Efeito do fluoreto de sódio sobre a qualidade óssea das vértebras lombares de ratas ovariectomizadas.
Abstract
Osteoporosis is characterised by a reduced bone mass, followed by microstructural
changes in the bone tissue, which increase the susceptibility to bone fractures. This pathology is
most commonly found in women after menopause, being responsible for severe social and
economic consequences. The use of fluoride has demonstrated the possibility to increase bone
mass, especially of the axial skeleton. However, its effects on the bone quality are still
controversial. The aim of this work was to investigate the effects of fluoride, as sodium fluoride
(NaF), on bone tissue of ovariectomized rats (Ovx), which were used as an experimental model
for osteoporosis, through the analysis of biomechanical, physical and biochemical parameters of
the lumbar vertebrae. Wistar female rats of four-month age were divided in the following
experimental groups: Baseline (sacrificed at the beginning of the experiment); Intact; Ovx; Ovx +
20, 40, 60, 80 and 100 ppm of NaF, delivered in drinking water. These groups were sacrificed
after different periods of time (4, 6, and 8 months). Biometrical, biomechanical, physical and
biochemical parameters of the vertebral body (L5) of the animals were measured, together with
the fluoride content of the right tibia. Fluoride content present in the right tibia showed a good
numerical correlation with the administered dosage for the three different periods of treatment.
The ovariectomy promoted a higher body weight gain, and also, a decrease in the values of the
biomechanical, physical and biochemical parameters of the vertebral body of the animals for all
the periods analysed. Treatment using fluoride at high dosage levels (60, 80, and 100 ppm of NaF)
resulted in an increase of bone mass, for the periods of 4 and 8 month of treatment. However, this
increase did not induce a higher mechanical resistance of the bones, although at low dosages, 20
and 40 ppm, administered during a 6-month period, a protective effect on the bone tissue was
observed, thus preventing a decrease in the biomechanical parameters induced by ovariectomy. As
a conclusion, this study showed that low dosages of fluoride can act as a promising therapeutic
agent for the prevention of human postmenopausal osteoporosis.