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Abe C, Yamaoka Y, Maejima Y, Mikami T, Morita H. Hypergravity-induced plastic alteration of the vestibulo-sympathetic reflex involves decrease in responsiveness of CAMK2-expressing neurons in the vestibular nuclear complex. J Physiol Sci 2019; 69:903-917. [PMID: 31435871 PMCID: PMC10942005 DOI: 10.1007/s12576-019-00705-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 08/09/2019] [Indexed: 01/18/2023]
Abstract
The vestibular system contributes to not only eye movement and posture but also the sympathetic response. Plastic alteration of the vestibulo-sympathetic reflex is induced by hypergravity load; however, the mechanism remains unknown. Here, we examined 2 g-induced changing in responsiveness of CAMK2-expressing neurons in the vestibular nucleus complex using optogenetic tools. The excitatory photostimulation of the CAMK2-expressing neurons in the unilateral vestibular nuclear complex induced body tilt to the contralateral side, while inhibitory photostimulation showed the opposite response. Photoactivation of either cell body or the axonal terminal in the rostral ventrolateral medulla showed sympathoexcitation followed by the pressor response. Furthermore, this response was significantly attenuated (49.8 ± 4%) after the 1st day of 2 g loading, and this value was further reduced by the 5th day (22.4 ± 3%), suggesting that 2 g-induced attenuation of the vestibulo-sympathetic reflex involves at least decrease in responsiveness of CAMK2-expressing neurons in the vestibular nuclear complex.
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Affiliation(s)
- Chikara Abe
- Department of Physiology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
| | - Yusuke Yamaoka
- Department of Physiology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Yui Maejima
- Department of Physiology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Tomoe Mikami
- Department of Physiology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
| | - Hironobu Morita
- Department of Physiology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan
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Expression of Hypoxia-Inducible Factor 1α (HIF-1α) and Genes of Related Pathways in Altered Gravity. Int J Mol Sci 2019; 20:ijms20020436. [PMID: 30669540 PMCID: PMC6358763 DOI: 10.3390/ijms20020436] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 12/28/2022] Open
Abstract
Immune system deterioration in space represents a major risk, which has to be mitigated for exploration-class missions into the solar system. Altered gravitational forces have been shown to regulate adaptation processes in cells of the immune system, which are important for appropriate risk management, monitoring and development of countermeasures. T lymphocytes and cells of the monocyte-macrophage system are highly migratory cell types that frequently encounter a wide range of oxygen tensions in human tissues and in hypoxic areas, even under homeostatic conditions. Hypoxia-inducible factor 1 and 2 (HIF's) might have an important role in activation of T cells and cells of the monocyte-macrophages system. Thus, we investigated the regulation of HIF-dependent and, therefore, hypoxia-signaling systems in both cell types in altered gravity and performed transcript and protein analysis from parabolic flight and suborbital ballistic rocket experiments. We found that HIF-1α and HIF-1-dependent transcripts were differently regulated in altered gravity, whereas HIF-1α-dependent gene expression adapted after 5 min microgravity. Inter-platform comparisons identified PDK1 as highly responsive to gravitational changes in human U937 myelomonocytic cells and in Jurkat T cells. We suggest HIF-1 as a potential pharmacological target for counteracting immune system deterioration during space flight.
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Zhang LF, Hargens AR. Spaceflight-Induced Intracranial Hypertension and Visual Impairment: Pathophysiology and Countermeasures. Physiol Rev 2017; 98:59-87. [PMID: 29167331 DOI: 10.1152/physrev.00017.2016] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 12/21/2022] Open
Abstract
Visual impairment intracranial pressure (VIIP) syndrome is considered an unexplained major risk for future long-duration spaceflight. NASA recently redefined this syndrome as Spaceflight-Associated Neuro-ocular Syndrome (SANS). Evidence thus reviewed supports that chronic, mildly elevated intracranial pressure (ICP) in space (as opposed to more variable ICP with posture and activity on Earth) is largely accounted for by loss of hydrostatic pressures and altered hemodynamics in the intracranial circulation and the cerebrospinal fluid system. In space, an elevated pressure gradient across the lamina cribrosa, caused by a chronic but mildly elevated ICP, likely elicits adaptations of multiple structures and fluid systems in the eye which manifest themselves as the VIIP syndrome. A chronic mismatch between ICP and intraocular pressure (IOP) in space may acclimate the optic nerve head, lamina cribrosa, and optic nerve subarachnoid space to a condition that is maladaptive to Earth, all contributing to the pathogenesis of space VIIP syndrome. Relevant findings help to evaluate whether artificial gravity is an appropriate countermeasure to prevent this seemingly adverse effect of long-duration spaceflight.
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Affiliation(s)
- Li-Fan Zhang
- Department of Aerospace Physiology, Fourth Military Medical University, Xi'an, China; and Department of Orthopaedic Surgery, University of California, San Diego, California
| | - Alan R Hargens
- Department of Aerospace Physiology, Fourth Military Medical University, Xi'an, China; and Department of Orthopaedic Surgery, University of California, San Diego, California
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Zhang LF. Region-specific vascular remodeling and its prevention by artificial gravity in weightless environment. Eur J Appl Physiol 2013; 113:2873-95. [DOI: 10.1007/s00421-013-2597-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 01/20/2013] [Indexed: 10/27/2022]
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Lin LJ, Gao F, Bai YG, Bao JX, Huang XF, Ma J, Zhang LF. Contrasting effects of simulated microgravity with and without daily −Gx gravitation on structure and function of cerebral and mesenteric small arteries in rats. J Appl Physiol (1985) 2009; 107:1710-21. [DOI: 10.1152/japplphysiol.00493.2009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study was designed to test the hypothesis that a 28-day tail suspension (SUS) could induce hypertrophy and enhanced myogenic and vasoconstrictor reactivity in middle cerebral arteries (MCAs), whereas atrophy and decreased myogenic and vasoconstrictor responses in mesenteric third-order arterioles (MSAs). Also, in addition to the functional enhancement in MCAs, structural changes in both kinds of arteries and functional decrement in MSAs could all be prevented by the intervention of daily 1-h dorsoventral (−Gx) gravitation by restoring to standing posture. To test this hypothesis, vessel diameters to pressure alterations and nonreceptor- and receptor-mediated agonists were determined using a pressure arteriograph with a procedure to measure in vivo length and decrease hysteresis of vessel segments and longitudinal middlemost sections of vessels fixed at maximally dilated state were examined using electron microscopy and histomorphometry. Functional studies showed that 28-day tail-suspended, head-down tilt (SUS) resulted in enhanced and decreased myogenic tone and vasoconstrictor responses, respectively, in MCAs and MSAs. Histomorphometric data revealed that SUS-induced hypertrophic changes in MCAs characterized by increases in thickness (T) and cross-sectional area (CSA) of the media and the number of vascular smooth-muscle-cell layers (NCL), whereas in MSAs, it induced decreases in medial CSA and T and NCL. Daily 1-h −Gx over 28 days can fully prevent these differential structural changes in both kinds of small arteries and the functional decrement in MSAs, but not the augmented myogenic tone and increased vasoreactivity in the MCAs. These findings have revealed special features of small resistance arteries during adaptation to microgravity with and without gravity-based countermeasure.
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Affiliation(s)
- Le-Jian Lin
- Department of Aerospace Physiology and Key Laboratory of Aerospace Medicine of Ministry of Education,
| | - Fang Gao
- Department of Aerospace Physiology and Key Laboratory of Aerospace Medicine of Ministry of Education,
| | - Yun-Gang Bai
- Department of Aerospace Physiology and Key Laboratory of Aerospace Medicine of Ministry of Education,
| | - Jun-Xiang Bao
- Department of Aerospace Physiology and Key Laboratory of Aerospace Medicine of Ministry of Education,
| | - Xiao-Feng Huang
- Central Laboratory, School of Basic Medicine, Fourth Military Medical University, Xi'an, China
| | - Jin Ma
- Department of Aerospace Physiology and Key Laboratory of Aerospace Medicine of Ministry of Education,
| | - Li-Fan Zhang
- Department of Aerospace Physiology and Key Laboratory of Aerospace Medicine of Ministry of Education,
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Gao F, Bao J, Xue J, Huang J, Huang W, Wu S, Zhang LF. Regional specificity of adaptation change in large elastic arteries of simulated microgravity rats. ACTA ACUST UNITED AC 2009; 96:167-87. [DOI: 10.1556/aphysiol.96.2009.2.3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Tanaka K, Gotoh TM, Awazu C, Morita H. Regional difference of blood flow in anesthetized rats during reduced gravity induced by parabolic flight. J Appl Physiol (1985) 2005; 99:2144-8. [PMID: 16081624 DOI: 10.1152/japplphysiol.00336.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To examine a hypothesis that change in regional blood flow due to decreased hydrostatic pressure gradient and redistribution of blood during reduced gravity (rG) is different between organs, changes in cerebrocortical blood flow (CBF) and blood flow in the temporal muscle (MBF) with exposure to rG were measured in anesthetized rats in head-up tilt and flat positions during parabolic flight. Carotid arterial pressure (CAP), jugular venous pressure (JVP), and abdominal aortic pressure were also measured simultaneously. In the head-up tilt group, CBF increased by 15 +/- 3% within 3 s of entry into rG and rapidly recovered during rG. MBF also increased, but the change was significantly greater than that of CBF. JVP increased by 1.8 +/- 0.5 mmHg, probably due to loss of hydrostatic pressure gradient, since the measuring point of JVP was 2-3 cm above the hydrostatic indifference point. CAP and abdominal aortic pressure increased by 16.7 +/- 2 and 7.7 +/- 2 mmHg, respectively, compared with the 1-G condition. Muscle vascular resistance [(CAP-JVP)/MBF] decreased on entry into rG, but no significant change was observed in cerebrocortical vascular resistance [(CAP-JVP)/CBF]. In the flat group, no significant change was observed in all the variables. The results indicate that arteriolar vasodilatation occurs in the temporal muscle but not in the cerebral cortex. Thus the blood flow control mechanism at the onset of rG is different between intra- and extracranial organs.
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Affiliation(s)
- Kunihiko Tanaka
- Dept. of Physiology, Gifu University, Graduate School of Medicine, Gifu, Japan.
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Abstract
There has been recent interest in the concept of connecting a computer to the brain to control brain functions. However, there are challenges that must be overcome in developing such a computer-brain interface, including a selection of nucleus that is stimulated, and an implantable electrode and electrical stimulator. Another important issue is the designing of the controller, that is, determining how to encode as an electrical signal the information to be sent to the brain. We have applied system identification theory, a method for evaluating dynamic characteristics of a system, to the arterial blood pressure control system of the brain. Our results show that (1) the stimulation-arterial blood pressure response relationship can be described as a mathematical model, which gives a good prediction of the arterial blood pressure response, facilitating the designing of a computer-brain interface, and (2) the arterial blood pressure can be actually controlled using a computer-brain interface.
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Affiliation(s)
- Taro M Gotoh
- Department of Physiology, Gifu University School of Medicine, 1-1 Yanagido, Gifu 501-1194, Japan.
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Gotoh TM, Fujiki N, Tanaka K, Morita H. Change in Intrathoracic Pressure in Rats with Spontaneous and Controlled Ventilation during Microgravity by Parabolic Flight. ACTA ACUST UNITED AC 2005; 55:69-74. [PMID: 15796791 DOI: 10.2170/jjphysiol.s636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We previously reported that the intrathoracic pressure (ITP) decreases and the transmural pressure of the aortic wall (TMP) increases during 4.5 s of microgravity (muG) induced by free drop. To examine the ITP response to a longer period of muG in the absence of the respiratory rate (RR) decrease, i.e., bradypnea, which occurs at the onset of muG, we measured the aortic blood pressure at the diaphragma level (AP) and ITP. We then calculated the TMP at the aortic arch level during 20 s of muG induced by parabolic flight in anesthetized rats (n = 7) with either spontaneous ventilation (SPN-V) or controlled ventilation (CONT-V). In the SPN-V group, the bradypnea was observed in all rats after the onset of the muG (RR change -13.9 +/- 2.9/min). The ITP during muG (-9.3 +/- 0.9 mmHg) was significantly lower than that during 1 G (-7.7 +/- 0.9 mmHg), and the TMP was significantly increased during muG (112 +/- 6 mmHg) compared to 1 G (103 +/- 5 mmHg). Similar changes in ITP and TMP were observed in the CONT-V group: During muG and 1G, respectively, the ITP was -8.4 +/- 0.6 mmHg and -5.9 +/- 0.7 mmHg, and the TMP was 112 +/- 6 mmHg and 101 +/- 6 mmHg, whereas no change in RR was observed because of the controlled ventilation. These results show that the ITP decreases and the TMP increases during muG, and they are not affected by a disturbance of respiratory rhythm.
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Affiliation(s)
- Taro Miyahara Gotoh
- Department of Physiology, Gifu University School of Medicine, Gifu, 501-1194 Japan.
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