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survival by preserving more NeuN positive cells than in control rats. Such
neuroprotective effects were blocked by co-treatment with GDNF neu-
tralizing antibody. Western blot analyses revealed that rat brains with
hNSC transplantation expressed higher levels of GDNF receptors, as well
as phosphorylated ERK, AKT and GSK3
b
-S9. In summary, our results
demonstrate that hNSC grafts have a beneficial effect on neuronal survival
in rat hippocampi after TBI plus hemorrhage, and the underlying mecha-
nism of this neuronal protection is at least partially due to GDNF-mediated
modulation of the key survival signaling pathways.
Keywords: traumatic brain injury, GDNF, neural stem cell, hip-
pocampus, signal pathway
A2-15
ACUTE EFFECTS OF 17ß-ESTRADIOL ON OXIDATIVE
STRESS RESPONSE PROTEINS AFTER TBI
Jutatip Guptarak
, Ya Ping Zeng, Maria-Adelaide Micci, Helen
Hellmich, Douglas DeWitt, Stacy Sell
University of Texas Medical Branch, Anesthesiology, Galveston, USA
Background:
Traumatic brain injury (TBI) induces secondary cellu-
lar damage mediated in part by reactive oxygen species that initiate
oxidative stress responses in neuronal and cerebrovascular tissue. The
expression of oxidative stress response genes is altered in both hip-
pocampus and cerebrovasculature by TBI and is partially restored by
acute treatment with 17
b
-estradiol (E
2
). Additionally, TBI alters the
expression of cerebrovascular gap junction proteins (connexins). Here
we investigate the effect of E
2
treatment after TBI on connexin pro-
teins and selected protein products of oxidative stress response genes.
Methods:
Ovariectomized female rats received moderate fluid-
percussion or sham injury followed 15 min later by vehicle (Veh, 1 ml/
kg, s.c.) or E
2
(33
l
g/kg, s.c.), providing three treatment groups
(Sham
+
Veh, TBI
+
Veh, or TBI
+
E
2
). Brains were harvested 15 min
after treatment and fresh frozen. Cerebral blood vessels were isolated
and total proteins extracted. Western blot analysis was performed
using antibodies against uncoupling protein 3 (UCP3), glutathione
peroxidase 2 (GPX2), and connexin 43 (Cx43).
Results:
One-way ANOVA followed by Tukey’s HSD test showed
an overall effect of treatment on UCP3 protein (F
(2,8)
=
21.191,
P
=
0.002) with significant differences between all three treatment
groups. TBI significantly reduced UCP3 protein level (
P
=
0.002). E
2
treatment increased UCP3 protein level (
P
=
0.042) but not to the same
level as the Sham
+
Veh group (
P
=
0.038). There were no significant
differences in GPX2 and Cx43 protein levels.
Conclusions:
Uncoupling proteins are mitochondrial inner mem-
brane anion carriers involved in the electrochemical gradient across
the mitochondrial membrane and mitochondrial production of reactive
oxygen species. Since estrogens are known to regulate mitochondrial
proteins; our data suggest that UCP3 may be a mediator of the pro-
tective effects of E
2
on cerebral blood vessels after TBI.
Support:
These studies were completed as part of an interdisci-
plinary research team funded by The Moody Project for Translational
Traumatic Brain Injury.
Keywords: estrogen, oxidative stress response, traumatic brain in-
jury, cerebral vasculature
A2-16
CHARACTERIZATION OF BRAIN MATERIAL PROPERTIES
FOLLOWING BRAIN BLAST INJURY
Ahmed Alshareef
1
, Lee Gabler
1
, James Stone
2
, Matthew Panzer
1
1
University of Virginia, Center for Applied Biomechanics, Charlot-
tesville, USA
2
University of Virginia, Department of Radiology and Medical Ima-
ging, Charlottesville, USA
Improvised explosive devices (IEDs) have caused traumatic brain injury
(TBI) in approximately 360,000 soldiers over the past decade, many of
whom suffer from long-term neurological consequences when treatment
is delayed. A better understanding of the mechanical response of the
brain during and after these events may assist diagnosis and outcome of
bTBI in both clinical and battlefield scenarios. Diagnostic methods
using non-invasive stiffness techniques, such as field-deployable ultra-
sound, rely on detecting changes to the mechanical properties of brain
tissue after injury; however, these tools require
a priori
information on
mechanical changes to injured tissue. Moreover, changes to the brain
mechanical properties with a blast injury may be a) region-specific, b)
time-specific, and c) blast severity-specific. The goal of this study is to
characterize changes in the mechanical response of brain tissue fol-
lowing blast injury. Thirty adult, male Sprague-Dawley rats were ex-
posed to a primary blast wave at one of two levels of blast severity: low
(18–20 psi peak overpressure) or high (30–25 psi peak overpressure).
Sham animals that were anesthetized but not blasted were used as a
control. Animals were sacrificed at either 2 or 24 hours following in-
jury, whole brains were extracted, and mechanical indentation tests
were used to characterize stiffness at five locations: frontal cortex,
midbrain superior, midbrain aqueduct, midbrain inferior, and brainstem.
Significantly higher forces were measured in the midbrain inferior re-
gion in the blast high 24 hour when compared to sham group (
+
50%,
p
<
0.05). In addition, we observed lower forces in the brainstem region
(
-
43%, p
<
0.05) of the blast low 24 hour as compared to the sham
group. There were no significant changes in the 2 hour groups. The
results show a temporal, regionally dependent mechanical response—
stiffening in the blast high 24 hour, softening in blast low 24 hour—to
injury. The mechanical changes can serve as correlates to injury to
improve detection and diagnosis of bTBI.
Keywords: Blast TBI
A2-17
SPINAL CORD INJURY CAUSES DISTINCT ACUTE AND
CHRONIC PHASES IN THE TESTES AND BLOOD TESTES
BARRIER OF A SPRAGUE-DAWLEY RAT MODEL
Ryan Fortune
1
, David Loose
1
, Raymond Grill
2
, Christine Beeton
3
1
UTHealth GSBS, Cell and Regulatory Biology and the MD/PhD
Programs, Houston, USA
2
University of Mississippi Medical Center, Neurobiology and Anato-
mical Sciences, Jackson, USA
3
Baylor College of Medicine, Molecular Physiology and Biophysics,
Houston, USA
Spinal Cord Injury (SCI) has been shown to reduce fertility in human
and rodent males. We have previously shown that SCI causes a
sustained breakdown of the blood testis barrier. Increased inflam-
matory and oxidative conditions in this setting could lead to an
immunological infertility due to exposure to the fragile and antigenic
cells in the seminiferous tubules. RNA and metabolomics data from
these animals support this hypothesis. We have given Sprague-
Dawley rats a thoracic contusion SCI, with cohorts in both acute and
chronic time points. Acutely, we see time dependent increases in
inflammatory and oxidative markers and a massive decrease in
transcription of testosterone producing enzymes followed by a de-
crease in cell cycle regulators, indicating that sperm production is
highly disrupted only after the initial fallout of the injury is fully
realized. Chronically, we see maintenance of a low level of immune
activity and a new steady state different from both naı¨ve and sham
A-24