CELLULAR-CHANGES DURING COLD ACCLIMATATION IN ADIPOSE TISSUES

Cold exposure is a well-known physiological stimulus that activates th e sympathetic nervous system and induces brown adipose tissue (BAT) hy perplasia. The effects of cold exposure or cold acclimatation have bee n extensively studied in interscapular BAT (IBAT). However, it has bee n recently shown that brown adipocytes are present in adipose deposits considered as white fat such as periovarian (PO) fat pad. We have inv estigated the kinetic of brown precursor recruitment in adipose tissue s using DNA measurement and specific marker expression. In IBAT, cold exposure induces proliferation of precursor cells and differentiation into preadipocytes characterized by the expression of A2COL6, a marker specific to early steps of the differentiation process. A chronic sti mulation of the tissue is necessary to observe the full effect. In PO fat pad, no proliferation can be detected, whereas differentiation of brown preadipocytes and maybe phenotypic conversion of white adipocyte s seems to be promoted. In conclusion, these data demonstrated that 1) the same stimulus (cold exposure) does not induce the same response i n terms of preadipocyte proliferation and differentiation in periovari an and brown adipose tissues, although both contain brown adipocytes, and 2) preadipocyte recruitment in adipose tissues after cold exposure depends on the predominant type of fat cells. (C) 1996 Wiley-Liss, In c.