The Toxicologist - Society of Toxicology

460 SULFORAPHANE PREVENTS ACETAMINOPHEN-
INDUCED HEPATIC INJURY IN MICE.
R. Schmidt 1, 2 , K. C. Falkner 2, 3 , J. Beier 1, 2 and G. Arteel 1, 2 . 1 Pharmacology &
Toxicology, University of Louisville, Louisville, KY, 2 Alcohol Research Center,
University of Louisville, Louisville, KY and 3 Medicine, University of Louisville,
Louisville, KY. Sponsor: C. States.
Background. Sulforaphane (SFN), an isothiocyanate found in cruciferous vegetables,
is known to confer antioxidant protection in vivo. Rather than directly reacting
with free radicals, however, SFN works by inducing Nrf2, a transcription factor
that binds to the promoter regions of several known antioxidant genes and enhances
detoxification. Because oxidative stress is a major contributor to acetaminophen
(APAP)-induced toxicity, SFN may defend the liver against APAP overdose by
activating the Nrf2 pathway and increasing endogenous antioxidant response.
Methods. Six-week-old C57BL/6 mice were acclimated to AIN-76A purified diet,
then pre-treated with 10 mg/kg SFN i.g. for four days, and injected with APAP
(300 mg/kg i.p.) on the fifth day. Six hours after APAP injection, mice were euthanized
with ketamine/xylazine, and their blood and livers were harvested. Liver tissue
was snap-frozen in liquid nitrogen or fixed in 10% formalin for sectioning and
mounting on microscope slides. Some snap-frozen liver was homogenized in 4.4%
metaphosphoric acid for detection of glutathione. Results. APAP overdose caused
massive spikes in serum liver enzyme activity, indicating hepatic injury. SFN prevented
this injury, as evidenced by a 3-fold reduction in ALT activity and a 5-fold
reduction in AST. Total liver glutathione was depleted by APAP overdose, but protected
by SFN. Finally, histological indices of liver damage were markedly reduced
by SFN. Red blood cell infiltration at pericentral regions of the liver was identified
with chloroacetate esterase staining, and found to be minimized by SFN treatment.
Similarly, 4-hydroxynonenal adducts were seen after APAP overdose, but these
adducts were diminished with SFN. Conclusion. These data support the hypothesis
that SFN attenuates acute APAP-induced liver injury. This decrease in injury results
from the increased availability of glutathione to conjugate the reactive metabolites
of APAP.
461 ACETAMINOPHEN (APAP) AND S-ADENOSYL-L-
METHIONINE (SAME) EFFECTS ON OXIDATIVE
STRESS ENZYMES: ATTENUATION BY SAME.
J. Brown, J. G. Ball, T. Ahmad and M. Valentovic. Pharmacology, Physiology and
Toxicology, Marshall University School of Medicine, Huntington, WV.
Acetaminophen (APAP) is the primary cause of drug induced liver failure in the
United States. S-adenosyl-L-methionine (SAMe) participates in the transsulfuration
pathway to provide cellular glutathione. SAMe is involved in transmethylation
reactions and is critical for growth of liver cells. The transmethylation and transsulfuration
pathways are important in recovery from APAP hepatic toxicity. This study
tested the hypothesis that SAMe treatment 1 h after APAP overdose would preserve
hepatic function by reducing oxidative stress. Male C57BL/6 mice (16-22 grams)
were divided into the following groups: vehicle treated with water (VEH; water
15ml/kg ip injections), 250 mg/kg APAP (15 ml/kg, ip) or SAMe (1.25 mmol/kg)
which was administered 1 h after APAP injection (SAMe and SAMe+APAP).
Hepatic toxicity was evaluated 2 and 4 h after APAP administration. APAP depressed
(p