|Nielsen, Forrest - Frosty|
Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/1996
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: In a previous study rats fed propylthiouracil (PTU), an antithyroid agent, exhibited changes in ornithine aminotransferase activity. Discontinuation of PTU treatment and maintenance of rats on a low silicon (Si) diet resulted in an elevation of the ornithine aminotransferase activity when these rats were compared to Si-adequate rats identically treated with PTU. As this finding probably represented an aberration of collagen metabolism exerted by an interaction between PTU and Si, a study was conducted to examine the effects of dietary silicon on several enzymes associated with collagen synthesis. Twenty-four rats were fed a corn-casein based diet with either low (2.5 ug/g Si) or adequate silicon (10 ug/g Si). Silicon did not significantly affect growth. Femur copper and manganese concentrations were significantly higher in Si-adequate than Si-low rats. Pyrroline-5-carboxylase activity was not significantly different between Si-low rats (0.069 +/- 0.004 units/mg protein) and Si-adequate rats (0.073 +/- 0.009 units/mg protein). Total proline in plasma also was not significantly affected by dietary Si. However, ornithine aminotransferase activity was significantly lower in the Si-low rats (46.2 +/- 11 units/g tissue) than in Si-adequate rats (61.3 +/- 11 units/g tissue). Silicon apparently affects a key enzyme in collagen synthesis. Because pyrroline- 5-carboxylate is formed as a result of ornithine aminotransferase activity, concentrations of pyrroline-5-carboxylate may be found to be valuable in evaluating the nutritional status of Si.