multi-electrode array technique - characterization of ltp profiles in wt and ko mice
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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 )
Norm
alize
d fEPSP
am
plitu
de
W T m ic e (3 m ic e , 9 s lic e s , 1 2 3 e le c t ro d e s )
K O m ic e (3 m ic e , 9 s l ic e s , 1 2 0 e le c t ro 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
WT
KO
0
2 0
4 0
6 0
8 0
1 0 0
% o
f pote
ntiation
(ove
r 50' p
ost H
FS)
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