Effects of Genistein in Adipocyte Differentiation and PPARg Expression in Juvenile Mice
Adipose tissue differentiation is regulated by many transcriptional factors such as Peroxisome proliferator- activating receptor g (PPARg). PPARg is an orphan nuclear receptor that plays an important role in regulating gene expression in adipocyte formation. White adipose tissue has high amounts of estrogen receptor alpha (ERa); it has been shown that estrogen decreases adipose size and number by acting upon the enzyme lipoprotein lipase. Genistein, a soy isoflavone with estrogenic abilities, may be considered to have the same potential effects on adipocyte differentiation and as a consequence in PPARg mRNA levels. Elevated genistein levels in soy-based foods, including soy based infant formulas, can be interpreted by the body as elevated levels of estrogen and therefore act upon adipocyte differentiation. To explore the possible effects of genistein in adipocyte differentiation during early development, we treated three groups of C57BL/6 mice for twelve days after parturition. In the first group, dams received 1500 ppm of genistein in feed and the pups received the genistein through the maternal milk. In the next group dams received 0 ppm genistein in feed (control); and in the last group, dams were treated likewise and the neonates received daily injections of E2 I.P. Results showed that genistein reduced adipocyte size, indicating that it does present estrogenic activity in early adipocyte differentiation. The uterus was collected to analyze possible effects; estrogen increased the uterus size while genistein did not show estrogenic activity. QPCR analysis confirmed our hypothesis; estrogen and genistein both reduced PPAR? mRNA expression in adipose tissue. Estrogen decreased expression by 50% and genistein by 40%, presumably due to genistein's lower binding abilities to estrogen receptors. We can therefore say that genistein has an estrogenic effect in adipose tissue differentiation, by directly reducing PPAR? levels. Furthermore genistein can ultimately affect early age onset obesity by altering adipocyte formation.
School:
University of Puerto Rico at Mayagüez
Department:
Industrial Microbiology
Research Advisor:
Paul S. Cooke
Department of Research Advisor:
Veterinary Biosciences
Year of Publication:
2003