Alterations in fetal adipose tissue leptin expression correlate with the development of adipose tissue

Control pig fetuses and fetuses hypophysectomized (hypox) at 70 days of ges tation were treated with hormones on day 90. At 105 days of gestation, subc utaneous adipose tissue was prepared for morphological studies, leptin Nort hern blot and Western blot analysis. Fetal ontogeny studies showed that lep tin mRNA in adipose tissue increased with morphological development, and th e highest level of leptin mRNA was observed in 105-day fetal pigs. In hyper fetuses, levels of leptin mRNA were similar to those in controls. Treatmen t with either hydrocortisone (HC) or thyroxine (T-4) resulted in a slight i ncrease in leptin mRNA levels in hyper fetuses but not in intact fetuses. S upplementation with both HC and T-4 markedly stimulated leptin mRNA express ion in both hyper and intact fetuses. Morphological data showed that hyper slightly enhanced lipid accretion and treatment of hyper fetuses with HC an d T-4 increased lipid accretion to a greater degree than did either HC or T -4 alone. However, serum leptin levels were not influenced by age, hyper or hormone treatment. Leptin protein expression was not detected in adipose t issue of hyper or intact fetuses regardless of hormone treatment. Leptin pr otein was detected in adipose tissue of 7-day-old pigs and placenta. As com pared to 7-day postnatal adipose tissue, placenta showed a higher level of leptin protein expression. Leptin mRNA expression in feta I adipose tissue was not correlated with body weight and organ weight. The expression of lon g-form leptin receptor mRNA was detected in fetal adipose tissue. Our resul ts indicate that adipose tissue leptin may not be the main source of serum leptin in the fetus and may not be involved in general prenatal growth and development. But adi pose tissue leptin may act as an autocrine or paracrin e factor in the development of fetal adipose tissue. Copyright (C) 2000 S. Karger AG, Basel.