Page 103 - NNS 2014 Program & Abstract Book

B5-02
DECREASED SEROTONIN TRANSPORTER EXPRESSION
AFTER TRAUMATIC BRAIN INJURY IN A RAT CON-
TROLLED CORTICAL IMPACT MODEL
Kibayashi, K., Shimada, R.
Department of Legal Medicine, School of Medicine, Tokyo Women’s
Medical University, Tokyo, Japan
Depression, higher brain dysfunction and aggression have been
shown to occur after traumatic brain injury (TBI). Selective sero-
tonin reuptake inhibitors (SSRIs) are effective in the treatment of
such morbid states. Necropsy of the brain of patients showing
mental depression revealed decreased density of serotonin trans-
porter (5-HTT). We hypothesized that the serotonin transporter
expression changes in the brain following TBI. We performed real-
time polymerase chain reaction (PCR) analysis for mRNA and
western blot analysis for protein to examine the time-dependent
changes in the expression of 5-HTT in the brain during the first 14
days after TBI in a controlled cortical impact (CCI) model of rat
brain. Compared to sham, decreased expressions of 5-HTT mRNA
and protein were noted in the cortex on the side ipsilateral to the
site of injury at 7 days after injury (p < 0.05). The findings indicated
that TBI induced changes in 5-HTT expression in the ipsilateral
cortex. The role of the serotonin transporter is to transport sero-
tonin from the synaptic cleft into the synaptic region, enabling its
use by the presynaptic neuron. Thus, the serotonin transporter
regulates serotonin concentration in the synapse by recycling se-
rotonin, and thereby affects the receiving neuron receptors. The
decreased expression of 5-HTT after TBI could result in decreased
serotonin neurotransmission in the brain.
Key words
controlled cortical impact, depression, serotonin, serotonin transporter
B5-03
LEUKEMIA INHIBITORY FACTOR DEFICIENT MICE
HAVE AN INCREASED VULNERABILITY TO MILD PRE-
DIATRIC TRAUMATIC BRAIN INJURY
Goodus, M.T., Ahmed, N., Levison, S.W.
Rutgers University, Newark, USA
Cytokines and growth factors are key candidates for mediating the
changes induced by damage to the brain as they can affect astrocyte
proliferation, microglial activation and cell survival. Leukemia
inhibitory factor (LIF), a member of the interleukin-6-type cyto-
kine family, is rapidly induced after CNS injury and participates in
all of these processes. However, whether LIF signaling is necessary
for these injury responses has not been established. Therefore, to
test the hypothesis that LIF is required for normal responses to
pediatric traumatic brain damage, we compared the extent of
damage to neocortical and subcortical white matter in LIF het-
erozygous and wild type (WT) mice. We performed a mild, closed-
head controlled cortical impact (CCI) model at postnatal day 18 on
WT and LIF heterozygous mice. In WT mice LIF transcripts in-
creased *15 fold 24 hours following mild TBI. This response was
significantly reduced in LIF heterozygous mice. LIF haplodefi-
ciency resulted in decreased astroglial activation (decreased GFAP
expression) and a blunted microglial response (reduced Iba1
staining) after both mild and severe TBI in the neocortex and ad-
jacent subcortical white matter. LIF deficient juvenile mice also
exhibited greater apoptosis as demonstrated by increased in situ
end labeling (ISEL) and increased neuronal cell death as shown by
Fluorojade C staining in the neocortex and corpus callosum after
mild TBI. These results indicate that LIF is necessary for the
normal astrocytic and microglial responses to mechanical brain
injury in immature mice. Supported by grant # CBIR13IRG017
from the NJ Commission on Brain Injury Research awarded to
SWL.
Key words
leukemia inhibitory factor, pediatric mild TBI
B5-04
ACUTE ALTERATIONS IN GLUTAMATE NEURO-
TRANSMISSION AFTER CONCUSSIVE BRAIN INJURY
McGuire, J.L.1, Dorsett, C.2 , Floyd, C.L.2,3, McCullumsmith, R.E.1
1University of Cincinnati, Department of Psychiatry and Behavioral
Neuroscience, Cincinnati, USA
2University of Alabama, Birmingham, Department of Physical Medi-
cine and Rehabilitation, Birmingham, USA
3University of Alabama, Birmingham, Department of Neurobiology,
Birmingham, USA
Traumatic brain injury (TBI) is a major cause of morbidity and
mortality, often leading to chronic neuropsychiatric symptoms.
Glutamate neurotransmission requires neuron-astroglia-coupled
regulation of synaptic and extrasynaptic glutamate levels. Gluta-
mate mismanagement negatively impacts molecular correlates of
cognition. We hypothesize that altered post-TBI intracellular sig-
naling leads to dysregulated glutamate neurotransmission. TBI was
initiated in parietal cortex using lateral fluid percussion (LFPI).
The excitatory amino acid transporter 2 (EAAT2) was examined in
synaptosomes isolated from ipsilateral LFPI cortex, sham-surgery,
and naı¨ve cohorts (n = 5) twenty-four hours post-LFPI using Wes-
tern blot and 3H-labelled glutamate uptake. Serine/threonine kinase
signaling was investigated in cortical and hippocampal homoge-
nates using PamGene kinome arrays. Ingenuity Pathway Analysis
(IPA) identified cellular processes corresponding to altered kinase
activity. Twenty-four hours after LFPI, EAAT2 protein was de-
creased in cortical homogenate in LFPI, but not synaptosomes.
Synaptosomal glutamate uptake decreased after LFPI. Twenty-
seven kinome array substrates in cortex, and nineteen in hip-
pocampus were differentially phoshorylated between LFPI and
controls (fold change + / - 1.15). Among these, were components of
multiple mitogen-activated protein kinase (MAPK) cascades which
are instrumental in mediating both inflammation and glutamate
regulation. In cortex, IPA identified cell death and survival, or-
ganismal survival, and glucocorticoid signaling as the most prob-
able cellular functions, physiological systems and signaling
pathways affected by the alterations in kinase activity. In hippo-
campus, LFPI impacted cellular assembly and organization, ner-
vous system development and function, and Protein Kinase A
signaling. These data identify molecular cascades and subsequent
glutamate dysregulation as a potential mechanism for cognitive and
behavioral impairment after TBI. These findings highlight the
importance of determining the long-term status of the EAAT2
system and synaptic glutamate management after TBI.
Key words
excitatory amino acid transporter, extrasynaptic, glutamamte, lateral
fluid percussion, localization
A-71