Endocrine Abstracts

Obesity is known to be associated with increased heat production. To maintain normothermia, heat retention in areas of the body with greater adiposity is counteracted by an augmented heat release from the extremities, as the fingernail-beds of hands. A possible cause of the altered thermoregulation in obesity is a dysfunction of the neuro-endocrine system. Repetitive deep Transcranial Magnetic Stimulation (dTMS) was proved to be an effective tool in inducing long lasting changes in neural excitability and dopamine release, causing satiety and weight loss. Aims of this study were to investigate the acute and chronic effects of dTMS on body temperature measured by Infrared Thermography in obese subjects. Twenty-nine obese subjects (6 M, 23 F; 48.3±11.8 years; BMI: 37.7±4.3 kg/m²), seeking treatment for weight control, were randomized into 3 groups receiving 15 sessions (3 per week for 5 weeks) of high frequency (18 Hz), low-frequency (1 Hz) or sham stimulation. Under neutral thermal conditions, fingernail-bed of both hands, abdominal and interscapular skin temperature was measured by Infrared Thermography (AVIO TVS700 camera, 320×240 pixel, spatial resolution 1.4 mrad, temperature resolution 0.08°C). After a single session of 18 Hz dTMS, the average fingernail-bed of both hands temperature significantly decreased (right hand: −4.4±0.3%, P<0.05 vs baseline; left hand: −2.7±0.2%, P<0.05 vs baseline). Concurrently, was found a significant increase of norepinephrine (+18.8±7.7%, P<0.05 vs baseline) and of β-endorphin (+14.3±5.4%, P<0.05 vs Sham). After a single session of both 18 and 1 Hz dTMS, a trend to increase in abdominal skin temperature was observed (18 Hz group: +0.9±0.9%, P<0.01 vs Sham group; 1 Hz group: +1.2±1.7%, P<0.05 vs Sham group). In 2 subjects receiving high frequency stimulation, an increase of interscapular temperature was observed (+6.0±1.0%), suggesting an activation of brown adipose tissue. After 15 dTMS sessions, analysis revealed a significant decrease of body weight (−4.1±0.6%, P<0.05 vs baseline, P<0.05 vs Sham) and a decrease of abdominal skin temperature (−2.3±2.9%, P<0.05) in 18 Hz group. Deep TMS revealed to be effective in modulating body temperature in obese subjects, reversing obesity-induced alterations in heat production and dissipation.