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The effect of food restriction and simulated microgravity on the rat skeleton
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Bone loss commonly occurs during space flight, creating an increased risk for fractures. It is also known that undereating commonly occurs on space flight missions, and ingesting insufficient calories has been shown to have detrimental effects on the skeleton. This food deficit combined with microgravity could create an additive loss of bone for astronauts. Forty eight Sprague-Dawley adult male rats were subjected to hindlimb suspension (HLS), to simulate the weightless environment of outer space on bone. These rats were randomly divided into four groups of 12 rats each: in the CON-100 group, the rats were fed 100% of their usual food intake, and allowed regular activity. In the CON-70 group, the rats were fed 70% of their usual food intake, and also allowed regular activity. The HLS-100 group was fed 100% of their usual food intake, but put into HLS. Likewise the HLS-70 group was subjected to HLS, but they were fed 70% of their usual food intake. Compared to all CON animals, results demonstrated that all HLS rats combined exhibited a numerical increase in urine deoxypyridinoline crosslinks, with a significant reduction in proximal tibial metaphyseal total BMC and total BMD, and tibial cortical shell area. These rats also experienced significantly lower humeral metaphyseal total BMC and trabecular BMD, total area, cortical shell area, and marrow area. In addition, humeral cortical shell BMD was significantly greater in all HLS rats. Three-point bending of the tibia and humerus revealed no change in bone strength. Also, serum osteocalcin concentration had decreased significantly in all HLS rats, and decreased even more in all food-restricted rats. Additionally an interaction occurred among treatments with serum osteocalcin. This suggests that 1 month of HLS causes structural changes within bone sooner than food restriction, without concomitant changes in bone strength. Food restriction may take longer to affect bone structurally, but does exhibit whole-body biochemical changes after 1 month. In addition, the combination of food restriction and HLS causes a synergistic effect on serum osteocalcin. This project reveals that eating well while in space will be instrumental for astronauts to avoid additional bone loss and fractures.
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Includes bibliographical references (leaves 57-66).
Issued also on microfiche from Lange Micrographics.
Currado, Alicia Anne (2002). The effect of food restriction and simulated microgravity on the rat skeleton. Master's thesis, Texas A&M University. Available electronically from
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