Brown adipose tissue-derived FGF21 mediates the cardioprotection of dexmedetomidine in myocardial ischemia/reperfusion injury

Brown adipose tissue (BAT) plays a critical role in regulating cardiovascular homeostasis through the secretion of adipokines, such as fibroblast growth factor 21 (FGF21). Dexmedetomidine (DEX) is a selective α2-adrenergic receptor agonist with a protection against myocardial ischemia/reperfusion injury (MI/RI). It remains largely unknown whether or not BAT-derived FGF21 is involved in DEX-induced cardioprotection in the context of MI/RI. Herein, we demonstrated that DEX alleviated MI/RI and improved heart function through promoting the release of FGF21 from interscapular BAT (iBAT). Surgical iBAT depletion or supplementation with a FGF21 neutralizing antibody attenuated the beneficial effects of DEX. AMPK/PGC1α signaling-induced fibroblast growth factor 21 (FGF21) release in brown adipocytes is required for DEX-mediated cardioprotection since blockade of the AMPK/PGC1α axis weakened the salutary effects of DEX. Co-culture experiments showed that DEX-induced FGF21 from brown adipocytes increased the resistance of cardiomyocytes to hypoxia/reoxygenation (H/R) injury via modulating the Keap1/Nrf2 pathway. Our results provided robust evidence that the BAT-cardiomyocyte interaction is required for DEX cardioprotection, and revealed an endocrine role of BAT in DEX-mediating protection of hearts against MIRI.