BASIC FIBROBLAST GROWTH-FACTOR (BFGF) CONTRIBUTES TO THE ENLARGEMENT OF BROWN ADIPOSE-TISSUE DURING COLD-ACCLIMATION

The contribution of basic fibroblast growth factor to brown adipose ti ssue (BAT) enlargement during cold acclimation was investigated using rat brown adipocytes in primary culture. After cold exposure (at 5 deg rees C) for 28 days, the level of bFGF messenger ribonucleic acid (mRN A) in BAT of cold-acclimated rats was markedly increased with the incr ease in the BAT weight. In addition, the blood plasma from cold-acclim ated rats considerably enhanced the expression of basic fibroblast gro wth factor mRNA in rat brown adipocytes. Likewise, the blood plasma fr om cold-acclimated rats significantly stimulated the growth of rat bro wn adipocyte precursor cells compared with that from warm-acclimated r ats, whereas there was no difference of effect between the two blood p lasmas on the growth of bovine capillary endothelial cells. Basic fibr oblast growth factor, but not platelet-derived growth factor stimulate d the growth of brown adipocyte precursor cells. The conditioned mediu m from brown adipocyte primary culture markedly stimulated the growth of bovine capillary endothelial cells and the effect was inhibited con siderably by anti-basic fibroblast growth factor antibody. These resul ts suggest that some factors concerned with the growth of brown adipoc yte precursor cells are present in the blood plasma from cold-acclimat ed rats, and that basic fibroblast growth factor produced by brown adi pocytes may significantly contribute to BAT enlargement by autocrine m echanisms during cold exposure.