Abstract
In order to confirm whether dibutylphthalate (DBP), widely utilized plasticizer, induces cytochrome P-450 system, sleeping time of rats fed on the diet with and without DBP by injection of pentobarbital was measured. Sleeping time of rats fed on DBP diet was 101.0±11.6 min, on the other hand, that of rats fed on DBP diet was 60.7±16.8 min. This suggests that DBP may induce cytochrome P-450 system under this condition. It was also investigated whether or/not an increase in growth rate and an acceleration of the Trp-NAD pathway were caused by Trp-sufficient diet with DBP as in the rats fed on a Trp-limited diet. The DBP addition to the Trp-sufficient diet did not cause increase in growth rate comparing to the rats fed on none-DBP diet (Trp-sufficient diet). However, the levels of quino-linic acid, nicotinic acid, N1-methylnicotinamide and ascorbic acid in urine were higher in the DBP diet group than those in the none-DBP diet group. Accordingly, the conversion of anthranilic acid to 3-hydroxyanthranilic acid was considered to be increased by the administration of DBP, presumaly by induction of cytochrome P-450 system. This phenomenone was independent of Trp level in the diet.
