AMPK Activation by MK-8722 Measured with [¹⁸F]FDG-PET Imaging in Rodents and Non-Human Primates

The adenosine monophosphate-activated protein kinase (AMPK) induces glucose uptake by increasing the expression of glucose transporter 4 (GLUT4), and [¹⁸F]Fluorodeoxyglucose (FDG) is readily transported into tissues with high GLUT4 expression. Thus, positron emission tomography with FDG (FDG-PET) could serve as an important pharmacodynamic readout of AMPK activation. In this study, the impact of treatment with the pan-AMPK activator MK-8722 on FDG uptake was evaluated in rats and Rhesus monkeys.

Rats were evaluated with FDG-PET following intravenous (IV) or oral (PO) administration of MK-8722. Rhesus monkeys were orally dosed and evaluated with FDG-PET. FDG uptake was measured in skeletal and cardiac muscle, and the incorporation rate was calculated using the Patlak graphical method.

In rats, the highest IV dose of MK-8722 (5 mg/kg) and both PO doses (4 mg/kg and 10 mg/kg) given 4 h prior to FDG-PET resulted in a significant increase in forelimb skeletal muscle FDG uptake (p < 0.01). In Rhesus monkeys, chronic oral administration of 10 mg/kg MK-8722 QD resulted in significantly higher FDG uptake in bicep skeletal muscle than vehicle treatment after 2 and 4 weeks of treatment (p < 0.01), but no difference was observed after 5 weeks of drug washout (p > 0.05). FDG uptake in cardiac muscle was significantly reduced with MK-8722 treatment in rats, but no significant changes in cardiac muscle FDG uptake were measured in Rhesus monkey.

FDG-PET can be used as a pharmacodynamic readout for systemic pharmacological activation of AMPK for preclinical studies and potentially be extended to study humans.