Submitted to: Journal of Trace Elements in Medicine and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 2007
Publication Date: January 15, 2008
Repository URL: http://handle.nal.usda.gov/10113/35266
Citation: Nielsen, F.H. 2008. A novel silicon complex is as effective as sodium metasilicate in enhancing the collagen-induced inflammatory response of silicon-deprived rats. Journal of Trace Elements in Medicine and Biology. 22:39-49. Interpretive Summary: Cell culture studies have indicated that silicon has beneficial effects on the immune or inflammatory response. Thus, an experiment with rats was conducted to determine whether silicon deprivation would adversely affect the response to the injection of type II collagen, which induces an inflammatory response and arthritis similar to rheumatoid arthritis in humans. The experiment also determined whether an organic form of silicon that could be used as a supplement was as effective as soluble inorganic form of silicon that is not suitable for use in supplements in affecting the inflammatory response. Based on changes in the amount of circulating blood cells involved in the inflammatory response after the injections of type II collagen, the silicon-supplemented rats generally exhibited a more marked inflammatory response than silicon-deprived rats. The silicon-supplemented rats also had higher excretion of magnesium, and higher plasma concentrations of magnesium and copper, which also suggested a greater inflammatory response. The changes in plasma magnesium and copper were more marked in male than female rats. The organic and inorganic forms were equally effective in enhancing the inflammatory response. The findings suggest that, in rodents, physiological amounts of silicon promote the immune response, sex may influence the response to dietary silicon, and that organic forms of silicon have similar effects as soluble inorganic forms of silicon in preventing the effects of silicon deprivation.
Technical Abstract: An experiment was conducted with rats to determine whether silicon deprivation affects the inflammatory response to the injection of type II collagen, and to compare the effectiveness of the organic complex arginine silicate inositol (ASI) with inorganic silicon (NaSiO3) in mitigating any observed change in response. Dark Agouti rats were fed a ground corn-casein-safflower based diet containing about 2.8 mg Si/kg. The experimental variables were supplemental 0 and 35 mg Si/kg as either ASI or NaSiO3. After five weeks on their respective treatments, each rat was injected with type II collagen and euthanized four weeks later. Urine was collected before injection during week five and week nine before euthanasia. The silicon-supplemented rats generally exhibited a more marked inflammatory response than the silicon-deprived rats. The circulating number of lymphocytes was higher (p<0.003) and number of neutrophils was lower (p<0.008) in silicon-deprived than silicon-supplemented rats. ASI and NaSiO3 were about equally effective in enhancing these changes. Post-injection of tibial release of prostaglandin E2 (p<0.04), urinary excretion of magnesium (p<0.03) and deoxypyridinoline (p<0.009), and plasma osteopontin (p<0.009), magnesium (p<0.0007) and copper (p<0.004) were higher in silicon-supplemented than silicon-deprived rats. The increases in plasma magnesium (Si x sex, p<0.04) and copper (Si x sex, p<0.02) were more marked in male than female rats. One but not the other silicon supplement when compared to silicon deprivation significantly affected some variables, including tibial release of PGE2, and plasma copper and iron concentrations. However, with the exception of the pre-injection urinary excretion of helical peptide, there was no significant difference in any determined variable between rats fed ASI and NaSiO3. The findings suggest that, in rodents, physiological amounts of silicon promote the immune response, sex may influence the response to dietary silicon, and that both organic silicon complexes and inorganic silicon are similarly effective in preventing changes in inflammation induced by silicon deprivation.