EFFECTS OF FAT DEPOT SITE ON DIFFERENTIATION-DEPENDENT GENE-EXPRESSION IN RAT PREADIPOCYTES

Variability in physiological characteristics among adipose depots coul d be caused, in part, by mechanisms intrinsic to cells comprising the depots. To evaluate the contribution of intrinsic mechanisms to depot variability, we studied levels of differentiation-dependent mRNAs in d ifferentiating cultured rat epididymal and perirenal preadipocytes and in fat cells isolated from these depots, The magnitude of the change in levels of adipsin and glycerol-3-phosphate dehydrogenase mRNAs, whi ch increase late during differentiation, was greater in perirenal than epididymal preadipocytes, The magnitude of the change in beta-actin m RNA, which decreases early during differentiation, was not sits-depend ent, Effects of anatomic site on changes in differentiation-dependent mRNAs observed in differentiating preadipocytes in vitro were similar to effects of site on these mRNAs in freshly isolated fat cells: those mRNA species whose levels increase late during preadipocyte different iation were present in greater abundance in perirenal than epididymal fat cells, Hence, mechanisms which underlie site-dependent variability in adipose function may be intrinsic and could become evident midway through the differentiation process.