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Effects of Hypergravity and Adrenalectomy on Total Body Bone Mineral Content in Male RatsThe effects of 14 days of increased gravitational load, and the absence of adrenal stress hormones on total body bone mineral content (BMC) were examined in male Sprague-Dawley rats. Centrifugation at 2 Gs (2G) was used to increase the gravitational load, and bilateral adrenalectomy (ADX) was used to eliminate the production of adrenal stress hormones. Stationary groups at 1 G (1G) and sham operated (SHAM) animals served as controls. Thirty rats (n=6 or 8) made up the four experimental groups (1G SHAM, 1G ADX, 2G SHAM and 2G ADX). BMC was assessed by dual energy X-ray absorptiometry (DXA) and activity was determined through biotelemetry. Body mass and food intake were also measured. Multi-factorial analysis of variance (MANCOVA) and Newman Keuls post hoc tests were used to analyze significant effects (p less than 0.05) for the primary variables. Results indicated that BMC decreased significantly with increased G for both the SHAM and ADX groups. The BMC for the 1 G ADX group was also significantly lower than the 1G SHAM group, however the 2G SHAM and ADX groups were not significantly different. There was a significant decrease in body mass with increased G and there was no ADX effect on body mass. When BMC was normalized for body mass changes, there were no significant group differences. Activity level decreased with body mass, and food intake data showed there was significant hypophagia during the first few days of centrifugation. These results suggest that the decrease in total body BMC seen with hypergravity may be based to a large extent on the differences in body mass induced by the 2 G load.
Document ID
20010007243
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Girten, Beverly
(Lockheed Martin Corp. United States)
Moran, Megan
(Lockheed Martin Corp. United States)
Baer, Lisa
(Lockheed Martin Corp. United States)
Pruitt, Sean
(Lockheed Martin Corp. United States)
O'Brien, Cheryl
(Lockheed Martin Corp. United States)
Arnaud, Sara
(NASA Ames Research Center Moffett Field, CA United States)
Wade, Charles
(NASA Ames Research Center Moffett Field, CA United States)
Bowley, Susan M.
Date Acquired
August 20, 2013
Publication Date
January 1, 2000
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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