The Toxicologist - Society of Toxicology

2586 ENHANCED NRF2 ACTIVATION ATTENUATES
FASTING-INDUCED FATTY LIVER.
J. Xu 1 , J. Moscovitz 1 , M. Yamamoto 2 and A. L. Slitt 1 . 1 Biomedical and
Pharmaceutical Sciences, University of Rhode Island, Kingston, RI and 2 Medical
Biochemistry, Tohoku University Graduate School of Medicine, Sendai, Japan.
Non-Alcoholic fatty liver disease (NAFLD) affects 20% of the U.S. population.
Approximately 15 to 20% of patients with fatty liver develop a severe form of hepatic
disease known as nonalcoholic steatohepatitis (NASH). The high prevalence
of fatty liver and NASH warrants research into the signaling mechanisms responsible
for hepatic lipid accumulation. Nuclear factor-erythroid 2-related factor 2
(Nrf2, Nfe2l2), a bZIP family transcription factor, is protective against xenobioticrelated
toxicity and chemical-induced carcinogenesis. However little information
about Nrf2 function on lipid metabolism is available. Male C57BL/6 and Keap1-
KD mice were fed ad libitum or withheld food (fasted) for 24 hours to determine
whether enhanced Nrf2 activation in liver could prevent fasting-induced steatosis.
In C57BL/6 mice, fasting increased hepatic triglyceride content 240%, and serum
triglyceride concentrations 21% compared to fed mice. In contrast, Keap1-KD
mice were resistant to fasting, with hepatic triglyceride increased 1.3 fold, and
serum triglyceride levels decreased about 6% compared to fed Keap-KD mice.
Fasting increased serum free fatty acid levels 110% in C57BL/6, but only 61%
Keap1-KD mice. Keap1-KD mice exhibit decreased basal expression of FAS,
ACC-1 and SCD-1 in liver, genes important for regulating lipid synthesis, compared
to C57BL/6 mice. Fasting decreased FAS, ACC-1 and SCD-1 mRNA expression
in liver to a much greater degree in Keap1-KD compared to C57BL/6
mice, 54%, 31% and 81% respectively. These data demonstrated that Keap1-KD
mice are resistant to fasting-induced steatosis. Future work will focus on the mechanism
by which Nrf2 activity modulates fatty acid synthesis gene expression in liver
and promotes resistance to fasting. In conclusion, enhances Nrf2 activation by
Keap1 knockdown prevents fasting induced steatosis, pointing to an important
function on lipid metabolism (NIH 3R01ES016042-02S2).
2587 PROTECTION OF RETINAL VESSELS FROM
HYPEROXIC INJURY BY β-NAPHTHOFLAVONE (BNF)
IN NEWBORN RATS.
X. Couroucli, Y. W. Liang, L. Wang, W. Jiang and B. Moorthy. Pediatrics,
Baylor College of Medicine, Houston, TX.
Supplemental oxygen administration, which is routinely encountered in the treatment
of premature infants suffering from respiratory distress, contributes to
retinopathy of prematurity (ROP). In this study, we tested the hypothesis that exposure
of newborn rats to a combination of β-napthoflavone (BNF) and hyperoxia
would alleviate retinopathy and abnormal neovascularization compared to those exposed
to hyperoxia alone. Newborn Fisher 344 rats were maintained in room air or
exposed to hyperoxia ([gt] than 95% O2) for 7 days. Some animals were treated i.p.
with BNF (20 mg/kg) or vehicle (saline), once daily for the first 4 days of hyperoxic
exposures, and were sacrificed at selected time points after termination of hyperoxia.
Vascular densities of flat mounted retinas were assessed. mRNA expression of
VEGF, its receptors (VEGFR-1/sFLT-1 and VEGFR-2), and cytochrome P4501B1
(CYP1B1) was determined by real time RT-PCR. Immediately after 7 days of exposure
to hyperoxia, we observed severe vaso-obliteration, compared to the hyperoxia
+ BNF. Seven to thirty days after termination of hyperoxia, the animals displayed
abnormal retinal vessels, whereas those given BNF+ hyperoxia showed
significantly lesser extent of neovascularization. At the later time points, VEGF
mRNA expression in the hyperoxia group was much higher than that of the BNF+
hyperoxia group. On the other hand, the expression of VEGFR-1 and sFLT-1, but
not VEGFR2, was upregulated by BNF + hyperoxia, compared to the hyperoxia
only group. Interestingly, retinal CYP1B1 expression was also augmented in the
BNF + hyperoxia group. Our study supported the hypothesis that BNF protects
retinas from oxygen-induced retinopathy, and that upregulation of VEGFR1 as
well as CYP1B1 contributes to the retinoprotective effects of BNF. Further studies
are needed to elucidate the mechanisms of the protective action of BNF, which
could lead to clinical trials in infants who are at risk of developing ROP.
2588 HYPOXIA-ISCHEMIA TRIGGERS BAX
PHOSPHORYLATION, TRANSLOCATION, AND
RESULTANT CELL DEATH PHENOTYPE.
S. Krishnan 1 , M. Gill 2 and R. Perez-Polo 1 . 1 Biochemistry and Molecular Biology,
University of Texas Medical Branch, Galveston, TX and 2 Northwestern University,
Chicago, IL. Sponsor: J. Ward.
Hypoxia-ischemia (HI) in the neonatal brain can lead to DNA damage, inflammation,
and cell death, all of which ultimately produce neurodevelopmental deficits.
Neuronal cell death caused by HI is characterized by an array of cell death pheno-
554 SOT 2011 ANNUAL MEETING
types with necrotic and/or apoptotic characteristics, in which the Bcl-2 family of
proteins, including Bax, play a role. Here, we use well-established in vivo and in
vitro models of neonatal cerebral HI, and standard molecular techniques to investigate
whether HI-dependent phosphorylation of Bax at Ser163, Thr167, and/or
Ser184 residues determines Bax multi-organelle localization and correlation with
organelle-specific cell death signaling after HI. In rotenone-treated SH-SY5Y cells,
a significant increase in p-BaxThr167 was found in mitochondrial fractions when
compared to control ½ hour after treatment. In vivo, we also found an increase in
p-BaxThr167 in the nucleus at 1 hour after treatment, which correlates with a decrease
in mitochondrial p-BaxThr167. This may indicate that phosphorylation of
BaxThr167 leads to Bax translocation to the nucleus from mitochondria. We also
observed an increase of p-BaxThr167 in cytosolic fractions at 1 hour, indicating
that phosphorylation of BaxThr167 may be generally responsible for Bax translocation
out of mitochondria. Lastly, no significant changes in p-BaxSer163 were observed
up to 6 hours after HI. Interestingly, we observed a decreasing trend in cytosolic
p-BaxSer163 gradually from 0 to 6 hours, as well as a significant decrease in
p-BaxSer163 in the mitochondrial fraction at 6 hours after HI. These data suggest
a role for phosphorylation in the translocation of Bax after HI. Understanding the
mechanisms of Bax translocation will aid in the rational design of specified therapeutic
strategies which could potentially involve altering Bax subcellular redistribution
to decrease the irreversible trauma resulting from a prolonged inflammatory
response.
2589 ESTIMATING THE GLOBAL PUBLIC HEALTH
IMPLICATIONS OF ELECTRICITY AND COAL
CONSUMPTION.
J. M. Gohlke 1, 4 , R. Thomas 4 , A. Woodward 3 , D. Campbell-Lendrum 2 , A.
Pruss-Ustun 2 , S. Hales 2 and C. J. Portier 4 . 1 Environmental Health Sciences,
University of Alabama at Birmingham, Birmingham, AL, 2 Public Health and
Environment, World Health Organization, Geneva, Switzerland, 3 Population Health,
University of Auckland, Auckland, New Zealand and 4 Laboratory of Molecular
Toxicology, NIEHS, Research Triangle Park, NC.
The growing health risks associated with greenhouse gas emissions has resulted in a
global call for development of new energy policies emphasizing efficiency and lowcarbon
energy cycles, yet the economic and social development often associated
with access to affordable energy are important considerations for improving health
in developing nations. Here we assess the relationship between electricity consumption
and health outcomes. Using time-series datasets across 41 countries with varying
development trajectories between 1965 and 2005, an autoregressive model of
life expectancy (LE) and infant mortality (IM) was developed based on electricity
consumption, coal consumption, and previous year’s LE or IM. The model predicts
increased electricity consumption is associated with reduced IM for countries starting
with relatively high IM (above 100 per 1000 births), whereas LE was not significantly
associated with electricity consumption in any of the models. In addition,
the model suggests increasing coal consumption that is not explained by electricity
use is associated with increased IM and reduced LE. These results are compared
with previously published estimates of disease burdens attributable to energy-related
environmental factors including indoor and outdoor air pollution, and water
and sanitation. In addition, prediction of health impacts from an integrated air pollution
emissions health impact model for coal-fired power plants is compared to the
time-series model results. Consistency across analyses of historical time-series and
health impact models suggest health benefits may be related to increasing electricity
consumption in those countries with very high IM, while negative health impacts
of coal consumption are predicted across all countries.
2590 SELENIUM FROM OCEAN FISH PREVENTS
METHYLMERCURY TOXICITY.
L. Raymond and N. Ralston. Energy & Environmental Research Center, University
of North Dakota, Grand Forks, ND.
Supplemental selenium (Se) has been known to counteract mercury (Hg) toxicity
since 1967, but the mechanisms of this protective effect have only recently become
clear. Methylmercury (MeHg) is a highly specific irreversible inhibitor of Se-dependent
enzymes (Se-enzymes). Supplemental dietary Se replenishes Se lost to
MeHg binding, thereby maintaining normal Se-enzyme activities. Rationale and
scope; Our prior animal studies have shown that the normal range of dietary Se (as
sodium selenite) is effective in preventing and reversing MeHg toxicity. Since ocean
fish are among the richest sources of dietary Se, we hypothesized that their Se contents
would protect against the adverse effects otherwise associated with MeHg exposures
from seafood consumption. Experimental procedure; In this study, 120
weanling male Long Evans rats were fed diets containing either low or high MeHg
(0.5 or 50 nmol MeHg/g). These diets were augmented with either sodium selenite
(~0.1, 1.0, or 10 nmol Se/g) or Se from delipidated protein isolates from bigeye