Responsiveness to adipogenic agents in stromal-vascular cultures derived from lean and preobese pig fetuses: an ontogeny study.

Primary cultures of stromal-vascular (S-V) cells from adipose tissue were used to evaluate characteristics of preadipocytes from lean and preobese fetuses at several ages (50, 75, and 110 d). In insulin-supplemented (1 microM) cultures (serum free) there was a significant age x fetal genotype interaction (P less than .01) for glycerol-phosphate dehydrogenase specific activity (GPDH); GPDH activity was genotype-dependent at 110 d (preobese greater than lean). The responses of S-V cultures (preadipocyte development) to 2% pig serum and to insulin (serum free) were similar. Main effects of genotype and age were significant (P less than .05) for protein levels in pig serum and insulin-treated cultures. There was a significant genotype x age (P less than .05) interaction for GPDH activity and protein levels in cultures treated with dexamethasone + 3-isobutyl-1-methylxanthine (DEX-IBMX). Treatment with DEX-IBMX induced more preadipocyte development in cultures from preobese fetuses than in cultures from lean fetuses at 110 d (P less than .05). The responsiveness of S-V cultures to DEX-IBMX (enhanced development) increased considerably between 50 and 75 d regardless of fetal genotype, but there was little response in cultures form 50-d fetuses. Preadipocyte development in lean and preobese fetuses diverged between 75 and 110 d, resulting in many more preadipocytes in preobese fetuses at 110 d. Therefore, S-V cells from preobese fetuses (late term) may be inherently more sensitive to adipogenic agents than S-V cells from lean fetuses.