EFFECTS OF 14 DAYS OF SPACEFLIGHT AND 9 DAYS OF RECOVERY ON CELL-BODY-SIZE AND SUCCINATE-DEHYDROGENASE ACTIVITY OF RAT DORSAL-ROOT GANGLIONNEURONS

The cross-sectional areas and succinate dehydrogenase activities of L- 5 dorsal root ganglion neurons in rats were determined after 14 days o f spaceflight and after nine days of recovery. The mean and distributi on of the cross-sectional areas were similar to age-matched, ground-ba sed controls for both the spaceflight and for the spaceflight plus rec overy groups. The mean succinate dehydrogenase activity was significan tly lower in spaceflight compared to aged-matched control rats, wherea s the mean succinate dehydrogenase activity was similar in age-matched control and spaceflight plus recovery rats. The mean succinate dehydr ogenase activity of neurons with cross-sectional areas between 1000 an d 2000 mu m(2) was lower (between 7 and 10%) in both the spaceflight a nd the spaceflight plus recovery groups compared to the appropriate co ntrol groups. The reduction in the oxidative capacity of a subpopulati on of sensory neurons having relatively large cross-sectional areas im mediately following spaceflight and the sustained depression for nine days after returning to 1 g suggest that the 0 g environment induced s ignificant alterations in proprioceptive function. (C) 1997 IBRO. Publ ished by Elsevier Science Ltd.