© Borgis - New Medicine 3/2009, s. 56-57
*Ewa Ogłodek1, Danuta Mo?2, Aleksander Araszkiewicz1
Effects of a 50 Hz magnetic field on the female rat´s thyroid gland in production of C cells
1Department of Clinical Psychiatry of the Nicolaus Copernicus University in Toruń
2Collegium Medicum in Bydgoszcz, Poland
2Individual medical practice
Summary
Aim: The aim of this study was to assess the effect of extremely low-frequency magnetic fields (ELF-MF) featuring magnetotherapeutic parameters used for analgesia and cell metabolism stimulation on the activity of the female rat´s thyroid gland in production of C cells synthesizing calcitonin. The ELF-MF boost secretion of calcitonin through the impact on the nerve fibres of the C cells which are located in proximity of their basement membrane.
MATERIAL AND METHOD: 24 female Wistar rats, Hannover substrain, aged 10 months, weighing 300 +/- 50 g each, were included in the experiment. Each of the rats underwent ovariectomy from a lumbar approach in the 6th month of life. The rats were divided into 2 groups: group "40”, exposed to extremely low-frequency magnetic fields of frequency 40 Hz; and control group "C” – sham exposure.
Results: In the thyroid preparations C cells and in rat´s serum calcium complex concentrations (CC-C) and calcium ion concentrations (CI-C) were evaluated.
Conclusions: The mean R-CALCY, calcium complex concentrations (CC-C) and calcium ion concentrations (CI-C) in group ´40´ were significantly different from the mean R-CALCY, CC-C and CI-C in group ´C´. ELF-MF stimulate the body to secrete calcitonin and deposit calcium in the osseous tissue. ELF-MF show a therapeutic effect on the bones, as more calcium accumulates in the bones under its influence.
INTRODUCTION
The biological effect of extremely low-frequency magnetic fields (ELF-MF) was assessed based on the model of ionic cyclotron resonance [1]. It is a theory assuming that calcium ions, which play a crucial role in cell metabolism, work as a sort of homing guidance for the impact of the magnetic field on living matter [3]. ELF-MF have an influence on ion transport, especially of calcium ones, through the calcium channels of the cytoplasmic membranes. Sustaining a calcium concentration gradient inside a cell is affected by the activity of Na+, K+/ATP and magnesium-dependent Ca++/ATP [6]. The magnesium-dependent Ca++/ATP is a catalyst for the transport of Ca++ from the cytoplasm to the extracellular space. In this study, tests were carried out on female rats which were subjected to prior experimental ovariectomy in order to achieve the effect of menopause observed in women. Menopause is connected with oestrogen-gestagen imbalance, deficit of these hormones and increased bone resorption, which leads to decrease of the BMD and the spongy bone area [9].
AIM
The aim of this study was to assess the effect of extremely low-frequency magnetic fields featuring magnetotherapeutic parameters used for analgesia and cell metabolism stimulation on the activity of the female rat´s thyroid gland in production of C cells synthesizing calcitonin.
MATERIAL AND METHOD
24 female Wistar rats, Hannover substrain, aged 10 months, weighing 300 +/- 50 g each, were included in the experiment. Each of the rats underwent ovariectomy from a lumbar approach in the 6th month of life. The rats were divided into 2 groups: group "40”, exposed to extremely low-frequency magnetic fields of frequency 40 Hz; and control group "C” – sham exposure. Microscopic slides were made from the rats´ thyroid glands. After rinsing the preparations in PBS buffer solution, they were marked with an antibody against calcitonin leading to induction of an immunoenzymatic reaction, which resulted in brown staining of the C cells. A quantitative analysis of the C cells in the prepared slides was performed consisting in evaluation of 50 view fields of each of the slides. In the rat serum were evaluated calcium complex concentrations (CC-C) and calcium ion concentrations (CI-C).
The following methods were used for the purpose of the statistical analysis: ANOVA for a single variable was performed using the following tests: Cochran-Cox test and investigation of significance of differences between the mean values (post-hoc analysis) by means of Tukey´s test.
RESULTS
Table 1 shows the mean values of R-CALCY, calcium complex concentrations (CC-C) and calcium ion concentrations (CI-C).
Table 1. Parameters: R-CALCY, calcium complex concentrations ´CC-C´, calcium ion concentrations ´CI-C´.
| Parameter | Group ´40´ (mean value and SD for each group) | Group ´C´ (mean value and SD for each group) | Group ´40´ and ´C´ (significance of differences) | Cochran-Cox Test 40´ and ´C´ | Tukey Test ´40´ and ´C´ |
| R/CALCY | 0.34(+/-0.05) | 0.08(+/-0.07) | p<0.0001 | 0.663 | 0.00002 |
| ´CC-C´Calcium complex concentration [mmol/l] | 1.41(+/-0.06) | 2.32(+/-0.04) | p<0.0001 | 1.853 | 0.00002 |
| ´CI-C´Calcium ion concentration [mmol/l] | 0.78(+/-0.06) | 1.23(+/-0.03) | p<0.0001 | 1.434 | 0.00002 |
The mean R-CALCY, CC-C and CI-C in group ´40´ were significantly different from the mean R-CALCY, CC-C and CI-C in group ´C´. The growth of the ELF-MF frequency resulted in a significant increase in C cells count and decreased CC-C and CI-C. The increase of C cells count is probably connected with a growth of calcitonin secretion.
DISCUSSION
The parameters of the magnetic field applied in the investigation corresponded to the typical values applied for magnetic field therapy in humans [3].
In order to eliminate the effect of activation of sexual gland hormones on metabolism of female rats´ thyroid glands with the rats being a source of thyroid gland for investigation, the rats underwent ovariectomy in the time preceding the experiment [5, 6].
As a result of the above-mentioned operation, the level of steroid hormones in the investigated rats corresponded to the level of these hormones in the early follicular phase and was also observed in menopausal women. At the same time, it can be stated on the basis of the available literature that in physiological conditions the menopause does not cause significant involution of the thyroid gland [2, 10].
The female rat´s exposures to the 40 Hz ELF-MF for several months resulted in stimulation of growth of the thyroid gland and parathyroid glands, and thus in increased production of C cells, which synthesized calcitonin and decreased calcium complex and calcium ion concentrations in the rat´s serum [2, 4].
Again, according to the literature, ELF-MF significantly stimulate the circulation of calcium in the body [5, 7]. After magnetic fields C cells stimulation on the activity of the female rat´s thyroid gland in production of C cells synthesizing calcitonin. Calcitonin plays an important role in regulation of calcaemia, as it stimulates absorption of calcium from the digestive tract [8, 10].
In stimulation of the thyroid gland and parathyroid glands, the nucleus and the Golgi apparatus become enlarged and change their location, becoming the secretory surface of the C cells. The cellular nucleus is the final place of the activity of thyroid and parathyroid hormones. After activation of the DNA domain, known as ´thyroid-hormone response element – TRE´, an increase of nuclear concentration of RNA occurs. The nuclear receptors are peptides built as typical transcription factors, which means that they possess the linking DNA domain responsible for oligomerization and the domain linking DNA of the zinc finger structure [7, 9].
CONCLUSIONS
1. The results of this study confirm the stimulating effect of exposure to ELF-MF, featuring various physical parameters used routinely in magnetotherapy, on the increased C cells count in female rats after experimental ovariectomy and decreased calcium complex and calcium ion concentrations in rat serum.
2. The thyroid gland is an important link in the chain of regulation of the calcium–phosphorus balance due to secretion of calcitonin by its C cells.
Piśmiennictwo
1. Chen H, et al.: Morphological study of the parathyroid gland and thyroid C cell in senescence-accelerated mouse (SAMP6), a murine model for senile osteoporosis. Tissue Cell. 2004; 36(6): 409-15. 2. Huang CL, et al.: Molecular physiology and pharmacology of calcitonin. Cell Mol Biol. 2006; 52(3): 33-43. 3. Huang LQ, et al.: Clinical update of pulsed electromagnetic fields on osteoporosis. Chin Med J. 2008; 121(20): 2095-9. 4. Icaro Cornaglia A, et al.: Stimulation of osteoblast growth by an electromagnetic field in a model of bone-like construct. Eur J Histochem. 2006; 50(3): 199-204. 5. Kleerekoper M: Osteoporosis prevention and therapy: preserving and building strength through bone quality. Osteoporos Int. 2006; 17(12): 1707-15. 6. Lerner UH, et al.: Osteotropic effects by the neuropeptides calcitonin gene-related peptide, substance P and vasoactive intestinal peptide. J Musculoskelet Neuronal Interact. 2008; 8(2): 154-65. 7. Markaki AE, et al.: Magneto-mechanical stimulation of bone growth in a bonded array of ferromagnetic fibres. Biomaterials. 2004; 25(19): 4805-15. 8. Rubin CD: Emerging concepts in osteoporosis and bone strength. Curr Med Res Opin. 200; 21(7): 1049-56. 9. Stanosz S, et al.: The appreciation of bone growth factor in women with osteoporosis exposing on freetransition magnetic field]. Pol Merkur Lekarski. 2004; 17(99): 229-31. 10. Titova MA, et al.: C-cells of the thyroid gland in experimental osteoporosis]. Morfologiia. 2003; 123(2): 68-72.
