ing them within subject and injury-group to pre-implant/injury
baseline behavior.
Whereas our previous work based solely on behavior of adult
subjects showed no cognitive recovery upto PID17, this study
of juveniles (5 naı¨ve, 4 sham-implanted, 4 mTBI-implanted)
shows prospect of behavioral recovery by PID17 (p
=
0.248)
without such effects at PID3 (p
=
0.001) or PID10 (p
=
0.039),
relative to pre-injury behavior at PND31. Comparing novel object
preference against naı¨ves we find limited injury due to implan-
tation alone (mTBI-implanted p
=
0.015; sham-implanted
p
=
0.0578). Following exclusion of electro-mechanical interfer-
ences, cross-frequency power maps (4–40) Hz spanning theta and
low-gamma ranges, indicate aperiodic changes in concurrency
from electrode located nearest FPI site (Left-Anterior) with
neighboring (Right-Anterior and Left-Posterior) sites in injured
subjects during routine exploration and during object approach
relative to shams.
We hypothesize (
H
1
[1]
) that mildly injured (loss-of-consciousness
<
45s) PND35 rats demonstrate partial recovery of working memory by
adulthood (PND52). We additionally hypothesize (
H
1
[2]
) that such re-
covery does not occur in moderately or severely injured juveniles (loss-
of-consciousness
>
45 sec). Evidence in the form of cross-frequency
concurrency maps, correlated with real-time stereotyped behaviors
during stages of NOR, will be presented. This research was supported by
NSF ECCS-0847088, UCLA BIRC, NS027544 and NS05489.
Key words
concurrency, cross-frequency, injury signature, mote, wireless
B4-17
NEUROLOGICAL DEFICITS FOLLOWING TRAUMATIC
BRAIN INJURY IS AFFECTED BY AGE AND SEVERITY OF
INJURY IN PART DUE TO MYOSIN LIGHT CHAIN KINASE
INTERACTING WITH ISG15
Rossi, J.L.
1,3
, Todd, T.
2,3
, Daniels, Z.
3
, Bazan, N.G.
3
, Belayev, L.
1,3
1
Department of Neurosurgery, New Orleans, USA
2
Department of Pediatrics Division of Critical Care Children’s
Hospital, New Orleans, USA
3
Neuroscience Center of Excellence Louisiana State University
Health Science Center, New Orleans, USA
Recent studies have shown that MLCK (Myosin light chain kinase)
plays a pivotal role in development of cerebral edema, a known
complication following TBI in children and a contributing factor to
worsened neurologic recovery. Lately, increased levels of ISG15 an
ubiquitin-like protein, has been seen after global ischemia, focal is-
chemia, and are neuroprotective. The significant role of ISG15 after
TBI is not yet studied.
PND21 and PND24 (n
=
6 per group) mice were anesthetized with
avertin, mechanically ventilated, physiologically regulated, and sub-
jected to lateral closed-skull injury model with impact depth of 2 or
2.25 mm (bregma level - 0.10 mm). Neurological outcome was ex-
amined at 7d with two-object novel recognition and wire hang tests.
Mice were sacrificed at 6, 12, 24, 48, 72 h and 7d. ISG15 and MLCK
analyzed by western blot, immunohistochemistry; BBB disruption
with Evans Blue (EB) and wet/dry weights.
Two-object novel recognition:
Number of touches: novel vs. old
objects, PND21 (2.00 mm: 12.92 vs. 13.33 and 2.25 mm: 36 vs. 66,
respectively) PND24 (2.00 mm: 31 vs. 42 and 2.25 mm: 40 vs. 60,
respectively).
Wire hang-motor test:
Latency to fall in seconds (s): PND21: 2.00
mm: 21s, 2.25 mm: 2s. PND24 2.00: 14s, 2.25: 5s.
ISG15 upregulation
: PND21 normalized to actin (pixel density)
12 h 2.00 mm: 1.539, 2.25 mm: 1.889 and 72 h 2.00 mm: 1.349,
2.25 mm: 2.659. PND24 6 h 2.00 mm: 1.774, 2.25 mm: 2.168. Co-
localization of ISG15 and MLCK is confirmed by immunohisto-
chemistry.
Wet/dry weights (g)
: PND21 72 h 2.00 mm: 2.035, 2.25 mm: 2.143,
7 D, 2.00 mm: 1.797, 2.25 mm: PND24 72 h 2.00 mm: 1.842, 2.25 m:
2.47, 7D 2.00 mm: 1.778, 2.25 mm: 1.745.
EB ng/grams of brain
: PND21 72 h 2.00 mm: 3074.55, 2.25 mm:
6027.62, 7D 2.00 mm: 1878.771, 2.25 mm: 2927.94. PND24 72 h
2.00 mm: 3045.995, 2.25 mm: 7408.914; 7D: 2.00 mm: 924.623,
2.25 mm: 951.625.
ISG15 is elevated following TBI in PND 21 and 24 mice preceding
the elevation of MLCK and the development of BBB disruption and
cerebral edema.
Key words
blood brain barrier, immature brain, ISG15, MLCK, TBI
B4-18
NEUROPROTECTIVE MECHANISMS OF DOCOSAHEX-
AENOIC ACID IN RAT PUPS AFTER TRAUMATIC BRAIN
INJURY
Schober, M.E.
1
, Pauly, J.R.
2
, Requena, D.
1
, Cusick, M.
1
1
University of Utah, Salt Lake City, USA
2
University of Kentucky, Lexington, USA
Dietary Docosahexaenoic Acid (DHA) improved white matter injury
and cognitive impairment in our rat pup controlled cortical impact
(CCI) model of developmental TBI, associated with decreased oxi-
dative stress and inflammation. Mechanisms of DHA’s neuropro-
tection are poorly understood. Microglia, the brain’s resident
macrophages, mediate oxidative stress and inflammation after TBI.
In systemic macrophages, DHA decreases inflammatory (M1) acti-
vation while promoting reparatory (M2) activation. Effects of DHA
on microglia after TBI are not known.
We hypothesized that DHA would decrease microglial activation
and markers of M1 transformation after CCI in the 17 day old rat.
CCI or SHAM surgery was delivered to 17 day old male rats ex-
posed to 0.1% DHA (DHA) or otherwise equivalent chow (REG).
TSPO imaging and histology at post injury day (PID) 3 and 50 were
done to assess microglial activation and lesion volume. mRNA levels
of M1 (IL-1
b
, IL-12
b
, IL-6, IL-18rap, CCL2, INF Y, TNF
a
, iNOS)
and M2 (IL-4, L-1R
a
, CD206, IL-10, TGF
b
and Arg1) markers were
measured in microglia isolated by flow cytometry and in injured tissue
at PID 2 and 3.
Preliminary results suggest decreased microglial activation at
PID3. DHA decreased M1 marker mRNA IL6 (to 71
–
4% REGCCI),
IL-1
b
(to 59.6
–
7%), IL-18rap (49.8
–
4%), CCL2 (to 18.2 3%
–
3
%), TNF
a
(to 75
–
6%) and INF Y (to 51
–
4%) in PID2 hippocampi
(p
<
0.05). Partial results suggest DHA decreased lesion volume
(21.6 vs 29.8% loss, p
=
0.06) without changing microglial activation
at PID50.
Exposure to a 0.1% DHA diet after CCI is associated with de-
creased M1 activation markers in hippocampus at PID2. Preliminary
data suggests DHA decreases microglial activation at PID3 and lesion
volume at PID50. We anticipate that DHA will decrease M1 marker
mRNA in isolated microglia. We speculate that DHA improves cog-
nitive function after CCI via immunomodulation.
Key words
developmental, docosahexaenoic acid, traumatic brain injury
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