Ramírez-López F et al.xlsx

Prolonged dopamine replacement therapy commonly leads to incapacitating movements known as L-DOPA-induced dyskinesias in Parkinson’s disease. Recently, transcranial magnetic stimulation has been used as a non-invasive therapy for motor symptoms and dyskinesias in this disease. Several studies suggest that the motor effects of transcranial magnetic stimulation might be the result of dopamine system modulation. Nevertheless, the mechanisms underlying transcranial magnetic stimulation are not thoroughly understood. In the present study, we investigated whether transcranial magnetic stimulation regulates cellular activation as shown by c- Fos immunoreactivity, on dopamine D1 receptor positive cells of the striatum and motor cortex of dyskinetic and naïve rats. Furthermore, we evaluated transcranial magnetic stimulation effect on dyskinesias along with its molecular marker, FosB and motor execution of hemiparkinsonian rats. Our results show that transcranial magnetic stimulation reduces c-Fos expression in dopamine D1 receptor positive cells in the striatum and motor cortex. In addition, this treatment significantly attenuated dyskinesias, an effect accompanied by a low expression of FosB in the striatum and the improvement of motor execution. This study proposes that transcranial magnetic stimulation might modulate the activity of dopamine D1 receptors containing cells in the motor cortex and striatum and highlights the therapeutic potential of this technique in Parkinson’s disease. However, further investigation is needed to examine the role of dopamine D2 receptors and other regions in the effects of this treatment.