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Altered gravity downregulates aquaporin-1 protein expression in choroid plexus
C Masseguin1, M Corcoran, C Carcenac
1Institut des Neurosciences, Centre National de la Recherche Scientifique UMR 7624, Université Pierre et Marie Curie-Paris VI, Paris, France 75252, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|March 10, 2000
Summary
Aquaporin-1 (AQP1) water channels in rat eyes decrease with spaceflight and simulated weightlessness. AQP1 levels rapidly recover upon return to normal gravity, suggesting altered water transport during space missions.
Area of Science:
- Space Biology
- Physiology
- Cell Biology
Background:
- Aquaporin-1 (AQP1) is a crucial water channel protein found in choroidal epithelial cells.
- Choroidal epithelial cells play a role in cerebrospinal fluid production, influencing intraocular pressure.
Purpose of the Study:
- To investigate the impact of altered gravity, including spaceflight and simulated conditions, on AQP1 expression in rat choroid plexus.
- To understand the dynamic changes in AQP1 expression during and after exposure to altered gravity environments.
Main Methods:
- Quantitative immunocytochemistry and confocal microscopy were used to measure AQP1 protein levels.
- Rats were exposed to actual spaceflight, head-down suspension (simulating weightlessness), and hypergravity (centrifuge).
Main Results:
- Spaceflight and head-down suspension significantly decreased apical AQP1 expression in choroidal cells.
- AQP1 levels showed rapid, transient increases upon readaptation to normal gravity.
- Hypergravity adaptation also led to a dose-dependent reduction in apical AQP1 expression.
Conclusions:
- Altered gravity conditions, including spaceflight and hypergravity, downregulate apical AQP1 in choroidal cells.
- The observed changes in AQP1 suggest a potential decrease in water transport and cerebrospinal fluid production during spaceflight.
- Rapid AQP1 restoration upon return to normal gravity indicates adaptive mechanisms for fluid balance.