Fluoride, parathyroid hormone and calcitonin: effects on metabolic processes involved in bone resorption.

Abstract

The effects of fluoride, parathyroid hormone and calcitonin on acid production and bone phosphatases were investigated using half-calvaria of 5-day-old mice in a stationary culture system. Fluoride was incorporated into the bones before culture by administering fluoride to the mothers and pups. Parathyroid hormone (0.2 U/ml) stimulated the production of both lactic and citric acids, while calcitonin (4.0 mU/ml) did not influence acid production, relative to control cultures. Half-calvaria with high and low fluoride contents produced similar quantities of both acids, and responded similarly to parathyroid hormone. The alkaline phosphatase activity of freshly-dissected half-calvaria was not influenced by their fluoride content, but acid phosphatase activity was 72% higher in bones with high fluoride contents than in bones with low fluoride contents. Parathyroid hormone stimulated acid phosphatase to a greater extent in low fluoride bones than in high fluoride bones. Calcitonin stimulated both alkaline and acid phosphatase activities, with a greater increase in acid phosphatase activity than in alkaline phosphatase activity. Fluoride did not appear to modify the influence of calcitonin on phosphatase activity. Since fluoride did not inhibit acid production or acid phosphatase activity, the inhibition of bone resorption by fluoride can best be explained by its effect on bone mineral solubility.