Fig. 2.

Cool temperatures induce a thermogenic program in isolated white adipocytes. Cultured and fully differentiated 3T3-F442A adipocytes were exposed to 39 °C, 37 °C, 33 °C, 30 °C, and 27 °C for 4 h before mRNA was harvested (Materials and Methods). The mRNA expression of thermogenic genes (A) and adipose markers (B) were measured by qPCR. (C) 3T3-F442A adipocytes were exposed to 31 °C for 1, 2, 4, and 8 h before mRNA was harvested and analyzed by qPCR. The values were normalized to cells kept in 37 °C from the same times. (D) 3T3-F442A adipocytes were differentiated and maintained in 37 °C or 33 °C for 10 d (day 0–10). mRNA was analyzed by qPCR for thermogenic gene expression. (E) 3T3-F442A adipocytes were first exposed to 31 °C for 4 h, and then the temperature was changed back to 37 °C for an additional 4–8 h. mRNA was analyzed by qPCR and normalized to cells kept in 37 °C from the same times. (F) Total and uncoupled respiration (as oxygen consumption rate) in 3T3-F442A adipocytes were measured after 6 h incubation in 37 °C or 31 °C. Data are presented as mean ± SD (n = 6 in each group).