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Remzső G, Kovács V, Tóth-Szűki V, Domoki F. The effects of CO 2 levels and body temperature on brain interstitial pH alterations during the induction of hypoxic-ischemic encephalopathy in newborn pigs. Heliyon 2024; 10:e28607. [PMID: 38571587 PMCID: PMC10988055 DOI: 10.1016/j.heliyon.2024.e28607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 04/05/2024] Open
Abstract
Brain interstitial pH (pHbrain) alterations play a crucial role in the development of hypoxic-ischemic (HI) encephalopathy (HIE) caused by asphyxia in neonates. The newborn pig is one of the most suitable large animal models for studying HIE, however, compared to rats, experimental data on pHbrain alterations during HIE induction are limited. The major objective of the present study was thus to compare pHbrain changes during HIE development induced by experimental normocapnic hypoxia (H) or asphyxia (A), elicited with ventilation of a gas mixture containing 6%O2 or 6%O2/20%CO2, respectively for 20 min, under either normothermia (NT) or hypothermia (HT) (38.5 ± 0.5 °C or 33.5 ± 0.5 °C core temperature, respectively) in anesthetized piglets yielding four groups: H-NT, A-NT, H-HT, and A-HT. pHbrain changes during HI stress and the 60 min reoxygenation period were measured using a pH-selective microelectrode inserted into the parietal cortex through an open cranial window. In all groups, the pHbrain response to HI stress was acidosis, at the nadir pHbrain values dropped from the baseline of 7.27 ± 0.02 to H-NT:5.93 ± 0.30, A-NT:5.90 ± 0.52, H-HT:6.81 ± 0.27, and A-HT:6.27 ± 0.24 indicating that (1) H and A elicited similar, severe brain acidosis under NT greatly exceeding pH changes in arterial blood (pHa dropped to 7.24 ± 0.07 and 6.78 ± 0.03 from 7.52 ± 0.06 and 7.50 ± 0.05, respectively), and (2) HT ameliorated more the brain acidosis induced by H than by A. In all four groups, pHbrain was restored to baseline values without an alkalotic overshoot during the observed reoxygenation, Our findings suggest that under NT either H or A - both commonly employed HI stresses to elicit HIE in piglet models - would result in a similar acidotic pHbrain response without an alkalotic component either during the HI stress or the early reoxygenation period.
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Affiliation(s)
- Gábor Remzső
- Department of Physiology, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - Viktória Kovács
- Department of Physiology, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - Valéria Tóth-Szűki
- Department of Physiology, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - Ferenc Domoki
- Department of Physiology, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
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Ala‐Kurikka T, Pospelov A, Summanen M, Alafuzoff A, Kurki S, Voipio J, Kaila K. A physiologically validated rat model of term birth asphyxia with seizure generation after, not during, brain hypoxia. Epilepsia 2021; 62:908-919. [PMID: 33338272 PMCID: PMC8246723 DOI: 10.1111/epi.16790] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/24/2020] [Accepted: 11/24/2020] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Birth asphyxia (BA) is often associated with seizures that may exacerbate the ensuing hypoxic-ischemic encephalopathy. In rodent models of BA, exposure to hypoxia is used to evoke seizures, that commence already during the insult. This is in stark contrast to clinical BA, in which seizures are typically seen upon recovery. Here, we introduce a term-equivalent rat model of BA, in which seizures are triggered after exposure to asphyxia. METHODS Postnatal day 11-12 male rat pups were exposed to steady asphyxia (15 min; air containing 5% O2 + 20% CO2 ) or to intermittent asphyxia (30 min; three 5 + 5-min cycles of 9% and 5% O2 at 20% CO2 ). Cortical activity and electrographic seizures were recorded in freely behaving animals. Simultaneous electrode measurements of intracortical pH, Po2 , and local field potentials (LFPs) were made under urethane anesthesia. RESULTS Both protocols decreased blood pH to <7.0 and brain pH from 7.3 to 6.7 and led to a fall in base excess by 20 mmol·L-1 . Electrographic seizures with convulsions spanning the entire Racine scale were triggered after intermittent but not steady asphyxia. In the presence of 20% CO2 , brain Po2 was only transiently affected by 9% ambient O2 but fell below detection level during the steps to 5% O2 , and LFP activity was nearly abolished. Post-asphyxia seizures were strongly suppressed when brain pH recovery was slowed down by 5% CO2 . SIGNIFICANCE The rate of brain pH recovery has a strong influence on post-asphyxia seizure propensity. The recurring hypoxic episodes during intermittent asphyxia promote neuronal excitability, which leads to seizures only after the suppressing effect of the hypercapnic acidosis is relieved. The present rodent model of BA is to our best knowledge the first one in which, consistent with clinical BA, behavioral and electrographic seizures are triggered after and not during the BA-mimicking insult.
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Affiliation(s)
- Tommi Ala‐Kurikka
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Alexey Pospelov
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Milla Summanen
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Aleksander Alafuzoff
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Samu Kurki
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Juha Voipio
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
| | - Kai Kaila
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
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Brain interstitial pH changes in the subacute phase of hypoxic-ischemic encephalopathy in newborn pigs. PLoS One 2020; 15:e0233851. [PMID: 32470084 PMCID: PMC7259698 DOI: 10.1371/journal.pone.0233851] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/13/2020] [Indexed: 01/24/2023] Open
Abstract
Brain interstitial pH (pHbrain) alterations play an important role in the mechanisms of neuronal injury in neonatal hypoxic-ischemic encephalopathy (HIE) induced by perinatal asphyxia. The newborn pig is an established large animal model to study HIE, however, only limited information on pHbrain alterations is available in this species and it is restricted to experimental perinatal asphyxia (PA) and the immediate reventilation. Therefore, we sought to determine pHbrain over the first 24h of HIE development in piglets. Anaesthetized, ventilated newborn pigs (n = 16) were instrumented to control major physiological parameters. pHbrain was determined in the parietal cortex using a pH-selective microelectrode. PA was induced by ventilation with a gas mixture containing 6%O2-20%CO2 for 20 min, followed by reventilation with air for 24h, then the brains were processed for histopathology assessment. The core temperature was maintained unchanged during PA (38.4±0.1 vs 38.3±0.1°C, at baseline versus the end of PA, respectively; mean±SEM). In the arterial blood, PA resulted in severe hypoxia (PaO2: 65±4 vs 23±1*mmHg, *p<0.05) as well as acidosis (pHa: 7.53±0.03 vs 6.79±0.02*) that is consistent with the observed hypercapnia (PaCO2: 37±3 vs 160±6*mmHg) and lactacidemia (1.6±0.3 vs 10.3±0.7*mmol/L). Meanwhile, pHbrain decreased progressively from 7.21±0.03 to 5.94±0.11*. Reventilation restored pHa, blood gases and metabolites within 4 hours except for PaCO2 that remained slightly elevated. pHbrain returned to 7.0 in 29.4±5.5 min and then recovered to its baseline level without showing secondary alterations during the 24 h observation period. Neuropathological assessment also confirmed neuronal injury. In conclusion, in spite of the severe acidosis and alterations in blood gases during experimental PA, pHbrain recovered rapidly and notably, there was no post-asphyxia hypocapnia that is commonly observed in many HIE babies. Thus, the neuronal injury in our piglet model is not associated with abnormal pHbrain or low PaCO2 over the first 24 h after PA.
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Geng X, Sy CA, Kwiecien TD, Ji X, Peng C, Rastogi R, Cai L, Du H, Brogan D, Singh S, Rafols JA, Ding Y. Reduced cerebral monocarboxylate transporters and lactate levels by ethanol and normobaric oxygen therapy in severe transient and permanent ischemic stroke. Brain Res 2015; 1603:65-75. [PMID: 25641040 DOI: 10.1016/j.brainres.2015.01.040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 01/16/2015] [Accepted: 01/20/2015] [Indexed: 01/04/2023]
Abstract
OBJECTIVES Neuroprotective benefits of ethanol (EtOH) and normobaric oxygenation (NBO) were previously demonstrated in transient and permanent ischemic stroke. Here we sought to identify whether the enhanced lactic acidosis and increased expression of monocarboxylate transporters (MCTs) observed after stroke might be attenuated by single and/or combined EtOH and NBO therapies. METHODS Sprague-Dawley rats (n=96) were subjected to right middle cerebral artery occlusion (MCAO) for 2 or 4h (transient ischemia), or 28 h (permanent ischemia) followed by 3, 24h, or no reperfusion. Rats received: (1) either an intraperitoneal injection of saline (sham treatment), one dose of EtOH (1.5 g/kg), two doses of EtOH (1.5 g/kg at 2h of MCAO, followed by 1.0 g/kg 2h after 1st dose), or (2) EtOH+95% NBO (at 2h of MCAO for 6h in permanent ischemia). Lactate levels were detected at 3 and 24h of reperfusion. Gene and protein expressions of MCT-1, -2, -4 were assessed by real-time PCR and western blotting. RESULTS A dose-dependent EtOH neuroprotection was found in transient ischemia. Following transient ischemia, a single dose of EtOH (in 2h-MCAO) or a double dose (in 4h-MCAO), significantly attenuated lactate levels, as well as the mRNAs and protein expressions of MCT-1, MCT-2, and MCT-4. However, while two doses of EtOH alone was ineffective in permanent stroke, the combined therapy (EtOH+95% NBO) resulted in a more significant attenuation in all the above levels and expressions. CONCLUSIONS Our study demonstrates that acute EtOH administration attenuated lactic acidosis in transient or permanent ischemic stroke. This EtOH-induced beneficial effect was potentiated by NBO therapy in permanent ischemia. Because both EtOH and NBO are readily available, inexpensive and easy to administer, their combination could be implemented in the clinics shortly after stroke.
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Affiliation(s)
- Xiaokun Geng
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Christopher A Sy
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Timothy D Kwiecien
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Xunming Ji
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurosurgery, Xuanwu Hospital, China-America Institute of Neuroscience, Luhe Hospital Capital Medical University, Beijing 100053, China.
| | - Changya Peng
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Radhika Rastogi
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Lipeng Cai
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Huishan Du
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China
| | - David Brogan
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Sunpreet Singh
- Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA
| | - Jose A Rafols
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Yuchuan Ding
- China-America Institute of Neuroscience, Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurological Surgery, Wayne State University School of Medicine, 550 E Canfield, Detroit, MI 48201, USA.
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Harris TA, Healy GN, Colditz PB, Lingwood BE. Associations between serum cortisol, cardiovascular function and neurological outcome following acute global hypoxia in the newborn piglet. Stress 2009; 12:294-304. [PMID: 18951250 DOI: 10.1080/10253890802372414] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Perinatal asphyxia is a significant contributor to neonatal brain injury. However, there is significant variability in neurological outcome in neonates after global hypoxia-ischemia. The aims of this study were to identify which physiological response/s during global hypoxia-ischemia influence the severity of brain injury and to assess their relative importance. Hypoxia/hypercapnia was induced in 20 anaesthetized piglets by reducing the inspired oxygen fraction to 10% and the ventilation rate from 30 to 10 breaths per minute for 45 min. Neurological outcome was assessed using functional markers including cerebral function amplitude (via electroencephalography) and cerebral impedance, and the structural marker microtubule associated protein-2 by immunohistochemistry at 6 h post hypoxia. Significant variability in neurological outcome was observed following the constant hypoxia/hypercapnia insult. There was a high degree of variability in cardiovascular function (mean arterial blood pressure and heart rate) and serum cortisol concentrations in response to hypoxia. More effective maintenance of cardiovascular function and higher serum cortisol concentrations were associated with a better outcome. These two variables were strongly associated with neurological outcome, and together explained 68% of the variation in the severity of neurological outcome. The variability in the cardiovascular and cortisol responses to hypoxia may be a more important determinant of neurological outcome then previously recognized.
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Affiliation(s)
- Thomas A Harris
- Perinatal Research Centre, University of Queensland Centre for Clinical Research, Royal Brisbane and Women's Hospital, Herston, QLD, Australia
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Harris TA, Healy GN, Colditz PB, Lingwood BE. Oscillations in cardiovascular function during acute hypoxia in the newborn piglet are associated with less neurological damage and occur more frequently in females. Pediatr Res 2009; 65:504-8. [PMID: 19190542 DOI: 10.1203/pdr.0b013e31819d9747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The function of the cardiovascular system during hypoxia is an important determinant of neurologic outcome. Oscillations in blood pressure, particularly type-3 waves with a duration of 10 to 160 s, have been shown to occur in the presence of hypoxia in the neonatal rat. The aim of this study was to determine the characteristics and occurrence of type-3 waves in the neonatal piglet and any relationship to neurologic damage after acute global hypoxia. Hypoxia/hypercarbia was induced in 32 anesthetized piglets by reducing the fraction of inspired oxygen to 0.1 and the ventilation rate from 30 to 10 breaths per minute for 45 min. The degree of neurologic damage was assessed using both physiologic (EEG amplitude and cerebral impedance at 6 h posthypoxia) and structural (microtubule associated protein-2 immunohistochemistry) markers. Type-3 waves in cardiovascular function occurred in 56% of animals. An oscillating pattern was significantly associated with less neurologic damage (p = 0.01) and a lower duration of hypotension during hypoxia (p = 0.02), and occurred more frequently in females (p = 0.024).
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Affiliation(s)
- Thomas A Harris
- Perinatal Research Centre, University of Queensland Centre for Clinical Research, The University of Queensland, Royal Brisbane and Women's Hospital, Queensland, Australia 4029
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