| NaF rats_weanling 6 weeks |
Subchronic (30-90 days) |
Prenatal exposure: Twenty-nine timed pregnant dams were obtained on gestational day (GD) 8 (vaginal plug = day 1) and individually housed throughout gestation and lactation. At birth, litters were culled to 10 pups/dam with an equal number of males and females whenever possible. The diet of the dams consisted of Purina Rat Chow (Formulab), and the pups received Certified Purina Rat Chow (5002) after weaning on GD 21. Drinking water for both was deionized water throughout the study. On GDs 14-18 or 17-19, experimental dams (n = 7 and 9, respectively) received SC injections of 0.13 mg/kg sodium fluoride (in saline) two or three times daily (a total of 9 injections per group) at least 4 h apart. Control dams (13 total) received SC injection of an equal volume/ body weight of saline on the same gestational days to match each experimental group. This route and concentration of fluoride exposure produces peak plasma fluoride levels of 0.15- 0.20 ppm which return to control levels within 4 h in nongravid females. Beyond the prenatal period, these pups received no other experimental fluoride treatment.
Weanling exposure: At 19 days of age, male and female pups were shipped with dams having 10 pups/litter. When weaned on GD 21, the pups (n = 19-27/sex and treatment) were maintained thereafter on a low fluoride diet (< 10 ppm fluoride, Purina 5010, or Teklad L356, Madison, WI). When teeth were broken in either the control or experimental groups, this diet was given in powdered form for a few days until normal occlusion returned. Their drinking water contained either 0, 75, 100, 125, or 175 ppm fluoride (3.9, 5.3, 6.6, or 9.2 mM NaF in deionized water, respectively) for 6 or 20 weeks. The 175 ppm level, studied only in females, resulted in dehydration and the death of 10 of the exposed animals within 10 days. Therefore, the 175 ppm exposure was discontinued after 10 days, and the 11 survivors were given deionized water for the remainder of the study. Each fluoride treatment group had matching controls who received deionized water only. This range of fluoride exposures was selected because 100 ppm fluoride in drinking water produces dental fluorosis without other overt signs of toxicity in rats.
Weanling exposure: Male and female rats (n = 21-24/sex/ treatment) were obtained at 10 weeks of age and given 0 or 100 ppm sodium fluoride in deionized water for 5 to 6 weeks starting at 12 weeks of age. They were fed the same low fluoride diet as in the weanling exposure.; Five hundred and thirty-two pathogen-free Sprague-Dawley rats from the Charles River Laboratories (Kingston, RI) were evaluated in this study. All procedures were conducted under the auspices of Forsyth Dental Center’s Animal Care and Use Committee. The animals were assigned randomly to either experimental or control groups and housed 2/cage/ treatment and sex. Light cycles were maintained as 12L : 12D cycle (6:00 a.m. to 6:00 p.m.), and food and water were given ad lib except during the behavioral observation periods. Body weight was recorded once weekly and a t test was applied with a p < 0.01 required for significance. Further details of treatment protocols depended on the age at exposure. |
| NaF rats_pup 16 weeks |
Subchronic (30-90 days) |
Prenatal exposure: Twenty-nine timed pregnant dams were obtained on gestational day (GD) 8 (vaginal plug = day 1) and individually housed throughout gestation and lactation. At birth, litters were culled to 10 pups/dam with an equal number of males and females whenever possible. The diet of the dams consisted of Purina Rat Chow (Formulab), and the pups received Certified Purina Rat Chow (5002) after weaning on GD 21. Drinking water for both was deionized water throughout the study. On GDs 14-18 or 17-19, experimental dams (n = 7 and 9, respectively) received SC injections of 0.13 mg/kg sodium fluoride (in saline) two or three times daily (a total of 9 injections per group) at least 4 h apart. Control dams (13 total) received SC injection of an equal volume/ body weight of saline on the same gestational days to match each experimental group. This route and concentration of fluoride exposure produces peak plasma fluoride levels of 0.15- 0.20 ppm which return to control levels within 4 h in nongravid females. Beyond the prenatal period, these pups received no other experimental fluoride treatment.
Weanling exposure: At 19 days of age, male and female pups were shipped with dams having 10 pups/litter. When weaned on GD 21, the pups (n = 19-27/sex and treatment) were maintained thereafter on a low fluoride diet (< 10 ppm fluoride, Purina 5010, or Teklad L356, Madison, WI). When teeth were broken in either the control or experimental groups, this diet was given in powdered form for a few days until normal occlusion returned. Their drinking water contained either 0, 75, 100, 125, or 175 ppm fluoride (3.9, 5.3, 6.6, or 9.2 mM NaF in deionized water, respectively) for 6 or 20 weeks. The 175 ppm level, studied only in females, resulted in dehydration and the death of 10 of the exposed animals within 10 days. Therefore, the 175 ppm exposure was discontinued after 10 days, and the 11 survivors were given deionized water for the remainder of the study. Each fluoride treatment group had matching controls who received deionized water only. This range of fluoride exposures was selected because 100 ppm fluoride in drinking water produces dental fluorosis without other overt signs of toxicity in rats.
Weanling exposure: Male and female rats (n = 21-24/sex/ treatment) were obtained at 10 weeks of age and given 0 or 100 ppm sodium fluoride in deionized water for 5 to 6 weeks starting at 12 weeks of age. They were fed the same low fluoride diet as in the weanling exposure.; Five hundred and thirty-two pathogen-free Sprague-Dawley rats from the Charles River Laboratories (Kingston, RI) were evaluated in this study. All procedures were conducted under the auspices of Forsyth Dental Center’s Animal Care and Use Committee. The animals were assigned randomly to either experimental or control groups and housed 2/cage/ treatment and sex. Light cycles were maintained as 12L : 12D cycle (6:00 a.m. to 6:00 p.m.), and food and water were given ad lib except during the behavioral observation periods. Body weight was recorded once weekly and a t test was applied with a p < 0.01 required for significance. Further details of treatment protocols depended on the age at exposure. |
| NaF prenatal only |
Developmental |
Twenty-nine timed pregnant dams
were obtained on gestational day (GD) 8 (vaginal plug = day
1) and individually housed throughout gestation and lactation.
At birth, litters were culled to 10 pups/dam with an equal
number of males and females whenever possible. The diet of
the dams consisted of Purina Rat Chow (Formulab), and the
pups received Certified Purina Rat Chow (5002) after weaning
on GD 21. Drinking water for both was deionized water
throughout the study. On GDs 14-18 or 17-19, experimental
dams (n = 7 and 9, respectively) received SC injections of
0.13 mg/kg sodium fluoride (in saline) two or three times daily
(a total of 9 injections per group) at least 4 h apart. Control
dams (13 total) received SC injection of an equal volume/
body weight of saline on the same gestational days to match
each experimental group. This route and concentration of fluoride
exposure produces peak plasma fluoride levels of 0.15-
0.20 ppm which return to control levels within 4 h in nongravid
females (4). Beyond the prenatal period, these pups
received no other experimental fluoride treatment. |