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Gerlach, D.A. and Manuel, J. and Kronsbein, H. and Hoffmann, F. and Heusser, K. and Ehmke, H. and Jordan, J. and Beissner, F. and Tank, J. (2022) HYPOXIC CHALLENGE ACTIVATES HUMAN SYMPATHETIC BRAINSTEM AND HYPOTHALAMIC SITES. NASA Human Research Program Investigators' Workshop, Online.

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BACKGROUND: Peripheral carotid chemoreceptors, which raise sympathetic activation at the brainstem level, may be altered trough atmospheric condition and is further affected by weightlessness-induced neural plasticity. However, human peripheral chemoreflex regulation in the brainstem is poorly understood due to the lack of suitable methodologies. Therefore, we combined measurements of beat-by-beat blood pressure and SpO2, and high-resolution functional magnetic resonance imaging (fMRI) to elucidate human brainstem circuits engaged through hypoxic peripheral chemoreceptor activation. METHOD AND MATERIAL: We submitted 12 healthy men (29.7 ±6.6 years; 24.0 ±1.86 kg/m2) to five hypoxic episodes by breathing 10% oxygen for 180 seconds followed by 90 seconds normoxia during multiband fMRI brain acquisitions. We monitored continuous finger arterial blood pressure using customized hardware, ECG, and SpO2. Brainstem and hypothalamus fMRI images were analyzed to identify nuclei involved in peripheral chemoreflex processing. Systolic blood pressure (SBP) and SpO2 time courses were correlated with the blood-oxygen-level-dependent signals with a general linear model. RESULTS: With hypoxia, SpO2 decreased by 12.32 ±3.68% (p < 0.01), heart rate increased 13.86 ±3.47 (p < 0.01), and SBP decreased with hypoxia 5.45 ±5.5 mmHg (p < 0.01). In the brainstem, the nucleus tractus solitarii (t-values: SpO2: 5.9; SBP: 4.79), the caudal ventrolateral medulla (SBP: 5.59), intermediate reticular nucleus (SBP: 5.98), nucleus ambiguus (SBP: 5.59), dorsal motor nucleus of the vagal nerve (SBP: 4.79), and inferior olive (SpO2: 4.7, SBP: 6.16) were identified with high sensitivity and corrected for multiple comparisons (p < 0.01). Furthermore, we observed activation of the following hypothalamic nuclei: paraventricular nucleus (SpO2: 7.67), anterior and lateral hypothalamic area (SpO2: 7.67, SBP: 4.79), supraoptic nucleus, and tuberomammillary nucleus (SpO2: 7.07). CONCLUSION: High-resolution brainstem fMRI during repeated hypoxia traces brainstem circuits engaged by peripheral chemoreceptors. This methodology allows the analysis of neural adaptation to atmospheric conditioning and short- and long term weightlessness. Furthermore, the understanding of the peripheral chemoreceptor contributions to human cardiovascular disease may enlighten not only antihypertensive therapy.

Item URL in elib:https://elib.dlr.de/185656/
Document Type:Conference or Workshop Item (Poster)
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Gerlach, D.A.Cardiovascular Aerospace Medicine Department, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germanyhttps://orcid.org/0000-0001-7044-6065UNSPECIFIED
Manuel, J.Somatosensory and Autonomic Therapy Research, Institute for Neuroradiology, Hannover Medical School, Hannover , DE and Institute of Aerospace Medicine, German Aerospace Centre , Cologne, GermanyUNSPECIFIEDUNSPECIFIED
Kronsbein, H.Institute of Aerospace Medicine, German Aerospace Center, Cologne, GermanyUNSPECIFIEDUNSPECIFIED
Hoffmann, F.Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany.;Department of Cardiology, Pneumology, and Angiology, Heart Center of the University of Cologne, GermanyUNSPECIFIEDUNSPECIFIED
Heusser, K.UNSPECIFIEDhttps://orcid.org/0000-0002-2571-5585UNSPECIFIED
Ehmke, H.Institute of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, GermanyUNSPECIFIEDUNSPECIFIED
Jordan, J.UNSPECIFIEDhttps://orcid.org/0000-0003-4518-0706UNSPECIFIED
Beissner, F.Somatosensory and Autonomic Therapy Research, Institute for Neuroradiology, Hannover Medical School, Hannover , DEUNSPECIFIEDUNSPECIFIED
Tank, J.UNSPECIFIEDhttps://orcid.org/0000-0002-5672-1187UNSPECIFIED
Date:8 April 2022
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:hypoxic challenge; sympathetic Brainstem; Hypothalamic Sites;
Event Title:NASA Human Research Program Investigators' Workshop
Event Location:Online
Event Type:international Conference
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Research under Space Conditions
DLR - Research theme (Project):R - CardioBrain
Location: Köln-Porz
Institutes and Institutions:Institute of Aerospace Medicine
Institute of Aerospace Medicine > Cardiovascular Medicine in Aerospace
Institute of Aerospace Medicine > Leitungsbereich ME
Deposited By: Schrage, Larissa
Deposited On:08 Apr 2022 13:33
Last Modified:13 Oct 2022 12:48

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