| 60 day study |
Subchronic (30-90 days) |
Sodium fluoride (LR, Qualigens Fine
Chemicals, Mumbai, India) was administered ad libitum in the drinking
(tap) water at a concentration of 500 ppm NaF (= 226 ppm of fluoride ion)
ad libitum. Guidelines for Breeding of and Experiments on Animals, 1998,
published by the ministry of Social Justice Empowerment, Government of
India, were followed in this investigation.
Since NaF administered at a concentration of 226 ppm fluoride ion in the
drinking water for 4 weeks produced growth retardation and skeletal fluorosis
rats in a previous study,8 this concentration was used in the present study
designed for 60 days.
Another two groups of animals received vitamin D (cholecalciferol, Duphar
Interferan Ltd., Mumbai, India), alone and in combination with NaF,
for 60 days. The vitamin D (arachitol 300,000 IU per mL) was made into a
fine emulsion with 1% gum acacia powder in distilled water. The emulsion
was administered by oral intubation in a volume of 0.1 mL/100 g body
weight at 200 IU/kg daily for 60 days. In a preliminary study in this laboratory,
vitamin D at 100 IU/kg/day for 60 days did not change the toxic effects
of fluoride. Hence, the higher dose was chosen for this study. Experiments
were carried out 24 hr after the 60th day of treatment in test and control animals.; Colony-bred adult 4-5 month old female Wistar rats weighing 130–150 g
were used. Since male rats were found in a previous study to be more susceptible
than females to effects of chronic fluoride treatment,5 only female
rats were used in this work. Eight animals were chosen randomly for each test and control group. Except those used for recording food intake, the rats
were caged in groups (4 per cage) and were maintained at room temperature
(22–26°C) with a normal 12-hr light/dark cycle. The animals were fed a balanced
commercially available pelleted rat chow (Gold Mohur, M/S Hindustan
Lever Ltd., Mumbai, India). |