Page 108 - NNS 2014 Program & Abstract Book

enhance recovery. Methods to functionally dissect locomotor circuitry
primarily consist of non-specific spinal lesions or a limited number of
neuron-specific, fate-mapped transgenic strains. A conditional two
viral vector system was recently developed, allowing specific neuro-
nal pathways to be functionally silenced based solely on their anat-
omy. Targeted neurons are silenced in vivo through reversible
expression of enhanced tetanus neurotoxin (eTeNT) that proteolyti-
cally cleaves vesicle-associated membrane protein 2, which is essen-
tial for synaptic vesicle exocytosis. Here, we conditionally silenced L2
interneurons with descending projections to L5. Those neurons were
double-infected by bilateral injections of HiRet-TRE-EGFP.eTeNT at
L5 and the tetracycline-responsive AAV2-CMV-rtTAV16 at L2. Dox-
ycycline (DOX, 15mg/ml) was given ad libitum to induce eTeNT ex-
pression. Behavioral, kinematic, gait, and electrophysiological
assessments were performed pre-injections, before DOX-induced neu-
rotransmission silencing, during DOX treatment (DOXON), and post-
DOX. DOXON was repeated one month later to assess reproducibility.
Silencing descending L2 interneurons induced a hop-like phenotype in
the hindlimbs. Hopping was quantified by a significant increase in av-
erage hip excursion and changes to locomotor-related measures, in-
cluding hindlimb swing, stance, and stride during volitional and
treadmill-based stepping. L2-L5 interneuron silencing switched the step
sequence pattern from alternate to cruciate wherein forelimb stepping
precedes hindlimb, as opposed to alternation. These DOXON functional
changes were replicated one month after DOX washout. Current studies
focus on long ascending propriospinal neurons (LAPNs), a neural
pathway thought to functionally interconnect hind- and forelimb central
pattern generators. Bilateral injections of eTeNT at C6 and rtTAV16 at
L2 doubly-infected LAPNs. DOX treatment induced a symmetrical hop-
like gait involving both fore- and hindlimbs during volitional locomo-
tion. Ongoing behavioral, kinematic, gait, and electrophysiological an-
alyses are being performed to quantitatively describe this locomotor
behavior. This approach enables delineation of the functional contri-
bution of propriospinal pathways in normal locomotor function, after
spinal cord injury, and importantly after targeted rehabilitative therapy.
Support: GM103507,KSCHIRT 13–14.
Key words
locomotion, molecular biology, motor pathways, spinal circuitry
C1-11
INDUCED HYPERTENSION DOES NOT IMPROVE OUT-
COMES IN PENETRATING SPINAL CORD INJURY
Saigal, R.1,2, Whetstone, W.2, Hawryluk, G.W.1,2, Bresnahan, J.C.1,2,
Beattie, M.S.1,2, Manley, G.T.1,2, Dhall, S.S.1,2
1University of California San Francisco, Department of Neurological
Surgery, San Francisco, USA
2San Francisco General Hospital, Brain and Spinal Injury Center,
San Francisco, USA
Many trauma centers treat traumatic spinal cord injured-patients with
MAP goals greater than 85–90 mm Hg. However, there is a lack of
high grade evidence to support this practice or to identify the best
target blood pressure. There is even less evidence to weigh towards
specific BP goals for penetrating spinal cord injuries (SCI). We
studied our own experience in using pressors to maintain a MAP goal
greater than 85–90 in patients with penetrating SCI.
We retrospectively reviewed penetrating spinal cord injuries treated
at a single academic medical center (San Francisco General Hospital)
from 2005–2011. For inclusion, we required an ASIA grade on ad-
mission and discharge. Exclusion criteria included inadequate clinical
documentation and non-penetrating injury.
Nineteen cases met inclusion criteria. 1 case was excluded for in-
adequate documentation of the ASIA grade. In the remaining 19
cases, mean age was 40.1 (range 18–93). Mean injury severity score
was 28.8 (range 9–75). Mean hospital stay was 20.6 days (range 1–
151). Six patients had concomitant TBI. Initial American Spinal In-
jury Association (ASIA) grade was A for 13 patients, C for 1 patient,
and D for 5 patients. 18 patients received pressors in order to maintain
MAP goals. 17 ASIA grades were unchanged at the time of discharge.
Two patients improved: one from ASIA A to B and the second from C
to D. One patient worsened from ASIA C to B.
There was no obvious benefit to blood pressure augmentation in a
retrospective, single-center study of penetrating, traumatic SCI. Two
patients improved by one ASIA grade and another worsened by one
ASIA grades. Further study is needed to assess whether there is a role
for blood pressure augmentation in patients with penetrating SCI.
Key words
mean arterial pressure (MAP), penetrating spinal cord injury
C2-01
COMBINATION THERAPY WITH PROGESTERONE AND
VITAMIN D PROTECTS THE NEUROVASCULAR UNIT
AFTER TRAUMATIC BRAIN INJURY
Tang, H.1, Hua, F.1,2, Wang, J.1, Yousuf, S.1 , Atif, F.1, Sayeed, I.1,
Stein, D.G.1
1Emory University, Department of Emergency Medicine, Atlanta, US
2Xuzhou Medical College, Department of Neurology, Xuzhou, China
Traumatic brain injury (TBI) is a highly complicated disease which
comprises a primary insult and a progressive secondary cascade of
inflammatory and immune responses resulting in neurological deficits.
Previous studies have shown that progesterone and vitamin D hor-
mone (VDH) can individually reduce inflammatory responses induced
by TBI and this effect might be modulated through TLR-mediated
pathways. In the present study, we investigated the effect of proges-
terone (i.p., 16 mg/kg body weight) combined with VDH (1ug/kg
body weight) on maintaining neurovascular unit integrity by helping
to control acute neuroinflammation post-TBI. We observed that the
expression of TLR4 but not TLR2/6 increased significantly at 24 h
after TBI insult. Immunostaining showed that increased expression of
TLR4 was labeled extensively on neurons, endothelial cells and mi-
croglia. The combination treatment, but not either individual treat-
ment, significantly reduced TLR2/4 expression at 24 h post-TBI.
Neither the combination treatment nor individual treatment affected
TLR6 expression at 24 h post-TBI. Progesterone and VDH as well as the
combination treatments inhibited the expression of pro-inflammatory
factor IL-1b compared to vehicle alone. However, only the combi-
nation treatment was statistically significant in inhibiting the ex-
pression of TNF a compared to vehicle. Importantly, the combination
treatment reduced neuron loss and inhibited astrocyte activation
significantly compared with the two individual drugs evaluated by
Western blot. Immunostaining for CD68, CD31, and claudin-5
showed that combination treatment inhibited the activation of mi-
croglia and enhanced blood-brain barrier integrity significantly
compared to progesterone or VDH given separately. In conclusion,
our results suggest that combination therapy results in better pro-
tection of the neurovascular unit after TBI than progesterone or
VDH given individually. The combination therapy helps to modulate
TLR-mediated acute neuroinflammation.
Key words
combination therapy, progesterone, secondary injury, toll-like receptor
A-76