Seasonality of leptin levels in the BAT of the common shrew (Sorex araneus)

Leptin concentrations in the interscapular brown adipose tissue (IBAT) of t he common shrew (Sorex araneus) were measured in different seasons. The lep tin concentrations in IBAT were much higher than in the liver, where leptin is supposed to be of blood origin. In the heart muscle no detectable amoun t of leptin was found. There were clear seasonal variations in the leptin c oncentrations in IBAT. Leptin levels in IBAT were the lowest in November at the beginning of the winter. The concentrations increased, however, strong ly after the onset of the permanent snow cover, and the highest concentrati ons were measured in December-January, when the weight of the animals was v ery low. In April-May, at the time when shrews attain sexual maturity, lept in concentrations in IBAT were lower than in the mid-winter, but significan tly higher than in November. In overwintered adults the leptin concentratio ns were at the same level as in nonwintered subadults. Leptin originating f rom BAT may inform the central nervous system about the amount of nonshiver ing thermogenesis as well as the amount of feeding necessary for survival i n the winter months.