Abstract:
Fluoride (F) is known to affect mineralizing tissues, but
effects upon the developing brain have not been previously
considered. This study in Sprague-Dawley rats compares
behavior, body weight, plasma and brain F levels after
sodium fluoride (NaF) exposures during late gestation, at
weaning or in adults. For prenatal exposures, dams received
injections (SC) of 0.13 mg/kg NaF or saline on gestational
days 14-18 or 17-19. Weanlings received drinking water
containing 0, 75, 100, or 125 ppm F for 6 or 20 weeks, and 3
month-old adults received water containing 100 ppm F for 6
weeks. Behavior was tested in a computer pattern recognition
system that classified acts in a novel environment and
quantified act initiations, total times and time structures.
Fluoride exposures caused sex- and dose-specific behavioral
deficits with a common pattern. Males were most sensitive to
prenatal day 17-19 exposure, whereas females were more
sensitive to weanling and adult exposures. After fluoride
ingestion, the severity of the effect on behavior increased
directly with plasma F levels and F concentrations in
specific brain regions. Such association is important
considering that plasma levels in this rat model (0.059 to
0.640 ppm F) are similar to those reported in humans exposed
to high levels of fluoride.
See also comment in: Neurotoxicology and Teratology, 1995 Nov-Dec;17(6):685-688