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Demchenko IT, Zhilyaev SY, Platonova TF, Alekseeva OS, Nikitina ER. Inhibition of GABA-Transaminase and GABA-Transporters in the Brain by Vigabatrin and Tiagabine Prevents Seizure Development in Rats Breathing Hyperbaric Oxygen. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021050112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Stavitzski NM, Landon CS, Hinojo CM, Poff AM, Rogers CQ, D'Agostino DP, Dean JB. Exogenous ketone ester delays CNS oxygen toxicity without impairing cognitive and motor performance in male Sprague-Dawley rats. Am J Physiol Regul Integr Comp Physiol 2021; 321:R100-R111. [PMID: 34132115 DOI: 10.1152/ajpregu.00088.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 06/11/2021] [Indexed: 11/22/2022]
Abstract
Hyperbaric oxygen (HBO2) is breathing >1 atmosphere absolute (ATA; 101.3 kPa) O2 and is used in HBO2 therapy and undersea medicine. What limits the use of HBO2 is the risk of developing central nervous system (CNS) oxygen toxicity (CNS-OT). A promising therapy for delaying CNS-OT is ketone metabolic therapy either through diet or exogenous ketone ester (KE) supplement. Previous studies indicate that KE induces ketosis and delays the onset of CNS-OT; however, the effects of exogeneous KE on cognition and performance are understudied. Accordingly, we tested the hypothesis that oral gavage with 7.5 g/kg induces ketosis and increases the latency time to seizure (LSz) without impairing cognition and performance. A single oral dose of 7.5 g/kg KE increases systemic β-hydroxybutyrate (BHB) levels within 0.5 h and remains elevated for 4 h. Male rats were separated into three groups: control (no gavage), water-gavage, or KE-gavage, and were subjected to behavioral testing while breathing 1 ATA (101.3 kPa) of air. Testing included the following: DigiGait (DG), light/dark (LD), open field (OF), and novel object recognition (NOR). There were no adverse effects of KE on gait or motor performance (DG), cognition (NOR), and anxiety (LD, OF). In fact, KE had an anxiolytic effect (OF, LD). The LSz during exposure to 5 ATA (506.6 kPa) O2 (≤90 min) increased 307% in KE-treated rats compared with control rats. In addition, KE prevented seizures in some animals. We conclude that 7.5 g/kg is an optimal dose of KE in the male Sprague-Dawley rat model of CNS-OT.
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Affiliation(s)
- Nicole M Stavitzski
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Carol S Landon
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Christopher M Hinojo
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Angela M Poff
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Christopher Q Rogers
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Dominic P D'Agostino
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, Florida
- Institute of Human Machine and Cognition, Ocala, Florida
| | - Jay B Dean
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, Florida
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Ciarlone GE, Hinojo CM, Stavitzski NM, Dean JB. CNS function and dysfunction during exposure to hyperbaric oxygen in operational and clinical settings. Redox Biol 2019; 27:101159. [PMID: 30902504 PMCID: PMC6859559 DOI: 10.1016/j.redox.2019.101159] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/20/2019] [Accepted: 03/01/2019] [Indexed: 12/26/2022] Open
Abstract
Hyperbaric oxygen (HBO2) is breathed during hyperbaric oxygen therapy and during certain undersea pursuits in diving and submarine operations. What limits exposure to HBO2 in these situations is the acute onset of central nervous system oxygen toxicity (CNS-OT) following a latent period of safe oxygen breathing. CNS-OT presents as various non-convulsive signs and symptoms, many of which appear to be of brainstem origin involving cranial nerve nuclei and autonomic and cardiorespiratory centers, which ultimately spread to higher cortical centers and terminate as generalized tonic-clonic seizures. The initial safe latent period makes the use of HBO2 practical in hyperbaric and undersea medicine; however, the latent period is highly variable between individuals and within the same individual on different days, making it difficult to predict onset of toxic indications. Consequently, currently accepted guidelines for safe HBO2 exposure are highly conservative. This review examines the disorder of CNS-OT and summarizes current ideas on its underlying pathophysiology, including specific areas of the CNS and fundamental neural and redox signaling mechanisms that are thought to be involved in seizure genesis and propagation. In addition, conditions that accelerate the onset of seizures are discussed, as are current mitigation strategies under investigation for neuroprotection against redox stress while breathing HBO2 that extend the latent period, thus enabling safer and longer exposures for diving and medical therapies.
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Affiliation(s)
- Geoffrey E Ciarlone
- Undersea Medicine Department, Naval Medical Research Center, 503 Robert Grant Ave., Silver Spring, MD, USA
| | - Christopher M Hinojo
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Nicole M Stavitzski
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Jay B Dean
- Department of Molecular Pharmacology and Physiology, Hyperbaric Biomedical Research Laboratory, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.
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Demchenko IT, Zhilyaev SY, Alekseeva OS, Krivchenko AI, Piantadosi CA, Gasier HG. Increased Antiseizure Effectiveness with Tiagabine Combined with Sodium Channel Antagonists in Mice Exposed to Hyperbaric Oxygen. Neurotox Res 2019; 36:788-795. [PMID: 31148118 DOI: 10.1007/s12640-019-00063-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/24/2019] [Accepted: 05/09/2019] [Indexed: 10/26/2022]
Abstract
Hyperbaric oxygen (HBO2) is acutely toxic to the central nervous system, culminating in EEG spikes and tonic-clonic convulsions. GABA enhancers and sodium channel antagonists improve seizure latencies in HBO2 when administered individually, while combining antiepileptic drugs from different functional classes can provide greater seizure latency. We examined the combined effectiveness of GABA enhancers (tiagabine and gabapentin) with sodium channel antagonists (carbamazepine and lamotrigine) in delaying HBO2-induced seizures. A series of experiments in C57BL/6 mice exposed to 100% oxygen at 5 atmospheres absolute (ATA) were performed. We predicted equally effective doses from individual drug-dose response curves, and the combinations of tiagabine + carbamazepine or lamotrigine were tested to determine the maximally effective combined doses to be used in subsequent experiments designed to identify the type of pharmacodynamic interaction for three fixed-ratio combinations (1:3, 1:1, and 3:1) using isobolographic analysis. For both combinations, the maximally effective combined doses increased seizure latency over controls > 5-fold and were determined to interact synergistically for fixed ratios 1:1 and 3:1, additive for 1:3. These results led us to explore whether the benefits of these drug combinations could be extended to the lungs, since a centrally mediated mechanism is believed to mediate hyperoxic-induced cardiogenic lung injury. Indeed, both combinations attenuated bronchoalveolar lavage protein content by ~ 50%. Combining tiagabine with carbamazepine or lamotrigine not only affords greater antiseizure protection in HBO2 but also allows for lower doses to be used, minimizing side effects, and attenuating acute lung injury.
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Affiliation(s)
- Ivan T Demchenko
- Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Durham, NC, USA.,Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Sergei Yu Zhilyaev
- Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Olga S Alekseeva
- Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Alexander I Krivchenko
- Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Claude A Piantadosi
- Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Durham, NC, USA.,Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA.,Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Heath G Gasier
- Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
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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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Petersen K, Regis DP. Safety of antimalarial medications for use while scuba diving in malaria Endemic Regions. TROPICAL DISEASES TRAVEL MEDICINE AND VACCINES 2017; 2:23. [PMID: 28883967 PMCID: PMC5530948 DOI: 10.1186/s40794-016-0041-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 10/07/2016] [Indexed: 11/24/2022]
Abstract
Background Recreational diving occurs annually in areas of the world where malaria is endemic. The safety and efficacy of antimalarials for travelers in a hyperbaric environment is unknown. Of particular concern would be medications with adverse effects that could either mimic diving related illnesses such as barotrauma, decompression sickness (DCS) and gas toxicities, or increase the risk for such illnesses. Methods We conducted a review of PubMed and Cochrane databases to determine rates of neurologic adverse effects or other effects from antimalarials that may be a problem in the diving environment. Results One case report was found on diving and mefloquine. Multiple case reports and clinical trials were found describing neurologic adverse effects of the major chemoprophylactic medications atovaquone/proguanil, chloroquine, doxycycline, mefloquine, and primaquine. Conclusions Of the available literature, atovaquone/proguanil and doxycycline are most likely the safest agents and should be preferred; atovaquone/proguanil is superior due to reduced rates of sunburn in the marine environment. Primaquine also appears to be safe, but has reduced efficacy against P. falciparum; mefloquine possesses the highest rate of neurologic side effects and therefore these agents should be limited to extreme cases of patients intolerant to other agents. Chloroquine appears unsafe in the hyperbaric environment and should be avoided. More studies are required to include database reviews of returned divers traveling to malaria endemic areas and randomized controlled trials in the hyperbaric environments.
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Affiliation(s)
- Kyle Petersen
- Department of Medicine, Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, 4301 Jones Bridge Rd, Bethesda, MD 20814 USA
| | - David P Regis
- Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, 4301 Jones Bridge Rd, Bethesda, MD 20814 USA
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Gasier HG, Demchenko IT, Tatro LG, Piantadosi CA. S-nitrosylation of GAD65 is implicated in decreased GAD activity and oxygen-induced seizures. Neurosci Lett 2017; 653:283-287. [PMID: 28579483 DOI: 10.1016/j.neulet.2017.05.067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 05/22/2017] [Accepted: 05/30/2017] [Indexed: 11/19/2022]
Abstract
Breathing oxygen at partial pressures ≥2.5 atmospheres absolute, which can occur in diving and hyperbaric oxygen (HBO2) therapy, can rapidly become toxic to the central nervous system (CNS). This neurotoxicity culminates in generalized EEG epileptiform discharges, tonic-clonic convulsions and ultimately death. Increased production of neuronal nitric oxide (NO) has been implicated in eliciting hyperoxic seizures by altering the equilibrium between glutamatergic and GABAergic synaptic transmission. Inhibition of glutamic acid decarboxylase (GAD) activity in HBO2 promotes this imbalance; however, the mechanisms by which this occurs is unknown. Therefore, we conducted a series of experiments using mice, a species that is highly susceptible to CNS oxygen toxicity, to explore the possibility that NO modulates GABA metabolism. Mice were exposed to 100% oxygen at 4 ATA for various durations, and brain GAD and GABA transaminase (GABA-T) activity, as well as S-nitrosylation of GAD65 and GAD67 were determined. HBO2 inhibited GAD activity by 50% and this was negatively correlated with S-nitrosylation of GAD65, whereas GABA-T activity and S-nitrosylation of GAD67 were unaltered. These results suggest a new mechanism by which NO alters GABA metabolism, leading to neuroexcitation and seizures in HBO2.
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Affiliation(s)
- Heath G Gasier
- Department of Military and Emergency Medicine, Uniformed Services University of the Health Science, Bethesda, MD, 20814, USA.
| | - Ivan T Demchenko
- Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Lynn G Tatro
- Durham Veterans Affairs Hospital, Durham, NC, 20814, USA
| | - Claude A Piantadosi
- Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA; Durham Veterans Affairs Hospital, Durham, NC, 20814, USA; Departments of Medicine and Pathology, Duke University Medical Center, Durham, NC, 27710, USA
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Demchenko IT, Zhilyaev SY, Moskvin AN, Krivchenko AI, Piantadosi CA, Allen BW. Antiepileptic drugs prevent seizures in hyperbaric oxygen: A novel model of epileptiform activity. Brain Res 2017; 1657:347-354. [DOI: 10.1016/j.brainres.2016.12.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/29/2016] [Accepted: 12/31/2016] [Indexed: 11/25/2022]
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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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