Influence of electric transcranial direct current stimulation (tDCS) on the elemental and molecular composition of brain reward system structures in obese rats.

The objective of our study was to investigate the effect of transcranial direct current stimulation (tDCS) on molecular and elemental changes in the brain reward system of obese rodents. The tDCS of the prefrontal cortex could serve as an innovative adjunctive method in the treatment of obesity. In the experiment we used rats with high calorie diet-induced obesity and subsequently treated with tDCS. Thin sections of rat brains were investigated using infrared microspectroscopy coupled with synchrotron radiation X-ray fluorescence. We found, that in the brain cortex, the level of fatty acid chain length parameter was significantly lower in the anodal tDCS (atDCS) group compared to both the cathodal tDCS (ctDCS) and sham stimulated (Sh) animals. On the other hand, ctDCS caused a significant decrease in the level of the lipid to protein ratio in the substantia nigra as well as in the β to α protein secondary structure ratio in the striatum. Moreover, we observed that the greatest differences related to elemental composition between the studied groups primarily occur in the ventral tegmental area. In this region, significant increase in the levels of Na, Ca, Mg, Cu, and Zn was identified in the atDCS group, and Zn in the ctDCS group. In the brain cortex, a decrease in Mg and Zn levels was observed in the ctDCS compared to the Sh individuals. The studies revealed that tDCS elicits significant molecular and elemental modifications within the brain's reward system, albeit restricted to distinct regions.