Transcriptional Regulation of Brain ABC Transporters during Acute Acetaminophen (APAP) Intoxication in Mice and the Possible Role of the Nuclear Factor-Erythroid 2-Related Factor 2 (Nrf2)

GHANEM CI.; RUDRAIAH S; MANAUTOU JE

Congreso; 53rd Annual Meeting and ToxExpo; 2014

Society of Toxicology

Changes in gene and protein expression of liver ABC transporters have been previously described during acute APAP intoxication. However, the effect of hepatotoxic doses of APAP on brain ABC transporters has never been studied. The aim of this study was to evaluate the effect of APAP on brain ABC transporter expression and the role of the transcription factor and the oxidative stress sensor Nrf2 thereon. For this purpose, male C57BL6 mice received APAP (400mg/kg) or vehicle. 24 h later, brains were removed and protein expression of Mrp1-Mrp5, Bcrp and P-gp was determined by Western blotting from total brain homogenates. mRNA expression for these ABC transporters was also assayed by q-RT PCR between 6 and 24 hr after APAP. The results show that APAP treatment significantly increases the expression of brain P-gp (195%), Mrp2 (293%) and Mrp4 (38%) proteins relative to controls, with no changes in Bcrp, Mrp1 and Mrp5 detected. Mrp3 protein was not detectable in either group. The increased protein expression for P-gp, Mrp2 and Mrp4 correlated with changes in mRNA expression. In agreement with protein content, mRNA expression for Bcrp, Mrp1, Mrp3, and Mrp5 did not change with APAP treatment. Indicative of Nrf2 activation, mRNA and protein expression of NAD(P)H:quinone oxidoreductase 1 increased significantly in brain tissue with APAP treatment. Furthermore, nuclear content of Nrf2 protein was found to increase by 50% at 12 hr after APAP. In conclusion, acute APAP intoxication induces protein expression of several brain ABC transporters through a transcriptional mechanism. This study also suggests that these changes may be due to in situ Nrf2 activation by APAP. The functional consequences of these changes in brain ABC transporters by APAP deserve further attention.