Page 118 - NNS 2014 Program & Abstract Book

only increased HIF-1a/VEGF and vessel density but also improved
neurobehavioral functions.
Oxidative stress (peroxynitrite) causes a sustained activation of
AMPK in the acute phase leading to BBB disruption and edema. On
the other hand, pharmacological inhibition of AMPK activity in the
chronic phase hampers functional recovery. These observations pro-
vided us rationale for the use of GSNO which protected BBB integrity
by reducing peroxynitrite in the acute phase. In the chronic phase,
GSNO aids in functional recovery by up regulating the neurorepair-
associated HIF-1a/VEGF pathway and angiogenesis. GSNO is a
natural molecule and its exogenous administration has not shown
toxicity or side effects in humans.
The study was supported by grant from the NIH NS-72511.
Key words
AMPK, functional recovery, GSNO, HIF-1 alpha, neurorepair, vessel
density
C2-27
KNOCKOUT OF CYCLOPHILIN D PREVENTS INCREASED
INTRINSIC AND SYNAPTIC NEURONAL EXCITABILITY
AFTER MILD TRAUMATIC BRAIN INJURY (MTBI)
Sun, J., Jacobs, K.M.
Virginia Commonwealth University, Richmond, USA
Mitochondria are central to Ca2 + homeostasis. Dysfunction re-
sulting in mitochondrial permeability transition pore (MTP)
opening has been reported after mTBI. Cyclophilin D is an integral
part of the MTP. Recently our group has found that the extent of
axonal injury was diminished in neocortex after mTBI in cyclo-
philin D knockout (KO) mice. Here we tested whether this KO
could also provide protection from the increased intrinsic and
synaptic neuronal excitability previously described. In these ex-
periments a central fluid percussion injury was given to 6–8 week
old YFP-h mice. Whole cell patch clamp recordings from ax-
otomized (AX) and intact (IT) YFP + layerV pyramidal neurons
were made after 1–2 day survival. Action potentials (AP) were
recorded in current-clamp mode while neurons were maintained
at - 60 mV. Excitatory post synaptic currents (EPSCs) were re-
corded in voltage-clamp mode with neurons held at - 70 mV.
While AP are increased in amplitude in AX at 1–2 days and in IT at
1 day after injury, in KO mice this increase was prevented. After
mTBI in KO mice, the amplitude of AP in IT and AX neurons was
not different (1–2 day survival) from that in naı¨ve KO mice (AN-
OVA, p > 0.05, n ‡ 9 cells). There was however a trend towards an
increased AP amplitude for IT neurons at 1day (p < 0.5 with t-test).
Thus, there may be additional factors that contribute to the alter-
ation of this intrinsic property. This KO also prevented the changes
in EPSCs previously observed after mTBI. The frequency and
amplitude of spontaneous and miniature (1 mM TTX in bath)
EPSCs were not different between naı¨ve and mTBI at 1–2 day
survival times for AX and IT neurons from KO mice (ANOVA,
p > 0.05, n ‡ 8 cells). Thus, the CypD-mediated mitochondrial
permeability transition pore is linked to the cellular and synaptic
perturbations observed in the pathogenesis of mTBI. These data
support the idea that therapies aimed at mitochondrial protection
should prove clinically useful. Supported by NIH grant NS077675.
Mouse strain supplied by Michael Forte, Vollum Institute, OHSU.
Key words
action potential, cyclophilin D, excitatory synaptic transmission, mi-
tochondria
C2-28
THE NRF2-ARE PATHWAY AS A THERAPEUTIC TARGET
IN TRAUMATIC BRAIN INJURY: GENETIC AND PHAR-
MACOLOGICAL APPROACHES FOR NEUROPROTECTION
Miller, D.M., Singh, I.N., Wang, J.A., Hall, E.D.
University of Kentucky, SCoBIRC, Lexington, USA
The pathophysiological importance of oxidative damage after trau-
matic brain injury (TBI) has been extensively demonstrated in ex-
perimental models. The transcription factor Nrf2 mediates antioxidant
genes by binding to antioxidant response elements (ARE) within DNA
and upregulating these genes creating a pleiotropic cytoprotective-
defense pathway. Previously, we determined the post-TBI time-course
of Nrf2-ARE mediated gene expression in cortex and hippocampus
utilizing the unilateral controlled cortical impact (CCI) model. In-
creased Nrf2-ARE mediated expression closely followed that of post-
TBI oxidative damage markers 4-HNE and 3-NT (Miller et al., J.
Neurotrauma, March 2014, in press). Moreover, pre-treatment 48
hours prior with Nrf2-ARE activating drug carnosic acid (CA) (single
1.0 mg/kg i.p. administration) provides protection to cortical mito-
chondria bioenergetics after exposure to the toxic aldehyde 4-HNE
ex vivo that was accompanied by decreased 4-HNE bound to mito-
chondrial proteins (Miller et al., Free Rad. Biol. Med. 57:1-9, 2013).
In addition, we conducted a post-TBI dose response of CA and found
that a single 1.0 mg/kg i.p. administration 15 minutes post-TBI re-
duced levels of oxidative damage markers in cortex and hippocampus.
In the current study, we demonstrate for the first time that CA can
significantly improve ( p < 0.05) cortical mitochondrial respiratory
function at 24 hours post-TBI as compared to vehicle animals which is
accompanied by a concomitant reduction in oxidative damage to
mitochondrial proteins. Additionally, we have found that oxidative
damage is increased in Nrf2-knockout mice but attenuated in mice
overexpressing Nrf2. Current studies are determining if genetic ma-
nipulation attenuates behavioral deficits and neurodegeneration.
Pharmacological studies are also assessing the therapeutic window of
CA wherein initial administration is delayed to 1, 4, or 8 hours post-
TBI. Furthermore, an evaluation of CA’s capability to attenuate be-
havioral deficits and neurodegeneration post-TBI is also underway.
These studies will determine if targeting the Nrf2-ARE pathway post-
TBI has clinical relevance.
Key words
gene expression, neuroprotection, oxidative stress, TBI, transcription
factor
C2-29
EFFECTS OF ETHYL PYRUVATE ON MARKERS OF OXI-
DATIVE STRESS AND GLYCOLYTIC FUNCTION AFTER
TRAUMATIC BRAIN INJURY
Kutsuna, N., Shijo, K., Ghavim, S., Hovda, D.A., Sutton, R.L.
UCLA, Los Angeles, USA
The current study examined potential mechanisms by which ethyl
pyruvate (EP) improves cerebral glucose metabolism and reduces
neuronal injury after experimental traumatic brain injury (TBI). Adult
male Sprague-Dawley rats received sham injury or TBI (contusion) to
the left parietal cortex followed by injections of EP (40 mg/kg, IP) or
no treatments at 0, 1, 3 and 6 h. At 7 h post-injury left cortical tissue
was harvested and processed for Western blots, levels of nicotinamide
adenine dinucleotide (NAD +) and GAPDH enzyme activity. Protein
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