GDF15 links beta-adrenergic induced lipolysis with anxiety

Psychological stress activates the autonomic nervous system to protect organisms through an integrated response involving changes to both behavior and metabolism. Epinephrine is an important driver of this response, activating adipose tissue lipolysis3and inducing anxiety-like behavior. Interestingly, anxiety correlates with circulating free fatty acid levels and can be alleviated by a b-blocker that does not cross the blood brain barrier suggesting a peripheral signal linking metabolism with behavior, however, to date this has not been defined. Herein, we identify that the most upregulated secreted gene product induced by epinephrine within white adipose tissue of mice is growth differentiating factor 15 (GDF15). This increase in GDF15 occurs within one hour and is not observed in liver, brown adipose, kidney, or skeletal muscle, and is also observed with the more specific b2/3-agonist, CL316,243. Genetic inhibition of adipose triglyceride lipase (ATGL), the rate limiting enzyme for the release of free fatty acids in white adipose tissue, or genetic deletion of b-adrenergic receptors, blocks b-adrenergic induced increases in GDF15. Increases in circulating GDF15 are not derived from adipocytes but instead require free fatty acid-induced stimulation of macrophages within white adipose tissue. Remarkably, anxiety-like behavior elicited by epinephrine or restraint stress are eliminated in mice lacking the GDF15 receptor, GFRAL. Importantly in patients with severe burns, increases in catecholamines are associated with GDF15 and this relationship is eliminated with the b-blocker propranolol. These data provide important insight into the mechanisms linking metabolism and behavior and suggest that inhibition of GDF15-GFRAL signaling may be important for reducing acute anxiety. To investigate transcriptomic effects of anxiety, RNA-seq data was obtained from mice in two conditions, each with 6 biological replicates. First condition was 'Vehicle': mice injected with saline (control condition). Second condition was 'Epinephrine': mice injected with sodium epinephrine.