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WEIGHTLESSNESS-INDUCED ALTERATIONS IN THE GLIAL CELL MACHINERY.   B.M. Uva ¹, M.A. Masini¹, M. Sturla¹, G. Tagliafierro ¹ and F. Strollo².  ¹Dipartimento di Biologia Sperimentale, Universitа di Genova, Italy,  ² “Unitа Endocrinologica” INRCA & Universitа “La Sapienza” Roma, Italy.

   The Central Nervous System is made up of neurons and glia, the glia being by far the most abundant. In their response to injury, glial cells act as a vast network; disturbances at any one point of the net are rapidly reflected throughout the entire system.  As glia is essential for the correct functioning of neurons, any damages to the glia impair Central Nervous System activities. Our previous researches on cultured glial cells showed that simulated microgravity alters the cytoskeleton and causes programmed cell death of glial cells; the phenomenon is transient and, after 32h in simulated microgravity, new glial cells are born and normal cycling is restored. The integrity of intracellular machinery is essential to macromolecular transfer and ion transport; moreover, the integrity of inner and outer cell membranes is needed for ion channels to function properly and thus to go on playing their crucial roles in prevention of brain oedema. In fact, in the absence of any suitable compensatory mechanisms, brain oedema would be the obvious consequence of the typical cephalad blood shift experienced by humans during spaceflight. Aim of the present work was to investigate upon the integrity of intracellular organelles and of the inner and outer cell membranes in glial cells submitted to simulated microgravity using a Fokker Random Positioning Machine. The expression of the sodium pump and ion cotransport proteins was also studied. The results indicate that as early as 15 min in simulated microgravity alterations occur in cell cycling, in intracellular organelles and in the expression of the enzymes correlated to ion transport. The present investigation was carried out by immunohistochemistry using antibodies
to Na⁺/K⁺ATPase, to the inner mitochondrial membrane and to Na⁺/K⁺/Cl^- cotransport proteins. Transmission Electron Microscopy was used to investigate upon the integrity of various microstructure elements.

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