Vitamin D3, especially 1, 25-dihydroxyvitamin D3 (1, 25 (OH)2 D3), has been shown to inhibit the differentiation of preadipose cells. In the present study, the expression of vitamin D receptor (VDR) was examined by Northern blot analysis in rat adipose tissue and mouse 3T3-L1 adipose cells. The adipose tissue and 3T3-L1 cells expressed mRNA for VDR. Treatment of 3T3-L1 cells with 1 microM 1, 25 (OH)2 D3 led to a 4-5 fold increase in the VDR mRNA level. VDR mRNA expression was rapidly (within 4 hr) induced by physiological concentrations of 1,25 (OH)2 D3 in a dose-dependent manner. The induction of VDR expression did not require de novo protein synthesis but was completely abolished by an inhibitor of RNA synthesis.