Influence of thyroxine and hydrocortisone in vivo on porcine preadipocyte recruitment, development and expression of C/EBP binding proteins in fetal stromal vascular (S-V) cell cultures.

At 90 days of gestation hypophysectomized (hypox) porcine fetuses were treated with hydrocortisone (HC) or thyroxine (T4) and S-V cultures prepared from intact, treated and untreated hypox fetuses at 105 days of gestation. After 24 h, cultures were stained for the AD-3 antigen and the transcription factors, C/EBP alpha and delta. The proportion of preadipocytes (AD-3+) was doubled in cultures derived from HC treated hypox fetuses compared to cultures from intact, untreated and T4 treated hypox fetuses. Compared to cultures from intact fetuses, proportions of C/EBP delta reactive cells (approximately 40%) were increased similarly in cultures from untreated and HC treated hypox fetuses. Compared to day 0-1, preadipocyte proportions were markedly reduced in cultures from untreated and HC treated fetuses and increased in cultures from intact and T4 treated fetuses after three days of fetal bovine serum (FBS; day 0-3). After six days of insulin (FBS day 0-3-->insulin, transferrin and selenium; ITS), fat cell numbers were 5 fold higher in cultures from T4 treated fetuses compared to cultures from untreated and HC treated hypox fetuses. Other cultures were seeded and plated in FBS + 80 nM dexamethasone (DEX; day 0-3) followed by insulin (day 3-9). Preadipocyte development was independent of the source of S-V cells in cultures treated with FBS + DEX-->insulin. These data indicate that, compared to preadipocyte recruitment, hormonal regulation of adipocyte differentiation may be more complex and involve more interactions.