Page 124 - NNS 2014 Program & Abstract Book

p < 0.05) and the CSD (93.0 – 13.1 s, p < 0.05). A higher dose of
TBOA induced CSDs even longer in duration (197.1 – 25.1 s, p < 0.05)
with a corresponding elongation in glutamate (188.1 – 19.4 s,
p < 0.05). These prolonged CSDs produced commensurate increases in
lesion size after 24 h (235 – 39 and 776 – 61 Flouro-Jade + cells, resp.,
p < 0.05), while neither CSDs under control conditions nor glutamate
injection caused significant neuronal death. Monitoring was per-
formed during focal cerebral ischemia to determine the association of
elevations in glutamate with CSDs in the natural evolution of lesion
development. Here, glutamate never increased except during sponta-
neously occurring CSDs. Multiple types of CSDs were detected in-
cluding anoxic terminal depolarizations (ischemic core) and
prolonged transient CSDs (penumbra) (145.6 – 19.7 s) that correlated
with glutamate signal (112.0 – 15.0 s) (r2 = 0.65, p < 0.05). These re-
sults show 1) elevations in glutamate are directly related to CSD, 2)
prolonged CSDs cause necrotic lesions, 3) excitotoxicity after ische-
mia occurs only during CSD. Since CSDs are observed abundantly in
clinical TBI and stroke, monitoring this pathomechanism could se-
lectively identify patients that may benefit from NMDAR antagonists.
Key words
cortical spreading depolarization, cortical spreading depression
C3-09
HIGH MOBILITY GROUP BOX-1 (HMGB1) EXPRESSION IN
OLIGODENDROCYTES OF RATS SUBJECTED TO LATE-
RAL FLUID PERCUSSION INJURY (LFPI)
Fujita, M.1, Miyauchi, T.1, Oda, Y.1, Tsuruta, R.1, Povlishock, J.T.2
1Advanced Medical Emergency and Critical Care Center, Yamaguchi
University Hospital, Ube, Yamaguchi, Japan
2Department of Anatomy and Neurobiology, Virginia Commonwealth
University Medical Center, Richmond, USA
HMGB1 is nonhistone DNA-binding protein. Recently, cytoplasmic
HMGB1 expression was reported to be associated with neuronal ne-
crosis in traumatic brain injury (TBI). However, little information
exists on HMGB1 expression in other CNS cell populations including
the oligodendrocytes.
Male adult Sprague-Dawley rats were subjected to a 2.4 atmosphere
LFPI. The animals were allowed to survive 10 min, 2 h, 6 h, and
24 h following injury (sham, n = 5; 10 min n = 8, 2 hrs n = 7, 6 hrs
n = 7, 24 hrs n = 6). At the appropriate survival times, cerebrospinal
fluid (CSF) and serum were sampled and the brain was prepared for
immunohistochemical analysis. Brain sections were reacted with an-
tibodies targeting HMGB1 and oligodendrocytes (CC-1) and/or beta
amyloid precursor protein (APP). HMGB1 labeled sections were also
analyzed by electron microscopy (EM).
In shams, HMGB1 was expressed in the nucleus of every cells
including the oligodendrocytes. In paraventricular area of corpus
callosum, cytoplasmic expression of HMGB1 was routinely observed
in oligodendrocytes within 10 min and 2 h of injury. The number of
cytoplasmic HMGB1-containing oligodendrocytes decreased with
time. Cytoplasmic HMGB1-containing oligodendrocytes were located
around APP-positive reactive axonal profiles, consistent with the
finding of diffuse axonal injury. EM revealed necrotic change in all
the oligodendrocytes revealing cytoplasmic HMGB1.
Collectively, our results support the premise that HMGB1 translo-
cates from the oligodendrocyte nucleus to the cytoplasm as early as
10 min post injury and that such cytoplasmic HMGB1 is associated
with oligodebdrocytic necrosis in the early phases of LFPI. Since these
necrotic changes accompanied local axonal damage, we posit that these
changes are associated with the onset of Wallerian degeneration.
This study is supported by NIH grants HD055813 and NS047463,
and by MEXT KAKENHI Grant Number 24592737.
Key words
high mobility group box-1 (HMGB1), necrosis, oligodendrocyte,
traumatic brain injury
C3-10
CORTICAL INJURY MODULATES THE PAIN PATHWAY
PARTIALLY THROUGH INDUCIBLE NITRIC OXIDE SYN-
THASE
Daiutolo, B.V.1, Macolino, C.M.1, Tyburski, A.L.1, Elliott, M.B.1,2
1Thomas Jefferson University Department of Neurological Surgery,
Philadelphia, USA
2Thomas Jefferson University Department of Neuroscience, Phila-
delphia, USA
Headache is a highly prevalent symptom in all severities of traumatic
brain injury (TBI) and is one of the most common symptoms of post-
concussion syndrome. Post-traumatic headache (PTH) disorders may
persist beyond the expected period of healing from inflammation after
TBI. Despite being a common symptom of concussion, little is known
about the pathogenesis of post-concussion headache. Release of the
nociceptive neuropeptide, calcitonin gene-related peptide (CGRP) and
nitric oxide within the pain pathway may contribute to chronic PTH, as
found for migraine. Excessive release of nitric oxide (NO), a damaging
and sensitizing free radical, is predominantly derived from the inducible
nitric oxide synthase (iNOS) isoform after injury. Evidence suggests
CGRP and iNOS/NO may have reciprocal interactions that facilitate a
pain phenotype. Using a controlled cortical impact (CCI) model,
changes in CGRP release and iNOS mRNA/protein levels in the
trigeminal ganglia and trigeminal nucleus caudalis (TNC) were deter-
mined using ELISA, qRT-PCR, and immunohistochemistry. Pharma-
cological blockade and genetic modulation were also used to tease out
the relationship between these two molecular targets. A rodent specific
CGRP antagonist (MK8825; 100mg/kg) or Sumatriptan (1mg/kg)
were administered to CCI mice to inhibit CGRP, while iNOS knockout
mice were compared to wild-type mice with CCI. Headache-like be-
havior (von Frey mechanical allodynia) was characterized along with
neurochemical pain correlates. iNOS mRNA and protein expression, as
well as CGRP expression, were increased in the trigeminal ganglia and
nucleus caudalis in CCI compared to controls, p < 0.01. CGRP and
iNOS were co-localized in both the ganglia and brainstem. Inhibition of
CGRP with an antagonist or sumatriptan significantly reduced the level
of iNOS mRNA and protein, whereas genetic deletion of iNOS reduced
the levels of CGRP. Significantly reduced mechanical von Frey
thresholds indicate central sensitization after CCI. Findings confirm a
reciprocal relationship between CGRP and iNOS exists and demon-
strate their importance in pathological underpinnings of PTH.
Key words
headache, migraine, nitric oxide, post-concussion syndrome
C3-11
INCREASED INTRACRANIAL PRESSURE FOLLOWING
CONTROLLED CORTICAL IMPACT EXACERBATES
WHITE MATTER AXONAL INJURY AND ATROPHY
Friess, S.H., Lapidus, J., Brody, D.L.
Washington University in St Louis, St Louis, USA
A-92