Brown adipose tissue (BAT) physiology and imaging have recently attracted considerable attention. BAT is characterized both by enhanced perfusio
n and increased mitochondrial activity. 99mTc-sestamibi is a lipophilic cationic
tracer that concentrates in mitochondria. Data on the accumulation of 99mTc-sestamibi in BAT are currently lacking. This study investigates the
in vivo99mTc-sestamibi uptake in rat BAT. 99mTc-sestamibi was administered in male Wistar rats of various age and body size. 99mTc-sestamibi uptake was measured in vitro in BAT and white fat (WF) together with cytochrome c oxidase activity. Both 99mTc-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 99mTc-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 99mTc-sestamibi uptake in BAT and body weight (negative allometry), is in accordance to increased needs of thermogenesis in smaller animals. Implications of increased 99mTc-sestamibi uptake in BAT in radionuclide imaging are also discussed.
The study investigates the effect of administered estrogen on plasma creatine kinase (CK) and lactate dehydrogenase (LD) levels in female ovariectomized rats after downhill running. Rats ovariectomized before sexual maturity were subcutaneously implanted with pellets containing 17β-estradiol or placebo. Three weeks later they were subjected to a 90-min intermittent downhill running protocol. Blood samples were obtained from the jugular vein immediately after and 72 h after exercise for determination of plasma CK, LD and 17β-estradiol levels. A two-way analysis of variance was used for data evaluation. Plasma CK and LD levels were significantly lower (p<0.05) in the estrogen-supplemented, ovariectomized animals which suggests that less muscle damage occurred compared to the controls immediately and 72 h after exercise. Estrogens may have a protective effect on muscle tissue possibly due to their antioxidant and membrane stabilizing properties., S. Sotiriadou, A. Kyparos, V. Mougios, Ch. Trontzos, G. Sidiras, Ch. Matziari., and Obsahuje bibliografii