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Stokum JA, Gerzanich V, Simard JM. Molecular pathophysiology of cerebral edema. J Cereb Blood Flow Metab 2016; 36:513-38. [PMID: 26661240 PMCID: PMC4776312 DOI: 10.1177/0271678x15617172] [Citation(s) in RCA: 357] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 12/25/2022]
Abstract
Advancements in molecular biology have led to a greater understanding of the individual proteins responsible for generating cerebral edema. In large part, the study of cerebral edema is the study of maladaptive ion transport. Following acute CNS injury, cells of the neurovascular unit, particularly brain endothelial cells and astrocytes, undergo a program of pre- and post-transcriptional changes in the activity of ion channels and transporters. These changes can result in maladaptive ion transport and the generation of abnormal osmotic forces that, ultimately, manifest as cerebral edema. This review discusses past models and current knowledge regarding the molecular and cellular pathophysiology of cerebral edema.
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Affiliation(s)
- Jesse A Stokum
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, USA
| | - Volodymyr Gerzanich
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, USA
| | - J Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, USA Department of Pathology, University of Maryland School of Medicine, Baltimore, USA Department of Physiology, University of Maryland School of Medicine, Baltimore, USA
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Lee JC, Cho JH, Kim IH, Ahn JH, Park JH, Cho GS, Chen BH, Shin BN, Tae HJ, Park SM, Ahn JY, Kim DW, Cho JH, Bae EJ, Yong JH, Kim YM, Won MH, Lee YL. Ischemic preconditioning inhibits expression of Na + /H + exchanger 1 (NHE1) in the gerbil hippocampal CA1 region after transient forebrain ischemia. J Neurol Sci 2015; 351:146-153. [DOI: 10.1016/j.jns.2015.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 02/09/2015] [Accepted: 03/03/2015] [Indexed: 12/26/2022]
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Stokum JA, Kurland DB, Gerzanich V, Simard JM. Mechanisms of astrocyte-mediated cerebral edema. Neurochem Res 2014; 40:317-28. [PMID: 24996934 DOI: 10.1007/s11064-014-1374-3] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/18/2014] [Accepted: 06/26/2014] [Indexed: 11/26/2022]
Abstract
Cerebral edema formation stems from disruption of blood brain barrier (BBB) integrity and occurs after injury to the CNS. Due to the restrictive skull, relatively small increases in brain volume can translate into impaired tissue perfusion and brain herniation. In excess, cerebral edema can be gravely harmful. Astrocytes are key participants in cerebral edema by virtue of their relationship with the cerebral vasculature, their unique compliment of solute and water transport proteins, and their general role in brain volume homeostasis. Following the discovery of aquaporins, passive conduits of water flow, aquaporin 4 (AQP4) was identified as the predominant astrocyte water channel. Normally, AQP4 is highly enriched at perivascular endfeet, the outermost layer of the BBB, whereas after injury, AQP4 expression disseminates to the entire astrocytic plasmalemma, a phenomenon termed dysregulation. Arguably, the most important role of AQP4 is to rapidly neutralize osmotic gradients generated by ionic transporters. In pathological conditions, AQP4 is believed to be intimately involved in the formation and clearance of cerebral edema. In this review, we discuss aquaporin function and localization in the BBB during health and injury, and we examine post-injury ionic events that modulate AQP4-dependent edema formation.
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Affiliation(s)
- Jesse A Stokum
- Department of Neurosurgery, University of Maryland School of Medicine, 22 S. Greene St., Suite S12D, Baltimore, MD, 21201-1595, USA
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Uria-Avellanal C, Robertson NJ. Na⁺/H⁺ exchangers and intracellular pH in perinatal brain injury. Transl Stroke Res 2014; 5:79-98. [PMID: 24452957 PMCID: PMC3913853 DOI: 10.1007/s12975-013-0322-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 12/23/2013] [Accepted: 12/30/2013] [Indexed: 12/12/2022]
Abstract
Encephalopathy consequent on perinatal hypoxia–ischemia occurs in 1–3 per 1,000 term births in the UK and frequently leads to serious and tragic consequences that devastate lives and families, with huge financial burdens for society. Although the recent introduction of cooling represents a significant advance, only 40 % survive with normal neurodevelopmental function. There is thus a significant unmet need for novel, safe, and effective therapies to optimize brain protection following brain injury around birth. The Na+/H+ exchanger (NHE) is a membrane protein present in many mammalian cell types. It is involved in regulating intracellular pH and cell volume. NHE1 is the most abundant isoform in the central nervous system and plays a role in cerebral damage after hypoxia–ischemia. Excessive NHE activation during hypoxia–ischemia leads to intracellular Na+ overload, which subsequently promotes Ca2+ entry via reversal of the Na+/Ca2+ exchanger. Increased cytosolic Ca2+ then triggers the neurotoxic cascade. Activation of NHE also leads to rapid normalization of pHi and an alkaline shift in pHi. This rapid recovery of brain intracellular pH has been termed pH paradox as, rather than causing cells to recover, this rapid return to normal and overshoot to alkaline values is deleterious to cell survival. Brain pHi changes are closely involved in the control of cell death after injury: an alkalosis enhances excitability while a mild acidosis has the opposite effect. We have observed a brain alkalosis in 78 babies with neonatal encephalopathy serially studied using phosphorus-31 magnetic resonance spectroscopy during the first year after birth (151 studies throughout the year including 56 studies of 50 infants during the first 2 weeks after birth). An alkaline brain pHi was associated with severely impaired outcome; the degree of brain alkalosis was related to the severity of brain injury on MRI and brain lactate concentration; and a persistence of an alkaline brain pHi was associated with cerebral atrophy on MRI. Experimental animal models of hypoxia–ischemia show that NHE inhibitors are neuroprotective. Here, we review the published data on brain pHi in neonatal encephalopathy and the experimental studies of NHE inhibition and neuroprotection following hypoxia–ischemia.
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Affiliation(s)
- Cristina Uria-Avellanal
- Neonatology, Institute for Women's Health, University College London, 74 Huntley Street, 4th floor, Room 401, London, WC1E 6AU, UK
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Wu D, Russano K, Kouz I, Abraham WM. NHE1 inhibition improves tissue perfusion and resuscitation outcome after severe hemorrhage. J Surg Res 2013; 181:e75-81. [DOI: 10.1016/j.jss.2012.07.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Revised: 07/05/2012] [Accepted: 07/11/2012] [Indexed: 11/25/2022]
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Lukashova V, Jinadasa T, Ilie A, Verbich D, Cooper E, Orlowski J. The Na(+)/H (+) exchanger NHE5 is sorted to discrete intracellular vesicles in the central and peripheral nervous systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:397-410. [PMID: 23224898 DOI: 10.1007/978-1-4614-4756-6_34] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The pH milieu of the central and peripheral nervous systems is an important determinant of neuronal excitability, function, and survival. In mammals, neural acid-base homeostasis is coordinately regulated by ion transporters belonging to the Na(+)/H(+) exchanger (NHE) and bicarbonate transporter gene families. However, the relative contributions of individual isoforms within the respective families are not fully understood. This report focuses on the NHE family, specifically the plasma membrane-type NHE5 which is preferentially transcribed in brain, but the distribution of the native protein has not been extensively characterized. To this end, we generated a rabbit polyclonal antibody that specifically recognizes NHE5. In both central (cortex, hippocampus) and peripheral (superior cervical ganglia, SCG) nervous tissue of mice, NHE5 immunostaining was punctate and highly concentrated in the somas and to lesser amounts in the dendrites of neurons. Very little signal was detected in axons. Similarly, in primary cultures of differentiated SCG neurons, NHE5 localized predominantly to vesicles in the somatodendritic compartment, though some immunostaining was also evident in punctate vesicles along the axons. NHE5 was also detected predominantly in intracellular vesicles of cultured SCG glial cells. Dual immunolabeling of SCG neurons showed that NHE5 did not colocalize with markers for early endosomes (EEA1) or synaptic vesicles (synaptophysin), but did partially colocalize with the transferrin receptor, a marker of recycling endosomes. Collectively, these data suggest that NHE5 partitions into a unique vesicular pool in neurons that shares some characteristics of recycling endosomes where it may serve as an important regulated store of functional transporters required to maintain cytoplasmic pH homeostasis.
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Sabiporide reduces ischemia-induced arrhythmias and myocardial infarction and attenuates ERK phosphorylation and iNOS induction in rats. BIOMED RESEARCH INTERNATIONAL 2012; 2013:504320. [PMID: 23484128 PMCID: PMC3591136 DOI: 10.1155/2013/504320] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Revised: 11/01/2012] [Accepted: 11/01/2012] [Indexed: 12/22/2022]
Abstract
The aim of the present study was to investigate the effects of sabiporide, a potent and selective NHE1 inhibitor, on myocardial ischemia-induced arrhythmias and myocardial infarction and the possible pathways related to the cardioprotection afforded by sabiporide treatment. Anesthetized rats were subjected to myocardial ischemia via left main coronary artery occlusion for 30 minutes, followed by 2 hours of reperfusion. Administration of sabiporide (0.01–3.0 mg/kg) prior to coronary artery occlusion dose-dependently reduced ischemia-induced arrhythmias and infarct size with an ED50 value of 0.14 mg/kg. Administration of sabiporide (1.0 mg/kg) prior to reperfusion also reduced infarct size by 38.6%. The reduction in infarct size was accompanied by a decrease in circulating levels of creatine phosphokinase and troponin I. In addition, sabiporide (1.0 mg/kg) given prior to coronary artery occlusion or immediately before reperfusion significantly reduced phosphorylation of the extracellular signal-regulated kinase (ERK1/2) and the expression of the inducible nitric oxide synthase (iNOS) following myocardial ischemia-reperfusion. This study demonstrates that sabiporide is a potent and effective cardioprotective agent during myocardial ischemia and reperfusion, by reducing serious ventricular arrhythmias and myocardial infarct size. The cardioprotection afforded by sabiporide is attributed in part to inhibition of ERK1/2 phosphorylation and suppression of iNOS expression.
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Hyun SW, Jang M, Park SW, Kim EJ, Jung YS. Onion (Allium cepa) extract attenuates brain edema. Nutrition 2012; 29:244-9. [PMID: 22771051 DOI: 10.1016/j.nut.2012.02.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 12/05/2011] [Accepted: 02/12/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVE This study investigated the potential beneficial effects of onion extract on brain ischemia-induced edema and blood-brain barrier (BBB) dysfunction. The possible underlying mechanisms are investigated, especially those linked to the antioxidant effects of the onion extract. METHODS Brain ischemia was induced by middle cerebral artery occlusion (MCAO) for 2 h followed by reperfusion in mice. Mice were treated intravenously with onion extract 30 min before MCAO. Brain edema and BBB hyperpermeability were evaluated by the measurement of the brain water content and Evans blue extravasation, respectively. The disruption of tight junction proteins was examined by immunohistochemical staining. The level of malondialdehyde was determined using the thiobarbituric acid method. The activities of glutathione peroxidase and catalase were determined by spectrophotometric assay. RESULTS Brain water content in the ischemic hemisphere was significantly reduced by treatment with onion extract. Onion extract also had a significant effect on both the decrease in Evans blue extravasation and the inhibition of zonula occludens-1 and occludin disruption caused by brain ischemia. In addition, onion extract significantly prevented brain ischemia-induced reduction in catalase and glutathione peroxidase activities and elevation of malondialdehyde level in the brain tissue. CONCLUSION The results from this study demonstrate that onion extract prevents brain edema, BBB hyperpermeability, and tight junction proteins disruption, possibly through its antioxidant effects in the mouse MCAO model. This study suggests that onion extract may be a beneficial nutrient for the prevention of BBB function during brain ischemia.
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Affiliation(s)
- Soo-Wang Hyun
- Department of Physiology, Ajou University School of Medicine, Suwon, Republic of Korea
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Lee BK, Jung YS. The Na+/H+ exchanger-1 inhibitor cariporide prevents glutamate-induced necrotic neuronal death by inhibiting mitochondrial Ca2+ overload. J Neurosci Res 2012; 90:860-9. [PMID: 22420041 DOI: 10.1002/jnr.22818] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In the brain, Na+/H+ exchanger-1 (NHE-1) activation has a significant impact on ischemic injury, and, in recent studies, NHE-1 inhibition has been found to protect neurons from ischemic injury. This protective effect has been ascribed to the prevention of apoptosis, but neuronal cell death following ischemia is a consequence of both necrotic and apoptotic cell death. Here, we evaluated the ability of the potent NHE-1 inhibitor cariporide to prevent necrotic cell death in an in vitro model of excitotoxic neuronal death. Cariporide (100 nM) was found to reduce both glutamate-induced necrotic and apoptotic neuronal cell death. Ca2+ concentrations were observed to peak twice in cytosol and mitochondria in cultured neuronal cells after glutamate exposure, and cariporide was found to reduce the second Ca2+ concentration increase, but not the first. Furthermore, glutamate-mediated mitochondrial death pathways involving loss of mitochondrial membrane potential and reactive oxygen species (ROS) accumulation were found to be attenuated by cariporide. In addition, cariporide effectively prevented necrosis following exposure to glutamate and ameliorated the mitochondrial Ca2+ and ROS production increases implicated in necrotic cell death. These results suggest that NHE-1 participates in the necrotic cell death process and that its inhibition offers a means of preventing both necrosis and apoptosis.
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Affiliation(s)
- Bo Kyung Lee
- College of Pharmacy, Ajou University, Suwon, Republic of Korea
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Lee BK, Lee SK, Yi KY, Yoo SE, Jung YS. KR-33028, a Novel Na+/H+Exchanger-1 Inhibitor, Attenuates Glutamate-Induced Apoptotic Cell Death through Maintaining Mitochondrial Function. Biomol Ther (Seoul) 2011. [DOI: 10.4062/biomolther.2011.19.4.445] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Akhtar M, Pillai KK, Najmi AK, Vohora D. Effect of amiloride: An Na / H exchange inhibitor in the middle cerebral artery occlusion model of focal cerebral ischemia in rats. JOURNAL OF PHARMACY AND BIOALLIED SCIENCES 2011; 3:519-24. [PMID: 22219585 PMCID: PMC3249699 DOI: 10.4103/0975-7406.90105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 03/26/2011] [Accepted: 05/06/2011] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The effect of pretreatment with amiloride (AML), an Na(+) / H(+) exchange inhibitor was studied in the middle cerebral artery occlusion (MCAO) model of focal cerebral ischemia in rats. MATERIALS AND METHODS Male wistar rats were subjected to 2 hr of MCAO followed by 22-hr reperfusion. Grip strength, locomotor activity, and spontaneous alternation performance were assessed after 24 hr. Immediately after behavioral activities, animals were sacrificed and the oxidative stress markers were estimated in brains. RESULTS An elevation of thiobarbituric acid reactive substances (TBARS), reduction in glutathione, and antioxidant enzymes activities, namely glutathione-S-transferase, glutathione peroxidase (GPx), glutathione reductase (GR), and superoxide dismutase (SOD) were observed following MCA occluded rats. Pretreatment with AML (0.91 and 1.82 mg/kg p.o) significantly reversed the MCAO-induced elevation in TBARS but could not reverse the other parameters. Paradoxically, AML further reduced the levels of GPx, GR, and SOD, but no significant changes were observed in the catalase activity, grip strength, and spontaneous alternation behavior of rats. Locomotor activity was reduced slightly but reversed on pretreatment with AML. CONCLUSIONS Although pretreatment with single dose of AML showed reduction in oxidative stress markers, further multiple doses of AML as pre- and post-treatments are required to establish its potential to be used in cerebral ischemia.
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Affiliation(s)
- Mohammad Akhtar
- Department of Pharmacology, Faculty of Pharmacy, Jamia Hamdard, Hamdard University, New Delhi, India
| | - K. K. Pillai
- Department of Pharmacology, Faculty of Pharmacy, Jamia Hamdard, Hamdard University, New Delhi, India
| | - Abul Kalam Najmi
- Department of Pharmacology, Faculty of Pharmacy, Jamia Hamdard, Hamdard University, New Delhi, India
| | - Divya Vohora
- Department of Pharmacology, Faculty of Pharmacy, Jamia Hamdard, Hamdard University, New Delhi, India
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Synthesis and Na+/H+ exchanger inhibitory activity of benzoylguanidine derivatives. Eur J Med Chem 2011; 46:4107-16. [PMID: 21724305 DOI: 10.1016/j.ejmech.2011.06.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/07/2011] [Accepted: 06/08/2011] [Indexed: 11/23/2022]
Abstract
Twenty-two compounds of substituted benzoylguanidine derivatives were designed and synthesized as potent NHE1 inhibitors. Twelve compounds showed more potent NHE1 inhibitory activity than cariporide. The activities of compounds 7e, 7h and 7j (IC(50) = 0.073 ± 0.021, 0.084 ± 0.012 and 0.068 ± 0.021 nmol/L, respectively) were two orders of magnitude higher than that of cariporide (30.7 ± 2.5 nmol/L). Myocardial cells in vitro screening showed 7j had highlighted protective effect on cardiomyocytes subjected to hypoxia/reoxygenation. Thus it is valuable for further investigation.
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Park SL, Lee DH, Yoo SE, Jung YS. The effect of Na+/H+ exchanger-1 inhibition by sabiporide on blood–brain barrier dysfunction after ischemia/hypoxia in vivo and in vitro. Brain Res 2010; 1366:189-96. [DOI: 10.1016/j.brainres.2010.09.077] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 09/20/2010] [Accepted: 09/21/2010] [Indexed: 10/19/2022]
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Mao D, Xu Y, Hu X, Zhang G, Dong J, Gong G. Synthesis and Na+/H+Exchanger-1 Inhibitory Activity of Substituted (Quinolinecarbonyl)guanidine Derivatives. Chem Biodivers 2009; 6:1727-36. [DOI: 10.1002/cbdv.200800268] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Xu WT, Jin N, Xu J, Xu YG, Wang QJ, You QD. Design, synthesis and biological evaluation of novel substituted benzoylguanidine derivatives as potent Na+/H+ exchanger inhibitors. Bioorg Med Chem Lett 2009; 19:3283-7. [DOI: 10.1016/j.bmcl.2009.04.079] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2008] [Revised: 03/30/2009] [Accepted: 04/20/2009] [Indexed: 10/20/2022]
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Lee BK, Lee DH, Park S, Park SL, Yoon JS, Lee MG, Lee S, Yi KY, Yoo SE, Lee KH, Kim YS, Lee SH, Baik EJ, Moon CH, Jung YS. Effects of KR-33028, a novel Na+/H+ exchanger-1 inhibitor, on glutamate-induced neuronal cell death and ischemia-induced cerebral infarct. Brain Res 2009; 1248:22-30. [DOI: 10.1016/j.brainres.2008.10.061] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 10/23/2008] [Accepted: 10/24/2008] [Indexed: 11/24/2022]
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Harguindey S, Orive G, Cacabelos R, Hevia EM, de Otazu RD, Arranz JL, Anitua E. An integral approach to the etiopathogenesis of human neurodegenerative diseases (HNDDs) and cancer. Possible therapeutic consequences within the frame of the trophic factor withdrawal syndrome (TFWS). Neuropsychiatr Dis Treat 2008; 4:1073-84. [PMID: 19337452 PMCID: PMC2646641 DOI: 10.2147/ndt.s3800] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A novel and integral approach to the understanding of human neurodegenerative diseases (HNDDs) and cancer based upon the disruption of the intracellular dynamics of the hydrogen ion (H(+)) and its physiopathology, is advanced. From an etiopathological perspective, the activity and/or deficiency of different growth factors (GFs) in these pathologies are studied, and their relationships to intracellular acid-base homeostasis reviewed. Growth and trophic factor withdrawal in HNDDs indicate the need to further investigate the potential utilization of certain GFs in the treatment of Alzheimer disease and other neurodegenerative diseases. Platelet abnormalities and the therapeutic potential of platelet-derived growth factors in these pathologies, either through platelet transfusions or other clinical methods, are considered. Finally, the etiopathogenic mechanisms of apoptosis and antiapoptosis in HNDDs and cancer are viewed as opposite biochemical and biological disorders of cellular acid-base balance and their secondary effects on intracellular signaling pathways and aberrant cell metabolism are considered in the light of the both the seminal and most recent data available. The "trophic factor withdrawal syndrome" is described for the first time in English-speaking medical literature, as well as a Darwinian-like interpretation of cellular behavior related to specific and nonspecific aspects of cell biology.
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Affiliation(s)
- Salvador Harguindey
- Institute of Clinical Biology and Metabolism, c/o Postas 13, 01004 Vitoria, Spain.
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Pettersen JC, Chouinard L, Kerlin RL, Groom SN, Botts S, Arezzo JC, Boucher MA, Frazier DE, Buchholz AR. Neurotoxic Effects of Zoniporide: A Selective Inhibitor of the Na+/H+ Exchanger Isoform 1. Toxicol Pathol 2008; 36:608-19. [DOI: 10.1177/0192623308318215] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Zoniporide, an inhibitor of the Na+-H+ exchanger-1, was administered by continuous intravenous infusion to rats and dogs for up to 1 month. In 1-month studies, histological and functional changes were observed in select portions of the peripheral nervous system; however, these findings were not detected in 2-week studies at similar or higher doses. In the 1-month rat study, there was dose-dependent, minimal, focal, or multifocal nerve fiber (axonal) degeneration in the spinal cord and/or sciatic nerve. In a follow-up rat study, findings included slowing of caudal nerve conduction velocity and axonal degeneration in the spinal cord (dorsal funiculus), dorsal roots, dorsal root ganglia (DRG), radial, sciatic, and tibial nerves. In the 1-month dog study, there was impairment of the patellar reflex and associated postural reaction changes, minimal to marked proximal nerve fiber degeneration in the DRG, and minimal nerve fiber degeneration in the dorsal roots and funiculi of the spinal cord. Minimal nerve fiber degeneration of equivocal significance was noted in various peripheral nerves. Taken together, these findings were consistent with a specific effect on peripheral sensory nerve fibers. These studies demonstrated that zoniporide produces clinical, electrophysiologic, and microscopic evidence of peripheral sensory axonopathy and establishes the importance of careful preclinical evaluation of neurological function.
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Affiliation(s)
- John C. Pettersen
- Pfizer Global Research and Development, Groton/New London Laboratories, Pfizer Inc., Groton, Connecticut, USA
| | - Luc Chouinard
- Charles River Laboratories, Preclinical Services, Montréal, Quebec, Canada
| | - Roy L. Kerlin
- Pfizer Global Research and Development, Groton/New London Laboratories, Pfizer Inc., Groton, Connecticut, USA
| | - Simon N. Groom
- Charles River Laboratories, Preclinical Services, Montréal, Quebec, Canada
| | - Suzanne Botts
- GlaxoSmithKline, Safety Assessment, Research Triangle Park, North Carolina, USA
| | - Joseph C. Arezzo
- Albert Einstein College of Medicine, Departments of Neuroscience and Neurology, Bronx, New York, USA
| | - Mary A. Boucher
- Pfizer Global Research and Development, Groton/New London Laboratories, Pfizer Inc., Groton, Connecticut, USA
| | | | - Allan R. Buchholz
- Pfizer Global Research and Development, Groton/New London Laboratories, Pfizer Inc., Groton, Connecticut, USA
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Hwang IK, Yoo KY, An SJ, Li H, Lee CH, Choi JH, Lee JY, Lee BH, Kim YM, Kwon YG, Won MH. Late expression of Na+/H+ exchanger 1 (NHE1) and neuroprotective effects of NHE inhibitor in the gerbil hippocampal CA1 region induced by transient ischemia. Exp Neurol 2008; 212:314-23. [PMID: 18511042 DOI: 10.1016/j.expneurol.2008.04.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 03/25/2008] [Accepted: 04/04/2008] [Indexed: 11/16/2022]
Abstract
Although acidosis may be involved in neuronal death, the participation of Na(+)/H(+) exchanger (NHE) in delayed neuronal death in the hippocampal CA1 region induced by transient forebrain ischemia has not been well established. In the present study, we investigated the chronological alterations of NHE1 in the hippocampal CA1 region using a gerbil model after ischemia/reperfusion. In the sham-operated group, NHE1 immunoreactivity was weakly detected in the CA1 region. Two and 3 days after ischemia/reperfusion, NHE1 immunoreactivity was observed in glial components, not in neurons, in the CA1 region. Four days after ischemia/reperfusion, NHE1 immunoreactivity was markedly increased in CA1 pyramidal neurons as well as glial cells. These glial cells were identified as astrocytes based on double immunofluorescence staining. Western blot analysis also showed that NHE protein level in the CA1 region began to increase 2 days after ischemia/reperfusion. The treatment of 10 mg/kg 5-(N-ethyl-N-isopropyl) amiloride, a NHE inhibitor, significantly reduced the ischemia-induced hyperactivity 1 day after ischemia/reperfusion. In addition, NHE inhibitor potently protected CA1 pyramidal neurons from ischemic damage, and NHE inhibitor attenuated the activation of astrocytes and microglia in the ischemic CA1 region. In addition, NHE inhibitor treatment blocked Na(+)/Ca(2+) exchanger 1 immunoreactivity in the CA1 region after transient forebrain ischemia. These results suggest that NHE1 may play a role in the delayed death, and the treatment with NHE inhibitor protects neurons from ischemic damage.
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Affiliation(s)
- In Koo Hwang
- Department of Anatomy and Cell Biology, College of Veterinary Medicine and BK21 Program for Veterinary Science, Seoul National University, Seoul 151-742, South Korea
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Mongin AA. Disruption of ionic and cell volume homeostasis in cerebral ischemia: The perfect storm. ACTA ACUST UNITED AC 2007; 14:183-93. [PMID: 17961999 DOI: 10.1016/j.pathophys.2007.09.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The mechanisms of brain tissue damage in stroke are strongly linked to the phenomenon of excitotoxicity, which is defined as damage or death of neural cells due to excessive activation of receptors for the excitatory neurotransmitters glutamate and aspartate. Under physiological conditions, ionotropic glutamate receptors mediate the processes of excitatory neurotransmission and synaptic plasticity. In ischemia, sustained pathological release of glutamate from neurons and glial cells causes prolonged activation of these receptors, resulting in massive depolarization and cytoplasmic Ca(2+) overload. High cytoplasmic levels of Ca(2+) activate many degradative processes that, depending on the metabolic status, cause immediate or delayed death of neural cells. This traditional view has been expanded by a number of observations that implicate Cl(-) channels and several types of non-channel transporter proteins, such as the Na(+),K(+),2Cl(-) cotransporter, Na(+)/H(+) exchanger, and Na(+)/Ca(2+) exchanger, in the development of glutamate toxicity. Some of these ion transporters increase tissue damage by promoting pathological cell swelling and necrotic cell death, while others contribute to a long-term accumulation of cytoplasmic Ca(2+). This brief review is aimed at illustrating how the dysregulation of various ion transport processes combine in a 'perfect storm' that disrupts neural ionic homeostasis and culminates in the irreversible damage and death of neural cells. The clinical relevance of individual transporters as targets for therapeutic intervention in stroke is also briefly discussed.
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Affiliation(s)
- Alexander A Mongin
- Center for Neuropharmacology and Neuroscience, Albany Medical College, 47 New Scotland Avenue (MC-136), Albany, NY 12208, USA
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