| Developmental study |
Developmental |
Animals within each sex were randomly divided into four groups: control group (tap water, fluoride was 0.34 mg/L) and three NaF-treated groups including 25, 50, and 100 mg/L (final concentrations, NaF was dissolved with tap water) groups. The exposure was continued until the pups were weaned. On PND 10, pups in each concentration group were randomly divided into 5 cages. On PND 21, the pups were weaned and separated for breeding according to gender. They continued to be raised in each group and were administered the same concentrations of NaF in drinking water as their mothers until they were 2 months old.; Twenty male and twenty female adult Sprague-Dawley rats (65 days old) were obtained from the Laboratory Animal Center of Huazhong University of Science and Technology. The rats were housed in 47.5 cm x 35 cm x 20 cm plastic cages with a metal top and sawdust as bedding in an air-conditioned room (temperature 18–21 C) with a 12:12-h light/dark cycle. The animals were supplied with standardized granular food purchased from the Laboratory Animal Center of Huazhong University of Science and Technology, and tap water or tap water with NaF was continuously available. After 10 days of exposure, the animals were randomly taken from each groups (male: female 1:1) and fed in a cage for pregnancy. The days of pups’ birth were recorded as postnatal day (PND) 0, and the pups were kept together with their respective mothers in the same plastic cage. On PND 4, the pups were adjusted to eight pups (male: female 1:1) in each litter. The experimental protocol was approved by the Ethics Review Committee for Animal Research at Huazhong University of Science and Technology. |