Is the growth of brown adipocytes necessary for cold acclimation in mice?

Chronic exposure to cold increases the growth of brown adipose tissue and t he resistance to more severe cold, thus improving thermogenesis. The presen t study examined the possibility that dietary compounds can modify cold acc limation. Adenosine (ADO) or adenine (ADE) were administered in drinking wa ter (0.05%, w/v) for 5 weeks to male ddY strain mice from 4 weeks of age. A t 5 weeks of age, the mice were exposed to 4 degrees C for 4 weeks. After t ermination of this period, the interscapular brown adipose tissue (IBAT) an d rectal temperature on acute exposure to severe cold (-20 degrees C) for 6 0 min were measured. Chronic exposure to cold increased the weight of IBAT and made mice resistant to a fall in rectal temperature on exposure to seve re cold. The growth of IBAT and improvement in thermogenesis can be used as a cold acclimation profile in ddY mice. The growth of IBAT was selectively prevented by ingestion of ADO. The improvement in thermogenesis was reduce d, but only a little, by the ingestion of either ADO or ADE. Thus, growth o f brown adipocytes might not be necessary for cold acclimation in mice.