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Sivakumar S, Ghasemi M, Schachter SC. Targeting NMDA Receptor Complex in Management of Epilepsy. Pharmaceuticals (Basel) 2022; 15:ph15101297. [PMID: 36297409 PMCID: PMC9609646 DOI: 10.3390/ph15101297] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 10/17/2022] [Accepted: 10/20/2022] [Indexed: 11/05/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are widely distributed in the central nervous system (CNS) and play critical roles in neuronal excitability in the CNS. Both clinical and preclinical studies have revealed that the abnormal expression or function of these receptors can underlie the pathophysiology of seizure disorders and epilepsy. Accordingly, NMDAR modulators have been shown to exert anticonvulsive effects in various preclinical models of seizures, as well as in patients with epilepsy. In this review, we provide an update on the pathologic role of NMDARs in epilepsy and an overview of the NMDAR antagonists that have been evaluated as anticonvulsive agents in clinical studies, as well as in preclinical seizure models.
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Affiliation(s)
- Shravan Sivakumar
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
| | - Mehdi Ghasemi
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
- Correspondence: (M.G.); (S.C.S.)
| | - Steven C. Schachter
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02114, USA
- Consortia for Improving Medicine with Innovation & Technology (CIMIT), Boston, MA 02114, USA
- Correspondence: (M.G.); (S.C.S.)
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Yi H, Yu S, Zhang Y, Li R, Zhang D, Zhang D, Xu W. Preventive effects of ketone ester BD-AcAc 2 on central nervous system oxygen toxicity and concomitant acute lung injury. Diving Hyperb Med 2019; 48:235-240. [PMID: 30517956 DOI: 10.28920/dhm48.4.235-240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 10/28/2018] [Indexed: 02/01/2023]
Abstract
BACKGROUND Recent studies indicated that ketone ester R,S-1,3-butanediol acetoacetate diester (BD-AcAc2) may be effective in preventing central nervous system oxygen toxicity (CNS-OT) and concomitant acute lung injury, a serious medical problem to be faced when breathing hyperbaric oxygen (HBO). This study aimed to further investigate the protective effects of BD-AcAc2 against CNS-OT and concomitant acute lung injury (ALI) in mice. METHODS Mice were treated with BD-AcAc2 in peanut oil vehicle (2.5, 5.0 or 10.0 g·kg⁻² body weight) by gavage 20 minutes before 600 kPa HBO exposure. Control mice received the vehicle only. Seizure latency was recorded. Malondialdehyde content in brain and lung tissues, total protein level in bronchoalveolar lavage fluid (BLF) and lung water content were measured 60 minutes after the hyperbaric exposure. Histopathology of lung tissue was undertaken. RESULTS Compared with the vehicle alone, BD-AcAc2 prolonged seizure latency in a dose-dependent manner (P < 0.01). The HBO-induced increase in brain malondialdehyde, BLF protein and lung water were significantly reduced by BD-AcAc2 (P < 0.01). CONCLUSION Oral administration of the ketone ester BD-AcAc2 significantly protected against CNS-OT and concomitant ALI. Alleviation of oxidative stress may be one underlying mechanism providing this effect.
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Affiliation(s)
- Hongjie Yi
- Department of Diving and Hyperbaric Medicine, Naval Medical University, Shanghai, P R China
| | - Shichong Yu
- Department of Organic Chemistry, Naval Medical University, Shanghai
| | - Yanan Zhang
- Department of Diving and Hyperbaric Medicine, Naval Medical University, Shanghai, P R China
| | - Runping Li
- Department of Diving and Hyperbaric Medicine, Naval Medical University, Shanghai, P R China
| | - Dazhi Zhang
- Department of Organic Chemistry, Naval Medical University, Shanghai
| | - Dazhi Zhang
- Department of Diving and Hyperbaric Medicine, Naval Medical University, Shanghai, P R China
| | - Weigang Xu
- Department of Diving and Hyperbaric Medicine, Naval Medical University, Shanghai, P R China.,Corresponding author: Department of Diving and Hyperbaric Medicine, Naval Medical University, Shanghai 200433, China,
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Ari C, Koutnik AP, DeBlasi J, Landon C, Rogers CQ, Vallas J, Bharwani S, Puchowicz M, Bederman I, Diamond DM, Kindy MS, Dean JB, D′Agostino DP. Delaying latency to hyperbaric oxygen-induced CNS oxygen toxicity seizures by combinations of exogenous ketone supplements. Physiol Rep 2019; 7:e13961. [PMID: 30604923 PMCID: PMC6317287 DOI: 10.14814/phy2.13961] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 11/28/2018] [Accepted: 11/29/2018] [Indexed: 11/24/2022] Open
Abstract
Central nervous system oxygen toxicity (CNS-OT) manifests as tonic-clonic seizures and is a limitation of hyperbaric oxygen therapy (HBOT), as well as of recreational and technical diving associated with elevated partial pressure of oxygen. A previous study showed that ketone ester (1,3-butanediol acetoacetate diester, KE) administration delayed latency to seizures (LS) in 3-month-old Sprague-Dawley (SD) rats. This study explores the effect of exogenous ketone supplements in additional dosages and formulations on CNS-OT seizures in 18 months old SD rats, an age group correlating to human middle age. Ketogenic agents were given orally 60 min prior to exposure to hyperbaric oxygen and included control (water), KE (10 g/kg), KE/2 (KE 5 g/kg + water 5 g/kg), KE + medium-chain triglycerides (KE 5 g/kg + MCT 5 g/kg), and ketone salt (Na+ /K+ βHB, KS) + MCT (KS 5 g/kg + MCT 5 g/kg). Rats were exposed to 100% oxygen at 5 atmospheres absolute (ATA). Upon seizure presentation (tonic-clonic movements) experiments were immediately terminated and blood was tested for glucose and D-beta-hydroxybutyrate (D-βHB) levels. While blood D-βHB levels were significantly elevated post-dive in all treatment groups, LS was significantly delayed only in KE (P = 0.0003), KE/2 (P = 0.023), and KE + MCT (P = 0.028) groups. In these groups, the severity of seizures appeared to be reduced, although these changes were significant only in KE-treated animals (P = 0.015). Acetoacetate (AcAc) levels were also significantly elevated in KE-treated animals. The LS in 18-month-old rats was delayed by 179% in KE, 219% in KE + MCT, and 55% in KE/2 groups, while only by 29% in KS + MCT. In conclusion, KE supplementation given alone and in combination with MCT elevated both βHB and AcAc, and delayed CNS-OT seizures.
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Affiliation(s)
- Csilla Ari
- Department of PsychologyHyperbaric Neuroscience Research LaboratoryUniversity of South FloridaTampaFlorida
| | - Andrew P. Koutnik
- Department of Molecular Pharmacology and PhysiologyLaboratory of Metabolic MedicineUniversity of South FloridaTampaFlorida
| | - Janine DeBlasi
- Department of Molecular Pharmacology and PhysiologyLaboratory of Metabolic MedicineUniversity of South FloridaTampaFlorida
| | - Carol Landon
- Department of Molecular Pharmacology and PhysiologyHyperbaric Biomedical Research LaboratoryUniversity of South FloridaTampaFlorida
| | - Christopher Q. Rogers
- Department of Molecular Pharmacology and PhysiologyLaboratory of Metabolic MedicineUniversity of South FloridaTampaFlorida
| | - John Vallas
- Department of PsychologyHyperbaric Neuroscience Research LaboratoryUniversity of South FloridaTampaFlorida
| | - Sahil Bharwani
- Department of PsychologyHyperbaric Neuroscience Research LaboratoryUniversity of South FloridaTampaFlorida
| | - Michelle Puchowicz
- Department of PediatricsUniversity of Tennessee Health Science CenterMemphisTennessee
| | - Ilya Bederman
- Department of PediatricsCase Western Reserve UniversityClevelandOhio
- Department of NutritionCase Western Reserve UniversityClevelandOhio
| | - David M. Diamond
- Department of PsychologyHyperbaric Neuroscience Research LaboratoryUniversity of South FloridaTampaFlorida
- Department of Molecular Pharmacology and PhysiologyLaboratory of Metabolic MedicineUniversity of South FloridaTampaFlorida
| | - Mark S. Kindy
- Department of Pharmaceutical SciencesCollege of PharmacyUniversity of South FloridaTampaFlorida
- James A. Haley VA Medical CenterTampaFlorida
- Shriners Hospital for ChildrenTampaFlorida
| | - Jay B. Dean
- Department of Molecular Pharmacology and PhysiologyHyperbaric Biomedical Research LaboratoryUniversity of South FloridaTampaFlorida
| | - Dominic P. D′Agostino
- Department of Molecular Pharmacology and PhysiologyLaboratory of Metabolic MedicineUniversity of South FloridaTampaFlorida
- Institute for Human and Machine CognitionOcalaFlorida
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Abstract
INTRODUCTION The use of hyperbaric oxygen (O2) as a therapeutic agent carries with it the risk of central nervous system (CNS) O2 toxicity. METHODS To further the understanding of this risk and the nature of its molecular mechanism, a review was conducted on the literature from various fields. RESULTS Numerous physiological changes are produced by increased partial pressures of oxygen (Po2), which may ultimately result in CNS O2 toxicity. The human body has several equilibrated safeguards that minimize effects of reactive species on neural networks, believed to play a primary role in CNS O2 toxicity. Increased partial pressure of oxygen (Po2) appears to saturate protective enzymes and unfavorably shift protective reactions in the direction of neural network overstimulation. Certain regions of the CNS appear more susceptible than others to these effects. Failure to decrease the elevated Po2 can result in a tonic-clonic seizure and death. Randomized, controlled studies in human populations would require a multicenter trial over a long period of time with numerous endpoints used to identify O2 toxicity. CONCLUSIONS The mounting scientific evidence and apparent increase in the number of hyperbaric O2 treatments demonstrate a need for further study in the near future.
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Alttas O, Haffor AS. Effects of hyperoxia periodic training on free radicals production, biological antioxidants potential and lactate dehydrogenase activity in the lungs of rats, Rattus norvigicus. Saudi J Biol Sci 2013; 17:65-71. [PMID: 23961060 DOI: 10.1016/j.sjbs.2009.12.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Oxygen therapy has been widely used in lung injury (Li), adult respiraotory syndrome (ARDS) and inflammatory lung diseases as well as in mechanical ventilation in intensive care units. Exposure to hyperoxia is known to induct the production of reactive oxygen species (ROS) by mitochondria. Despite decades of research, the role of hyperoxia training in oxidative stress and ROS formation in the lungs is not known. The purpose of this study was to examine the effects of periodic-hyperoxia training on biological antioxidants (BAP) and lactate dehydrogenase (LDH) activities and free radicals (FR) production. Thirty adult male rats, matched with age and body weigh, were randomly assigned to three groups. The first group served as control (C) and the second (HP) was exposed to hyperoxia for 48. Animals in the third group (HP-T) were trained on hyperoxia for 1.5 h daily for three weeks. Following the exposure period for each group animals were sacrificed and lungs tissues were homogenized for BAP, LDH and FR determinations. LDH activity was determined by Randox protocol (Randox - UK). BAP and FR were determined using dROM method (H&D - Italy). Results showed that mean (±SD) BAP activity increased significantly (p < 0.05) from the baseline control of 7105.88 ± 2021.49 to 8611.20 ± 1245.26 (U/L) after hyperoxia training; then dropped to 6784.00 ± 1879.50 during hyperoxia exposure for 48 h. Whereas mean (±SD) FR production increased significantly (p < 0.05) from the baseline control of 262.50 ± 67.52 to 339.90 ± 64.84 during HP exposure for 48 h, then dropped to 211.13 ± 52.05 (Carr), during HP training. Similarly, LDH activity increased significantly (p < 0.05) from the baseline control of 210.31 ± 70.93 to 339.90 ± 64.84 during HP exposure for 48 h, then dropped to 159.30 ± 20.61(U/L), following HP-periodic training. Furthermore, the correlation (r = 0.67×) of LDH on FR was significant (p < 0.05), implying that reduction in ROS generation induced by HP-periodic training is related to reduced rate of cell apoptosis caused oxidative stress. Based on the results of the present study HP-periodic training is recommended in order to resist oxidative damage in the lungs.
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Affiliation(s)
- Omar Alttas
- Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
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D'Agostino DP, Pilla R, Held HE, Landon CS, Puchowicz M, Brunengraber H, Ari C, Arnold P, Dean JB. Therapeutic ketosis with ketone ester delays central nervous system oxygen toxicity seizures in rats. Am J Physiol Regul Integr Comp Physiol 2013; 304:R829-36. [PMID: 23552496 DOI: 10.1152/ajpregu.00506.2012] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Central nervous system oxygen toxicity (CNS-OT) seizures occur with little or no warning, and no effective mitigation strategy has been identified. Ketogenic diets (KD) elevate blood ketones and have successfully treated drug-resistant epilepsy. We hypothesized that a ketone ester given orally as R,S-1,3-butanediol acetoacetate diester (BD-AcAc(2)) would delay CNS-OT seizures in rats breathing hyperbaric oxygen (HBO(2)). Adult male rats (n = 60) were implanted with radiotelemetry units to measure electroencephalogram (EEG). One week postsurgery, rats were administered a single oral dose of BD-AcAc(2), 1,3-butanediol (BD), or water 30 min before being placed into a hyperbaric chamber and pressurized to 5 atmospheres absolute (ATA) O2. Latency to seizure (LS) was measured from the time maximum pressure was reached until the onset of increased EEG activity and tonic-clonic contractions. Blood was drawn at room pressure from an arterial catheter in an additional 18 animals that were administered the same compounds, and levels of glucose, pH, Po(2), Pco(2), β-hydroxybutyrate (BHB), acetoacetate (AcAc), and acetone were analyzed. BD-AcAc(2) caused a rapid (30 min) and sustained (>4 h) elevation of BHB (>3 mM) and AcAc (>3 mM), which exceeded values reported with a KD or starvation. BD-AcAc(2) increased LS by 574 ± 116% compared with control (water) and was due to the effect of AcAc and acetone but not BHB. BD produced ketosis in rats by elevating BHB (>5 mM), but AcAc and acetone remained low or undetectable. BD did not increase LS. In conclusion, acute oral administration of BD-AcAc(2) produced sustained ketosis and significantly delayed CNS-OT seizures by elevating AcAc and acetone.
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Affiliation(s)
- Dominic P D'Agostino
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
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Ghasemi M, Schachter SC. The NMDA receptor complex as a therapeutic target in epilepsy: a review. Epilepsy Behav 2011; 22:617-40. [PMID: 22056342 DOI: 10.1016/j.yebeh.2011.07.024] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 07/01/2011] [Accepted: 07/18/2011] [Indexed: 01/02/2023]
Abstract
A substantial amount of research has shown that N-methyl-D-aspartate receptors (NMDARs) may play a key role in the pathophysiology of several neurological diseases, including epilepsy. Animal models of epilepsy and clinical studies demonstrate that NMDAR activity and expression can be altered in association with epilepsy and particularly in some specific seizure types. NMDAR antagonists have been shown to have antiepileptic effects in both clinical and preclinical studies. There is some evidence that conventional antiepileptic drugs may also affect NMDAR function. In this review, we describe the evidence for the involvement of NMDARs in the pathophysiology of epilepsy and provide an overview of NMDAR antagonists that have been investigated in clinical trials and animal models of epilepsy.
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Affiliation(s)
- Mehdi Ghasemi
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Park JH, Lee HJ, Koh SB, Ban JY, Seong YH. Protection of NMDA-induced neuronal cell damage by methanol extract of zizyphi spinosi semen in cultured rat cerebellar granule cells. JOURNAL OF ETHNOPHARMACOLOGY 2004; 95:39-45. [PMID: 15374605 DOI: 10.1016/j.jep.2004.06.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2003] [Revised: 04/24/2004] [Accepted: 06/08/2004] [Indexed: 05/24/2023]
Abstract
Zizypus is one of the herbs widely used in Korea and China due to the CNS calming effect. The present study aims to investigate the effect of the methanol extract of Zizyphi Spinosi Semen (ZSS), the seeds of Zizyphus jujuba Mill var. spinosa, on N-methyl-D-aspartate (NMDA)-induced neurotoxicity in cultured rat cerebellar granule neuron. ZSS, over a concentration range of 0.05-5 microg/ml, inhibited NMDA (1 mM)-induced neuronal cell death, which was measured by a trypan blue exclusion test and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay. ZSS (0.5 microg/ml) inhibited glutamate release into medium induced by NMDA (1mM), which was measured by HPLC. Pretreatment of ZSS (0.5 microg/ml) inhibited NMDA (1mM)-induced elevation of cytosolic calcium concentration ([Ca(2+)](c)), which was measured by a fluorescent dye, Fura 2-AM, and generation of reactive oxygen species (ROS). These results suggest that ZSS prevents NMDA-induced neuronal cell damage in vitro.
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Affiliation(s)
- Jeong Hee Park
- College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk 361-763, South Korea
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Tuovinen K. Organophosphate-induced convulsions and prevention of neuropathological damages. Toxicology 2004; 196:31-9. [PMID: 15036754 DOI: 10.1016/j.tox.2003.10.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Revised: 09/29/2003] [Accepted: 10/24/2003] [Indexed: 11/27/2022]
Abstract
Such organophosphorus (OP) compounds as diisopropylfluorophosphate (DFP), sarin and soman are potent inhibitors of acetylcholinesterases (AChEs) and butyrylcholinesterases (BChEs). The acute toxicity of OPs is the result of their irreversible binding with AChEs in the central nervous system (CNS), which elevates acetylcholine (ACh) levels. The protective action of subcutaneously (SC) administered antidotes or their combinations in DFP (2.0 mg/kg BW) intoxication was studied in 9-10-weeks-old Han-Wistar male rats. The rats received AChE reactivator pralidoxime-2-chloride (2PAM) (30.0 mg/kg BW), anticonvulsant diazepam (2.0 mg/kg BW), A(1)-adenosine receptor agonist N(6)-cyclopentyl adenosine (CPA) (2.0 mg/kg BW), NMDA-receptor antagonist dizocilpine maleate (+-MK801 hydrogen maleate) (2.0 mg/kg BW) or their combinations with cholinolytic drug atropine sulfate (50.0 mg/kg BW) immediately or 30 min after the single SC injection of DFP. The control rats received atropine sulfate, but also saline and olive oil instead of other antidotes and DFP, respectively. All rats were terminated either 24 h or 3 weeks after the DFP injection. The rats treated with DFP-atropine showed severe typical OP-induced toxicity signs. When CPA, diazepam or 2PAM was given immediately after DFP-atropine, these treatments prevented, delayed or shortened the occurrence of serious signs of poisoning. Atropine-MK801 did not offer any additional protection against DFP toxicity. In conclusion, CPA, diazepam and 2PAM in combination with atropine prevented the occurrence of serious signs of poisoning and thus reduced the toxicity of DFP in rat.
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Affiliation(s)
- Kai Tuovinen
- Department of Physiology, University of Kuopio, P.O. Box 1627, SF-70211 Kuopio, Finland
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Dean JB, Mulkey DK, Garcia AJ, Putnam RW, Henderson RA. Neuronal sensitivity to hyperoxia, hypercapnia, and inert gases at hyperbaric pressures. J Appl Physiol (1985) 2003; 95:883-909. [PMID: 12909594 DOI: 10.1152/japplphysiol.00920.2002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
As ambient pressure increases, hydrostatic compression of the central nervous system, combined with increasing levels of inspired Po2, Pco2, and N2 partial pressure, has deleterious effects on neuronal function, resulting in O2 toxicity, CO2 toxicity, N2 narcosis, and high-pressure nervous syndrome. The cellular mechanisms responsible for each disorder have been difficult to study by using classic in vitro electrophysiological methods, due to the physical barrier imposed by the sealed pressure chamber and mechanical disturbances during tissue compression. Improved chamber designs and methods have made such experiments feasible in mammalian neurons, especially at ambient pressures <5 atmospheres absolute (ATA). Here we summarize these methods, the physiologically relevant test pressures, potential research applications, and results of previous research, focusing on the significance of electrophysiological studies at <5 ATA. Intracellular recordings and tissue Po2 measurements in slices of rat brain demonstrate how to differentiate the neuronal effects of increased gas pressures from pressure per se. Examples also highlight the use of hyperoxia (<or=3 ATA O2) as a model for studying the cellular mechanisms of oxidative stress in the mammalian central nervous system.
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Affiliation(s)
- Jay B Dean
- Department of Anatomy and Physiology, Wright State University, Dayton, OH 45435, USA.
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Manjarrez J, Alvarado R, Camacho-Arroyo I. Differential effects of NMDA antagonists microinjections into the nucleus reticularis pontis caudalis on seizures induced by pentylenetetrazol in the rat. Epilepsy Res 2001; 46:39-44. [PMID: 11395287 DOI: 10.1016/s0920-1211(01)00256-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
It has been shown that NMDA antagonists block the tonic but not the clonic component of seizures when they are injected in the oral region of the rat pontine reticular formation (PRF). The participation of the caudal PRF in the effects of NMDA antagonists upon the tonic and the clonic components of generalized seizures induced by pentylenetetrazol (PTZ) is unknown. The aim of the present study was to evaluate the effects of unilateral microinjections of competitive and non-competitive NMDA antagonists, 2-amino-7-phosphonoheptanoic acid (AP-7) and dizocilpine (MK-801), respectively, into the nucleus reticularis pontis caudalis of the rat PRF upon seizures induced by PTZ (70 mg/kg i.p.). MK-801 induced a dose-related decrease both in the incidence of generalized tonic-clonic seizures (GTCS) and in the presence of spikes in the EEG. MK-801 also increased GTCS latency. On the contrary, AP-7 did not have effects on GTCS. Interestingly, it induced ipsilateral circling behavior. These results suggest that in the caudal region of the rat PRF only non-competitive NMDA antagonists should block the generation of tonic and clonic components of generalized seizures.
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Affiliation(s)
- J Manjarrez
- Unidad de Investigaciones Cerebrales, Instituto Nacional de Neurología y Neurocirugía MVS, México, D.F. Mexico
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Chavko M, Xing G, Keyser DO. Increased sensitivity to seizures in repeated exposures to hyperbaric oxygen: role of NOS activation. Brain Res 2001; 900:227-33. [PMID: 11334802 DOI: 10.1016/s0006-8993(01)02301-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitric oxide is involved in the mechanism of hyperbaric oxygen (HBO(2)) brain toxicity as nitric oxide synthase (NOS) inhibitors delay latent time before the onset of seizures. The purpose of this study was to investigate if seizures affect sensitivity to convulsions during subsequent exposure to HBO(2) and to determine if NOS activity and expression is changed after HBO(2) seizures. Rats were exposed to 5 atm (gauge pressure) 100% O(2) until seizures recorded by electroencephalograph (EEG) and reexposed 1, 2, or 6 days later. Latency to seizures was significantly shorter (P<0.05) in animals reexposed 1 or 2 days after the first exposure. Activity of calcium-dependent NOS activity in cortex was significantly higher 1 and 2 days after seizures compared with controls (P<0.05), while calcium-independent NOS activity was not changed during the 6-day post-seizure interval. The expression of neuronal NOS (nNOS) protein determined by Western blot was higher 1 and 2 days after seizures (P<0.05), while the expression of endothelial (eNOS) and inducible (iNOS) remained unchanged. nNOS upregulation 1 and 2 days after seizures and protection against HBO(2) seizures by nNOS-specific inhibitor 7-nitroindazole (7-NI) suggest possible involvement of NO in the mechanism of increased sensitivity to HBO(2) in reexposures.
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Affiliation(s)
- M Chavko
- Environmental Physiology Department, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
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13
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Badr AE, Yin W, Mychaskiw G, Zhang JH. Dual effect of HBO on cerebral infarction in MCAO rats. Am J Physiol Regul Integr Comp Physiol 2001; 280:R766-70. [PMID: 11171656 DOI: 10.1152/ajpregu.2001.280.3.r766] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Various reports in the literature have shown that hyperbaric oxygen (HBO) reduces cerebral infarction both in animals and humans. After the initial ischemic insult, however, initiating HBO treatment at different intervals has yielded conflicting results. The present study was undertaken to determine the optimal therapeutic window in which to start HBO treatment for cerebral infarction after transient focal ischemia. In this study, the operator occluded the middle cerebral artery (MCA) of anesthetized rats by introducing a blunted nylon filament into the proximal MCA from the dissected external carotid artery. When the operator removed the filament after 2 h, focal ischemia and reperfusion occurred. The operator then placed the rat in the HBO chamber and administered 3 atm absolute HBO for 1 h according to the protocol. The rat was killed 24 h after reperfusion, and the percentage of infarction (infarct ratio) was calculated by dividing the infarction area by the total area of the ipsilateral hemisphere. The results showed that the percentage of infarcted area decreased significantly (P < 0.05) both in the 3- (7.59%) and 6-h (5.35%) HBO-treatment groups compared with the control (no treatment) group (11.34%). However, the percentage of infarcted area increased significantly (P < 0.01 and P < 0.05, respectively) both in the 12- (23%) and 23-h (20%) treatment groups. The results of this study suggest that applying HBO within 6 h of ischemia-reperfusion injury could benefit the patient but that applying HBO 12 h or more after injury could harm the patient.
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Affiliation(s)
- A E Badr
- Department of Neurosurgery, the University of Mississippi Medical Center, Jackson, Mississippi 39216-4505, USA
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