Nrf2 gene deletion fails to alter psychostimulant-induced behavior or neurotoxicity

The transcription factor NF-E2-related factor (Nrf2) regulates the induction of phase 2 detoxifying enzymes by oxidative stress, including synthesis of the catalytic subunit (xCT) of the heterodimeric cystine-glutamate exchanger (system xc-). Repeated cocaine treatment in rats causes persistent neuroadaptations in glutamate neurotransmission in the nucleus accumbens that result, in part, from reduced activity of system xc-. Since in vitro under- or over-expression of Nrf2 regulates system xc- activity and xCT content, it was hypothesized that in vivo deletion of the Nrf2 gene would: 1) decrease system xc- activity, 2) produce a behavioral phenotype resembling that elicited by chronic cocaine administration, and 3) enhance dopamine depletion after methamphetamine-induced oxidative stress. In all three experiments no genotypic difference was measured between mice sustaining homozygous Nrf2 gene deletion and wild-type littermates. Thus, while Nrf2 is a transcriptional regulator of xCT and capable of protecting cells from oxidative stress, following Nrf2 gene deletion this role can be partially compensated by other mechanisms and methamphetamine-induced oxidative stress and dopamine toxicity does not significantly involve Nrf2.