Changes of pyridine nucleotide levels during adipocyte differentiation of mouse 3T3-L1 cells

The levels of NAD and NADP were measured in 3T3-L1 cells during a different iation from preadipocytes to adipocytes. The cells were grown in the ordina ry medium and differentiated in the medium by adding dexamethasone, 1-methy l-3-isobutylxanthine, and insulin for 2 days, and then they were grown in t he medium by adding only insulin for another 8 days to accumulate fat. The levels of cellular NAD and NADP increased abruptly with days after differen tiation, and the levels of NAD and NADP reached maximum at day 7, and at da y 10 the values were decreased compared with the maximum values. These resu lts suggest that expression of the pyridine nucleotide biosynthesis genes i s induced in the differentiation process.