Memory of long-term cold acclimation in deacclimated Wistar rats

Long-term cold exposure (10 °C for 11weeks) led to hyperplasia of brown adipose tissue (BAT) in rats. After deacclimation (25 °C for 2 weeks, after 10 °C for 9 weeks), BAT retained almost the same mass as in cold acclimation, and lipid content and droplet size decreased slightly, although the droplets fused with each other. The increased amounts of UCP1 and GLUT4 in BAT in the cold were maintained, and the levels of plasma insulin, leptin and triacylglycerol that decreased in the cold were increased to greater levels than the control after deacclimation. UCP3 in skeletal muscle in the cold decreased, in contrast to that in BAT, and returned to the control level. Predominant use of lipid for non-shivering thermogenesis was preserved for cold after deacclimation.