Endocrine Abstracts

Deep Transcranical Magnetic Stimulation (dTMS) is a non-invasive modulation technique of cortical excitability that has shown to affect the mesolimbic and mesostriatal dopaminergic pathways. Consistent with these assets, dTMS is widely used as a therapeutic tool in neuro-psychiatric disorders associated with abnormal cortical excitability and dopaminergic activity, as addiction. Hence, considering the dysfuncional role of PFC and dopaminergic reward system in controlling appetite, dTMS was suggested to be affective in reducing food craving and in controlling body weight in obese subjects. However, the underlying physiological mechanisms of the dTMS effects are not fully know. Aim of this study was to investigate the effects of a single dTMS session on neuro-endocrine pathways in obesity. Fourty obese patients (11 M, 29 M; age: 48.0±1.6; BMI: 36.3±0.7) were assigned to receive one session of high frequency (18 Hz, HF), low frequency (1 Hz, LF) or Sham stimulation via an H-coil dTMS. H-coil was targeted to stimulate Prefrontal Cortex and Insula, bilaterally. Metabolic and neuro-endocrine parameters were evaluated before and after a single dTMS session. Following the 18 Hz dTMS session, a significant increase of norepinephrine was found (5.6±0.9 vs 6.5±1.2 ng/ml, +18.0±6.8%, P=0.01; P=0.05 vs LF); a rise in β-endorphins levels was also shown (0.338±0.049 vs 0.372±0.048 ng/ml, +13.9±4.6%, P=0.017; P=0.010 vs Sham; P=0.011 vs LF). In the same group, glucose levels significantly increased (90.2±4.1 vs 96.2±4.2 mg/dl, +7.0±1.8%, P=0.002), whilst leptin levels significantly decreased (66.9±10.5 vs 56.3±9.0 ng/ml, −16.3±3.0%, P=0.002). Furthermore, pituitary hormones significantly decreased after a single 18 Hz dTMS session, specifically TSH (2.71±0.25 vs 2.09±0.18 μU/ml, −20.7±4.7%, P=0.001) and prolactin (17.1±1.3 vs 10.6±0.8 ng/ml, −34.7±4.7%, P<0.0001). In the LF, a significant reduction of salivary cortisol was also observed (−29.4±9.3%, P=0.015). These results suggest that dTMS can acutely affect orexygenic pathways and metabolic parameters mainly via modulation of the sympathetic activity and hypothalamic-pituitary-adrenal axis. The increase of β-endorphins could suggest a potential role of HF dTMS in inducing the dopaminergic system activation and therefore, in modulating the food reward system. Together these findings support the role of dTMS as a novel promising treatment for obesity.