Chapter 4 Gravitational Neuromorphology

Abstract

Morphological studies of the nervous system in animals exposed to hypergravity or microgravity for extended periods of time started almost 20 years ago; however, a series of systematic studies began only recently. Nevertheless, many data have been obtained already, and their significance for understanding the mechanisms of mammalian adaptation to altered gravity and the specificity of gravity as an acting factor allow speaking of the appearance of a new branch in the morphology of the nervous system—namely, gravitational neuromorphology. This chapter describes a new trend in neuromorphological research without covering the entire spectrum of publications in this field. The majority of the data presented have been acquired through the morphological analysis of the nervous system in animals exposed to prolonged microgravity during spaceflight or to prolonged hypergravity during rotation on a centrifuge. Morphological studies of the brain, spinal cord, and peripheral nervous system of animals exposed to minogravity have been performed with Wsrar and Wisrar specific pathogen free (SPF) rats, pocket mice, and steppe turtles flown aboard biosatellites Cosmos-605, Cosmos-782, Cosmos-936, Cosmos-1514, Cosmos-1887, and Cosmos-2044 and aboard spacecraft Apollo-17 and Soyuz-20. Studies of the nervous system in animals exposed to hypergravity have been performed with Wistar rats. Methods used in these studies include light and electron microscopy; quantitative cyto- and histochemical analysis of enzyme activity; determinations of RNA and protein content in neurons, glia cells, and layered structures; morphometric analysis of neuronal structures; histofluorescence, immunohistochemical, and stereological methods; and quantitative assay of mRNA in neurons by means of hybridization in situ .