Brown adipose tissue uptake of triglyceride-rich lipoprotein-derived fatty acids in diabetic or obese mice under different temperature conditions

Background In vivo imaging of glucose analogue 2-deoxy-2-[F-18]fluoro-d-glucose ([F-18]FDG) via positron emission tomography (PET) is the current gold standard to visualize and assess brown adipose tissue (BAT) activity. However, glucose metabolism is only a part of the metabolic activity of BAT. [F-18]FDG-PET has been shown in clinical trials to often fail to visualize BAT under insulin-resistant conditions associated with aging and weight gain. We employed a novel developed triglyceride-based tracer to visualize BATs metabolic activity under different temperature conditions as well as under diabetic and obese conditions in preclinical models. Results [F-18]BDP-TG-chylomicron-like particles visualized BAT in control, streptozocin-induced diabetes and obese mice. Increased BAT tracer uptake was found in control mice acutely exposed to cold but not in cold-acclimated animals. Diabetes did not remove BAT tracer uptake, but did limit BAT tracer uptake to levels of control mice housed at 21 degrees C. In obese animals, BAT tracer uptake was significantly reduced, although the stimulating effect of cold exposure could still be noted. Conclusion BAT was visualized in control, diabetic and obese conditions. Streptozocin-induced diabetes, but not obesity, inhibited the stimulatory effect of cold exposure.