Page 107 - NNS 2014 Program & Abstract Book

ded, randomized preclinical trials to investigate the potential for diclo-
fenamic acid (DFA), a potent L-selectin sheddase approved by the FDA
for the treatment of inflammatory disorders in humans, as a therapeutic
following SCI. We first utilized enzyme-linked immunosorbent assays
and flow cytometry to quantify L-selectin sheddase activity post-SCI in
blood and cord after intraperitoneal administration of DFA (at 1, 5, 10,
20, 40, or 60mg/kg) and determined the minimally effective dose to be
40mg/kg. Next, 40mg/kg DFA or vehicle was administered to mice
immediately following either a moderate or severe contusion SCI (n = 15/
group). Locomotor recovery, based upon the Basso Mouse Scale, was
significantly improved with DFA treatment relative to vehicle controls in
both injury severities. Critically, the percentage of moderately injured
mice frequently/consistently stepping improved from 45% (vehicle) to
92% (DFA) and of severely injured mice stepping from 8% (vehicle) to
70% (DFA). Finally, efficacy of 40mg/kg DFA was investigated when
treatment was delayed 3 hours post injury (n = 15/group). DFA treatment
again showed significant locomotor recovery in severely injured mice
with the percentage of mice stepping improving from 18% (vehicle) to
62% (DFA). Together, these encouraging data support the repurposing of
FDA-approved DFA for the treatment of SCI.
Key words
diclofenamic acid, inflammation, L-selectin, secondary demyelin-
ation, spinal cord injury
C1-08
ROLE OF CPLA2 IN THE PATHOGENESIS OF SPINAL
CORD INJURY
Liu, N.K.1, Deng, L.X.1, Zhang, Y.P.2, Lu, Q.B.1, Wang, X.F.1, Hu,
J.G.1, Oakes, E.1, Bonventre, J.V.3 , Shields, C.B.2, Xu, X.M.1
1University of Indiana, Department of Neurological Surgery, In-
dianapolis, USA
2Norton Healthcare, Liuousville, USA
3Harvard Medical School, Boston, USA
Several lines of evidence suggest that phospholipase A2 (PLA2) may
play a key role in mediating secondary spinal cord injury (SCI). PLA2
are a diverse family of lipolytic enzymes which hydrolyze phospho-
lipids to produce free fatty acids and lysophospholipids. Cytosolic
PLA2 (cPLA2) is one of the most important PLA2 isozymes. However,
the role of cPLA2 in the pathogenesis of SCI has not yet been fully
understood, and is even controversial. In this study, we investigated
whether cPLA2 plays a role in the pathogenesis of SCI using multiple
approaches including cellular, molecular, pharmacological, genetic, and
behavior assessments. The results showed that SCI significantly in-
duced cPLA2 expression and activation. Activated cPLA 2 was localized
mainly in neurons and oligodendrocytes. Notably, SCI-induced cPLA2
activation was mediated, at least in part, by the ERK signaling pathway.
In vitro experiments showed that activation of cPLA2 by ceramide-1-
phosphate, a direct cPLA2 activator, or A23187, an indirect cPLA 2
activator, induced spinal neuronal death, which was substantially re-
versed by AACOCF3, a cPLA2 inhibitor. TUNEL staining and Western
blot further revealed that cPLA2 activation induced neuronal death
through apoptosis. Remarkably, blocking cPLA2 pharmacologically
with AACOCF3 reduced cPLA2 activity, membrane injury, inflam-
mation, cell death, and tissue damage, as well as improved behavioral
recovery in C57BL/6 mice after SCI. A important finding of the present
study is that genetic deletion of cPLA2 resulted in neuroprotection and
behavioral recovery following SCI. Genetic deletion of cPLA2 also
inhibited the expression of active caspase-3 after SCI, suggesting that
cPLA2 activation mediates neural apoptosis. These findings collectively
suggest that cPLA2 may play a key role in the pathogenesis of SCI, and
this molecule could be an attractive therapeutic target for ameliorating
secondary tissue damage and promoting recovery of function after SCI.
Key words
behavioral function, cytosolic phospholipase A2, inflammation, neu-
ronal death, spinal cord injury
C1-09
AC105 INCREASES DELIVERY OF EXTRACELLULAR
MAGNESIUM TO INJURED SPINAL CORD TISSUE IN RATS
Filipovic, Z., Huang, Z., Ung, C., Troy, E.L., Colburn, R.W., Iaci,
J.F., Button, D., Caggiano, A.O., Parry, T.J.
Acorda Therapeutics, Inc., Ardsley, New York, United States
Magnesium (Mg + + ) plays an essential role in maintenance of numer-
ous cellular functions and has beneficial effects in rat models of spinal
cord injury (SCI). Studies have shown that the neuroprotective effects
of supplemental Mg + + following SCI were achieved only with ex-
tremely high doses of MgSO4 . It was recently reported that infusion of
MgCl2 in a polyethylene glycol (PEG, MW 3350 g/mol) formulation
(named AC105 and currently under clinical development for SCI by
Acorda Therapeutics Inc.) was neuroprotective at a relatively low dose
of Mg+ + . The aim of this study was to compare the extracellular Mg + +
levels in SCI rats after treatment with AC105, MgSO4 or saline. SCI
was induced in isoflurane-anesthetized rats (female Long Evans, 200–
250 g) by temporary compression of the spinal cord following lami-
nectomy at the T9/T10 vertebral level. Two microdialysis probes were
inserted transversely through the spinal cord, one positioned at the
center of the compression site and the other 1mm rostral to the com-
pression site (peri-lesion zone). Dialysates were collected every 15
minutes for 4 hours following SCI. AC105 (MgCl2, 192 lmol/kg,
n = 15), MgSO 4 (192 lmol/kg, n = 15), or saline (5mL/kg, n = 15) was
intravenously infused over 30 minutes beginning 2 hours after SCI.
Dialysate samples were analyzed for Mg + + and K + concentrations
using inductively coupled plasma optical emission spectrometry. We
find that AC105 treatment produced a sustained, significant increase in
extracellular Mg + + both within the compression zone (*1.5- to 2-fold,
p < 0.01, two way ANOVA followed by Bonferroni test) and the ad-
jacent rostral zone (*1.3- to 1.5-fold, p < 0.01) following SCI, relative
to saline, while MgSO4 produced a slight but not statistically significant
increase in the respective dialyzed zones after SCI. No statistically
significant change in extracellular K+ concentration was observed be-
tween pre- and post-treatment in all three groups. These results indicate
that AC105, compared to equimolar MgSO4, enhances delivery of
extracellular Mg + + to spinal cord tissue following traumatic injury.
Key words
magnesium, microdialysis, polyethylene glycol, rats, spinal cord in-
jury
C1-10
CONDITIONAL SILENCING OF ADULT RAT SPINAL LO-
COMOTOR CIRCUITRY INDUCES HOPPING
Pocratsky, A.M., Riegler, A.S., Morehouse, J.M., Burke, D.B.,
Hardin, J.T., Howard, R.M., Magnuson, D.S., Whittemore, S.R.
University of Louisville, Louisville, USA
Identifying the functional role of spared neural pathways post-spinal
cord injury can help design targeted rehabilitation strategies to
A-75