THE INTERACTION BETWEEN VITAMIN-A AND THIAZOLIDINEDIONE ON BOVINE ADIPOCYTE DIFFERENTIATION IN PRIMARY CULTURE

We studied the effects of a thiazolidinedione (T-174) and retinoids on adipocyte differentiation in beef cattle. Stromal-vascular (SV) cells containing preadipocytes were prepared from perirenal adipose tissue of 21-mo-old Japanese Black steers. After confluence, these cells were cultured in 25 mu M T-174, which is a specific ligand for an adipogen esis stimulating nuclear receptor (i.e., gamma subtype of peroxisome p roliferator-activated receptor [PPAR gamma]), with 1 mu M all-trans re tinoic acid (RA) or .4 to 40 mu g/100 mL of retinol for 10 to 14 d. Th e number of cells accumulating lipid droplets was counted as morpholog ically differentiated adipocytes, and the activity of glycerol-3-phosp hate dehydrogenase (GPDH), a biochemical index for the differentiation , was determined. The number of lipid-laden cells and GPDH activity we re increased by the addition of T-174. All-trans retinoic acid complet ely blocked the stimulative action of T-174. The addition of retinol a lso decreased the number of lipid-laden cells and GPDH activity in a d ose-dependent manner. These results showed that the thiazolidinedione stimulated adipocyte differentiation and the retinoids blocked the adi pogenesis induced by the thiazolidinedione in primary culture of bovin e SV cells. Peroxisome proliferator-activated receptor gamma may play an important role in adipocyte differentiation, and retinoids may inte rfere with the action of PPAR gamma in cattle.