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Fukushi I, Ikeda K, Takeda K, Yoshizawa M, Kono Y, Hasebe Y, Pokorski M, Okada Y. Minocycline prevents hypoxia-induced seizures. Front Neural Circuits 2023; 17:1006424. [PMID: 37035503 PMCID: PMC10073501 DOI: 10.3389/fncir.2023.1006424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 02/27/2023] [Indexed: 04/11/2023] Open
Abstract
Severe hypoxia induces seizures, which reduces ventilation and worsens the ictal state. It is a health threat to patients, particularly those with underlying hypoxic respiratory pathologies, which may be conducive to a sudden unexpected death in epilepsy (SUDEP). Recent studies provide evidence that brain microglia are involved with both respiratory and ictal processes. Here, we investigated the hypothesis that microglia could interact with hypoxia-induced seizures. To this end, we recorded electroencephalogram (EEG) and acute ventilatory responses to hypoxia (5% O2 in N2) in conscious, spontaneously breathing adult mice. We compared control vehicle pre-treated animals with those pre-treated with minocycline, an inhibitory modulator of microglial activation. First, we histologically confirmed that hypoxia activates microglia and that pre-treatment with minocycline blocks hypoxia-induced microglial activation. Then, we analyzed the effects of minocycline pre-treatment on ventilatory responses to hypoxia by plethysmography. Minocycline alone failed to affect respiratory variables in room air or the initial respiratory augmentation in hypoxia. The comparative results showed that hypoxia caused seizures, which were accompanied by the late phase ventilatory suppression in all but one minocycline pre-treated mouse. Compared to the vehicle pre-treated, the minocycline pre-treated mice showed a delayed occurrence of seizures. Further, minocycline pre-treated mice tended to resist post-ictal respiratory arrest. These results suggest that microglia are conducive to seizure activity in severe hypoxia. Thus, inhibition of microglial activation may help suppress or prevent hypoxia-induced ictal episodes.
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Affiliation(s)
- Isato Fukushi
- Faculty of Health Sciences, Aomori University of Health and Welfare, Aomori, Japan
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
- *Correspondence: Isato Fukushi
| | - Keiko Ikeda
- Homeostatic Mechanism Research Unit, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Kotaro Takeda
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
- Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - Masashi Yoshizawa
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Chuo, Japan
| | - Yosuke Kono
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Chuo, Japan
| | - Yohei Hasebe
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Chuo, Japan
| | | | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
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Fukushi I, Takeda K, Uchiyama M, Kurita Y, Pokorski M, Yokota S, Okazaki S, Horiuchi J, Mori Y, Okada Y. Blockade of astrocytic activation delays the occurrence of severe hypoxia-induced seizure and respiratory arrest in mice. J Comp Neurol 2019; 528:1257-1264. [PMID: 31769022 DOI: 10.1002/cne.24828] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/08/2019] [Accepted: 11/08/2019] [Indexed: 01/10/2023]
Abstract
Seizures are induced when subjects are exposed to severe hypoxia. It is followed by ventilatory fall-off and eventual respiratory arrest, which may underlie the pathophysiology of death in patients with epilepsy and severe respiratory disorders. However, the mechanisms of hypoxia-induced seizures have not been fully understood. Because astrocytes are involved in various neurological disorders, we aimed to investigate whether astrocytes are operational in seizure generation and respiratory arrest in a severe hypoxic condition. We examined the effects of astrocytic activation blockade on responses of EEG and ventilation to severe hypoxia. Adult mice were divided into two groups; in one group (n = 24) only vehicle was injected, and in the other group (n = 24) arundic acid, an inhibitory modulator of astrocytic activation, was administered before initiation of recording. After recording EEG and ventilation by whole body plethysmography in room air, the gas in the recording chamber was switched to 5% oxygen (nitrogen balanced) until a seizure and ventilatory depression occurred, followed by prompt switch back to room air. Severe hypoxia initially increased ventilation, followed by a seizure and ventilatory suppression in all mice examined. Fourteen mice without arundic acid showed respiratory arrest during loading of hypoxia. However, 22 mice pretreated with arundic acid did not suffer from respiratory arrest. Time from the onset of hypoxia to the occurrence of seizures was significantly longer in the group with arundic acid than that in the group without arundic acid. We suggest that blockade of astrocytic activation delays the occurrence of seizures and prevents respiratory arrest.
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Affiliation(s)
- Isato Fukushi
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan.,Faculty of Health Sciences, Iryo Sosei University, Iwaki, Japan
| | - Kotaro Takeda
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan.,Faculty of Rehabilitation, School of Healthcare, Fujita Health University, Toyoake, Japan
| | - Makoto Uchiyama
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan.,Department of Synthetic Chemistry and Biological Chemistry Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Yuki Kurita
- Department of Synthetic Chemistry and Biological Chemistry Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Mieczyslaw Pokorski
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan.,Faculty of Physiotherapy, Opole Medical School, Opole, Poland
| | - Shigefumi Yokota
- Department of Anatomy and Neuroscience, Shimane University School of Medicine, Izumo, Japan
| | - Shuntaro Okazaki
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan.,Faculty of Human Sciences, Waseda University, Tokorozawa, Japan
| | - Jouji Horiuchi
- Department of Biomedical Engineering, Graduate School of Science and Engineering, Toyo University, Kawagoe, Japan
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Japan
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Fukushi I, Takeda K, Yokota S, Hasebe Y, Sato Y, Pokorski M, Horiuchi J, Okada Y. Effects of arundic acid, an astrocytic modulator, on the cerebral and respiratory functions in severe hypoxia. Respir Physiol Neurobiol 2016; 226:24-9. [DOI: 10.1016/j.resp.2015.11.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/12/2015] [Accepted: 11/13/2015] [Indexed: 12/18/2022]
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Ramirez JM, Doi A, Garcia AJ, Elsen FP, Koch H, Wei AD. The cellular building blocks of breathing. Compr Physiol 2013; 2:2683-731. [PMID: 23720262 DOI: 10.1002/cphy.c110033] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Respiratory brainstem neurons fulfill critical roles in controlling breathing: they generate the activity patterns for breathing and contribute to various sensory responses including changes in O2 and CO2. These complex sensorimotor tasks depend on the dynamic interplay between numerous cellular building blocks that consist of voltage-, calcium-, and ATP-dependent ionic conductances, various ionotropic and metabotropic synaptic mechanisms, as well as neuromodulators acting on G-protein coupled receptors and second messenger systems. As described in this review, the sensorimotor responses of the respiratory network emerge through the state-dependent integration of all these building blocks. There is no known respiratory function that involves only a small number of intrinsic, synaptic, or modulatory properties. Because of the complex integration of numerous intrinsic, synaptic, and modulatory mechanisms, the respiratory network is capable of continuously adapting to changes in the external and internal environment, which makes breathing one of the most integrated behaviors. Not surprisingly, inspiration is critical not only in the control of ventilation, but also in the context of "inspiring behaviors" such as arousal of the mind and even creativity. Far-reaching implications apply also to the underlying network mechanisms, as lessons learned from the respiratory network apply to network functions in general.
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Affiliation(s)
- J M Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institut, Seattle, Washington, USA.
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Quintana A, Zanella S, Koch H, Kruse SE, Lee D, Ramirez JM, Palmiter RD. Fatal breathing dysfunction in a mouse model of Leigh syndrome. J Clin Invest 2012; 122:2359-68. [PMID: 22653057 DOI: 10.1172/jci62923] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 04/18/2012] [Indexed: 01/27/2023] Open
Abstract
Leigh syndrome (LS) is a subacute necrotizing encephalomyelopathy with gliosis in several brain regions that usually results in infantile death. Loss of murine Ndufs4, which encodes NADH dehydrogenase (ubiquinone) iron-sulfur protein 4, results in compromised activity of mitochondrial complex I as well as progressive neurodegenerative and behavioral changes that resemble LS. Here, we report the development of breathing abnormalities in a murine model of LS. Magnetic resonance imaging revealed hyperintense bilateral lesions in the dorsal brain stem vestibular nucleus (VN) and cerebellum of severely affected mice. The mutant mice manifested a progressive increase in apnea and had aberrant responses to hypoxia. Electrophysiological recordings within the ventral brain stem pre-Bötzinger respiratory complex were also abnormal. Selective inactivation of Ndufs4 in the VN, one of the principle sites of gliosis, also led to breathing abnormalities and premature death. Conversely, Ndufs4 restoration in the VN corrected breathing deficits and prolonged the life span of knockout mice. These data demonstrate that mitochondrial dysfunction within the VN results in aberrant regulation of respiration and contributes to the lethality of Ndufs4-knockout mice.
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Affiliation(s)
- Albert Quintana
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, WA, USA
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Chen L, Bai S, Su W, Song X, Zhang P, Li L, Ji JJ. Transient oxygen-glucose deprivation causes immediate changes in redox activity in mouse brain tissue. Brain Res 2011; 1390:99-107. [PMID: 21414304 DOI: 10.1016/j.brainres.2011.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 03/08/2011] [Accepted: 03/09/2011] [Indexed: 12/22/2022]
Abstract
Redox activity is an important property of living cells, and decreases in redox activity are likely to be an upstream event in ischemic brain injuries. In this study, immediate changes in redox activity caused by ischemic injury were investigated in oxygen-glucose deprivation (OGD) treated mouse brain tissue. Adult mouse brain slices were subjected to 10 min or 15 min OGD treatments and were immediately stained with an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) staining procedure. After 10 min OGD, the redox activity decreased in the lateral globus pallidus (LGP), medial globus pallidus (MGP), pyramidal cell layer of hippocampus CA1 (CA1(PL)) and the granular layer of the cerebellum (cereb(GL)). After 15 min OGD, decreases also occurred in the substantia nigra (SN) and several other areas of the brain stem. Hoechst 33342 was used to confirm that changes in redox activity occurred before morphological alterations in the cellular nuclei--morphological changes were not observed even after a 60 min OGD. The results presented here indicate that functional ischemic vulnerability exists in several brain regions, and will be helpful for systematic research on mammalian brain injury caused by transient metabolic stress.
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Affiliation(s)
- Lianwan Chen
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
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Anatomical architecture and responses to acidosis of a novel respiratory neuron group in the high cervical spinal cord (HCRG) of the neonatal rat. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 648:387-94. [PMID: 19536503 DOI: 10.1007/978-90-481-2259-2_44] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
It has been postulated that there exists a neuronal mechanism that generates respiratory rhythm and modulates respiratory output pattern in the high cervical spinal cord. Recently, we have found a novel respiratory neuron group in the ventral portion of the high cervical spinal cord, and named it the high cervical spinal cord respiratory group (HCRG). In the present study, we analyzed the detailed anatomical architecture of the HCRG region by double immunostaining of the region using a neuron-specific marker (NeuN) and a marker for motoneurons (ChAT) in the neonatal rat. We found a large number of small NeuN-positive cells without ChAT-immunoreactivity, which were considered interneurons. We also found two and three clusters of motoneurons in the ventral portion of the ventral horn at C1 and C2 levels, respectively. Next, we examined responses of HCRG neurons to respiratory and metabolic acidosis in vitro by voltage-imaging together with cross correlation techniques, i.e., by correlation coefficient imaging, in order to understand the functional role of HCRG neurons. Both respiratory and metabolic acidosis caused the same pattern of changes in their spatiotemporal activation profiles, and the respiratory-related area was enlarged in the HCRG region. After acidosis was introduced, preinspiratory phase-dominant activity was recruited in a number of pixels, and more remarkably inspiratory phase-dominant activity was recruited in a large number of pixels. We suggest that the HCRG composes a local respiratory neuronal network consisting of interneurons and motoneurons and plays an important role in respiratory augmentation in response to acidosis.
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Oyamada Y, Murai M, Harada N, Ishizaka A, Okada Y. Age-dependent involvement of ATP-sensitive potassium channel Kir6.2 in hypoxic ventilatory depression of mouse. Respir Physiol Neurobiol 2008; 162:80-4. [PMID: 18524696 DOI: 10.1016/j.resp.2008.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2007] [Revised: 04/06/2008] [Accepted: 04/08/2008] [Indexed: 11/16/2022]
Abstract
In order to examine whether ATP-sensitive potassium channel Kir6.2 is involved in hypoxic ventilatory responses, especially in hypoxic ventilatory depression (HVD), and whether the involvement shows age-dependence, we measured the hypoxic ventilatory response in the Kir6.2-knockout mouse (Kir6.2-/-) in an unanesthetized unrestrained state by means of pressure plethysmography in the 2nd and 4th postnatal weeks, and compared the response with that of its wild type counterpart, the C57BL6/J mouse. In the 4th postnatal week, but not in the 2nd week, the Kir6.2-/- exhibited a larger and longer initial augmentation and a weaker subsequent depression of respiratory frequency and ventilation in response to hypoxia (FIO(2)=0.12 in N(2)). These findings suggest that Kir6.2 is involved in HVD of the mouse at a certain point during the postnatal development.
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Affiliation(s)
- Yoshitaka Oyamada
- Department of Pulmonary Medicine, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo, Japan.
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