The Toxicologist - Society of Toxicology

its nuclear translocation was reduced by 2.7-fold in the arsenic treated cells. We
have also found several other transcription factors that interact with the hypomethylated
CpG at -207, as well as hypermethylated CpG at -236, using pull
down assays. In conclusion, 20nM sodium arsenite exposure to C2C12 cells results
in induction of EZH2 and reduction of Mef2C, which may be responsible for the
delayed muscle differentiation. Additionally, the hypermethylated CpG at -236 and
the hypomethylated CpG at -207 in myogenin promoter may also play a role in
myogenin expression by blocking the binding of transcription factors (or repressors)
to these CpGs.
1622 EFFECTS OF LOW-DOSE PRENATAL PFOA EXPOSURE
ON THE MAMMARY GLAND OF CD-1 MICE.
M. B. Macon 1, 2 , L. R. Villanueva 3, 4 , R. D. Zehr 5 , K. Tatum-Gibbs 1, 4 , M. J.
Strynar 5 , J. P. Stanko 2 , S. S. White 2 , L. Helfant 5 and S. E. Fenton 2 . 1 Toxicology,
University of North Carolina, Chapel Hill, NC, 2 NTP, NIEHS, Research Triangle
Park, NC, 3 Chemistry, North Carolina Central University, Durham, NC, 4 TAD,
NHEERL, ORD, U.S. EPA, Research Triangle Park, NC and 5 HEASD, NERL,
ORD, U.S. EPA, Research Triangle Park, NC.
Perfluorooctanoic acid (PFOA) is an environmental contaminant that has been
shown to delay mammary gland (MG) development in prenatally exposed mice.
The effects of PFOA on MG development were investigated at varying low doses
and exposure lengths. Timed-pregnant CD-1 mice were gavaged with 0, 0.3, 1.0,
and 3.0 mg PFOA/kg body weight (BW) daily from gestation days (GD)1-17 or 0,
0.01, 0.1, and 1.0 mg PFOA/kg BW daily from GD10-17. MGs, liver, and trunk
blood were collected from offspring on postnatal day (PND) 7, 14, 21, 28, 42, 63,
and 84 in the GD1-17 exposure and on PND 1, 4, 7, 14, and 21 in the GD10-17
exposure. Serum was analyzed for PFOA concentration using HPLC-MS/MS.
MGs were prepared as whole mounts, histologically evaluated for growth hallmarks,
and assigned developmental scores on a scale of 1-4 (1=least developed;
4=normal/best developed). MGs of offspring exposed on GD10-17 were also evaluated
for quantitative characteristics. When compared to controls, all PFOAtreated
groups displayed signs of aberrant MG growth. These effects were significant
from as early as PND7 to PND84 in the GD1-17 exposure and at PND21 in
the GD10-17 exposure study. MGs of the 1.0 mg/kg groups exposed for GD10-17
were smaller in size, had less longitudinal epithelial growth, and fewer terminal end
buds relative to controls. PFOA serum concentrations remained elevated for up to
six weeks and was detected in the brain for up to 4 weeks. Across time, serum levels
were highest at PND 14 in offspring of dams exposed from GD1-17.
Hepatomegaly was evident in all GD1-17 PFOA exposure groups and in the 1.0
mg/kg group of the GD10-17 exposure study. These findings suggest that lowest
observable adverse effect level (LOAEL) of prenatal PFOA exposure on liver weight
is 0.03 mg/kg and the LOAEL on the MG is 0.01 mg/kg. However, the persistence
of the MG effect is unclear. This abstract does not necessarily reflect NIEHS or
EPA policy.
1623 PYRIMETHAMINE – INVESTIGATIVE EMBRYO-FETAL
DEVELOPMENT STUDY BY THE ORAL ROUTE
(GAVAGE) IN THE MINIPIG WITH MID-TERM
CAESAREAN SECTIONS.
E. C. Marsden, C. Pique and P. C. Barrow. Ricerca Biosciences SAS, Lyon, France.
The minipig may be ignored as an alternative non-rodent species for embryo-fetal
development studies for reasons of cost and study duration. The principal objective
of our study was to evaluate if fetal abnormalities associated with a known teratogen,
pyrimethamine, could be detected in the minipig if fetal examinations are performed
mid-term (close to gestation day (GD) 60) compared with current standard
examinations at term (close to GD 110). Thirty six 6 to 8 month old mated
Göttingen Minipig gilts were divided into two groups of 18 females each; one was
administered pyrimethamine by daily gavage at 3.6 mg/kg/day and the other received
the vehicle (1 % CMC). Each group was further divided into two subgroups
of 9 minipigs each and underwent either mid-term or term caesarean section.
The females were dosed throughout the major period of organogenesis (GD’s
11 to 35). Maternal clinical condition and body weight were monitored throughout
the study. At necropsy, the females were examined macroscopically, litter parameters
were recorded and fetuses were weighed and sexed. The fetuses (mid-term
and term) were initially examined for external and visceral abnormalities and then
processed for skeletal examination. There were no remarkable compound-related
maternal effects. At scheduled caesarean section, 16 and 18 females were pregnant
in the control and pyrimethamine groups, respectively. Although a low number of
viable litters was available due to a high incidence of compound-related embryofetal
death, fetal abnormalities consistent with those described in the literature,
principally limb malformations, micrognathia and cleft palate, were detected at the
mid-term examinations. We conclude that mid-term fetal examinations are feasible
technically, provide numerous practical and time saving advantages with respect to
term caesareans and thus provide a realistic alternative for the testing of small molecules,
ultimately reducing study duration and associated costs.
1624 WNT INHIBITORY FACTOR 1 (WIF1) PROMOTES
PROSTATIC BUD FORMATION AND MAY PARTIALLY
PROTECT AGAINST DEFECTS IN PROSTATE
DEVELOPMENT CAUSED BY TCDD EXPOSURE.
A. Branam 1 , R. W. Moore 1 , L. L. Abler 2 , S. H. Allgeier 1 , V. Mehta 2 , C. M.
Vezina 2 and R. E. Peterson 1 . 1 School of Pharmacy, University of Wisconsin, Madison,
WI and 2 Comparative Biosciences, University of Wisconsin, Madison, WI.
Prostatic buds are derived from the urogenital sinus (UGS) and later form into
prostate ducts in adult mammals. In utero TCDD exposure causes dorsal and lateral
prostatic buds in male mice to form in inappropriate positions and prevents
formation of ventral and some dorsal prostatic buds. Wnt signaling has been implicated
as having important roles in prostatic bud formation. Our previous results
showed that in vitro treatment of male UGSs with either TCDD or WNT5A decreased
prostatic bud formation, and that antibody against WNT5A rescued the effects
caused by TCDD. We propose that TCDD causes an imbalance in Wnt signaling
leading to defects in prostate development, and we hypothesize that
extracellular antagonists of Wnt signaling can rescue the effects of TCDD via a similar
mechanism as the WNT5A antibody by preventing WNT5A from binding its
receptors and thus inhibiting its effects. C57BL/6J dams were dosed with TCDD
(5 μg/kg, po) or vehicle on e15.5 and UGSs were harvested on e16.5. Sectional
ISH analysis using probes directed against genes for the Wnt antagonists (Sfrp2,
Sfrp3, Dkk1, Dkk2, and Wif1) were performed to look for differences in expression
patterns between vehicle- and TCDD-treated UGSs. Wif1 was the only gene
examined that showed a response to TCDD, a decrease in expression. RT-PCR
confirmed these results. This effect is seen in the ventral UGS, the site most affected
by TCDD exposure. Furthermore, addition of WIF1 to in vitro UGS cultures containing
DHT increased the number of prostatic buds formed as compared to control
UGSs treated with DHT alone. Preliminary evidence suggests that addition of
WIF1 may partially protect against the effects of TCDD in culture. These results
suggest that WIF1 may be a key modulator of prostatic bud formation and that addition
of WIF1 may reduce the effects of TCDD exposure on prostate development.
(Grant support: ES01332, T32 ES007015, DK083425)
1625 EFFECTS OF PERFLUORINATED PHOSPHONIC ACID
EXPOSURE DURING PREGNANCY IN THE MOUSE.
K. R. Tatum-Gibbs 1 , K. P. Das 2 , B. Grey 2 , M. Strynar 3 , A. Lindstrom 3 and C.
Lau 2 . 1 Curriculum in Toxicology, University of North Carolina-Chapel Hill, Research
Triangle Park, NC, 2 Developmental Toxicology Branch, U.S. EPA -RTP, Research
Triangle Park, NC and 3 HEASD, U.S. EPA -RTP, Research Triangle Park, NC.
Perfluorinated phosphonic acids (PFPAs) are a member of the perfluoroalkyl acid
(PFAA) family, and are structurally similar to the perfluoroalkyl sulfonates and perfluoroalkyl
carboxylates. These chemicals have recently been detected in the environment,
particularly in surface water and in effluent of wastewater treatment
plants. PFPAs are used primarily as a surfactant defoaming agent in the textile industry
and in pesticide production. Previous studies from our laboratory have identified
developmental toxicity associated with gestational exposure to perfluorooctane
sulfonate (PFOS) and perfluorooctanoic acid (PFOA), but little is known
about this emerging class of perfluorinated chemicals. Therefore, the current study
examined the developmental effects of PFPA in the mouse. A mixture of PFPAs
(Masurf-780) was given to timed-pregnant CD-1 mice by oral gavage daily
throughout gestation (GD 1-17) at doses of 5, 10, 20, 30 or 40 mg/kg; controls received
deionized water vehicle. PFPA did not alter maternal weight gain, but significantly
increased maternal liver weight at term (GD-17) at all dose groups.
Recovery in maternal liver weight was observed by weaning (PND 21). Chemical
exposure did not influence the number of live fetuses or fetus weights at GD-17,
except in the 40 mg/kg group where mortality was observed. In contrast, fetal liver
weight was significantly increased at doses greater than 5 mg/kg. Neonatal survival
and growth was monitored on postnatal days 1-42 and were generally not altered
except in the 40 mg/kg group, where the increase in neonatal liver weight persisted.
These data suggest that gestational exposure to PFPA at doses less than 40 mg/kg
SOT 2011 ANNUAL MEETING 349