ISSN:
1432-0827
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
,
Physics
Notes:
Abstract We have recently demonstrated that phenytoin is an osteogenic agent at low doses. The present paper describes observations that a mitogenic dose (i.e., 20 μM in BGJb medium) of fluoride significantly augments the phenytoin-dependent stimulation of normal human bone cell proliferation and alkaline phosphatase (ALP) activity in cell culture. Additionally, the present study was designed to investigate whether fluoride and phenytoin would interact to increase bone formation in rats in vivo. Four groups of weight-matched adult male rats received daily I.P. injection of (1) vehicle (10% DMSO), (2) 5 mg/kg/day phenytoin, (3) 5 mg/kg/day phenytoin and 50 ppm NaF, and (4) 50 ppm NaF and vehicle, respectively, for 36 days. Sodium fluoride (NaF) was delivered in drinking water. Blood samples were drawn weekly and analyzed for serum osteocalcin, ALP, calcium, phosphorus, and 25 (OH)D3. Rats were labeled with fetracycline at day 21 and 30 and histomorphometric analysis was carried out on the tibia at the end of the experiment. Neither agent by itself or together affected the serum calcium, phosphorus, or 25 (OH)D3 levels. All measures of bone formation, i.e., serum osteocalcin level and ALP activity, bone ALP specific activity, mineral apposition rate, bone formation rate, and % bone formation surface, were increased by each agent. Fluoride and phenytoin together produced bigger increases in each parameter than did each agent alone. Trabecular bone volume was increased in the bibial metaphysis by fluoride or phenytoin alone; and when administered together, the two agents produced a greater increase. The combined effect of fluoride and phenytoin on each serum and bone formation parameter appeared to be less than additive. Phenytoin or fluoride alone did not significantly reduce the metaphyseal % resorptive surface. However, treatments with both agents together caused a highly significant reduction in the metaphyseal % resorptive surface. Phenytoin and fluoride together also significantly reduced (by 36%) the mineralization lag time, indicating that these agents did not promote osteomalacia. In summary, fluoride and phenytoin act in concert to stimulate bone formation and increase trabecular bone volume without causing mineralization defects in vivo and thus, may be a potential combination therapy for low bone mass in osteoporosis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00301608
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