## 3 Results  
In order to clarify the molecular mechanism of the interaction of fluoride with a static magnetic field, four study groups were distinguished: control cells (C), F\({}^{-}\)-treated cells (F), SMF-treated cells (SMF) and cells that had simultaneously been exposed to a static magnetic field and F\({}^{-}\) (SMF + F). The Effect of Fluoride and the Static Magnetic Field Action on the Expression of the Melatonin-Associated Genes  
The exposure of fibroblasts to the fluoride resulted in a statistically significant change in the expression of one transcript, which had been up-regulated ([PERSON] post hoc test, \(p\) < 0.05, FC > 1.1). In turn, as a result of the action of a static magnetic field alone on the cells, the expression level of five transcripts was statistically significantly higher ([PERSON] post hoc test, \(p\) < 0.05, FC > 1.1). For the skin fibroblasts that had simultaneously been exposed to fluoride and a static magnetic field compared to the F\({}^{-}\)-treated cells, one transcript was differentiated, which had been down-regulated ([PERSON] post hoc test, \(p\) < 0.05, FC > 1.1) (Table 1). In the next stage, the differentially expressed genes that had been characterized by the greatest change in the FC value (FC \(\geq\) 1.2) were selected to validate the results using the RT-qPCR technique (_IL27 RA_, _NR1D1_). The RT-qPCR analysis mostly confirmed the direction of the changes in the expression of the _IL27 RA_ and _NR1D1_ genes as a result of the exposure of a cell to a static magnetic field and fluoride (Table 2). In the cells that had simultaneously been exposed to fluoride and a static magnetic field, there was a tendency to compensate for the expression of the differentiating genes that was altered by the presence of fluoride (Figures 1 and 2). \begin{table}
\begin{tabular}{l l l l l l} \hline \hline \multirow{2}{*}{**ID mRNA**} & \multirow{2}{*}{**Gene Symbol**} & \multirow{2}{*}{**Gene Name**} & **F vs. C** & **SMF vs. C** & **SMF + F vs. F** \\ \cline{5-6}  & & & & **FC** & \\ \hline
205926\_at & _IL27 RA_ & interleukin 27 receptor subunit alpha & 1.13\(\uparrow\) * & 1.22\(\uparrow\) * & 1.01\(\downarrow\) \\ \hline
204760\_s\_at & _NR1D1_ & nuclear receptor subfamily 1 group D member 1 & 1.08\(\downarrow\) & 1.23\(\uparrow\) * & 1.14\(\uparrow\) \\ \hline
202937\_x\_at & _RRP7A_ & ribosomal RNA processing 7 homolog A & 1.05\(\uparrow\) & 1.19\(\uparrow\) * & 1.04\(\downarrow\) \\ \hline
33307\_at & _RRP7A_ & ribosomal RNA processing 7 homolog A & 1.02\(\uparrow\) & 1.11\(\uparrow\) * & 1.03\(\downarrow\) \\ \hline
214733\_s\_at & _YIPF1_ & yip1 domain family member 1 & 1.05\(\uparrow\) & 1.11\(\uparrow\) * & 1.02\(\downarrow\) \\ \hline
222067\_x\_at & _HIST1H2 BD_ & histone H2B type 1-D & 1.03\(\uparrow\) & 1.03\(\uparrow\) & 1.14\(\downarrow\) * \\ \hline \hline \end{tabular}  
* C—control cells, F—F”-treated cells; SMF—cells that had been exposed to a static magnetic field; SMF + F—cells that had simultaneously been exposed to a static magnetic field and F”; FC—fold change; \(\uparrow\), \(\downarrow\)—up- or down-regulation of gene; statistical significance: *\(p\) < 0.05 vs. F.  
\end{table} 
Table 1: List of differentially expressed genes determined by the oligonucleotide microarray technique. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline \multirow{2}{*}{**Gene Symbol**} & \multirow{2}{*}{**Gene Name**} & **F vs. C** & **SMF vs. C** & **SMF + F vs. F** \\ \cline{3-6}  & & & & **FC** & \\ \hline _IL27 RA_ & interleukin 27 receptor subunit alpha & 1.51\(\uparrow\) & 1.05\(\uparrow\) & 1.91\(\downarrow\) \\ \hline _NR1D1_ & nuclear receptor subfamily 1 group D member 1 & 1.84\(\downarrow\) & 1.16\(\downarrow\) & 1.05\(\uparrow\) \\ \hline \hline \end{tabular}  
* C—control cells, F—F”-treated cells; SMF—cells that had been exposed to a static magnetic field; SMF + F—cells that had simultaneously been exposed to a static magnetic field and F”; FC—fold change; \(\uparrow\), \(\downarrow\)—up- or down-regulation of gene.  
\end{table}