The long-term effect of a calcium diet on the bone tissue, C-cells and parathyroid glands of the rat

Logonder-Mlinšek, M.; Pajer, Zdenka

doi:10.1007/bf03348912

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…The observation of increased C-cell tumors was unexpected in that no studies in the epidemiology literature have identified the thyroid as a possible target for magnetic field action (46,51). Although Ccells are sensitive to calcium levels (5,8), modest changes in intracellular calcium have not been shown to alter C-cell tumor rates in animals (29). Although relevant experimental data are very limited, we have found that subchronic exposure to magnetic fields has no effect on serum calcium levels in male F344 rats (McCormick and Cahill, unpublished observations).…”

Section: Discussionmentioning

confidence: 99%

Chronic Toxicity/Oncogenicity Evaluation of 60 Hz (Power Frequency) Magnetic Fields in F344/N Rats

Boorman

McCormick²,

Findlay³

et al. 1999

Toxicol Pathol

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A 2-yr whole-body exposure study was conducted to evaluate the chronic toxicity and possible oncogenicity of 60 Hz (power frequency) magnetic fields in rats. Groups of 100 male and 100 female F344/N rats were exposed continuously to pure, linearly polarized, transient-free 60 Hz magnetic fields at flux densities of 0 Gauss (G) (sham control), 20 milligauss (mG), 2 G, and 10 G; an additional group of 100 male and 100 female F344/N rats received intermittent (1 hr on/1 hr off) exposure to 10 G fields. Mortality patterns, body weight gains throughout the study, and the total incidence and number of malignant and benign tumors in all groups exposed to magnetic fields were similar to those found in sex-matched sham controls. Statistically significant increases in the combined incidence of C-cell adenomas and carcinomas of the thyroid were seen in male rats chronically exposed to 20 mG and 2 G magnetic fields. These increases were not seen in male rats exposed continuously or intermittently to 10 G fields or in female rats at any magnetic field exposure level. No increases in the incidence of neoplasms, which have been identified in epidemiology studies as possible targets of magnetic field action (leukemia, breast cancer, and brain cancer), were found in any group exposed to magnetic fields. There was a decrease in leukemia in male rats exposed to 10 G intermittent fields. The occurrence of C-cell tumors at the 2 lower field intensities in male rats is interpreted as equivocal evidence of carcinogenicity; data from female rats provides no evidence of carcinogenicity in that sex. These data, when considered as a whole, are interpreted as indicating that chronic exposure to pure linearly polarized 60 Hz magnetic fields has little or no effect on cancer development in the F344/N rat.

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Section: Discussionmentioning

confidence: 99%

Chronic Toxicity/Oncogenicity Evaluation of 60 Hz (Power Frequency) Magnetic Fields in F344/N Rats

Boorman

McCormick²,

Findlay³

et al. 1999

Toxicol Pathol

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Chronic hypervitaminosis D3 determines a decrease in C-cell numbers and calcitonin levels in rats

Martín-Lacave

Ramos

Utrilla

et al. 1998

J Endocrinol Invest

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Many papers have reported that chronic hypercalcemia induced either by large doses of vitamin D or by the administration of calcium or parathormone, produces hypertrophy and hyperplasia of C cells. However, more recent studies suggest that the effect of elevated calcium or 1.25(OH)2D3 concentration on the production of calcitonin may be more complex than previously suspected. To assess the validity of such a response an experimental model, where hypercalcemia was induced with vitamin D3 overdose, was designed. Male Wistar rats were administered vitamin D3 chronically (50,000 IU per 100 ml of drinking water with or without CaCl2). Serum calcium and calcitonin levels were determined. C cells were stained by immunohistochemistry using calcitonin and neuronal specific enolase (NSE) antibodies and their percentage was calculated by a morphometric analysis. We also investigated the ultrastructural characteristic of the C cells under experimental conditions. C cells did not have a proliferative response rather a decrease in their number was observed after 1 month of treatment with 25,000 IU of vitamin D3 (1.55 vs 2.43% in control animals) and 3 months with vitamin plus CaCl2 (2.27% vs 3.62% in control animals). In addition, no significant changes in serum calcitonin levels were observed during the experimental period. We conclude that rat C cells do not respond with hypertrophic and hyperplastic changes in a hypercalcemic state due to an intoxication with vitamin D3.

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The long-term effect of a calcium diet on the bone tissue, C-cells and parathyroid glands of the rat

Cited by 2 publications

References 15 publications

Chronic Toxicity/Oncogenicity Evaluation of 60 Hz (Power Frequency) Magnetic Fields in F344/N Rats

Chronic Toxicity/Oncogenicity Evaluation of 60 Hz (Power Frequency) Magnetic Fields in F344/N Rats

Chronic hypervitaminosis D3 determines a decrease in C-cell numbers and calcitonin levels in rats

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