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Collagen in Juvenile through mature adult rat metatarsals increases linearly relative to body weight.  M.J. Palm¹ and B. Johnson-Wint¹.¹ Department of Biological Sciences, Northern Illinois University, DeKalb, IL

     Embryonic skeletal development has been studied extensively but there have been limited studies on the progression of post-partum growth through mature homeostasis of skeletal bones.  Previous studies of male and female Sprauge-Dawley (SD) rats have shown a clear positive relationship between body weight and overall skeletal mass, but did not address specifically load bearing bones or collagen content. Since bone receives its tensile strength from collagen, the goal of this study was to investigate collagen content of loaded bones per age and body weight in both male and female SD rats.  The metatarsal bones of SD rats were studied to determine if age, body weight and collagen content correlated.  Rat body and metatarsal weight were recorded.  Metatarsals two, three, and four from both hind feet of normal male and female rats were collected and protein extracted.  The extracted protein and residual bone were acid hydrolyzed and collagen amount was determined using the hydroxyproline assay. Bones collected ranged from 17days-post-partum through 452 days of age. Both males and females experienced a rapid growth phase from day 17 through approximately day 60 and then body weight gain continued to increase but at a decreased rate through day 452.  The body weights of the male and female rats were shown to be statistically significantly different, with males larger then females per age (p<.001). Overall, total metatarsal collagen per age followed the same trends but showed no difference between males and females, whereas total collagen per body weight was statistically more in females then in males (p<.05).  Metatarsal collagen density per body weight showed a positive linear trend for both male and female rats with female being higher then male collagen density.  These results suggest that the amount and density of collagen in metatarsals are positively linearly related to body weight, hence load.  In addition, over the time course female metatarsals showed a higher amount and density of collagen per body weight then males.