NNS 2015 Program & Abstract Book

function of the CST after SCI. In transgenic mice that expressed chan-

nelrhodopsin-2 in cortical layer V pyramidal neurons, we used a blue

laser to scan the region of motor cortex through intact skull. Optogen-

etically evoked limb movements were precisely detected by motion de-

tectors or by recording electromyogram (EMG). In uninjured mice,

motor maps of the forelimb area made at different times were generally

stable and reproducible. To determine whether optogenetic mapping

would reflect CST function at different stages after SCI, we simulta-

neously assessed changes in motor maps and motor behavior of the

forelimb before and at different times following unilateral pyramidotomy

or cervical spinal hemicontusion. Unilateral pyramidotomy caused im-

mediate loss of the forelimb motor area, which was followed by partial

recovery of motor map and behavior in 3–4 weeks after SCI. In contrast,

spinal hemicontusion at the cervical level (C5) resulted in an acute ex-

pansion of the motor map, which was followed by progressive loss of

map area and impairment of motor behavior at 3–4 weeks after injury.

Further analyses indicated positive correlations between map size and

motor function. We conclude that optogenetic mapping of cortical motor

area may be an efficient and minimally invasive technique for longitu-

dinal functional evaluation of the CST following SCI.

Keywords: Optogenetic, Motor cortex, Spinal cord injury, Corti-

cospinal tract

S11-03

3D IMAGING OF AXONS IN TRANSPARENT SPINAL CORDS

FROM RODENTS AND NON-HUMAN PRIMATES

Pantelis Tsoulfas

, Cynthia Soderblom, Do Hun Lee, Abdul Dawood,

Vance Lemmon, Jae Lee

University of Miami School of Medicine, Neurosurgery and The Mi-

ami Project to Cure Paralysis, Miami, USA

Failure of axons to regenerate is the primary reason for paralysis after

spinal cord injury (SCI). Thus, discovering mechanisms to promote

axon regeneration has been an intense area of research. A technical

challenge has been visualizing axon trajectory in the injured spinal

cord to provide clear origin-target information. Recent advances in

tissue clearing methods have made it possible to overcome this hurdle,

but previous studies have been performed with transgenic mice in

which the axons were pre-labeled with green fluorescent protein

(GFP). Thus, while these studies have provided a proof-of-concept, a

more practical approach to investigating axon regeneration requires

axon tracing. Using mouse and rat models of SCI, we labeled different

axon tracts using several types of adeno-associated viruses and per-

formed tissue clearing to image axons using light sheet (LSFM) and

confocal microscopy. AAV8-pUBC-eGFP and tdTomato viral axon

labeling combined with a tetrahydrofuran (THF)/benzyl alcohol-

benzyl benzoate (BABB) tissue clearing method is effective in visu-

alizing different axons in the intact and injured mouse and rat spinal

cord. While a LSFM can image the spinal cord with exceptional

speed, fine axonal projections such as corticospinal axons are better

suited for confocal microscopy imaging.

Keywords: Clearing, LSFM, Spinal cord injury, Light sheet fluo-

rescence microscopy, 3Disco, CST and RST

S11-04

TARGETING THE TRPV4 CHANNEL TO REDUCE IN-

FLAMMATION AND IMPROVE OUTCOME FOLLOWING SCI

Raymond Grill

University of Mississippi Medical Center, Department of Neurobiol-

ogy and Anatomical Sciences, Jackson, USA

Trauma to the spinal cord elicits a profound inflammatory response both

within the damaged cord as well as throughout the rest of the body. This

inflammatory response is further characterized by the activation and

mobilization of systemic as well as CNS immune components that are

thought to provide both beneficial as well as pathological aspects to the

healing process. Mechanisms underlying the activation and progression of

this immune/inflammatory activation continue to be unveiled. The

Transient Receptor Potential channel, subfamily V, member 4 (TRPV4) is

a calcium-permeable, non-selective cation channel expressed throughout

the body and serves as a molecular and mechanical sensor to detect

alterations in temperature, osmolality blood pressure, etc. Due to

TRPV4’s association with endothelial cells and role as regulator of vas-

cular tone, we hypothesized that aberrant activation of TRPV4 via me-

chanical insult may worsen spinal vascular leakage produced by

contusion injury. We determined that blood-spinal cord-barrier (BSCB)

breakdown was reduced in TRPV4-null mice compared to wild type (WT)

when assessed 48 hours post-spinal contusion injury. Utilizing additional

mutant mice in which TRPV4 is linked to GFP, we observed strong co-

association of GFP with both spinal microglia as well as splenic macro-

phages. This lead us to hypothesize that TRPV4 activation following

spinal cord injury (SCI) may contribute to systemic immune activation/

inflammation following SCI. WT mice were treated with the selective

TRPV4 inhibitor, HC-067047, once daily (10mg/kg) for three days. We

observed that HC-067047 treatment lead to a significant reduction in both

microglial and astrocytic activation at the lesion site compared to vehicle-

treated controls. In addition, HC-067047-treatment significantly attenu-

ated the loss in splenic mass normally observed following CNS trauma.

Our results suggest that trpV4 inhibition may attenuate both spinal and

systemic immune activation/inflammation following SCI.

Support provided by: 1) Mission Connect, a Project of the TIRR

Foundation, and 2) The Gillson-Longenbaugh Foundation.

Keywords: blood spinal cord barrier, spleen, neuroimmune, trpv4,

macrophages

S11-05

ATTENUATING GASTROINTESTINAL VASCULAR PER-

MEABILITY AFTER SPINAL CORD INJURY

Juan Herrera

, Kurt Bockhorst

, Karen Uray

, Raymond Grill

Ponnada Narayana

UTHealth Medical School at Houston, Diagnostic and Interventional

Imaging, Houston, USA

UTHealth Medical School at Houston, Pediatric Surgery, Houston,

USA

University of Mississippi Medical Center, Neurobiology and Anato-

mical Sciences, Jackson, USA

Gastrointestinal (GI) hemorrhage is a dangerous complication after spi-

nal cord injury (SCI). Undiagnosed abdominal complications are the

third leading cause of death in paraplegic and quadriplegic patients after

the acute phase of injury. The main objectives of this study is to inves-

tigate the compromise of the GI vascular permeability in mice during the

acute phase of injury and to determine if this compromise can be atten-

uated by an intravenous (IV) administration of angiopoietin-1 (Ang-1).

Ang-1 is a vascular stabilizing protein expressed constitutively by en-

dothelial cells, pericytes, astrocytes, smooth muscle cells, and fibroblasts.

The study examined GI vasculature permeability using dynamic contrast

enhanced magnetic resonance imaging (DCE-MRI) 48 hours after a

spinal contusion injury. The contusion injury was delivered using the

Infinite Horizon Impactor (60 kDynes with a 1 second dwell time) at

thoracic level 8. Treatments groups received a single IV administration of

Ang-1 (30

g, 100

g, or 300

g) through the jugular vein three hours

A-146