The level and turnover rate (TR) of serotonin (5-HT) were determined in the brown adipose tissue (BAT) of rats born and reared at 28 degrees C and 16 degrees C. The serotonin/norepinephrine ratio was high in BAT of both groups for the first 2 days. Thereafter it fell. During the first 3 days, the TR was three times higher in 16 degrees C rats than in 28 degrees C rats. A similar difference was observed for the 5-HIAA/5-HT ratio during that period. It is concluded that 5-HT may act on BAT thermogenesis in cold-exposed pups but its mechanism of action is still hypothetical.
Adipose Tissue, Brown Animals