Anxiety induced by extra-hypothalamic BDNF deficiency instigates resistance to diet-induced obesity

Anxiety disorders are associated with body weight changes in humans. However, mechanisms underlying anxiety-related weight changes remain poorly understood. Using Emx1Cre/+ mice, we deleted the gene for brain-derived neurotrophic factor (BDNF) in the cortex, hippocampus, and some parts of the amygdala. The resulting mutant mice displayed elevated anxiety levels and were markedly lean when fed either chow diet or high-fat diet (HFD). The mice showed higher levels of sympathetic activity, thermogenesis and lipolysis in both brown and white adipose tissues, and higher oxygen consumption and body temperature, compared with control mice. They were still lean at thermoneurality when fed HFD, indicating elevated basal metabolism in addition to activated thermogenesis. Anxiety induced by site-specific Bdnf deletion similarly increased energy expenditure and minimized HFD-induced weight gain. These results reveal that anxiety can stimulate adaptive thermogenesis and basal metabolism by activating sympathetic nervous system, which enhances lipolysis and limits weight gain.