抄録
Background
Benzo (a) pyrene (BaP) is a procarcinogen derived from incomplete combustion of petroleum and charcoal; it is metabolized by Cytochrome P450 1A1 (CYP1A1) to a highly reactive component that form adducts with biomolecules like proteins and DNA. CYP1A1 expression is modulated by aryl hydrocarbon receptor and regulated by circadian rhythm. In the liver, circadian rhythm is modified through feeding cycles, in which the animal promotes a readaptation of behavioral, physiological and molecular parameters previous to the period of access to food. Hence, the present study aimed to characterize the induction of CYP1A1 by BaP in a daytime food synchronization (DFS) in rats.
Methods
Male Wistar rats weighing 200 g were maintained in constant conditions of 12 h: 12 h light-dark cycles (lights on at 6 AM) for one week for acclimation. Four groups of 6 animals each were formed: rats fed ad libitum; rats under DFS with mealtime from 10:00 to 12:00 for 21 days. On the last day, both groups were be administered intraperitoneally with 10 mg/Kg of BaP at 09:00 AM (before exposure to food). Two other groups were as described but without BaP exposure.
On the day 22, all groups were sacrificed 24 hours post BaP exposure. The liver was collected and processed to quantification of mRNA and protein CYP1A1.
Result
DFS group increase two-fold CYP1A1 mRNA, but protein concentration remain unchanged (in contrast with group ad libitum); however DFS+BaP group decreased to half mRNA CYP1A1 but protein increase 0.25-fold in contrast with group ad libitum+BaP.
Conclusion
Daytime food synchronization decreases the expression of CYP1A1, increases the presence of protein when the rats were administered with 10 mg/kg of BaP.
