Figure 2.

The molecular networks by which exercise promotes adipose tissue browning and thermogenesis. Exercise stimulates sympathetic excitation and releases norepinephrine binding to β-adrenergic receptors to promote adipose tissue thermogenesis and browning. In addition, exercise promotes the muscular release of irisin and hepatic release of FGF21. Irisin not only regulates the browning of adipocytes directly, but also promotes the release of BDNF from the brain through “muscle-brain crosstalk” and thus increases adipose tissue thermogenesis and browning. BDNF also acts on the sympathetic nervous system to mediate WAT browning. Circulating metabolites (such as creatine, acetate and FFA) produced by exercise also enhance adipose tissue thermogenesis and browning directly or indirectly. All these pathways ultimately target thermogenic gene expression and mitochondrial biogenesis.