Page 139 - NNS 2014 Program & Abstract Book

D1-18
ER STRESS INHIBITOR SALUBRINAL IS NEUROPROTEC-
TIVE AFTER TBI
Nakka, V.P., Bodden, L.O., Vemuganti, R.
University of Wisconsin, Department of Neurological Surgery,
Madison, WI, USA
The newly translated proteins undergo post-translational modifications
and folding in the endoplasmic reticulum (ER). The unfolded (mis-
folded) proteins are efficiently cleared by the ubiquitin-proteasome
system. Injury to the cells disrupt these processes leading to increased
load of unfolded proteins in ER which activates the intrinsic ER stress
signaling pathways mediated by ATF6, IRE1 and PERK. All these are
considered as the endogenous neuroprotective mechanisms to protect
the brain under stress. However, uncontrolled activation of PERK
pathway promotes cell death by inducing pro-apoptotic signaling.
Using the controlled cortical impact (CCI) model of TBI in adult rats,
we currently observed increased phosphorylation of PERK and its
down-stream eIF2a in the ipsilateral cerebral cortex. The eIF2a
phosphorylation inhibits protein synthesis and thus decreases unfolded
protein load. However, we also observed induction of pro-apoptotic
transcription factors ATF4 and CHOP which are down-stream to
eIF2a , and further down-stream apoptotic genes PUMA and BIM
following TBI. In addition, GADD34 that mediates dephosphorylation
of p-eIF2a leading to translational recovery was also induced. We
tested if treatment with salubrinal (a GADD34 inhibitor) following
TBI prolongs the life of p-eIF2a to sustain translational arrest leading
to decreased new protein load and thus neuroprotection. In adult SD
rats, salubrinal treatment (1 mg/Kg at 5 min and 12 h; i.p.) increased
p-eIF2a levels, curtailed ubiquitin-conjugated protein levels (both at
1 day after TBI) and decreased the cortical cavitation volume (at 7
days after TBI; by 39.3% – 7.1%; p < 0.05; n = 6/group) compared to
vehicle control. Salubrinal treatment (1.5 mg/Kg at 5 min, 2 h and
24 h) in adult C57/BL6 mice also significantly decreased cortical
cavitation compared to vehicle control (at 7 days after TBI; by
48.7 – 9.8%; p < 0.05; n = 9/group). Similar neuroprotection (42.4% –
8%; p < 0.05; n = 9/group) was also seen when the first dose of salu-
brinal was delayed to 2 h and 4 h after CCI injury. In conclusion, these
studies show that TBI leads to over-activation of PERK-mediated ER
stress signaling in rodent brain and its inhibition is neuroprotective.
Supported by NIH.
Key words
endoplasmic reticulum, PERK, salubrinal, therapeutic window, ubi-
quitination, unfolded protein response
D1-19
DOSE-RESPONSE EVALUATION OF SIMVASTATIN IN THE
CONTROLLED CORTICAL IMPACT MODEL: OPERATION
BRAIN TRAUMA THERAPY CONSORTIUM
Dixon, C.E.1,2,4, Yan, H.Q.1,4, Ma, X.1,4, Empey, P.3, Poloyac, S.3,
Feldman, K.2 , Kochanek, P.M.2
1Neurosurgery, University Pittsburgh, Pittsburgh, USA
2CCM, Safar Center for Resuscitation, University of Pittsburgh,
Pittsburgh, USA
3Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, USA
4VA Pittsburgh Healthcare System, Pittsburgh, USA
The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor
simvastatin reduces serum cholesterol but also has potent inhibitory
effects on neuro-inflammation and possible effects on brain edema,
Akt, CBF and trophic factor production. Simvastatin was screened in
the Operation Brain Trauma Therapy (OBTT) consortium for efficacy
as a sustained therapy to improve neurobehavioral and neuropatho-
logical outcomes in the controlled cortical impact (CCI) model. Forty
male Sprague-Dawley rats were anesthetized and surgically prepared
for CCI injury (4 m/sec, 2.5-mm deformation) or sham surgery. Rats
were randomized into four groups: CCI + vehicle (3% methylcellulose
in distilled water), CCI + simvastatin (1mg/kg), CCI + simvstatin
(5 mg/kg), and sham. Simvastatin was given PO with the first dose at
3 h after injury and subsequent doses daily for 14 d. Motor function
(beam balance and walking) were evaluated on d1-5 and Morris water
maze (MWM) (acquisition and probe trial) on d14-20. Rats were
sacrificed on d21 to assess lesion and hemispheric volumes. In the
beam balance test, the CCI + vehicle and CCI + simvastatin (1mg/kg)
performed significantly worse than sham while the CCI + simvastatin
(5 mg/kg) did not differ from sham. In the beam walking test and
MWM acquistion, all of the CCI groups performed significantly worse
than sham and neither simvastatin-treated group differed vs. vehicle.
In the MWM probe trial (% time in target quadrant), there were no
differences between CCI groups. Neither lesion volume nor hemi-
spheric volume loss were reduced by treatment. Surprisingly, our
study did not replicate the benefit of simvastatin shown in previous
work. Similar to the fluid percussion and penetrating ballistic-like
brain injury models also used in OBTT, modest benefit was limited to
motor performance after CCI. Support: US Army, W81XWH-10-1-
0623.
Key words
consortium, controlled cortical impact, rats, simvastatin
D1-20
MINOCYCLINE AND N-ACETYLCYSTEINE LIMIT THE
HETEROGENEOUS INJURY THAT ARISES FROM A SIN-
GLE CLOSED HEAD IMPACT
Bergold, P.J., Sangobowale, M., Haber, M., Li, Y., Grin’kina, N.M.
SUNY Downstate Medical Center, Brooklyn, NY
Minocycline (MINO) and N-acetylcysteine (NAC) synergistically
limit deficits in cognition and memory in a rat controlled cortical
impact (CCI) model of traumatic brain injury (TBI). The combination
works, in part, by the novel mechanism of repairing injured white
matter by remyelination. We therefore wanted to test the efficacy of
the drug combination in a closed head injury (CHI) model that pro-
duces a different brain injury than CCI. As we characterized the CHI
model, we saw that a single impact to the head of adult mouse (C57Bl/
6, 26-28 g) consistently produced two injury syndromes (CHI-1 and
CHI-2). These two injury syndromes differ in immediate physiolog-
ical responses, behavioral deficits and histological damage. Differ-
ences in recovery of normal breathing and righting reflex allowed the
CHI-1 and CHI-2 groups to be separated within minutes after impact.
CHI-1 mice began breathing within 30 seconds and regained righting
reflex in 312 – 42 seconds. CHI-2 mice did not reinitiate breathing and
required cardiopulmonary resuscitation. Righting reflex was regained
after 528 – 72 seconds. On behavioral testing 7 days post-injury, CHI-
1 mice acquired an active place avoidance task, yet had no long-term
retention. CHI-2 mice were completely impaired in task acquisition.
Behavioral deficits of CHI-1 and CHI-2 mice remained unchanged
one month after injury. CHI-1 mice had a minor loss of hippocampal
neurons and localized white matter. CHI-2 mice had widespread white
matter injury and hippocampal neuronal loss. Treatment with MINO
plus NAC improved cognition and memory in both CHI-1 and CHI-2
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