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GRAVITATIONAL VECTOR CHANGES: ALTERATIONS AND SUBSEQUENT ADAPTATION IN CULTURED NERVOUS CELLS. B.M. Uva¹, M. Sturla¹, F. Ricci², G. Tagliafierro¹, F. Strollo³ and M.A. Masini¹.  ¹Dept. of Biology, Univ. of Genoa, Italy; ²ENEA-Casaccia, Rome, Italy and ³Endocrine Unit INRCA & Univ. “La Sapienza”, Rome, Italy.

   The central nervous system houses two main kind of cells: (i) neurons, responsible for elaboration and transmission of signals and (ii) glia, which exerts a nutritional and supporting role but is also required for neurogenesis, synaptognesis, and synaptic efficiency. In previous experiments on cultured glial cells we observed severe damages at subcellular level under simulated weightlessness conditions (Uva et al., 2002, Brain Res. 132-139: Uva et al., 2002 E.J.H., 209-214; Uva et al., 2002. J.Gravit. Physiol.,275-276). The aim of the present research was to investigate upon the hypergravity-induced (2.5 x g) alterations at the subcellular level in cultured astrocytes and neurons, and upon nervous cells adaptation mechanisms to altered gravity vector. Hypo- and hypergravity-exposed cells were fixed before undergoing immunohistochemistry (IHC) or Electron Microscope procedures. IHC was performed using antisera to a-tubulin, to proteins of the inner mitochondrial membranes (AMA), to the Golgi apparatus, to the transmembrane ion transport proteins, to the water channel aquaporin AQP₄, to the proliferating cell nuclear antigen (PCNA), and to the heath shock proteins (HSPs) 27 and 70. Cytochemical labelling of F-actin was also performed. After only few minutes alterations were observed in the cytoskeleton and the cellular organelles both in simulated 0xg and 2.5xg with HSPs expression. After 20h under both experimental conditions, many cells showed  undamaged cytoskeleton and intracellular organelles again, while cell divisions increased and clusters of newly formed cells were present.
   We conclude that gravity vector changes may induce only transient alterations in the nervous cells: the cultured nervous cell population adapt to the low and high gravity and restart normal cycling processes.

(Supported by ASI)