In addition, serotonin antidepressant drugs are widely used among those with obesity and chronic injuries, suggesting its role in energy balance and NEAT, and one such drug, fluoxetine, increases the expression of OX2R in the thalamus and hypothalamus (Bross & Hoffer, 1995; Nollet et al., 2011). This evidence concerns the gene HCRTR2 and obesity due to melanocortin 4 receptor deficiency.