Journal Article

Human brown adipose tissue 15OO2 PET imaging in the presence and absence of cold stimulus

Kudomi, Nobu, Parkkola, Riitta, Virtanen, Kirsi A., Savisto, Nina, Sipilä, Hannu T, Raiko, Juho, Tolvanen, Tuula, Saari, Teemu, u Din, Mueez, Teuho, Jarmo, Oikonen, Vesa, Nuutila, Pirjo

2016

Overview

Purpose Brown adipose tissue (BAT) is considered a potential target for combatting obesity, as it produces heat instead of ATP in cellular respiration due to uncoupling protein-1 (UCP-1) in mitochondria. However, BAT-specific thermogenic capacity, in comparison to whole-body thermogenesis during cold stimulus, is still controversial. In our present study, we aimed to determine human BAT oxygen consumption with [ 15 O]O 2 positron emission tomography (PET) imaging. Further, we explored whether BAT-specific energy expenditure (EE) is associated with BAT blood flow, non-esterified fatty acid (NEFA) uptake, and whole-body EE. Methods Seven healthy study subjects were studied at two different scanning sessions, 1) at room temperature (RT) and 2) with acute cold exposure. Radiotracers [ 15 O]O 2 , [ 15 O]H 2 O, and [ 18 F]FTHA were given for the measurements of BAT oxygen consumption, blood flow, and NEFA uptake, respectively, with PET-CT. Indirect calorimetry was performed to assess differences in whole-body EE between RT and cold. Results BAT-specific EE and oxygen consumption was higher during cold stimulus (approx. 50 %); similarly, whole-body EE was higher during cold stimulus (range 2–47 %). However, there was no association in BAT-specific EE and whole-body EE. BAT-specific EE was found to be a minor contributor in cold induced whole-body thermogenesis (almost 1 % of total whole-body elevation in EE). Certain deep muscles in the cervico-thoracic region made a major contribution to this cold-induced thermogenesis (CIT) without any visual signs or individual perception of shivering. Moreover, BAT-specific EE associated with BAT blood flow and NEFA uptake both at RT and during cold stimulus. Conclusion Our study suggests that BAT is a minor and deep muscles are a major contributor to CIT. In BAT, both in RT and during cold, cellular respiration is linked with circulatory NEFA uptake.

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Adipose Tissue, Brown - diagnostic imaging / Adipose Tissue, Brown - physiology / Adult / Body fat / Cardiology / Cold / Cold Temperature / Cold-Shock Response - physiology / Female / Humans / Imaging / Male / Medical imaging / Medicine / Medicine & Public Health / NMR / Nuclear magnetic resonance / Nuclear Medicine / Oncology / Original / Original Article / Orthopedics / Oxygen Consumption - physiology / Oxygen Radioisotopes / Positron-Emission Tomography - methods / Radiology / Radiopharmaceuticals / Reproducibility of Results / Sensitivity and Specificity / Thermogenesis - physiology / Tissues