| gavage rat NaF |
Developmental |
The route chosen in this study for exposure
was via drinking water to mimic human exposure.
Starting from day 1 of gestation and daily
through postnatal day 9, experimental female rats
were administered, by intragastric gavage, a solution
of sodium fluoride (NaF, Novartis S.p.a.,
Origgio, VA, Italy) dissolved in deionized water.
Drinking water was deionized water throughout
the study. Preliminary experiments were performed
with the following experimental groups:
1) undisturbed animals (no gavage at all); 2) 1
ml/kg of deionized water by gavage; 3) solution
containing NaF 2.5 mg/kg/ml dissolved in deionized
water by gavage; 4) solution containing NaF 5.0 mg/kg/ml dissolved in deionized water by
gavage. Once comparisons between first and second
group gave no statistical differences in all
tests performed during the preliminary part of
this research, which considered doses up to 20
mg/kg/ml, the treatment schedule was set up
without the control group which was scheduled
without any manipulation (gavage). Doses over
10 mg/kg were not considered due to the detection
of some structural anomaly found in the offspring.
Consequently, the doses of NaF employed
in the present study were 2.5 and 5.0
mg/kg which respectively correspond to the upper
level and twofold greater than the concentration
level of the fluoride recommended dose (1,2
mg/ litre in drinking water). On the day following
parturition (PND 1), all litters were reduced
to a standard size of four male and four female
pups per litter, when possible. Pups were then examined,
weighed, sexed and marked with black
ink on their backs for individual identification.
They were weaned on PND 21 and the four
males and four females of each litter were
housed separately in cages identical to the home
cage. One pup per litter from different litters per
treatment group was then used in all experiments.
Each pup was used for a single test and
tested only once.; Animal experimentation was performed in accordance
with the EU directive 86/609 EEC,
with the guidelines released by the Italian Ministry
of Health (D.L. 116/92 and D.L. 111/94-B),
with the UK Animals Act 1986 and associated
guidelines, and with the “Guide for the Care and
Use of Laboratory Animals” as adopted and promulgated
by the National Institutes of Health.
According to the above guidelines, all efforts
were made to minimise the number of animals
and their suffering.
Primiparous Wistar female rats (Harlan SRC,
Milan, Italy), weighing 200-260 g were used.
Animals were allowed free access to food and
water, housed at constant room temperature (20-
22°C) and exposed to a light cycle of 12 h day
(08:00-20:00 h) for 2 weeks before the experiment.
Pairs of females were placed with a single
male rat in the late afternoon. Each female rat
was inspected for vaginal smears on the following
morning at 09:00 h. The day on which sperm
were present was designated as day 0 of gestation. |