Abstract
Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been shown to increase ketone bodies in patients with type 2 diabetes; however, the underlying mechanisms have not been fully elucidated. Here we examined the effect of the SGLT2 inhibitor dapagliflozin (1 mg/kg/day, formulated in a water, PEG400, ethanol, propylene glycol solution, 4 weeks) on lipid metabolism in obese Zucker rats. Fasting FFA metabolism was assessed in the anesthetized state using a [9,10-(3)H(N)]-palmitic acid tracer by estimating rates of plasma FFA appearance (R(a)), whole-body FFA oxidation (R(ox)), and nonoxidative disposal (R(st)). In the liver, clearance (K(β-ox)) and flux (R(β-ox)) of FFA into β-oxidation were estimated using [9,10-(3)H]-(R)-bromopalmitate/[U-(14)C]palmitate tracers. As expected, dapagliflozin induced glycosuria and a robust antidiabetic effect; treatment reduced fasting plasma glucose and insulin, lowered glycated hemoglobin, and increased pancreatic insulin content compared with vehicle controls. Dapagliflozin also increased plasma FFA, R(a), R(ox), and R(st) with enhanced channeling toward oxidation versus storage. In the liver, there was also enhanced channeling of FFA to β-oxidation, with increased K(β-ox), R(β-ox) and tissue acetyl-CoA, compared with controls. Finally, dapagliflozin increased hepatic HMG-CoA and plasma β-hydroxybutyrate, consistent with a specific enhancement of ketogenesis. Since ketogenesis has not been directly measured, we cannot exclude an additional contribution of impaired ketone body clearance to the ketosis. In conclusion, this study provides evidence that the dapagliflozin-induced increase in plasma ketone bodies is driven by the combined action of FFA mobilization from adipose tissue and diversion of hepatic FFA toward β-oxidation.