Similarly, Siteneski et al. (2018) demonstrated that irisin administered into the cerebral lateral ventricles reduced depressive-like behaviors in mice undergoing stressful situations by modulating the expression of the brain-derived neurotrophic factor (BDNF), whose low levels have been associated to depression in humans (Brunoni et al., 2008). The gene discussed is BDNF; the disease is major depressive disorder.