Fig. 1.

Schematic showing the mechanism of glucose uptake in a brown adipocyte. Aomoxetine (ATX) inhibits norepinephrine reuptake by blocking presynaptic norepinephrine transporter (NET), which results in a longer activation of postsynaptic β-adrenergic receptor. CL-316, 243 (CL) activate β₃-adrenergic receptor (β₃AR) directly. Production of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) trigger lipase and hydrolysis of triglycerides in one hand. On the other hand, it phosphorylates phosphoinositide-3-kinase (PI3 K) followed by a series of reactions resulting in synthesis and translocation of GLUT 1/4, and overexpression of hexokinase (HK), which leads to an increase in glucose and ¹⁸F-FDG uptake. ●, Norepinephrine; PKC, protein kinase C; Pyr,: pyruvate; UCP-1, uncoupling protein-1.