Fluoride Action Network


The aim of this study was to ascertain the effect of excessive ingestion of F on the metabolism of type I collagen in skeletal muscles of rats. Eight-week-old female rats (n = 36) were divided into two equal groups. Rats of group I served as control and received only tap water while those of group II received 200 mg NaF/L in their drinking water ad libitum for a period of 90 days. At the end of the experiment, the group II rats showed significantly higher concentrations of F in plasma, bone, urine, and faeces. On the other hand, the level of hydroxyproline in skeletal muscles of these F-exposed rats (452.10±22.54 ?g/gm) was significantly lower than in the group I control rats (817.51±32.06 ?g/gm). Acid- and pepsin-soluble collagen concentrations of skeletal muscles, however, were increased significantly (p < 0.05) in the group II rats (10.42±0.57 and 70.33±2.37 ?g/mg) compared to the group I control rats (6.48±0.38 and 41.99±1.25 ?g/mg), respectively). The expression level of type I collagen (COL1a1) gene in the F-exposed rats decreased by 54% as compared to the control rats. In conclusion, the study found that excessive F ingestion in rats leads to increased degradation and solubility of the collagen protein along with down- regulation of the expression of the COL1A1 gene in the skeletal muscles.