Choroidal responses in microgravity. (SLS-1, SLS-2 and hindlimb-suspension experiments)

Gabrion, Jacqueline; Herbuté, S; Oliver, J; Maurel, Daniel; Davet, Julien; Clavel, Benoît; Gharib, C; Fareh, Jeannette; S, Fagette; Nguyen, B.

doi:10.1016/0094-5765(95)00129-8

Cited by 15 publications

(8 citation statements)

References 15 publications

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“…In the same experiment, AQP1 was subsequently overexpressed upon readaptation to normal gravity for 2 days, indicating an aggressive upregulation in CSF production rate consistent with a rebound phenomenon . Other rodent studies performed in microgravity have also demonstrated evidence of downregulation of CSF production in the form of histologic and biochemical alteration of the choroid plexus . These animal studies are all consistent with an active physiologic response to elevated ICP consisting of downregulation of CSF production.…”

Section: Discussionsupporting

confidence: 54%

“…20 Other rodent studies performed in microgravity have also demonstrated evidence of downregulation of CSF production in the form of histologic and biochemical alteration of the choroid plexus. 26,27 These animal studies are all consistent with an active physiologic response to elevated ICP consisting of downregulation of CSF production. Overexpression of AQ1 in postflight rats suggests a potential mechanism for observed CSF upregulation in postflight astronauts.…”

Section: Discussionmentioning

confidence: 61%

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Mr‐derived cerebral spinal fluid hydrodynamics as a marker and a risk factor for intracranial hypertension in astronauts exposed to microgravity

Kramer

Hasan

Sargsyan

et al. 2015

Magnetic Resonance Imaging

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The increased postflight CSF production rate in astronauts with positive flattening is compatible with the hypothesis of microgravity-induced intracranial hypertension inferring downregulation in CSF production in microgravity that is upregulated upon return to normal gravity. Increased postflight CSF maximum systolic velocity in astronauts with negative flattening suggests increased craniospinal compliance and a potential negative risk factor to microgravity-induced intracranial hypertension.

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Section: Discussionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 61%

Mr‐derived cerebral spinal fluid hydrodynamics as a marker and a risk factor for intracranial hypertension in astronauts exposed to microgravity

Kramer

Hasan

Sargsyan

et al. 2015

Magnetic Resonance Imaging

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“…Adaptive mechanisms to weightlessness include a reduction in blood and total fluid volume (19), altered cerebral autoregulation (6), and changes in compliance of vasculature, membranes and bony structures (29,42). Gabrion et al (16) found that a head-ward fluid shift induced by either weightlessness (9 and 14 days during NASA STS 40 and 56 missions) or (9 or 14 days) tail suspension of rats caused similar changes in the choroidal plexus, indicating reduced CSF formation, which could attenuate ICP during long term head-down tilt or weightlessness (35). Shortly after return to earth or termination of tail-suspension (within 8 h), the rats displayed return towards normal choroidal differentiation (16).…”

Section: Discussionmentioning

confidence: 99%

“…Gabrion et al (16) found that a head-ward fluid shift induced by either weightlessness (9 and 14 days during NASA STS 40 and 56 missions) or (9 or 14 days) tail suspension of rats caused similar changes in the choroidal plexus, indicating reduced CSF formation, which could attenuate ICP during long term head-down tilt or weightlessness (35). Shortly after return to earth or termination of tail-suspension (within 8 h), the rats displayed return towards normal choroidal differentiation (16). ICP thus seems to adapt to weightlessness.…”

Section: Discussionmentioning

confidence: 99%

Postural influence on intracranial and cerebral perfusion pressure in ambulatory neurosurgical patients

Petersen

Andresen

et al. 2016

American Journal of Physiology-Regulatory, Integrative and Comp

114

113

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We evaluated postural effects on intracranial pressure (ICP) and cerebral perfusion pressure [CPP: mean arterial pressure (MAP) - ICP] in neurosurgical patients undergoing 24-h ICP monitoring as part of their diagnostic workup. We identified nine patients (5 women, age 44 ± 20 yr; means ± SD), who were "as normal as possible," i.e., without indication for neurosurgical intervention (e.g., focal lesions, global edema, abnormalities in ICP-profile, or cerebrospinal fluid dynamics). ICP (tip-transducer probe; Raumedic) in the brain parenchyma (n = 7) or in the lateral ventricles (n = 2) and cardiovascular variables (Nexfin) were determined from 20° head-down tilt to standing up. Compared with the supine position, ICP increased during 10° and 20° of head-down tilt (from 9.4 ± 3.8 to 14.3 ± 4.7 and 19 ± 4.7 mmHg; P < 0.001). Conversely, 10° and 20° head-up tilt reduced ICP to 4.8 ± 3.6 and 1.3 ± 3.6 mmHg and ICP reached -2.4 ± 4.2 mmHg in the standing position (P < 0.05). Concordant changes in MAP maintained CPP at 77 ± 7 mmHg regardless of body position (P = 0.95). During head-down tilt, the increase in ICP corresponded to a hydrostatic pressure gradient with reference just below the heart, likely reflecting the venous hydrostatic indifference point. When upright, the decrease in ICP was attenuated, corresponding to formation of a separate hydrostatic gradient with reference to the base of the skull, likely reflecting the site of venous collapse. ICP therefore seems to be governed by pressure in the draining veins and collapse of neck veins may protect the brain from being exposed to a large negative pressure when upright. Despite positional changes in ICP, MAP keeps CPP tightly regulated.

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“…70,85,87 In accordance with animal models of HC, 53 altered ICP, fluid flow physiology, and dynamics during HDT may be hypothesized to interfere with choroidal depolarization and AQP dysfunction. 88…”

Section: Sleep and Head-down Tiltmentioning

confidence: 99%

Hydrocephalus Revisited: New Insights into Dynamics of Neurofluids on Macro- and Microscales

et al. 2021

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New experimental and clinical findings question the historic view of hydrocephalus and its 100-year-old classification. In particular, real-time magnetic resonance imaging (MRI) evaluation of cerebrospinal fluid (CSF) flow and detailed insights into brain water regulation on the molecular scale indicate the existence of at least three main mechanisms that determine the dynamics of neurofluids: (1) inspiration is a major driving force; (2) adequate filling of brain ventricles by balanced CSF upsurge is sensed by cilia; and (3) the perivascular glial network connects the ependymal surface to the pericapillary Virchow–Robin spaces. Hitherto, these aspects have not been considered a common physiologic framework, improving knowledge and therapy for severe disorders of normal-pressure and posthemorrhagic hydrocephalus, spontaneous intracranial hypotension, and spaceflight disease.

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Choroidal responses in microgravity. (SLS-1, SLS-2 and hindlimb-suspension experiments)

Cited by 15 publications

References 15 publications

Mr‐derived cerebral spinal fluid hydrodynamics as a marker and a risk factor for intracranial hypertension in astronauts exposed to microgravity

Mr‐derived cerebral spinal fluid hydrodynamics as a marker and a risk factor for intracranial hypertension in astronauts exposed to microgravity

Postural influence on intracranial and cerebral perfusion pressure in ambulatory neurosurgical patients

Hydrocephalus Revisited: New Insights into Dynamics of Neurofluids on Macro- and Microscales

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