NNS 2015 Abstract Book

Poster Abstracts

A1 Poster Session I - Group A: Cell Death

A1-01

REPETITIVE PRIMARY BLAST-INDUCED VULNERABILITY

AND DEFICITS IN LONG-TERM POTENTIATION WITHOUT

CELL DEATH

Gwen Effgen

, Tiffany Ong

, Shruthi Nammalwar

, Andrea Ortuno

Dale Bass

, David Meaney

, Barclay Morrison

Columbia University, Biomedical Engineering, New York, USA

Duke University, Biomedical Engineering, Durham, USA

University of Pennsylvania, Bioengineering, Philadelphia, USA

Introduction:

Soldiers can experience 20 explosive detonations

during 5 days of practical training and report symptoms of mild

traumatic brain injury. It is unclear if primary blast (shock wave

loading) increases the brain’s vulnerability to subsequent injury re-

sulting in worse outcomes.

Methods:

Organotypic hippocampal slice cultures (OHSC) were

generated from P8-10 rat pups. Shock waves of varying intensities (9,

39, or 87 kPa*ms) were generated with a shock tube. For repetitive

blast studies, OHSC received 2 blasts 24 or 72h apart or 3 blasts

within 10 minutes. Cell death was quantified as the percentage area of

a specific region of interest (ROI) exhibiting propidium iodide (PI)

fluorescence above a threshold on day 3 following final exposure.

Electrophysiological function was evaluated by collecting stimulus-

response (S-R) and long-term potentiation (LTP) data with micro-

electrode arrays on days 3–5 following final exposure. As a positive

control OHSC were treated with glutamate (10 mM, 3 hours) fol-

lowing experimentation.

Results:

There was a significant decrease in LTP for OHSCs re-

ceiving 2 blasts of 39 kPa*ms delivered 24h or 72h apart compared to

sham. There was no significant difference in LTP among OHSCs

receiving 1 blast of 39 kPa*ms or 1 or 2 blasts of 9 kPa*ms. There was

a significant decrease in LTP for OHSCs receiving 1 blast of

87 kPa*ms. Cell death did not increase significantly following repet-

itive primary blast. The positive control indicated OHSC contained

viable cells that were not killed by blast injury. There was no sig-

nificant difference among OHSC receiving 0, 1, or 2 blasts of

37 kPa*ms for any S-R parameter.

Discussion:

A single 39 kPa*ms blast initiated a period of height-

ened vulnerability that persisted for at least 3 days. The thresh-

old for heightened blast-induced vulnerability was between 9 and

39 kPa*ms. Changes in LTP were observed in the absence of cell

death or significant changes in cell firing. This suggests that pri-

mary blast and repetitive primary blast can damage mechanisms

specific to LTP in the absence of gross structural damage to the

hippocampus.

Keywords: Blast, Neuron

A1-02

INHIBITION OF RNA-POLYMERASE-1 PROTECTS OLIGO-

DENDROCYTES AGAINST ENDOPLASMIC RETICULUM

STRESS

Michal Hetman

, Ewa Kilanczyk, Scott Whittemore

University of Louisville, Kentucky Spinal Cord Injury Research

Center, Louisville, USA

Recent work has documented that the conserved ER stress response

(ERSR) is activated after contusive SCI and that its genetic or pharma-

cological modification protects white matter, prevents oligodendrocyte

apoptosis and improves functional recovery after trauma. Ribosome is

the nexus of protein synthesis. Ribosomal biogenesis takes place in the

nucleolus where the RNA polymerase I (Pol1)-driven transcription of

ribosomal RNA (rRNA) initiates that process. As cancer cells hijack

ribosome biogenesis to fuel their growth, Pol1 became a target of novel

anti-cancer drugs including the clinically tested CX-5461 or the recently

identified BMH-21. Surprisingly, we found that ribosomal biogenesis is

increased after moderate thoracic SCI and remains active in cultured

oligodendrocytes precursor cells (OPC) that were challenged with ER

stress inducers including tunicamycin or thapsigargin. Importantly,

transient, non-toxic inhibition of ribosomal biogenesis using CX-5461 or

BMH-21 protected mouse or rat OPCs against ER stress toxicity. The

protection was accompanied by enhancement of the pro-survival phos-

phorylation of the eIF2alpha and moderate modulation of ER stress-

mediated inhibition of general protein synthesis. Induction of the ER

stress-related killer transcription factor CHOP was unaffected by Pol1

inhibitors. Instead, these agents activated p53 whose pharmacological

inhibition blocked the anti-ER stress protection. Most interestingly,

i.p.

treatment with BMH-21 inhibited ribosomal biogenesis in the mouse

spinal cord and increased expression of oligodendrocyte markers fol-

lowing SCI. These findings suggest that the nucleolar disruption and the

subsequent activation of p53 support OPC and/or oligodendrocyte sur-

vival under conditions of ER stress.

Keywords: nucleolus, endoplasmic reticulum stress, oligodendrocytes

A1-03

USE OF AN IN VITRO MODEL TO STUDY THE ACUTE EF-

FECTS OF BLAST OVERPRESSURE ON NEURONS AND

GLIAL CELLS

Anna Miller

1,2,4

, Alok S. Shah

1,4

, Brandy V. Aperi

1,4

, Matthew D.

Budde

1,4

, Frank A. Pintar

1,2,4

, Sergey Tarima

, Shekar N. Kurpad

1,2,4

Brian D. Stemper

1,4

, Aleksandra Glavaski-Joksimovic

1,2,4

MCW, Neurosurgery, Milwaukee, USA

MCW, CBNA, Milwaukee, USA

MCW, Biostatistics, IHS, Milwaukee, USA

Clement J. Zablocki VA Medical Center, Research, Milwaukee, USA

A-16