Decreased Succinate Dehydrogenase Activity of Gamma and Alpha Motoneurons in Mouse Spinal Cords Following 13 Weeks of Exposure to Microgravity
Akihiko Ishihara, Fumiko Nagatomo, Hidemi Fujino..., et. al. ; ASI sponsor
Oct - 2013
DOI: 10.1007/s11064-013-1124-y
ISSN : 1573-6903 ;
journal : Neurochemical Research

Volume : 38 ; Issue : 10
type: Article Journal

Abstract
Cell body size and succinate dehydrogenase activity of motoneurons in the dorsolateral region of the ventral horn in the lumbar and cervical segments of the mouse spinal cord were assessed after long-term exposure to microgravity and compared with those of ground-based controls. Mice were housed in a mouse drawer system on the International Space Station for 13 weeks. The mice were transported to the International Space Station by the Space Shuttle Discovery and returned to Earth by the Space Shuttle Atlantis. No changes in the cell body size of motoneurons were observed in either segment after exposure to microgravity, but succinate dehydrogenase activity of small-sized (<300 μm2) gamma and medium-sized (300–700 μm2) alpha motoneurons, which have higher succinate dehydrogenase activity than large-sized (>700 μm2) alpha motoneurons, in both segments was lower than that of ground-based controls. We concluded that exposure to microgravity for longer than 3 months induced decreased succinate dehydrogenase activity of both gamma and slow-type alpha motoneurons. In particular, the decreased succinate dehydrogenase activity of gamma motoneurons was observed only after long-term exposure to microgravity.

keywords : Long-term exposure to microgravity – Lumbar and cervical segments – Mouse – Spinal motoneuron – Succinate dehydrogenase activity