkins
- Department of Pharmacology and Neuroscience, Institute for Alzheimer’s Disease and Aging Research, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States of America
| | - Yi Wen
- Department of Pharmacology and Neuroscience, Institute for Alzheimer’s Disease and Aging Research, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States of America
| | - Shao-Hua Yang
- Department of Pharmacology and Neuroscience, Institute for Alzheimer’s Disease and Aging Research, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, United States of America
- * E-mail:
| |
Collapse
|
4
|
Cano-Ramírez D, Torres-Vargas CE, Guerrero-Castillo S, Uribe-Carvajal S, Hernández-Pando R, Pedraza-Chaverri J, Orozco-Ibarra M. Effect of glycolysis inhibition on mitochondrial function in rat brain. J Biochem Mol Toxicol 2012; 26:206-11. [PMID: 22539072 DOI: 10.1002/jbt.21404] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 12/22/2011] [Accepted: 12/30/2011] [Indexed: 11/06/2022]
Abstract
Inhibition of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase enhances the neural vulnerability to excitotoxicity both in vivo and in vitro through an unknown mechanism possibly related to mitochondrial failure. However, as the effect of glycolysis inhibition on mitochondrial function in brain has not been studied, the aim of the present work was to evaluate the effect of glycolysis inhibition induced by iodoacetate on mitochondrial function and oxidative stress in brain. Mitochondria were isolated from brain cortex, striatum and cerebellum of rats treated systemically with iodoacetate (25 mg/kg/day for 3 days). Oxygen consumption, ATP synthesis, transmembrane potential, reactive oxygen species production, lipoperoxidation, glutathione levels, and aconitase activity were assessed. Oxygen consumption and aconitase activity decreased in the brain cortex and striatum, showing that glycolysis inhibition did not trigger severe mitochondrial impairment, but a slight mitochondrial malfunction and oxidative stress were present.
Collapse
Affiliation(s)
- D Cano-Ramírez
- Departamento de Biología, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, México, DF, Mexico
| | | | | | | | | | | | | |
Collapse
|
5
|
Characterization of Novel Neuroprotective Lipid Analogues for the Treatment of Stroke. Transl Stroke Res 2012. [DOI: 10.1007/978-1-4419-9530-8_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
6
|
Chiruta C, Schubert D, Dargusch R, Maher P. Chemical modification of the multitarget neuroprotective compound fisetin. J Med Chem 2011; 55:378-89. [PMID: 22192055 DOI: 10.1021/jm2012563] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many factors are implicated in age-related central nervous system (CNS) disorders, making it unlikely that modulating only a single factor will provide effective treatment. Perhaps a better approach is to identify small molecules that have multiple biological activities relevant to the maintenance of brain function. Recently, we identified an orally active, neuroprotective, and cognition-enhancing molecule, the flavonoid fisetin, that is effective in several animal models of CNS disorders. Fisetin has direct antioxidant activity and can also increase the intracellular levels of glutathione (GSH), the major endogenous antioxidant. In addition, fisetin has both neurotrophic and anti-inflammatory activity. However, its relatively high EC(50) in cell based assays, low lipophilicity, high topological polar surface area (tPSA), and poor bioavailability suggest that there is room for medicinal chemical improvement. Here we describe a multitiered approach to screening that has allowed us to identify fisetin derivatives with significantly enhanced activity in an in vitro neuroprotection model while at the same time maintaining other key activities.
Collapse
Affiliation(s)
- Chandramouli Chiruta
- The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, California 92037, United States
| | | | | | | |
Collapse
|
7
|
Pals JA, Ang JK, Wagner ED, Plewa MJ. Biological mechanism for the toxicity of haloacetic acid drinking water disinfection byproducts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:5791-7. [PMID: 21671678 DOI: 10.1021/es2008159] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The halogenated acetic acids are a major class of drinking water disinfection byproducts (DBPs) with five haloacetic acids regulated by the U.S. EPA. These agents are cytotoxic, genotoxic, mutagenic, and teratogenic. The decreasing toxicity rank order of the monohalogenated acetic acids (monoHAAs) is iodo- > bromo- >> chloroacetic acid. We present data that the monoHAAs inhibit glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity in a concentration-dependent manner with the same rank order as above. The rate of inhibition of GAPDH and the toxic potency of the monoHAAs are highly correlated with their alkylating potential and the propensity of the halogen leaving group. This strong association between GAPDH inhibition and the monoHAA toxic potency supports a comprehensive mechanism for the adverse biological effects by this widely occurring class of regulated DBPs.
Collapse
Affiliation(s)
- Justin A Pals
- College of Agricultural, Consumer, and Environmental Sciences, Department of Crop Sciences, and the NSF WaterCAMPWS Center, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | | | | | | |
Collapse
|
8
|
Leite MR, Wilhelm EA, Jesse CR, Brandão R, Nogueira CW. Protective effect of caffeine and a selective A2A receptor antagonist on impairment of memory and oxidative stress of aged rats. Exp Gerontol 2010; 46:309-15. [PMID: 21122814 DOI: 10.1016/j.exger.2010.11.034] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 11/01/2010] [Accepted: 11/22/2010] [Indexed: 12/12/2022]
Abstract
In this study, the effects of caffeine (CAF) and SCH58261, a selective A(2A) receptor antagonist, on memory impairment and oxidative stress generated by aging in rats were investigated. Young and aged rats were treated daily per 10 days with CAF (30 mg/kg p.o.) or SCH58261 (0.5mg/kg, p.o.) or vehicle (1 ml/kg p.o.). Rats were trained and tested in a novel object recognition task. After the behavioral test, ascorbic acid and oxygen and nitrogen reactive species levels as well as Na(+)K(+) ATPase activity were determined in rat brain. The results demonstrated that the age-related memory deficit was reversed by treatment with CAF or SCH58261. Treatment with CAF or SCH58261 significantly normalized oxygen and nitrogen reactive species levels increased in brains of aged rats. Na(+)K(+) ATPase activity inhibited in brains of aged rats was also normalized by CAF or SCH58261 treatment. A decrease in basal ascorbic acid levels in brains of aged rats was not changed by CAF or SCH58261. These results demonstrated that CAF and SCH58261, modulators of adenosinergic receptors, were able to reverse age-associated memory impairment and to partially reduce oxidative stress.
Collapse
Affiliation(s)
- Marlon Régis Leite
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, CEP 97105-900, Santa Maria, RS, Brazil
| | | | | | | | | |
Collapse
|
9
|
González-Reyes S, Orozco-Ibarra M, Guzmán-Beltrán S, Molina-Jijón E, Massieu L, Pedraza-Chaverri J. Neuroprotective role of heme-oxygenase 1 against iodoacetate-induced toxicity in rat cerebellar granule neurons: Role of bilirubin. Free Radic Res 2009; 43:214-23. [PMID: 19177228 DOI: 10.1080/10715760802676670] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Heme oxygenase (HO) catalyses the breakdown of heme to iron, carbon monoxide and biliverdin, the latter being further reduced to bilirubin. A protective role of the inducible isoform, HO-1, has been described in pathological conditions associated with the production of reactive oxygen species (ROS). The aim of this study was to investigate the role of HO-1 in the neurotoxicity induced by iodoacetate (IAA) in primary cultures of cerebellar granule neurons (CGNs). IAA, an inhibitor of the glycolysis pathway, reduces cell survival, increases ROS production and enhances HO-1 expression in CGNs. Furthermore, the induction of HO-1 expression by cobalt protoporphyrin (CoPP) prevented cell death and ROS production induced by IAA, whereas the inhibition of HO activity with tin mesoporphyrin exacerbated the IAA-induced neurotoxicity. The protective effect elicited by CoPP was reproduced by bilirubin addition, suggesting that this molecule may be involved in the protective effect of HO-1 induction in this experimental model.
Collapse
|
10
|
Maher P, Hanneken A. Flavonoids protect retinal ganglion cells from ischemia in vitro. Exp Eye Res 2007; 86:366-74. [PMID: 18160067 DOI: 10.1016/j.exer.2007.11.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2007] [Revised: 09/27/2007] [Accepted: 11/15/2007] [Indexed: 12/22/2022]
Abstract
Retinal ischemia is a common cause of visual impairment and blindness. However, despite the significant advances that have been made in understanding the pathophysiology of retinal ischemia, effective treatments are still lacking. The goal of these studies was to use an in vitro model to identify molecules that could be neuroprotective for retinal ganglion cells exposed to ischemia. Ischemia was induced in the rat retinal ganglion cell line, RGC-5, using iodoacetic acid (IAA). Brief treatment with IAA resulted in RGC-5 cell death within 24 h by a non-apoptotic mechanism. Similar to ischemia in vivo, IAA treatment caused a rapid loss of ATP to approximately 50% of control levels. In contrast, changes in markers of oxidative stress occurred more slowly and included an increase in reactive oxygen species and a decrease in glutathione. Specific flavonoids were able to prevent the cell death caused by IAA treatment. Some of the flavonoids also prevented the loss of ATP as well as the changes in markers of oxidative stress. In contrast, classical antioxidants had only a very modest effect on IAA-induced cell death. These results suggest that specific flavonoids may be useful in preventing ischemia-induced retinal ganglion cell death in vivo.
Collapse
Affiliation(s)
- Pamela Maher
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
| | | |
Collapse
|
11
|
Lapchak PA, Maher P, Schubert D, Zivin JA. Baicalein, an antioxidant 12/15-lipoxygenase inhibitor improves clinical rating scores following multiple infarct embolic strokes. Neuroscience 2007; 150:585-91. [PMID: 17942241 DOI: 10.1016/j.neuroscience.2007.09.033] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 09/10/2007] [Accepted: 09/18/2007] [Indexed: 11/30/2022]
Abstract
The present study assessed whether baicalein (5,6,7-trihydroxyflavone), a polyphenolic antioxidant 12/15-lipoxygenase inhibitor would attenuate oxidative cell death in vitro using a mouse hippocampal HT22 cell assay. Moreover, we determined if baicalein would be useful to attenuate behavioral deficits associated with multiple infarct ischemic events in vivo using a rabbit small clot embolic stroke model (RSCEM). Using HT22 cell in vitro, baicalein was shown to significantly promote cell survival with an estimated dose for 50% cell survival of 2 muM following incubation in the presence of iodoacetic acid (20 muM), an irreversible inhibitor of the glycolytic pathway that results in the free radical production, lipid peroxidation and cell death. Since baicalein was neuroprotective and attenuated iodoacetic acid (IAA) toxicity in vitro, we studied its effects in vivo in an embolic stroke model using behavioral measures as the endpoint. Quantal analysis for each treatment in the embolism model identifies the quantity of microclots (mg) that produce neurologic dysfunction in 50% of a group of animals (P(50)), with intervention considered neuroprotective if it increases the P(50) compared with controls. Baicalein (100 mg/kg, s.c.) injected 5 and 60 min post-embolization significantly (P<0.05) improved behavioral function. The calculated P(50) values were 2.85+/-0.64 mg (n=21) and 2.15+/-0.12 mg (n=14), respectively compared with 1.37+/-0.20 mg (n=23) for the control group. In conclusion, we have shown that baicalein effectively attenuated cell death in vitro using HT22 cells and also significantly reduced behavioral deficits in rabbits when given up to 1 h following an embolic stroke. The results suggest that baicalein, or derivatives of baicalein with multiple pharmacological activities may be useful to develop as novel treatments for acute ischemic stroke.
Collapse
Affiliation(s)
- P A Lapchak
- University of California, San Diego, Department of Neuroscience, La Jolla, CA 92093-0624, USA.
| | | | | | | |
Collapse
|
12
|
Maher P, Salgado KF, Zivin JA, Lapchak PA. A novel approach to screening for new neuroprotective compounds for the treatment of stroke. Brain Res 2007; 1173:117-25. [PMID: 17765210 PMCID: PMC2111291 DOI: 10.1016/j.brainres.2007.07.061] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 07/30/2007] [Accepted: 07/31/2007] [Indexed: 11/16/2022]
Abstract
Despite the significant advances that have been made in understanding the pathophysiology of cerebral ischemia on the cellular and molecular level, only one drug, the thrombolytic tissue plasminogen activator (rt-PA), is approved by the FDA for use in patients with acute ischemic stroke. Therefore, there is a critical need for additional safe and effective treatments for stroke. In order to identify novel compounds that might be effective, we have developed a cell culture-based assay with death being an endpoint as a screening tool. We have performed an initial screening for potential neuroprotective drugs among a group of flavonoids by using the mouse hippocampal cell line, HT22, in combination with chemical ischemia. Further screens were provided by biochemical assays for ATP and glutathione, the major intracellular antioxidant, as well as for long-term induction of antioxidant proteins. Based upon the results of these screens, we tested the best flavonoid, fisetin, in the small clot embolism model of cerebral ischemia in rabbits. Fisetin significantly reduced the behavioral deficits following a stroke, providing proof of principle for this novel approach to identifying new compounds for the treatment of stroke.
Collapse
Affiliation(s)
- Pamela Maher
- The Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd., La Jolla, CA 92037, USA.
| | | | | | | |
Collapse
|
13
|
Mejía-Toiber J, Montiel T, Massieu L. D-beta-hydroxybutyrate prevents glutamate-mediated lipoperoxidation and neuronal damage elicited during glycolysis inhibition in vivo. Neurochem Res 2006; 31:1399-408. [PMID: 17115265 DOI: 10.1007/s11064-006-9189-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Accepted: 10/03/2006] [Indexed: 01/19/2023]
Abstract
Excitotoxic neuronal death mediated by over-activation of glutamate receptors has been implicated in ischemia, hypoglycemia and some neurodegenerative diseases. It involves oxidative stress and is highly facilitated during impairment of energy metabolism. We have shown previously that in vivo systemic glycolysis inhibition with iodoacetate (IOA), exacerbates glutamate excitotoxicity. We have now investigated whether this effect involves oxidative damage to membrane lipids, as evaluated by the presence of thiobarbituric acid-reactive substances. We have also tested whether the ketone body, D-beta-hydroxybutyrate (D-BHB), prevents lipoperoxidation and tissue damage. Results show that glutamate intrastriatal injection in control rats transiently enhances lipoperoxidation, while in IOA-treated animals increased lipoperoxidation is sustained. Treatment with D-BHB significantly reduces striatal lesions and lipoperoxidation. Vitamin E also reduced neuronal damage and lipoperoxidation. Results suggest that glycolysis impairment favors a pro-oxidant condition and situates oxidative damage as an important mediator of in vivo induced excitotoxicity. Results provide evidence for the neuroprotective effect of D-BHB against glutamate toxicity.
Collapse
Affiliation(s)
- Jana Mejía-Toiber
- Departamento de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, AP 70-253, 04510, Mexico DF, Mexico
| | | | | |
Collapse
|
14
|
Andrés N, Malpesa Y, Rodríguez MJ, Mahy N. Low sensitivity of retina to AMPA-induced calcification. J Neurosci Res 2003; 72:543-8. [PMID: 12704816 DOI: 10.1002/jnr.10601] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Glutamate is involved in most CNS neurodegenerative diseases. In particular, retinal diseases such as retinal ischemia, retinitis pigmentosa, and diabetic retinopathy are associated with an excessive synaptic concentration of this neurotransmitter. To gain more insight into retinal excitotoxicity, we carried out a dose-response study in adult rats using alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), a glutamate analogue. AMPA intraocular injections (between 0.27 and 10.8 nmol) caused no morphologic modification, but a 10.8 + 21 nmol double injection in a 10-day interval produced a lesion characterized by discrete neuronal loss, astroglial and microglial reactions, and calcium precipitation. Abundant calcium deposits similar to those present in rat and human brain excitotoxicity or hypoxia-ischemia neurodegeneration were detected by alizarin red staining within the retinal surface and the optic nerve. Glial reactivity, associated normally with astrocytes in the nerve fiber, was assessed in Müller cells. GABA immunoreactivity was detected not only in neuronal elements but also in Müller cells. In contrast to the high vulnerability of the brain to excitotoxin microinjection, AMPA-induced retinal neurodegeneration may provide a useful model of low central nervous system sensitivity to excitotoxicity.
Collapse
Affiliation(s)
- Noemí Andrés
- Unitat de Bioquímica, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
| | | | | | | |
Collapse
|
15
|
Abstract
This review presents an analysis of the current state of gerontological and geriatric research in Portugal, and highlights the need for a national consensus and funding for age-related research projects. Such efforts must be multidisciplinary, since the process of aging encompasses biological, psychological, social, economic and cultural aspects. Demographic studies reveal a growing population of elderly in Portugal as a result of a healthier population in general. This increased life expectancy, however, is accompanied by a parallel increase in degenerative pathologies and care costs among the elderly. Preventive medicine is an important tool to reduce health care costs and avoid or abbreviate suffering from age-related syndromes, but such projects on a national basis neither exists, nor does gerontology or geriatrics receive funding to perform needed research. Consequently, research on aging depends on the initiative of individual investigators who, without funding or cohesive programs, can do little to improve the low scientific output in this area. The implementation of a national program, that can establish health care policy and priorities as well as fund the necessary research, will permit organized cooperation among the different scientific disciplines related to aging. This is a crucial step toward improving present knowledge, ensuring application of experimental and statistical results to the clinical care of the aging population, and attract young investigators to this field.
Collapse
Affiliation(s)
- C Resende Oliveira
- Department of Biochemistry and Centre for Neurosciences, Faculty of Medicine, University of Coimbra, Rua Larga, 3004 504 Coimbra, Portugal.
| |
Collapse
|
16
|
Areias FM, Rego AC, Oliveira CR, Seabra RM. Antioxidant effect of flavonoids after ascorbate/Fe2+-induced oxidative stress in cultured retinal cells11Abbreviations: BME, basal medium of Eagle; DCFH2, 2′,7′-dichlorodihydrofluorescein; LDH, lactate dehydrogenase; PC, partition coefficient; Rf, retardation factor; ROS, reactive oxygen species; TBA, thiobarbituric acid; and TBARS, thiobarbituric acid-reactive substances. Biochem Pharmacol 2001; 62:111-8. [PMID: 11377402 DOI: 10.1016/s0006-2952(01)00621-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In this study, we investigated the structure-activity relationship of four flavonoids, i.e. eriodictyol, luteolin, quercetin, and taxifolin, in cultured retinal cells after ascorbate/Fe(2+)-induced oxidative stress. The relative order of antioxidant efficacy, determined by the thiobarbituric acid method, was the following: eriodictyol > quercetin > luteolin > taxifolin. Upon preincubation, the flavonoids were also effective in reducing the extent of lipid peroxidation. Oxidative stress, determined by the changes in fluorescence of 2',7'-dichlorodihydrofluorescein, was also decreased in the presence of the flavonoids, showing the following order of antioxidant efficacy: eriodictyol > taxifolin approximately quercetin > luteolin. Ascorbate/Fe(2+)-induced oxidative stress or incubation in the presence of the flavonoids did not significantly affect the viability of retinal cells. We also evaluated the degree of membrane partition of the flavonoids. In this system, the results strongly suggest that the higher antioxidant activity of the flavonoids is not correlated with the presence of a double bond at C(2)-C(3) and/or a hydroxyl group at C(3) on the C ring, but rather may depend on the capacity to inhibit the production of reactive oxygen species to interact hydrophobically with membranes. Eriodictyol was shown to be the most efficient antioxidant in protecting against oxidative stress induced by ascorbate/Fe(2+) in the retinal cells.
Collapse
Affiliation(s)
- F M Areias
- CEQUP/Laboratory of Pharmacognosy, Faculty of Pharmacy, R. Anibal Cunha, University of Porto, 4050-047, Porto, Portugal
| | | | | | | |
Collapse
|