Objective  To investigate the combined effect of dibutyl phthalate (DBP) and benzo(a)pyrene (BaP) on the proliferation and lactate secretion in rat sertoli cells.   Methods  Rat testicular sertoli cells were isolated

purified

cultured

and identified with oil red O. The purity of rat sertoli cells was 90%. Then the purified sertoli cells were treated with the toxicants at different dose

i.e. DBP (0.1

1

10

100

500 μg/ml)

BaP (0.01

0.1

1

10

50 μg/ml) and their combination DBP+BaP (0.1+0.01

1+0.1

10+1

100+10

500+50 μg/ml). The viability of sertoli cells was determined by MTT method and the lactate concentration in the cultured medium was detected.   Results  As compared with DMSO control

the absorbance values in 100 μg/ml DBP and DBP+BaP (100+10 μg/ml) groups were significantly increased (P0.01)

but that in 500 μg/ml DBP group was decreased (P0.01) and those of BaP groups were of no statistical difference (P0.05). Lactate concentration in 100

500 μg/ml DBP groups

50 μg/ml BaP group and DBP+BaP (100+10

500+50 μg/ml) groups were increased (P0.05).   Conclusion  DBP at low dose can promote the proliferation and lactate secretion in sertoli cells

but BaP can only enhance the lactate secretion. The combination of DBP and BaP

if both at low doses

promotes the proliferation of sertoli cells; if both at high doses

inhibits the proliferation of sertoli cells with high dose. The combined effect of DBP and DaP is synergistic.