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Effects of chronic cold–stress on FDG uptake by brown adipose tissue (BAT) and brain

¹ Nuclear Medicine; ² Surgery, Massachusetts General Hospital & Shriners Hospital for Children, Boston, Massachusetts

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Objectives: BAT has the capacity to generate heat from substrates in the absence of ATP generation. Previous studies have shown that cold stress stimulates FDG uptake by BAT, however, it has not been demonstrated if this is reaction to acute stress or an adaptive response to the environment. In this study, we examined the effect of cold for 1&7 days on FDG uptake by BAT and brain in mice.

Methods: Groups of 6 mice were placed in a cold room at 4^o for 7 days with access to food and water. On day 6, an additional group of 6 mice was placed in the cold and all animals were fasted for 24 h. Control animals (n=6) were maintained at room temperature and fasted for 24 h. All animals were injected with 5.0 µCi of FDG, euthanized 1 hr later and biodistribution measured. Results were expressed as % ID/gram (mean ± sem).

Results: Cold stress for 24 h resulted in a dramatic increase in FDG uptake by BAT (78.1 ± 10.3 vs 2.0 ± 1.01, p<0.0001). Exposure to cold for 7 days also produced a marked increase in FDG uptake by BAT (42.5 ± 10.2 vs 2.0 ± 1.01, p<0.0001), however, the effect was significantly less (p<0.001) compared with animals exposed to the cold for 24 h. In contrast, cold stress for 24 h resulted in reduced uptake of FDG by the brain (4.3 ± 1.1 vs 14.2 ± 1.5; p<0.01) which was at control levels in animals exposed to cold for 7 days.

Conclusions: Both acute or chronic cold stress to mice increased uptake FDG by BAT, suggesting that this reaction is an adaptive response to environmental conditions rather than an effect of acute stress. This model may prove useful in probing the mechanism(s) of brown fat activation and its physiological significance.

Research Support: NIH & Shriners Hospitals for Children

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Carter, E. Articles by Fischman, A. PubMed Articles by Carter, E. Articles by Fischman, A.