The growth of brown adipose tissue in cold-acclimatized rats after depletion of mast cell histamine by compound 48/80.

Cold acclimatization (4-5 degree C) is accompanied by 2-3 fold increase of brown adipose tissue (BAT). This rapid growth of interscapular BAT was studied after histamine depletion. In control rats maintained at room temperature (28 +/- 2 degree C) the BAT histamine content was 23.4 +/- 5.9 (mean +/- SD) microgram/g of tissue and cold acclimatization (5 +/- 1 degree C) produced a significant increase of BAT weight, but reduced the histamine content to 8.4 +/- 1.9 microgram/g. The total weight of BAT after 20 days of acclimatization was unaffected by depletion of histamine due to compound 48/80. The low level of histamine in BAT of cold acclimatized rats could be due to a fast rate of amine utilization; alternatively an altered synthesis or storage process may occur during acclimatization.