linked to cognitive impairment. Insulin-like growth factor-1 (IGF1) is
a potent neurotrophic factor capable of mediating neuroprotective and
neuroreparative processes. We have shown that elevating brain levels
of IGF1 stimulates hippocampal neurogenesis, enhancing the recovery
of immature neuron numbers after severe TBI in mice. However, little
is known about the effectiveness of IGF1 to promote long-term sur-
vival of neurons born after injury. To this end, astrocyte-specific IGF1
conditionally overexpressing mice (IGF1-TG) and wild-type (WT)
mice received controlled cortical impact or sham injury and 50 mg/kg
BrdU (i.p.) twice daily for 7 days following TBI. At six weeks fol-
lowing injury, total numbers of proliferated cells (BrdU
+
) and the
subset expressing a mature neuronal marker (NeuN
+
/BrdU
+
) were
counted at the injury epicenter. IGF1 significantly increased NeuN
+
/
BrdU
+
cell density at 6 weeks post-injury (p
<
0.05, compared to WT
injured mice). These data suggest that IGF1 stimulates the formation
of new hippocampal neurons acutely after brain injury and that these
new neurons survive to maturity. Future studies will examine the
electrophysiological function of these newborn neurons.
Keywords: Neurogenesis, Survival, IGF1
D8-14
SYNERGISTIC EFFECTS OF
b
-HYDROXYBUTYRATE AND
ACETYL-L-CARNITINE ON MITOCHONDRIAL FUNCTION
AFTER SPINAL CORD INJURY
Samirkumar Patel
1
, Jenna VanRooyen
1
, Patrick Sullivan
2
,
Alexander Rabchevsky
1
1
University of Kentucky, Spinal Cord & Brain Injury Research Cen-
ter, Dept of Physiology, Lexington, USA
2
University of Kentucky, Spinal Cord & Brain Injury Research Cen-
ter, Dept of Anatomy & Neurobiology, Lexington, USA
Mitochondrial dysfunction and oxidative stress are key factors after
contusion spinal cord injury (SCI) that lead to cell death and ulti-
mately functional deficits and, therefore, serve as pivotal targets for
SCI therapeutics. The current study evaluated the effects of admin-
istering ketone bodies, namely
b
-hydroxybutyrate (BHB) on mito-
chondrial function and oxidative stress following SCI. Moreover, we
tested BHB treatment either alone or delivered in combination with
acetyl-l-carnitine (ALC), an alternative bio-fuel for mitochondria.
Injured Sprague-Dawley rats (250 kdyn at L1/L2 spinal level) were
divided into 3 treatment groups (n
=
6/group): 1) Vehicle-treated-in-
jured, 2) 1.66 mmol/kg BHB-treated injured and 3) 1.66 mmol/kg
BHB
+
300 mg/kg ALC-treated injured. Drugs were administered in-
traperitoneally at 1 hr post-injury followed by insertion of an osmotic
mini-pump (s.c.) to deliver Vehicle or BHB (1.66 mmols/kg/day) or
BHB
+
ALC (300 mg/kg/day) for 24 hrs. A Sham group received only
a T12 laminectomy. At 24 hr post-injury, spinal cord mitochondria
were isolated and assessed for oxygen consumption rate (OCR) using
Seahorse Bioscience XFe24 extracellular flux analyser, as well as for
content of endogenous antioxidant glutathione (GSH). Results showed
significantly (p
<
0.05) decreased OCR (
*
50%) in Vehicle-treated
injured group compared to Shams and that treatment with BHB alone
significantly (p
<
0.05) preserved mitochondrial OCR (
*
35% lower
than Sham) after 24 hrs. Furthermore, combined treatment with
BHB
+
ALC additively restored mitochondrial OCR (
*
10% lower
than Sham) compared to BHB alone. Notably, while SCI also resulted
in significant (p
<
0.05) depletion of GSH (
*
25%), continuous
treatment with BHB completely restored GSH to normal levels. On-
going experiments are assessing whether combined BHB
+
ALC ad-
ditively normalize oxidative stress parameters and activities of key
mitochondrial enzyme complexes at 24 hr post-injury. Planned ex-
periments will assess the effects of such combinatorial treatments on
tissue sparing and recovery of hindlimb function following SCI.
Keywords: mitochondrial respiration, functional recovery, gluta-
thione, oxidative stress
D8-15
RE-PURPOSING AN FDA-APPROVED DRUG AS AN ANTI-
OXIDANT TO SCAVENGE REACTIVE CARBONYLS FOL-
LOWING TBI-INDUCED LIPID PEROXIDATION
Johnny Cebak
, Indrapal Singh, Juan Wang, Edward Hall
University of Kentucky, Department of Anatomy and Neurobiology,
Lexington, USA
Lipid peroxidation is a key contributor to the pathology of traumatic
brain injury (TBI). Traditional antioxidant therapies are intended to
scavenge the free radicals responsible for either the initiation or prop-
agation of lipid peroxidation (LP). However, targeting free radicals after
TBI is difficult as they rapidly react with other cellular macromolecules.
Our laboratory utilizes a novel antioxidant approach that scavenges the
final stages of LP i.e., the formation of carbonyl-containing breakdown
products. By scavenging breakdown products such as the highly reac-
tive and neurotoxic aldehydes 4-hydroxynonenal (4-HNE) and acrolein,
we are able to prevent the covalent modification of cellular proteins.
Without intervention, carbonyl additions render cellular proteins non-
functional which initiates the loss of ionic homeostasis, mitochondrial
failure, and subsequent neuronal death. Phenelzine (PZ) is an FDA-
approved monoamine oxidase inhibitor traditionally used for the treat-
ment of depression. However, PZ also possesses a hydrazine functional
group capable of covalently binding carbonyls. We hypothesized that
PZ will protect mitochondrial function and reduce markers of oxidative
damage by scavenging reactive aldehydes. Indeed, in our
ex vivo
ex-
periments the exogenous application of 4-HNE or acrolein significantly
reduced respiratory function and increased markers of oxidative damage
(
p
<
0.05) in isolated non-injured rat cortical mitochondria, whereas PZ
pre-treatment significantly prevented mitochondrial dysfunction and
oxidative damage in a concentration-related manner (
p
<
0.05). We
attribute PZ’s neuroprotective effects to the hydrazine moiety based on
experiments demonstrating that a structurally similar MAO inhibitor,
pargyline, that lacks the hydrazine moiety was unable to protect mito-
chondria. Our
in vivo
experiments demonstrated that PZ treatment,
10mg/kg s.c. begun at 15 minutes and repeated q12 hrs, significantly
attenuated mitochondrial respiratory failure 72 hours post-injury fol-
lowing rat controlled cortical impact injury, while also significantly
reducing cortical lesion volume 2 weeks post-injury. We are presently
investigating the optimal PZ dosing regimen for improvement of cog-
nitive and motor behavioral recovery and the therapeutic window for
the neuroprotective effects of the drug to determine its feasibility for
translation into human TBI testing.
Keywords: Phenelzine, Mitochondria, Oxidative Damage, 4-HNE,
acrolein, TBI
D8-16
BIOMARKER PROFILES SUPPORT A NEUROPROTECTIVE
EFFECT OF LEVETIRACETAM IN TBI: FINDINGS FROM
OPERATION BRAIN TRAUMA THERAPY
Stefania Mondello
1
, Megan Browning
2
, Deborah A. Shear
3
, Helen M.
Bramlett
4
, C. Edward Dixon
2
, Kara Schmid
3
, W. Dalton Dietrich
4
,
Kevin K. Wang
5
, Ronald L. Hayes
6
, Frank C. Tortella
3
, Patrick M.
Kochanek
2
A-118