Transcript Acetylcholinesterase in Neuron Survival and

Regeneration: Role of
Nerotrophins and Nanotubes
Malathi Srivatsan, Ph.D.
Associate Professor, Department of Biological Sciences,
Arkansas State University, Jonesboro, AR 72401
Our Constantly Changing NS &
Neuronal Plasticity
 Neurons being postmitotic, have to be
viable for the entire life
span and hence have to
constantly adapt to the
changing environment.
 Successful Adaptation :
synaptic plasticity,
regeneration.
 Maladaptation or failure
to adapt: neuron death,
degeneration
Finding Cures for
Neurodegeneration is a formidable
and crucial Challenge
While regeneration is possible in PNS,
hardly any Regeneration happens at
CNS!
Result = neuron loss, functional
impairment for rest of the life
Each year 10,000 new spinal cord injury
occurs in USA
4.5 million patients currently
suffer from AD in USA
In the United States, it is
estimated that 60,000 new
cases are diagnosed each
year, joining the 1.5 million
Americans who currently
have Parkinson's disease.
Strategies to Promote Regeneration
 Infusion of Trophic
factors
 Guiding growing
axons (neurites) to
appropriate targets
 Strengthen axons and
synapses by
stimulation
 Stem cell therapy
Nanomaterials can
contribute
significantly to all of
these measures !
Basis for AChE’s possible diverse
functions (new?):
• AChE’s appearance even
before the evolution of a
distinct nervous system
• AChE’s widespread
presence in non-cholinergic
sites
• The multiple isoforms that
are expressed in a tissuespecific manner
• It’s sequence homology
with thyroglobin and
identity with cell adhesive
molecules (glutactin,
neurotactin)
DRG Neurons of Rat is a Good Model to Study
AChE Effects in vitro & in vivo
• DRG neurons of rat
express AChE
• DRG neurons are not
cholinergic
• There are no
synapses in DRG
• DRG neurons can be
maintained as neuron
enriched cultures
AChE promotes growth of multiple neurites in
DRG neurons via a non-catalytic mechanism
AChE promotes neurite growth of DRG neurons in time and
dose-dependent manner
24hrs
Increase (% of Control)
1000
100
10
1
0.1U/ml
0.2U/ml
# neu/N
neulen/N
0.3U/ml
Totneulen
Increase ( % of Control )
1000
100
10
1
0.1U/ml
0.2U/ml
#neu/N
48hrs
neulen/N
0.3U/ml
Totneulen
0.4U/ml
AChE enhances survival of DRG
neurons in culture
0.2
1.8
Control
AChE 0.1U/ml
Ratio of Live/Dead Cells
Released LDH
0.25
0.15
0.1
0.05
0
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
24 Hours
48 Hours
72 Hours
Duration of Treatment
Control
0.06 U/ml
0.09 U/ml
Acetylcholinesterase binds to neurons as
well as growing neurites
Gene Expression Altered by AChE
Nano neuro interaction
• CNTs can be a good,
growth promoting
substratum for sensory
neurons
Functionalized CNTs
Non-functionalized
Nanotubes can be coupled with
Growth factor for Neurons
Nanotube coupled
with nerve growth
factor
Growing
lamellipodium of
neurite
MNTs are Neuroprotective and need to
be explored for Enhancing Neuron
Survival
 MNTs are biocompatible as revealed by
reduced LDH release
 MNT bound NGF was available to PC 12 Cells
 MNTs themselves promote survival and
differentiation
1.400
1.200
*
**
LDH released
1.000
0.800
0.600
0.400
0.200
0.000
Differentiated Differentiated with Non-DifferentiatedNon-Differentiated
without nanotubes
nanotubes
without nanotubes with nanotubes
Maghemite nanorings (MNR) are
neuron friendly
No magnetic field
In ~ 9.7 Gauss magnetic field
13
5
14
6
Our Team & Collaborators
Funding from:
NIH/INBRE
NSF
NIH/NIDA
AR State Funds