Assessment of brown adipose tissue activity in rats by 99mTc-sestamibi uptake.
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.
Laboratory of Physiology, Department of Physical Education and Sports Science, Aristotle University of Thessaloniki, Greece.
D
D
Kyparos
G
G
Arsos
S
S
Georga
A
A
Petridou
A
A
Kyparos
E
E
Papageorgiou
V
V
Mougios
C
C
Matziari
C
C
Karakatsanis
D002001:Adipose Tissue, Brown / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000502:physiology; D052436:Adipose Tissue, White / Q000378:metabolism; D000367:Age Factors; D000375:Aging / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D003576:Electron Transport Complex IV / Q000378:metabolism; D008297:Male; D008928:Mitochondria / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000502:physiology; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017256:Technetium Tc 99m Sestamibi / Q000378:metabolism*; D022722:Thermogenesis
D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi; D003576:Electron Transport Complex IV