Download - Neuroprotective Effects of Memantine
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Neuroprotective Effects of
Memantine
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Hippocampal slice cultures
Brown et al., Soc. Neurosci 2003
Semi-chronic 3-NP toxicity in organotypic hippocampal cultures
Parallel incubation of 3-NP and memantine for 7 or 12 days
Cresyl violet staining
Homogenization Immunoblot Incubation with
synaptic markers
Memantine in an In Vitro Model for Neurodegeneration
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Semi-chronic 3-NP toxicity in organotypic hippocampal cultures
Brown et al., Soc. Neurosci 2003
3-NP for 7 days300
200
100
0Control 10 µM1 µM 5 µM
MemantineVehicle
Glu
R1
(a
rbit
ary
un
its
)Neuroprotective Effect of Memantine
In Vitro
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Semi-chronic 3-NP toxicity in organotypic hippocampal cultures
Brown et al., Soc. Neurosci 2003
3-NP for 7 days300
200
100
0VehicleControl 10 µM1 µM 5 µM
Memantine
Sy
na
ps
in II
b (
arb
itar
y u
nit
s)
Neuroprotective Effect of MemantineIn Vitro
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CA1
Control 3-NP 14 days 3-NP + Memantine
DG
Semi-chronic 3-NP toxicity in organotypic hippocampal cultures
Brown et al., Soc. Neurosci 2003
Neuroprotective Effect of MemantineIn Vitro
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orMemantine injection 30 min before NMDA
Memantine infusion for 2 weeks
Unilateral injection of NMDA (7.5 nmol) or 3NP (250 nmol) into the NBM
Biochemical assay
Choline acetyltransferase in the frontal cortex
2 weeks
Wenk et al., Eur J Pharmacol 1995, NeuroReport 1996
Memantine‘s effect on lesions of the nucleus basalis magnocellularis (NBM)
Memantine in an Animal Model for Neurodegenerative Dementia
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Ch
AT
act
ivit
y c
on
tro
l - le
sio
ne
d s
ide
(n
mo
l AC
h/h
*mg
pro
tein
e)
Wenk et al., Eur J Pharmacol 1995
8
6
4
2
0
10.01 0.1 10 100 1000
Memantine (ED50 = 2.8 mg/kg)
MK-801 (ED50 = 0.077 mg/kg)
Dose (mg/kg)
Memantine injection (i.p.) attenuated NMDA-induced lesion of the NBM
Protection of Cholinergic Neurons by Memantine
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Wenk et al., NeuroReport 1996
Co
rtic
al C
hA
T a
cti
vit
y c
on
tro
l - le
sio
ne
d s
ide
(n
mo
l AC
h/h
*mg
pro
tein
e)
* p < 0.01 versus control
3-NPlesion
NMDAlesion
0
-4
-8
-12
-16
-20
*
* Memantine
(20 mg/kg/d)
Control
Infusion of memantine attenuated damage to NBM neurones induced by injection of NMDA or 3-NP
Degeneration of Cholinergic Neurons was Attenuated by Memantine
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Memantine infusion(20 mg/kg/day)
7 days Immunohistochemistry in the hippocampus:
neuronal damage
GFAP
Miguel-Hidalgo et al., Brain Res 2002
Injection of ß-amyloid (1-40)into the hippocampus
2 days
Memantine‘s effect on ß-amyloid-induced lesion of the hippocampus
Memantine in an Animal Model for Alzheimer´s Disease
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Memantine
Placebo Extent of ß-amyloid-induced damage in the CA1 region
1000
800
600
400
200
0
Ex
ten
t (µ
m)
Vehicle Memantine
*
Miguel-Hidalgo et al., Brain Res 2002
* p < 0.02 versus placebo
Protection by Memantine Against A-Induced Neurodegeneration
Vehicle
Memantine
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Miguel-Hidalgo et al., Brain Res 2002
* p < 0.03 versus vehicle
Are
a (
%)
Protection by Memantine Against A-Induced Neurodegeneration
Area of GFAP profilesaround the injection site
30
25
20
15
10
5
0
Vehicle Memantine
*
Vehicle Memantine
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Memantine effect on lipopolysaccharide (LPS)-induced brain insult and inflammation
Memantine infusion(s.c. 20 mg/kg/day for 37 days)
Infusion of LPSinto the basal forebrain (37 days)
Willard et al., Exp Brain Res 2000
Biochemical analysis in the frontal cortex:
ChAT activity
10 days
Effect of Memantine on Inflammation Induced Neurodegeneration
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* p < 0.0001 versus control; ** p < 0.05 versus LPS
Willard et al., Exp Brain Res 2000
Effect of LPS infusion into the basal forebrain on cortical ChAT activity
5
0
-5
-10
-15
-20
-25
**
Control LPS LPS + Memantine
*De
clin
e in
co
rtic
al C
hA
T
act
ivit
y [%
]Memantine Protected Cholinergic
Neurons from Damage by Inflammation
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Effects of memantine on quinolinic acid-induced neurodegeneration
15 sec
10 trials/day5 days
T-maze alternation
Biochemicalanalysis
Removal of minipumps
3 days
Parallel infusion of memantine (s.c. 20 mg/kg/day) and
quinolinic acid (i.c.v.)
2 weeks
Misztal et al., Eur J Pharmacol 1996
Memantine in an Animal Model for Neurodegenerative Dementia
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Infusion of Memantine (20 mg/kg/day) attenuated T-maze learning deficit induced by chronic i.c.v. infusion of quinolinic acid (QA)
Day
Misztal et al., Eur J Pharmacol 1996
* p < 0.05 versus control and QA + Memantine
Control QA QA + Memantine
4
3
2
1
01 532 4
*
* **
*
Nu
mb
er
of
erro
rsAttenuation of Quinolinic Acid Induced
Memory Loss by Memantine
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Memantine (20 mg/kg/day) attenuated the hippocampal cholinergic deficit induced by chronic i.c.v. infusion of quinolinic acid (QA)
* p < 0.05 versus quinolinic acid
**
100
80
60
40
20
0Control QA QA + Memantine
Misztal et al., Eur J Pharmacol 1996
[H3]H
em
ich
olin
ium
-3
bin
din
g (
µm
ol/m
g t
iss
ue)
Attenuation of Quinolinic Acid Induced Neurodegeneration by Memantine
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Summary
Neuroprotective effects of memantine were shown,
in vivo on
Excitotoxic induced neurodegeneration
ß-amyloid induced neuronal damage
LPS induced inflammation
in vitro on
Metabolic disturbances due to mitochondrial dysfunction
Conclusion:
Neuroprotective effects of memantine have been shown under
various conditions which are clinically relevant for Alzheimer's
disease.
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Memantine Inhibits and Reverses the
Alzheimer Type Abnormal
Hyperphosphorylation of tau and
Associated Neurodegeneration
Li L., Sengupta A., Haque N., Grundke-Iqbal I. and Iqbal K.
FEBS Letters, 2004, 566 (1-3): 261-269
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Tau Hyperphosphorylation in Alzheimer‘s Disease
Alzheimer‘s disease In vitro model
Hippocampal culture
+ okadaic acid (OA)
PP-2A activity
CaMKII activity
PKA activity
Hyperphosphorylation
of tau
Therapeutic approach
Hyperphosphorylation
of tau
Tangle formation
Neurodegeneration
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Okadaic acid for 24h Memantine or vehicle for 24h
Hippocampal slices
Analysis
Effects of Memantine on Phosphorylation of tau - Methods
Assay for phosphatase- or kinase activity
Western blots (p-tau)
Assay for cell death
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Memantine Counteracted OA-induced PP-2A Inhibition
100 100 100 0 0
PP-2A activity
0 1 10 1 10
PP
-2A
ac
tivi
ty (
% o
f c
on
tro
l)
24 h OA + 24 h vehicle 24 h OA + 24 h Mem 24 h Mem
* p < 0.05 versus OA treated tissue
120
100
80
60
40
20
0nM OA
µM Mem
*
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CaMKII activity PKA activity
Memantine Restored CaMKII and PKA Activity
Kin
ase
ac
tiv
ity
( %
of
co
ntr
ol)
* p < 0.05 versus OA treated tissue
250
200
150
100
50
0
100 100 100 0 0
120
100
80
60
40
20
0
0 1 10 1 10
nM OA µM Mem
100 100 100 0 0 0 1 10 1 10
24 h OA + 24 h vehicle 24 h OA + 24 h Mem 24 h Mem
*
**
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Memantine Counteracted OA-induced Cell Death
10
8
6
4
2
0
Cell death assay
Control 24 h OA + 24 h vehicle 24 h OA + 24 h Mem 24 h Mem
LD
H r
ele
as
e(r
ati
o a
fte
r / b
efo
re t
rea
tme
nt)
nM OA 0 100 100 100 0 0
µM Mem 0 0 1 10 1 10
* *
* p < 0.05 versus OA treated tissue
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3 21
68
43
100 nM OA - + + 10 µM Mem - - +
Memantine Counteracted CaMKII-induced Phosphorylation of tau
[125I] Western blot with Antibody against pS-262
Control 24 h OA + 24 h vehicle 24 h OA + 24 h Mem (10 µM)
Ph
osp
ho
ryla
tio
n o
f ta
u
7
6
5
4
3
2
1
pSer262 pSer422
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Immunocytochemical staining of pSer-262
100 nM OA + + + 10 µM Mem - - -
100 nM OA - + + 10 µM Mem - - +
Memantine Counteracted OA-induced Phosphorylation of tau
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In an in vitro model using okadaic acid memantine was
shown to
Restore normal PP-2A, CaMKII and PKA activities
Prevent cell death
Positively influence phosphorylation / dephosphorylation
imbalance
Conclusion
Apart from the symptomatic benefits, memantine might also
positively influence pathological changes in AD.
Summary