ABSTRACT
Peroxisome proliferators-activated receptors (PPARs) are nuclear hormone receptors belonging to the superfamily of steroid/thyroid receptors. Three types of nuclear PPARs, PPARa, PPARb/d, and PPARg1/g2, have been identified and cloned, each being encoded by separate genes (1-8). Alternative splicing of one gene product yields two transcripts of PPARg: PPARg1 was found to predominate in adipose tissue and large intestines, whereas PPAR g2 seemed to be a minor isoform (9). These receptors have been named according to their capacity to be activated by many compounds, which share in common the property of inducing peroxisome proliferation, especially in rodent liver (10-12). They are involved in the control of genes encoding lipid metabolism-associated proteins, particularly those of peroxisomal b-oxidation (13-15), and are activated by physiological concentrations of fatty acids (16-18), fibrate hypolipidemic drugs (10,19), and certain plasticizers and herbicides (19,20).
