EFFECTS OF LOW FLUORIDE FEEDING THROUGH SUCCESSIVE GENERATIONS ON RATS

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  • 低フッ素累代飼育のラットに及ぼす影響
  • テイフッソ ルイダイ シイク ノ ラット ニ オヨボス エイキョウ トクニ フッソ ノ リニュウシ エ ノ イコウ ニ ツイテ
  • With Particular References to the Transfer of Fluoride to Weanlings
  • とくにフッ素の離乳仔への移行について

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Abstract

For the purpose to elucidate the nutritional essentiality or non-essentiality of minute fluoride and also the magnitude of the placental and mammary barrier for fluoride, the experiments of feeding rats defluoridated feed and fluoride water of graded dose through three generations were conducted.<BR>1. The determination of minute fluoride was done with the latest device, the fluoride ion electrode. It was found to be very quick and reliable.<BR>2. The basal diet contained 0.45ppm F which was as low as one hundredth of commercial rat compressed feed. The graded doses of fluoride water were 0, 0.5, 1, 10 and 50ppm.<BR>3. The growth was retarded at 50ppm in both generations and at 10ppm in males of the second generation.<BR>4. No significant difference was found in blood examinations between the dose levels, including erythrocytes and leucocytes count, hematocrit, ALP and GOT.<BR>5. The adult male rats of the first generation of low fluoride feeding contained 14.1ppm F in femurs and 15.1ppm F in incisors, decreasing to only three per cent and nine per cent resp. of that on commercial rat compressed feed.<BR>6. The adult male rats of the second generation showed no significant decrease of hard tissue fluoride compared with that of the first generation. It may be attributed to the accumulation from not so completely defluoridated feed through the growth.<BR>7. The mandible of weanlings of the second generation contained fluoride as low as 8.7 ppm F. equivalent to 40 per cent of the mother rats.<BR>8. The mandible of weanlings of the third generation contained 7.5ppm F, equivalent to 50 erpcent of the dams.<BR>9. At all dose levels through 0, 0.5, to 1ppm of fluoride, the bones of weanlings were keeping a constant level of fluoride around 10ppm, indicating an active physiological barrier in placenta and mammary glands.<BR>10. At 10 and 50ppm of dose level, the reduction of fluoride in hard tissues of weanlings showed a constant ratio around 10 per cent of that of dams, suggesting a passive physicochemical filtration. The absolute level in tissues of pups was consequently increased.<BR>11. At higher dose level, the pups of the second generation contained significantly higher fluoride in hard tisses compared with that of the first generation.

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