Valerian extract characterized by high valerenic acid and low acetoxy valerenic acid contents demonstrates anxiolytic activity

Article (PDF Available)inPhytomedicine: international journal of phytotherapy and phytopharmacology 19(13):1216-22 · August 2012with274 Reads
DOI: 10.1016/j.phymed.2012.08.003 · Source: PubMed
Abstract
Valerian is one of the most commonly used herbal remedies for the treatment of insomnia and anxiety. Valerian extracts allosterically modulate GABAA receptors, an action related to valerenic acid, which is one of the active compounds determined from pharmacological studies. Derivatives of valerenic acid, i.e. acetoxy valerenic acid or hydroxy valerenic acid, do not allosterically modulate GABAA receptors, but they bind to identical binding sites. Therefore, the question arises whether they might interfere with the effects of valerenic acid. Two valerian extracts were tested in the elevated plus maze test and the tail suspension test for anxiolytic and antidepressive activity, respectively. Reference substances were diazepam (1.0mg/kg) and imipramine (30mg/kg). The extracts were standardized to the identical total amounts of the acids (0.1; 0.5; 1.0 and 2.0mg/kg), i.e. valerenic and acetoxy valerenic acid, but the ratio between the acids was different (12:1 and 1:1.5). The extract with the ratio 12:1 prolonged the time spent on the open arm significantly when 0.5mg/kg was applied. Of the other extract, with the ratio 1:1.5, four times that amount was required (2.0mg/kg). Both of the tested extracts did not show any antidepressive effect, rather the other way around, the extract with the ratio 1:1.5 prolonged the immobility phase. However, since the core body temperature was reduced by the 1.0 and 2.0mg/kg extract dose, the prolongation may be related to the temperature phenomenon and is not indicative of a specific depressive action. In conclusion, the anxiolytic activity of the valerian extract seems rather related to valerenic acid and, moreover, standardization with respect to the total amount of valerenic acids, i.e. valerenic acid together with acetoxy valerenic acid, is misleading.
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Author's personal copy
Phytomedicine
19 (2012) 1216–
1222
Contents
lists
available
at
SciVerse
ScienceDirect
Phytomedicine
jou
rn
al
hom
epage:
www.elsevier.de/phymed
Valerian
extract
characterized
by
high
valerenic
acid
and
low
acetoxy
valerenic
acid
contents
demonstrates
anxiolytic
activity
F.
Felgentreff
a
,
A.
Becker
a
,
B.
Meier
b
,
A.
Brattström
c,
a
Inst.
Pharmacology
and
Toxicology,
Otto-von-Guericke
University,
Magdeburg,
Germany
b
Inst.
Biotechnology,
Zürich
University
of
Applied
Sciences,
Wädenswil,
Switzerland
c
Alexander
Puschkin
Str.
50,
39108
Magdeburg,
Germany
a
r
t
i
c
l
e
i
n
f
o
Keywords:
Valerian
extract
Valerenic
acid
Elevated
plus
maze
Tail
suspension
test
Anxiety
Body
core
temperature
a
b
s
t
r
a
c
t
Valerian
is
one
of
the
most
commonly
used
herbal
remedies
for
the
treatment
of
insomnia
and
anxiety.
Valerian
extracts
allosterically
modulate
GABAA
receptors,
an
action
related
to
valerenic
acid,
which
is
one
of
the
active
compounds
determined
from
pharmacological
studies.
Derivatives
of
valerenic
acid,
i.e.
acetoxy
valerenic
acid
or
hydroxy
valerenic
acid,
do
not
allosterically
modulate
GABAA
receptors,
but
they
bind
to
identical
binding
sites.
Therefore,
the
question
arises
whether
they
might
interfere
with
the
effects
of
valerenic
acid.
Two
valerian
extracts
were
tested
in
the
elevated
plus
maze
test
and
the
tail
suspension
test
for
anxiolytic
and
antidepressive
activity,
respectively.
Reference
substances
were
diazepam
(1.0
mg/kg)
and
imipramine
(30
mg/kg).
The
extracts
were
standardized
to
the
identical
total
amounts
of
the
acids
(0.1;
0.5;
1.0
and
2.0
mg/kg),
i.e.
valerenic
and
acetoxy
valerenic
acid,
but
the
ratio
between
the
acids
was
different
(12:1
and
1:1.5).
The
extract
with
the
ratio
12:1
prolonged
the
time
spent
on
the
open
arm
significantly
when
0.5
mg/kg
was
applied.
Of
the
other
extract,
with
the
ratio
1:1.5,
four
times
that
amount
was
required
(2.0
mg/kg).
Both
of
the
tested
extracts
did
not
show
any
antidepressive
effect,
rather
the
other
way
around,
the
extract
with
the
ratio
1:1.5
prolonged
the
immobility
phase.
However,
since
the
core
body
temperature
was
reduced
by
the
1.0
and
2.0
mg/kg
extract
dose,
the
prolongation
may
be
related
to
the
temperature
phenomenon
and
is
not
indicative
of
a
specific
depressive
action.
In
conclusion,
the
anxiolytic
activity
of
the
valerian
extract
seems
rather
related
to
valerenic
acid
and,
moreover,
standardization
with
respect
to
the
total
amount
of
valerenic
acids,
i.e.
valerenic
acid
together
with
acetoxy
valerenic
acid,
is
misleading.
© 2012 Elsevier GmbH. All rights reserved.
Introduction
Valerian
is
one
of
the
most
commonly
used
herbal
remedies
for
the
treatment
of
insomnia
and
anxiety.
For
medical
purposes
Valeriana
officinalis
L.
is
used.
Pharmacological
studies
identified
valerenic
acid
(VA)
as
one
of
the
active
compounds.
The
anxiolytic
potential
of
VA
is
supported
by
in
vitro
experiments
on
the
gamma-
aminobutyric
acid
type
A
receptor
(GABAA)
(Yuan
et
al.
2004;
Khom
et
al.
2007;
Sichardt
et
al.
2007;
Trauner
et
al.
2008;
Benke
et
al.
2009),
as
well
as
in
vivo
experiments
in
mice
(Benke
et
al.
2009;
Khom
et
al.
2010)
and
rats
(Murphy
et
al.
2010).
In
addition,
it
was
demonstrated
in
vitro
that
VA
activity
at
GABAA
receptors
is
medi-
ated
preferentially
by
the
3
subunits
(Khom
et
al.
2007,
2010).
This
Abbreviations:
AVA,
acetoxy
valerenic
acid;
BCT,
body
core
temperature;
EPM,
elevated
plus
maze;
HVA,
hydroxy
valerenic
acid;
VA,
valerenic
acid;
VE,
valerian
extract;
TST,
tail
suspension
test.
Corresponding
author.
Tel.:
+49
391
4009687.
E-mail
address:
Axel.Brattstroem@t-online.de
(A.
Brattström).
was
confirmed
by
in
vivo
studies
to
demonstrate
anxiolytic
activ-
ity,
since
point
mutation
in
the
3
subunit
abolished
the
anxiolytic
response
to
VA
but
not
to
diazepam
(Benke
et
al.
2009).
GABA
is
the
major
inhibitory
neurotransmitter
in
the
brain
and
essential
for
the
overall
balance
between
neuronal
excitation
and
inhibition,
therefore
vital
to
normal
brain
function.
Any
imbal-
ance
can
cause
disorders
like
depression
and
sedation,
or
anxiety,
restlessness
and
insomnia.
The
GABAA
receptor
is
a
chloride-
conducting
receptor
composed
most
frequently
of
alpha,
beta,
and
gamma
subunits
assembled
as
a
pentameric
structure,
forming
a
central
pore;
but
other
subunit
compositions
are
also
possi-
ble
(Sieghart
1995;
Olsen
and
Sieghart
2008).
Each
subunit
has
a
long
extracellular
agonist
binding
domain.
GABAA
receptors
are
the
site
of
action
for
a
variety
of
pharmacologically
and
clinically
important
agents,
such
as
benzodiazepines,
barbiturates,
neuroac-
tive
steroids,
anaesthetics,
and
convulsants
(Johnston
2005;
Atack
2005;
Rupprecht
et
al.
2006;
Möhler
2006).
Valerian
extracts
(VE)
allosterically
modulate
GABAA
receptors,
an
activity
related
to
valerenic
acid
(Trauner
et
al.
2008).
Khom
reported
that
GABAA
receptors
containing
2
or
3
subunits
are
0944-7113/$
see
front
matter ©
2012 Elsevier GmbH. All rights reserved.
http://dx.doi.org/10.1016/j.phymed.2012.08.003
Author's personal copy
F.
Felgentreff
et
al.
/
Phytomedicine
19 (2012) 1216–
1222 1217
Fig.
1.
Structure
formula
of
valerenic
acid
and
their
derivatives.
required
for
this
action.
Derivatives
of
valerenic
acid
(VA),
i.e.
ace-
toxy
valerenic
acid
(AVA)
or
hydroxy
valerenic
acid
(HVA)
(Fig.
1),
do
not
modulate
GABAA
receptors
allosterically
(Khom
et
al.
2007).
Identical
results
were
obtained
with
the
fraction
of
a
VE
that
contained
AVA
(Kim
et
al.
2008).
However,
AVA
at
higher
concen-
trations
was
able
to
block
the
open
GABAA
channel
(Khom
et
al.
2007)
like
VA,
and
additionally,
HVA
displaced
3
H
valerenic
acid
from
cerebral
membrane
binding
sites
(Benke
et
al.
2009),
indicat-
ing
that
both
derivatives
may
act
at
the
identical
binding
site,
even
if
they
fail
in
allosteric
modulation.
When
comparing
especially
prepared
valerian
extracts,
it
was
revealed
that
the
absence
of
valerenic
acids,
e.g.
VA
and
AVA,
led
to
a
loss
of
activity
at
the
GABAA
receptors,
whereas
trans-
formation
of
AVA
to
HVA
elevated
that
activity
caused
by
VA
(Trauner
et
al.
2008).
These
results,
obtained
from
in
vitro
exper-
iments,
could
suggest
that
AVA
is
capable
of
inhibiting
VA
action,
since
the
response
was
elevated
after
AVA
removal.
However,
this
remains
to
be
confirmed
in
vivo,
since
it
is
impossible
to
predict
in
vivo
results
from
experimental
in
vitro
conditions
(Khom
et
al.
2010).
The
aim
of
the
present
study
was
to
test
valerian
extracts
dis-
tinguishable
in
their
contents
of
VA
and
AVA
in
two
behavioural
tests,
i.e.
the
elevated
plus
maze
test
(EPM)
demonstrating
anxi-
olytic
efficacy,
and
the
tail
suspension
test
(TST)
as
an
equivalent
for
antidepressive
action.
The
orally
administered
extracts
were
adjusted
in
such
a
way
that
the
applied
sum
of
VA
and
AVA
was
identical
for
both
extracts,
however
with
a
different
ratio
of
VA
and
AVA.
Materials
and
methods
In
order
to
test
the
effect
of
VEs
with
different
ratios
of
VA:
AVA
on
GABA-related
in
vivo
models,
two
different
VEs
were
pre-
pared.
Valerian
roots
and
rhizomes
from
a
specifically
selected
species
were
used,
as
well
as
standard
material
from
Poland
(Euro-
pean
Pharmacopoeia,
Supplement
5.7.
Valerian
dry
hydroalcoholic
extract
(1898)).
A
sample
specimen
from
the
selected
species
(HAL
115562)
is
preserved
in
the
Herbarium
of
the
Institute
of
Biology,
Martin
Luther
University
Halle,
Germany.
The
dried
starting
mate-
rial
was
stirred
with
hydro-alcohol
(70%,
v/v)
in
a
ratio
of
1:5
at
45
C
for
31/2
days
and
then
separated
by
filtration
under
pres-
sure
of
2
bar.
The
obtained
tinctures
were
concentrated
using
a
rotary
evaporator.
Samples
of
both
extracts
were
analyzed
by
ultra
performance
liquid
chromatography
(UPLC)
(method
was
based
on
the
Ph
Eur
monograph
for
valerian
dry
hydro-alcoholic
extract
[6.8./1898]).
The
chromatograms
of
both
extracts
are
represented
in
Fig.
2
and
quantitative
data
are
given
in
Table
1.
The
results
for
the
extracts
with
respect
to
their
VA
to
AVA
ratio
are
given
in
Table
2.
Male
CD-1
mice
(Charles
River
Sulzfeld,
Germany)
were
kept
under
controlled
laboratory
conditions
with
a
light/dark
cycle
of
12:12
(lights
on
at
06.00
a.m.),
temperature
20
±
2
C,
and
air
humidity
55–60%.
The
animals
had
free
access
to
commercial
pel-
lets
(ssniff
R/M-H,
ssniff
Spezialdiäten
GmbH,
Soest,
Germany)
and
tap
water.
The
animals
were
housed
in
groups
of
10
in
Macrolon
III
cages.
At
the
beginning
of
the
experiments
the
mice
were
8
weeks
old.
The
number
of
animals
per
group
was
between
12
and
19.
The
work
reported
here
was
conducted
in
accordance
with
EC
regulations
and
the
National
Act
on
the
Use
of
Experimental
Ani-
mals
(Germany).
The
protocol
was
approved
by
the
Saxony-Anhalt
Committee
on
Animal
Care.
VEs
(0.1;
0.5;
1.0;
2.0
mg/kg,
with
respect
to
the
total
sum
of
VA
and
AVA),
diazepam
(Faustan®,
AWD
Pharma
GmbH
&
Co.
KG,
Dresden,
Germany),
and
imipramine
(Sigma,
Düsseldorf,
Germany)
as
references
were
administered
orally
using
a
mouse
gavage
feed-
ing
needle
(24
gauge,
FST,
Heidelberg,
Germany).
As
control
a
0.9%
Acetoxyvalerenic acid - 1.009
Valerenic acid - 1.695
AU
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
Minutes
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
2.20
2.40
2.60
2.8
0
Fig.
2.
Chromatogram
of
both
of
the
valerian
extracts.
Author's personal copy
1218 F.
Felgentreff
et
al.
/
Phytomedicine
19 (2012) 1216–
1222
Table
1
Content
of
valerenic
acid
as
well
as
acetoxy-valerenic
acid
in
both
of
the
valerian
extracts.
Sample
name
Content
valerenic
acid
(mg/l)
Content
acetoxy-valerenic
acid
(mg/l)
Sum
of
contents
valerenic
acid
+
acetoxy-valerenic
acid
(mg/l)
Ratio
valerenic
acid
acetoxy-valerenic
acid
Valerian
extract
1
(VE-1)
1165.5
98.3
1263.7
12:
1
Valerian
extract
2
(VE-2) 199.5
308.8
508.3
1:
1.5
Table
2
Composition
of
the
extracts
VE-1
and
VE-2
regarding
their
content
of
VA
and
AVA
as
well
as
the
per
os
administered
amount
of
the
extracts.
Content
VA
+
AVA
(mg/kg)
VE-1
VE-2
VA
AVA
Amount
(ml/kg)
p.o.
VA
AVA
Amount
(ml/kg)
p.o.
0.1
0.0922
0.00776
0.16
0.03925
0.06075
0.20
0.5
0.4610
0.0388
0.40
0.19630
0.30380
0.98
1.0
0.9220
0.0776
0.79
0.39250
0.60750
1.97
2.0
1.8440
0.1552
1.58
0.78500
1.21500
3.93
VA:
valerenic
acid;
AVA:
acetoxy-valerenic
acid.
saline
solution
was
administered.
The
given
volume
was
0.1
ml/10
g
body
weight.
Elevated
plus
maze
(EPM)
Situational
anxiety
was
measured
in
the
elevated
plus
maze
test
(Rodgers
1997).
The
maze
was
made
of
black
polyvinyl
chloride
and
had
two
open
and
two
closed
arms
(50
cm
× 10
cm
×
40
cm)
mounted
50
cm
above
the
floor.
The
floor
of
the
arms
was
smooth.
Light
intensity
was
30
lux.
A
mouse
was
placed
on
the
central
plat-
form
of
the
apparatus
facing
a
closed
arm.
A
camera
on
the
ceiling
of
the
test
room
was
used
to
score
and
tape
the
animals’
behaviours
from
an
adjacent
room
for
a
period
of
7
min.
The
number
of
entries
into
open
arms,
time
spent
on
open
arms,
and
the
time
spent
on
closed
arms
were
recorded.
To
evaluate
the
anxiolytic
effect,
the
time
spent
on
the
open
arm
was
determined,
which
is
prolonged
by
anxiolytic
substances.
In
addition,
total
changes
in
movements
were
also
analyzed,
which
reflect
locomotor
activity.
The
maze
was
cleaned
after
each
trial.
Tail
suspension
test
(TST)
The
antidepressant-like
effect
of
VE
was
measured
using
the
tail
suspension
test
(TST),
according
to
Steru
et
al.
(1985).
The
test
was
carried
out
immediately
after
measuring
anxiety
in
the
elevated
plus
maze
(Fig.
3).
The
mice
were
suspended
by
their
tails
using
adhesive
tape
placed
approximately
1
cm
from
the
tip
of
the
tail
and
hung
approximately
30
cm
above
the
table.
The
animals
were
suspended
for
6
min,
and
the
duration
of
immobility
was
scored
manually
during
the
test.
Immobility
is
reduced
with
antidepres-
sant
drugs.
Immobility
was
defined
as
the
absence
of
any
limb
or
body
movements,
with
the
exception
of
those
caused
by
respira-
tion,
when
the
mice
hung
passively
and
completely
motionless.
Valeria
n
extract
p.o.
EPM
TST
BCT
0
60
70
80
min
Experimen
tal sc
hedul
e
Fig.
3.
Schedule
of
the
experiment
sequence.
Immobility
was
measured
from
minute
1
to
minute
6.
The
values
from
the
2nd
to
the
6th
minute
were
used
to
evaluate
drug
effects.
Following
the
TST,
body
core
temperature
(BCT)
was
measured
with
a
digital
thermometer
(ama
digit)
manufactured
by
Amarell
GmbH
(Kreuzwertheim,
Germany).
For
that
purpose
the
lubricated
probe
1
mm)
was
gently
inserted
3
cm
into
the
rectum.
All
behavioural
tests
were
performed
in
the
light
period
between
8.00
a.m.
and
2.00
p.m.
The
animals
were
randomly
assigned
for
testing.
Statistics
Statistical
evaluation
was
carried
out
using
the
Kruskal–Wallies
H-test,
followed
by
the
Mann–Whitney
U-test.
The
animals
which
exhibited
exceptional
hypothermia
(9
out
of
27
in
the
VE-2
group
that
received
2
mg)
were
compared
using
the
contingency
table.
The
threshold
for
significance
was
generally
set
at
<0.05.
Results
Elevated
plus
maze
The
control
animals
(saline)
spent
12.92
±
2.49%
of
their
time
on
the
open
arm.
Animals
which
had
received
diazepam
(1
mg/kg)
sig-
nificantly
prolonged
that
time
to
24.5
±
2.2%
(p
=
0.003).
In
contrast,
for
animals
of
the
imipramine
group
(30
mg/kg)
that
time
was
only
insignificantly
changed
(Fig.
4).
Animals
which
had
received
VE-1
(total
amount
of
VAs
0.5
mg/kg)
exhibited
also
extended
times
on
the
open
arm
(17.62
±
2.31%;
p
=
0.032)
like
the
diazepam
reference
group.
There-
fore,
this
can
be
interpreted
as
an
anxiolytic
effect.
The
other
groups
(0.1,
1.0,
and
2.0
mg/kg)
were
in
the
range
of
the
saline
control
group.
VE-2
induced
different
effects
in
the
EPM.
Small
doses
of
the
VAs
(0.1
and
0.5
mg/kg)
reduced
the
time
spent
on
the
open
arm
indi-
cating
anxiogenic
activity
(5.5
±
1.46%
and
7.95
±
2.56%;
p
=
0.008
and
=
0.031).
Whereas
a
higher
dose,
i.e.
2
mg
VAs/kg
demonstrated
anxiolytic
activity
(27.07
±
3.88%;
p
=
0.039).
The
locomotor
activity
(total
arm
changes)
was
similar
in
all
experimental
groups
(Fig.
5).
Tail
suspension
test
Both
reference
substances
influenced
the
immobility
time
differently
when
compared
to
saline
(92
±
12.7
s).
Whilst
diazepam
significantly
prolonged
immobility
(143
±
35.51
s),
it
was
Author's personal copy
F.
Felgentreff
et
al.
/
Phytomedicine
19 (2012) 1216–
1222 1219
0
5
10
15
20
25
30
35
Time % open arm
Reference -
Elevated
Plu
sMa
ze
NaCl
1mg/k
g
DZP
30mg/kg
IMI
*
0
5
10
15
20
25
30
35
Time
open arm [%]
VE 1 -
Elevated
Plu
sMa
ze
0.1
0.5
1,0
2,0
NaC
l
*
0
5
10
15
20
25
30
35
Time open arm [%]
VE
2 - El
evated
Plu
sMa
ze
**
*
NaCl
0.1
0.5
1,0
2,0
Fig.
4.
Time
spent
of
the
open
arm
for
controls
and
reference
substances
as
well
as
for
both
of
the
extracts
(numbers
indicate
applied
amount
as
mg/kg
BW).
shortened
by
imipramine
(48
±
15.01
s)
indicating
an
antidepres-
sive
effect
(Fig.
6).
VE-1
did
not
change
the
immobility
time.
However,
VE-2
in
higher
doses
(1.0
and
2.0
mg/kg)
induced
prolongation
of
immo-
bility
(1.0:
99.9
±
23.67
s,
p
=
0.017;
2.0:
115.5
±
27.42
s,
p
<
0.001)
indicating
a
depressive
effect.
Body
core
temperature
Diazepam
significantly
reduced
the
BCT
(37.05
±
1.13
C)
whilst
imipramine
(37.8
±
0.12
C)
did
not
change
the
body
temperature
when
compared
to
saline
(37.7
±
0.12
C)
(Fig.
7).
However,
VE-1
(0.5:
37.0
±
0.29
C;
1.0:
37.2
±
0.23
C
and
2.0:
36.2
±
0.69
C),
as
well
as
VE-2
(1.0:
36.1
±
0.78
C
and
2.0:
34.8
±
0.46
C)
significantly
lowered
BCT
gradually
in
relation
to
the
applied
amounts.
0
10
20
30
40
50
Total
arm changes
Reference -
Elevated Plu
sMa
ze
NaCl
1mg/kg
DZP
30mg
/kg
IMI
0
10
20
30
40
50
Total
arm
changes
VE
1 -
Elevated
Plus Ma
ze
2,0
1,00,5
0,1
NaCl
0
10
20
30
40
50
Total
arm changes
VE
2 -
Elevated
Plus Ma
ze
NaCl
0,1
0,5
1,0
2,0
Fig.
5.
Total
arm
changes
within
the
test
period
for
controls
and
reference
sub-
stances
as
well
as
for
both
of
the
extracts
(numbers
indicate
applied
amount
as
mg/kg
BW).
Moreover,
VE-2
could
not
be
tested
in
doses
higher
than
2
mg
VAs/kg.
In
preliminary
tests
it
was
seen
that
animals
which
had
received
5
mg
demonstrated
a
dramatic
drop
in
BCT,
and
a
few
perished
with
signs
of
respiratory
paralysis.
After
administration
of
2
mg
VAs/kg,
the
temperature
was
reduced
below
34
C
in
9
out
of
27
animals.
The
results
of
these
animals
were
disregarded
for
evaluation.
After
applying
VE-1,
this
phenomenon
was
only
seen
in
one
animal.
This
difference
in
temperature
change
between
VE-1
and
VE-2
is
statistically
significant
(p
=
0.002).
Discussion
Valerian
extract
modulates
GABAA
receptor
function
after
oral
administration
and
demonstrates
anxiolytic
potential,
since
the
time
spent
on
the
open
arm
in
the
elevated
plus
maze
test
was
Author's personal copy
1220 F.
Felgentreff
et
al.
/
Phytomedicine
19 (2012) 1216–
1222
0
50
100
150
200
250
300
Immobility [sec] 2 nd - 6th min
Reference
-
Tail
Suspersion
Test
NaCl
1mg/kg
DZP
30mg/kg
IMI
*
*
0
50
100
150
200
250
300
Immobility [sec] 2 nd - 6th min
VE 1 -
Tail
Suspension
Test
NaCl
0,1
0,5
1,0
2,0
0
50
100
150
200
250
300
Immobility [sec] 2nd-6th min
VE 2 -
Tail
Suspension
Test
NaCl
0,1
0,5
1,0
2,0
*
*
Fig.
6.
Immobility
time
in
the
tail
suspension
test
for
controls
and
reference
sub-
stances
as
well
as
for
both
of
the
extracts
(numbers
indicate
applied
amount
as
mg/kg
BW).
prolonged
without
reducing
the
frequency
of
changing
positions.
The
results
are
restricted
to
the
animals
used
within
the
described
conditions.
However
the
experimental
approach
is
usually
used
for
detection
of
new
entities
which
might
be
effective
in
anxiolyse.
Next
step
in
the
development
process,
therefore,
has
to
be
a
clin-
ical
trial
in
subjects
suffering
from
anxiety.
This
is
very
important
since
the
dosage
which
was
efficient
in
the
rodents
cannot
easily
be
transferred
to
human
beings.
These
reported
results
confirm
earlier
findings
by
other
groups
(Hattesohl
et
al.
2008;
Benke
et
al.
2009;
Khom
et
al.
2010;
Murphy
et
al.
2010).
However,
the
necessary
amounts
of
both
tested
extracts
to
induce
such
an
effect
were
different.
Of
the
VE-2
four
times
(2.0
mg/kg)
the
amount
of
VA
+
AVA
was
needed
than
that
of
the
VA-1
extract
(0.5
mg/kg)
to
prolong
the
time
spent
on
the
open
arm
to
a
comparable
extent.
However,
with
this
regime
the
30
32
34
36
38
40
Temperature [°C]
Reference - Bo
dy Co
re
Temperature
NaCl
1mg/k
g
DZP
30mg/kg
IMI
*
30
32
34
36
38
40
Temperature [°C]
VE
1 - Bod
y
Core
Tempe
ratu
re
NaCl
0,1
0,5
1,0
2,0
*
*
*
30
32
34
36
38
40
Temperature
[°C]
VE
2 - Bod
y
Core
Tempe
ratu
re
NaCl
0,1
0,5
1,0
2,0
**
*
Fig.
7.
Body
core
temperature
for
controls
and
reference
substances
as
well
as
for
both
of
the
extracts
(numbers
indicate
applied
amount
as
mg/kg
BW).
body
temperature
in
the
animals
which
had
received
VE-2
had
already
been
remarkably
reduced,
which
could
indica