Transcranial direct current stimulation (tDCS) modulates biometric and inflammatory parameters and anxiety-like behavior in obese rats

Obesity is a multifactorial disease associated with metabolic dysfunction and the prevention and treatment of obesity are often unsatisfactory. Transcranial direct-current stimulation (tDCS) is a non-invasive brain stimulation technique that has proven promising in the treatment of eating disorders such as obesity. We investigate the effects of tDCS on locomotor and exploratory activities, anxiety-like and feeding behavior, and levels of brain-derived neurotrophic factor (BDNF), IL (interleukin)-10, IL-1 beta, and tumor necrosis factor-alpha (TNF-alpha) in the cerebral cortex of obese rats. A total of 40 adult male Wistar rats were used in our study. Animals were divided into groups of three or four animals per cage and allocated to four treatment groups: standard diet plus sham tDCS treatment (SDS), standard diet plus tDCS treatment (SDT), hypercaloric diet plus sham tDCS treatment (HDS), hypercaloric diet plus tDCS treatment (HDT). After 40 days on a hypercaloric diet and/or standard diet were to assessed the locomotor and exploratory activity and anxiety-like behavior to by the open field (OF) and elevated plus maze (EPM) tests respectively before and after exposure to tDCS treatment. The experimental groups were submitted to active or sham treatment tDCS during eight days. Palatable food consumption test (PFT) was performed 24 h after the last tDCS session under fasting and feeding conditions. Obese animals submitted to tDCS treatment showed a reduction in the Lee index, visceral adipose tissue weight, and food craving. In addition, bicephalic tDCS decreased the cerebral cortex levels of IL-1 beta and TNF-alpha in these animals. Exposure to a hypercaloric diet produced an anxiolytic effect, which was reversed by bicephalic tDCS treatment. These results suggest that, in accordance with studies in humans, bicephalic tDCS could modulate biometric and inflammatory parameters, as well as anxiety-like and feeding behavior, of rats subjected to the consumption of a hypercaloric diet.