This study compared profiles of long-term potentiation (LTP) in hippocampal slices from wild-type (WT) and knockout (KO) mice. Hippocampal slices were prepared from both types of mice and LTP was induced using high frequency stimulation. Recordings found that LTP was strongly impaired in slices from KO mice compared to WT mice, with potentiation values of 65% in WT slices versus 36% in KO slices. Although the LTP profile was similar, KO slices showed LTP amplitudes about 30% lower than WT slices throughout the recording period.

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Characterization of LTP profiles in
WT & KO mice
May, 2009

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SUMMARY
Introduc*on
Aim
of
the
study
Materials
&
Methods
Prepara*on
of
mice
hippocampal
slices
and
solu*ons
Perfusion
and
temperature
control
Electrophysiological
recordings
Experiments
Comparison
of
Long-­‐Term
Poten*a*on
(LTP)
profiles
from
KO
and
WT
mice

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INTRODUCTION
The
aim
of
the
present
study
is
to
compare
the
profile
of
Long-­‐Term
Potenta*on
(LTP)
recorded
in
hippocampal
slices
of
Knock-­‐Out
(KO)
mice
with
the
profile
of
LTP
recorded
in
slices
from
Wild-­‐Type
(WT)
mice.
Synap*c
transmission
and
plas*city
are
recorded
in
the
CA1
region
of
adult
mice
hippocampi
by
s*mula*ng
Schaeffer
collateral
fibres
at
the
CA3/CA1
interface.
Extracellular
recordings
(EPSP)
are
performed
with
Mul*-­‐Electrode
Arrays
(MEA).

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MATERIALS & METHODS
Prepara*on
of
acute
mice
hippocampal
slices
Experiments
are
carried
out
with
KO
and
WT
mice
provided
by
the
customer.
Hippocampal
slices
(350
µm
thickness)
are
cut
with
a
MacIIwain
*ssue
chopper
in
a
ice-­‐cold
oxygenated
sucrose
solu*on
(Saccharose
250,
Glucose
11,
NaHCO3
26,
KCl
2,
NaH2PO4
1.2,
MgCl2
7
and
CaCl2
0.5
in
mM).
Then,
slices
are
incubated
at
room
temperature
for
at
least
1
h
in
Ar*ficial
Cerebro-­‐Spinal
Fluid
(ACSF)
of
the
following
composi*on
:
NaCl
126,
KCl
3.5,
NaH2PO4
1.2,
MgCl2
1.3,
CaCl2
2,
NaHCO3
25,
D-­‐glucose
11
in
mM.
Perfusion
and
temperature
control
During
experiments,
the
slices
are
con*nuously
perfused
with
the
ACSF
(bubbled
with
95%
O2–5%
CO2)
at
the
rate
of
3
mL/min
with
a
peristal*c
pump
(MEA
chamber
volume:
~1
mL).
Complete
solu*on
exchange
in
the
MEA
chamber
is
achieved
20
s
aber
solu*ons
exchange.
The
perfusion
liquid
is
con*nuously
pre-­‐heated
at
37°C
just
before
reaching
the
MEA
chamber
with
a
heated-­‐perfusion
cannula
(PH01,
Mul*Channel
Systems,
Reutlingen,
Germany).
The
temperature
of
the
MEA
chamber
is
maintained
at
37
±
0.1°C
with
a
Pel*er
element
located
in
the
MEA
amplifier
headstage.
Electrophysiological
recordings
Basal
synap*c
transmission:
The
s*mulus
intensity
is
set
to
40%
Imax
(determined
by
an
input/output
curve)
at
0.033Hz.
Long-­‐Term
Poten*a*on
(LTP)
protocol:
High
frequency
s*mula*on
is
induced
by
two
1s
trains
at
100
Hz.

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EXPERIMENTS
Comparison of LTP profiles from KO and WT mice in the CA1 region of hippocampal slices
Long-­‐Term
Poten*a*on
is
strongly
impaired
in
slices
from
KO
mice
compared
to
WT
mice.
Thus,
at
the
end
of
the
experiments,
poten*a*on
values
are
65
±
8
%
in
slices
from
WT
mice
versus
36
±
5
%
in
slices
from
KO
mice.
0 1 0 2 0 3 0 4 0 5 0 6 0
1 .0
1 .5
2 .0
2 .5
T im e (m in )
Normalized fEPSP amplitude
W T
m ic e
(3
m ic e ,
9
slic e s,
1 2 3
e le c tro d e s)
K O
m ic e
(3
m ic e ,
9
slic e s,
1 2 0
e le c tro d e s)
H F S

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Although
a
similar
LTP
profile,
a
clear
difference
of
LTP
amplitude
is
observed
between
slices
from
WT
and
KO
mice.
Poten*a*on
values
are
about
30%
lower
in
slices
from
KO
mice
than
in
slices
from
WT
mice
throughout
the
post-­‐
HFS
period.
CONCLUSION
W
T
KO
0
2 0
4 0
6 0
8 0
1 0 0
% of potentiation
(over 50' post HFS)

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