Assessment of brown adipose tissue activity in rats by 99mTc-sestamibi uptake

• Published in: Physiological research Vol. 55; no. 6; pp. 653 - 659
• Main Authors: Kyparos, D, Arsos, G, Georga, S, Petridou, A, Kyparos, A, Papageorgiou, E, Mougios, V, Matziari, C, Karakatsanis, C
• Format: Journal Article
• Language: English
• Published: Czech Republic 2006
• Subjects: Adipose Tissue, Brown - diagnostic imaging; Adipose Tissue, Brown - metabolism; Adipose Tissue, Brown - physiology; Adipose Tissue, White - metabolism; Age Factors; Aging - metabolism; Animals; Body Weight; Electron Transport Complex IV - metabolism; Male; Mitochondria - diagnostic imaging; Mitochondria - metabolism; Mitochondria - physiology; Radionuclide Imaging; Radiopharmaceuticals - metabolism; Rats; Rats, Wistar; Technetium Tc 99m Sestamibi - metabolism; Thermogenesis
• ISSN: 0862-8408; 1802-9973
• DOI: 10.33549/physiolres.930890

Brown adipose tissue (BAT) physiology and imaging have recently attracted considerable attention. BAT is characterized both by enhanced perfusion and increased mitochondrial activity. (99m)Tc-sestamibi is a lipophilic cationic tracer that concentrates in mitochondria. Data on the accumulation of (99m)Tc-sestamibi in BAT are currently lacking. This study investigates the in vivo (99m)Tc-sestamibi uptake in rat BAT. (99m)Tc-sestamibi was administered in male Wistar rats of various age and body size. (99m)Tc-sestamibi uptake was measured in vitro in BAT and white fat (WF) together with cytochrome c oxidase activity. Both (99m)Tc-sestamibi uptake and cytochrome c oxidase activity were higher in BAT than in WF (P<0.05). (99m)Tc-Sestamibi uptake in both BAT and WF was negatively related to body weight (r = -0.96 and -0.89, respectively) as was the BAT/WF uptake ratio (r = -0.85). These data show a higher (99m)Tc-sestamibi uptake in BAT compared to WF, in agreement with the high mitochondrial content and respiratory activity of the former. The strong negative correlation between (99m)Tc-sestamibi uptake in BAT and body weight (negative allometry), is in accordance to increased needs of thermogenesis in smaller animals. Implications of increased (99m)Tc-sestamibi uptake in BAT in radionuclide imaging are also discussed.