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http://journals.tubitak.gov.tr/biology/
Turkish Journal of Biology
Turk J Biol
(2016) 40: 762-771
© TÜBİTAK
doi:10.3906/biy-1507-114
Lycium barbarum L. (goji berry) fruits improve anxiety, depression-like behaviors, and
learning performance: the moderating role of sex
Fatma PEHLİVAN KARAKAŞ1,2,*, Hamit COŞKUN3, Kadir SAĞLAM2, Bihter Gökçe BOZAT2
1Department of Field Crops, Faculty of Agriculture and Natural Sciences, Abant İzzet Baysal University, Bolu, Turkey
2Department of Biology, Faculty of Science and Art, Abant İzzet Baysal University, Bolu, Turkey
3Department of Psychology, Faculty of Science and Art, Abant İzzet Baysal University, Bolu, Turkey
* Correspondence: fatmapehlivankarakas@gmail.com
1. Introduction
Lycium barbarum L. (goji berry), a member of the family
Solanaceae, has received a great deal of research attention
because of its rich contents as well as its benecial eects
on health (Wang et al., 2010; Yao et al., 2011), such as
impacts on aging, neuroprotection, well-being, fatigue,
energy metabolism, diabetic control, the immune system,
antitumor activity, and antioxidant activity (Amagase and
Farnsworth, 2011; Song and Xu, 2013). Such benecial
eects of L. barbarum are usually attributed to high
amounts of polysaccharides (LBPs), avonoids, phenolic
acids, and carotenoids in its content (Endes et al., 2015).It
also includes essential oils, vitamins (A, B, and C), amino
acids, mineral elements (K, P, Ca, Mg, Fe, and Na), and
betaine (Potterat, 2010; Endes et al., 2015).
Despite these benets, its eects on behavioral
processes remain open to investigation because of a
lack of controlled experiments on this matter. us, we
investigated the eect of the methanol extract obtained
from L. barbarum fruits on anxiety, depression-like
behaviors, and spatial memory in Wistar albino rats
because anxiety and depression are the most common
psychological problem with a lifetime prevalence of 16.6%
(Ramsawh et al., 2010) and 17%–20% (Cryan et al., 2002),
respectively. Moreover, spatial memory, which is aected
by various factors such as sex, hormones, cues, training,
and emotions (Hawley et al., 2013), is also an essential part
of our ability to recognize our environment and its spatial
orientation. Just like humans, rats use spatial memory to
learn the location of food at the end of a maze or another
given place (Packard and McGaugh, 1996). For the
treatment or improvement of these behaviors, new drugs
and herbal treatment are sought since the side eects of
current drugs are still a great problem for scientists and
professionals.
e aim of the present study was to investigate how
behaviors such as anxiety, depression, and learning are
aected by the methanol extract of L. barbarum fruits.
If L. barbarum fruits are benecial to health (e.g., eects
on antiaging activity, neuroprotection, and general well-
being), it should also have antianxiety and antidepressant
activities. is study was carried out with both male and
female albino rats since females are reported to have
more hormonal activities and attentional properties than
males (Meyers-Levy, 1989). We also investigated whether
or not sex modulates the eect of the methanol extract
Abstract: e aim of this research was to investigate the eects of the methanol extract obtained from Lycium barbarum fruits on
anxiety, depression-like behaviors, and spatial memory in Wistar albino rats. A total of 28 rats were selected, randomly assigned to four
experimental groups, and tested by means of the open eld and elevated plus maze tests for anxiety-like behaviors, the forced swim
test for depression-like behaviors, and the Morris water maze test for spatial memory. e ndings demonstrated that in the open eld,
L. barbarum-administered rats spent more time at the center and showed more mobility and velocity than controls. In the elevated
plus maze, L. barbarum-administered rats spent more time in the open arms, spent less time in the closed arms, and showed more
mobility and velocity. In the Porsolt test, L. barbarum-administered rats showed less immobility. In the Morris water maze, L. barbarum-
administered rats took more time to nd the platform. However, females were better at nding the platform than males. e methanol
extract of L. barbarum fruits decreased anxiety and depression-like behaviors and interacted with sex on spatial memory.
Key words: Lycium barbarum (goji berry), anxiety, depression, spatial memory, Wistar albino rat (Rattus rattus)
Received: 24.07.2015 Accepted/Published Online: 11.11.2015 Final Version: 21.06.2016
Research Article
PEHLİVAN KARAKAŞ et al. / Turk J Biol
763
of L. barbarum fruits on anxiety, depression, and spatial
learning performance. To test these issues, the rats were put
into open eld and elevated plus maze tests for anxiety-like
behavior, a forced swim test for depression, and the Morris
water maze test for spatial memory.
Given the fact that previous studies overlooked the
relationships among anxiety, depression-like behaviors
and spatial learning behavior (Karakas et al., 2011; Coskun
et al., 2012), we also tried to investigate for the rst time
the role of the methanol extract of L. barbarum on anxiety,
depression, and spatial memory in a longitudinal fashion.
In these above-mentioned studies as well as the present
research, all animals were tested for these behaviors within
the span of 3 weeks. Despite the fact that this interval can
be regarded as a long enough time period for eliminating
carryover eects, one may wonder whether or not there
may be carryover eects for both control and treatment
conditions. Besides this plausible carryover eect, the
nature of the relationships among these variables is of great
importance. us, we separately conducted relationship
analyses for control and treatment conditions in order to
test whether or not these issues were meaningful.
2. Materials and methods
2.1. Plant material and extract preparation
e dried fruits of L. barbarum, produced by Bolu Kalite
Yem Sanayi A.Ş., were originally imported from China
and sold under the name of Naturol (code number: TR
14K00007). ey were ground and weighed. e powdered
fruits (30 g) were extracted with 300 mL of methanol
(MeOH) in a hot water bath at 35 °C for 16–24 h and then
ltered. e extraction solvent was then evaporated under
low pressure at a temperature not higher than 38 °C using
a rotary evaporator. e extraction solvent was evaporated
successfully and crude methanolic extracts of L. barbarum
were obtained and stored in refrigerator at 4 °C. e yield
of extract (w/w) was 30% (yield % = weight of extract /
powdered plant sample × 100).
2.2. Animal care
Adult Wistar albino rats (200–250 g; 14 males and 14
females) were acquired from the Center for Experimental
Animals and Applied Research at Abant İzzet Baysal
University, Bolu, Turkey. e procedures in this study
were carried out in accordance with the standard animal
scientic procedure and were approved by the Institutional
Animal Care and Use Committee (ethical code number:
2014/35). For all rats, plastic cages (16 × 31 × 42 cm),
which were exposed to 200 lx light, were used with pine
shavings as bedding. ey were maintained at 12 h of light
and 12 h of darkness with lights o at 1800 hours. Food
pellets and tap water were accessible ad libitum. Ambient
temperatures in the animal facilities were held constant at
22 ± 2 °C in air-ventilated rooms.
2.3. Experimental method
In the present study, a total of 28 adult rats were selected
and randomly assigned to four experimental groups
[control males (n = 7), L. barbarum-administered males
(n = 7), control females (n = 7), and L. barbarum-
administered females (n = 7)]. Each rat received 50 mL of
fresh drinking water that included 50 mg of L. barbarum
methanol extract every day ad libitum from the 1st day to
the end of the experiment (30 days). In the control group,
animals received the same amount of fresh drinking water
to obtain the same stress conditions as in the experimental
groups. Anxiety-like behaviors, depression-like behaviors,
and spatial memory of Wistar rats were measured by means
of open eld and elevated plus mazes, forced swimming,
and the Morris water maze test, respectively.
2.3.1. Open eld
e open eld consisted of an arena of 80 cm × 80 cm with
40-cm-high walls; it is a commonly used test in order to
investigate anxiety-like behaviors. is test has two main
areas: a plain and an illuminated arena. A video camera
was xed above the arena, recording behaviors into the
Ethovision video-tracking system (Noldus Ethovision,
Version 6, the Netherland; Commat Ltd. Şti., Ankara,
Turkey). is system recorded all the parameters of
anxiety-like behaviors such as distance, time on the edge,
time in the center, frequency on the edge, frequency in the
center, mobility, and velocity among the dierent areas of
the arena (Karakas et al., 2011).
2.3.2. Elevated plus maze
e elevated plus maze in a plus-sign conguration 55 cm
o the oor, which has been used as a test for acrophobia
or elevated anxiety. It consisted of two open and two
closed 10-cm-wide arms. e closed arms were enclosed
by 41-cm-tall black Plexiglas. All animals were tested
by means of the procedure described by Karakas et al.
(2011) and Kaya et al. (2011). Videotapes with Observer
Soware (Ethovision XT, Noldus Ethovision, Version 6)
were recorded and analyzed for all anxiety-like behaviors
(including distance, duration in the open arms, frequency
in the closed arms, mobility, and velocity).
2.3.3. Forced swim test (Porsolt test)
Depressive-like responses were measured by means of the
Porsolt test, which consists of an opaque cylinder tank (24
cm in diameter, 53 cm in height) lled with 17 cm of water
kept at 28 °C. Swimming behavior was recorded on video
for 5 min. A video camera was mounted above the arena,
recording behavior into the Ethovision video-tracking
system (Noldus Ethovision, Version 6) that provided a
variety of depression-like behaviors including mobility
time, mobility frequency, total distance travel, immobility
time, rotation, and velocity (Karakas et al., 2011).
PEHLİVAN KARAKAŞ et al. / Turk J Biol
764
2.3.4. Morris water maze
Spatial memory was measured by using the Morris water
maze, which consisted of a circular galvanized steel maze
(1.5 m in diameter and 60 cm in depth), which was lled
with 40 cm of water kept at 28 °C and rendered opaque
by the addition of a nontoxic, water-soluble dye. e maze
was surrounded by many visual cues external to the maze
(e.g., the experimenter, ceiling lights, a rack, pictures).
Locations of such cues were xed throughout the period of
testing. ere were four equally divided quadrants in the
pool. In one of the quadrants, a platform (2.0 cm below the
water surface, 10 cm in diameter) was submerged centrally
and xed in position, which was kept constant throughout
the acquisition trials. All the procedures in this test were
similar to the procedure described by Karakas et al. (2011).
A video camera was xed above the arena. All spatial
learning behaviors (distance, time on the edge, time in the
center, frequency on the edge, frequency in the center, and
immobility among the dierent areas of the arena) were
recorded by a means of the Ethovision video-tracking
system (Noldus Ethovision, Version 6).
2.4. Statistical analyses
Data were analyzed by two-treatment (L. barbarum
treatment and control) × two-sex (female and male)
ANOVA analysis with between-subject design and
correlational analyses using SPSS 22.0. Data are presented
as mean ± SEM aer back-transformation from ANOVA
results.
3. Results
3.1. Open eld measurements
3.1.1. Total distance traveled in the open eld
A signicant eect of sex was detected on the total distance
traveled in the open eld (F (1,50) = 23.14, P = 0.0001,
η2 = 0.34), with higher scores for females (M = 2337.15)
than males (M = 1858.82). L. barbarum treatment eect
was found for the total distance traveled in the open eld
(F (1,50) = 6.96, P = 0.01, η2 = 0.12), with a higher mean
of subjects in the treatment group (M = 2229.13) than the
control (M = 1966.84) (Figure 1a). is means that the
subjects in the treatment groups were less anxious than
those in the control groups.
3.1.2. Time spent at the edge of the open eld
A signicant eect of treatment was found for the time
spent at the edge of the open eld (F (1,50) = 4.35, P = 0.04,
η2 = 0.08). e subjects in the treatment groups (M = 4.56)
spent less time at the edge of the open eld than controls
(M = 4.68) (Figure 1b), indicating that the subjects in the
treatment groups were less anxious than the controls.
3.1.3. Time spent at the center of the open eld
A signicant eect of treatment was found for the time
spent at the center of the open eld (F (1,50) = 4.35, P
= 0.04, η2 = 0.08), with higher scores for subjects in the
treatment groups (M = 0.44) than controls (M = 0.32)
(Figure 1c).
3.1.4. Total entry to the edge of the open eld
A signicant eect of treatment was found for the entrance
frequency to the edge of the open eld (F (1,52) = 3.73, P
= 0.059, η2 = 0.07), with higher total entry of the subjects
in the treatment groups (M = 8.50) than the controls (M
= 6.27). e interaction eect between sex and treatment
was signicant (F (1,52) = 3.73, P = 0.059, η2 = 0.007).
Females were more anxious in treatment conditions (M =
9.57) than control conditions (M = 5.14), but males had
the same level of anxiety in both treatment (M = 7.43) and
control (M = 7.43) conditions (Figure 1d).
3.1.5. Total entry to the center of the open eld
A signicant eect of treatment was found for the entrance
frequency to the center of the open eld (F (1, 52) = 3.98,
P = 0.051, η2 = 0.071), with higher entry of subjects in the
treatment groups (M = 8.14) than controls (M = 5.93)
(Figure 1e).
3.1.6. Mobility in the open eld
A signicant eect of sex was found for mobility in the
open eld (F (1,50) = 8.67, P = 0.05, η2 = 0.15), with higher
mobility scores for males (M = 4.999) than females (M =
4.996). e main eect of treatment was signicant on the
mobility in the open eld (F (1,50) = 5.94, P = 0.02, η2 =
0.11), with higher mobility of subjects in the treatment
groups (M = 4.998) than controls (M = 4.996).
3.1.7. Velocity in open eld
A signicant eect of sex was found for velocity in the
open eld (F (1,50) = 8.67, P = 0.05, η2 = 0.15). Males (M
= 371.97) showed less velocity than females (M = 468.08).
e main eect of treatment was signicant on the velocity
in the open eld (F (1,50) = 6.85, P = 0.01, η2 = 0.12), with
a higher mean of subjects in the treatment groups (M =
446.05) than controls (M = 394.01) (Figure 1f).
3.2. Elevated plus maze measurements
3.2.1. Total distance traveled in the elevated arm maze
e main eect of sex was signicant on the total distance
traveled in the elevated plus maze (F (1,50) = 45.09, P =
0.0001, η2 = 0.47), with a higher mean of females (M =
1162.28) than males (M = 842.65) (Figure 2a).
3.2.2. Time spent in closed arms
A signicant eect of L. barbarum administration was
found for the time spent in closed arms (F (1,50) = 10.55,
P = 0.002, η2 = 0.17). e subjects in treatment groups (M
= 3.68) spent less time in the closed arms than the controls
(M = 4.33) (Figure 2b).
3.2.3. Total entry to closed arms
A signicant eect of sex was found for the entrance
frequency to the closed arms (F (1,50) = 17.83, P = 0.0001,
PEHLİVAN KARAKAŞ et al. / Turk J Biol
765
η2 = 0.26), with a higher entry of females (M = 7.36)
than males (M = 5.35). e main eect of treatment was
signicant on the entrance frequency to the closed arms (F
(1, 50) = 7.15, P = 0.01, η2 = 0.13), with higher entry of the
subjects in the treatment groups (M = 6.99) than controls
(M = 5.71). An interaction eect between sex and L.
TDT
Total distance traveled (cm)
0
500
1000
1500
2000
2500
3000 a
b
c
d
control treatment
male
control treatment
female
TSEO
Time spent at the edge of open field (min)
0
1
2
3
4
5
6
control treatment
male female
control treatment
a
ab
b
TSCO
Time spent at the center of the open field (min)
0.0
0.2
0.4
0.6
0.8
control treatment control treatment
male female
a
b
a
b
EFEO
Entrance frequency to edge of open field (number)
0
2
4
6
8
10
12
14
16
a
ab ab
b
control treatment
male female
control treatment
VEL
Velocity (cm/min)
0
100
200
300
400
500
600 a
b
c
d
male
control treatment control treatment
female
EFCO
Entrance frequency to the center of open field (number)
0
2
4
6
8
10
12
14 a
b
b
b
control treatment control treatment
male female
a b
c d
e f
Figure 1. (a) Total distance traveled on the open eld (TDT), (b) time spent at the edge of the open eld (TSEO), (c) time spent at
the center of the open eld (TSCO), (d) total entries to the edge of the open eld (EFEO), (e) total entries to the center of the open
eld (EFCO), and (f) velocity in the open eld (VEL) are represented for open eld measurements. Right striated bar represents
rats exposed to the methanol extract of L. barbarum (n = 14); dotted striated bar represents control conditions (n = 14). a, b, c, d:
mean values with the same letters above columns are not signicantly dierent (P > 0.05).
PEHLİVAN KARAKAŞ et al. / Turk J Biol
766
EFCA
Entrance frequency to the closed arms (number)
0
2
4
6
8
10
control treatment control treatment
male female
b
a
b
ab
TSOA
Time spent in open arm (min)
0.0
0.5
1.0
1.5
2.0
2.5
a
a
b
b
control treatment control treatment
female
male
EFOA
Entrance frequency to the open arm (number)
0
2
4
6
8
10
male
control treatment control treatment
female
a
a
b
bc
VEL
Velocity (cm/min)
0
50
100
150
200
250
300
male female
control treatment control treatment
a
a
b
b
TDT
Total distance traveled (cm)
0
200
400
600
800
1000
1200
1400
1600
control treatment control treatment
male female
a
a
bb
TSCA
Time spent in closed arms (min)
0
1
2
3
4
5
6
aa
b
b
male
control treatment control treatment
female
a b
c d
fe
Figure 2. (a) Total distance traveled in the elevated arm maze (TDT), (b) time spent in closed arms (TSCA), (c) total entries to
closed arms (EFCA), (d) time spent in open arm (TSOA), (e) total entries to open arm (EFOA), and (f) velocity (VEL) in elevated
plus maze are represented for elevated plus maze measurements. Right striated bar represents rats exposed to the methanol extract
of L. barbarum (n = 14); dotted striated bar represents control conditions (n = 14). a, b, c: mean values with the same letters above
columns are not signicantly dierent (P > 0.05).
PEHLİVAN KARAKAŞ et al. / Turk J Biol
767
barbarum administration was signicant (F (1,50) = 12.77,
P = 0.001, η2 = 0.20). is means that males were more
anxious in treatment conditions (M = 6.83) than control
conditions (M = 3.86), but females were less anxious in
treatment conditions (M = 7.14) than control conditions
(M = 7.57) (Figure 2c).
3.2.4. Time spent in open arms
A signicant eect of L. barbarum administration was
found for the time spent in open arms (F (1, 50) = 10.55,
P = 0.002, η2 = 0.17), with higher scores of the subjects in
the treatment groups (M = 1.33) than controls (M = 0.67)
(Figure 2d).
3.2.5. Total entry to open arms
A signicant eect of sex was found for the entrance
frequency to the open arms (F (1,50) = 22.01, P = 0.0001,
η2 = 0.31), with a higher total entry of females (M = 7.29)
than males (M = 4.94). An interaction eect between
sex and L. barbarum administration was also signicant
(F (1,50) = 9.15, P = 0.004, η2 = 0.16). Males were less
anxious in treatment conditions (M = 6.17) than control
conditions (M = 3.71), but females had the same level of
anxiety in both treatment (M = 7.00) and control (M =
7.57) conditions (Figure 2e).
3.2.6. Mobility in elevated plus maze
A signicant eect of sex was found for mobility (F (1,50)
= 5.72, P = 0.02, η2 = 0.10). Females (M = 4.986) were
less mobile than males (M = 4.990). An interaction eect
between sex and L. barbarum administration was also
signicant (F (1,50) = 4.76, P = 0.03, η2 = 0.09). As can be
seen, males were less anxious in treatment conditions (M
= 4.989) than control conditions (M = 4.992), but females
had the same level of anxiety in both treatment (M =
4.989) and control (M = 4.984) conditions.
3.2.7. Velocity in elevated plus maze
A signicant eect of sex was found for the velocity (F
(1,50) = 45.10, P = 0.0001, η2 = 0.47). Males (M = 169.07)
showed less velocity than females (M = 233.29) (Figure 2f).
3.3. Forced swim test (Porsolt) measurements
3.3.1. Total distance traveled in the Porsolt test
A signicant eect of treatment was found for the total
distance traveled (F (1,24) = 39.48, P = 0.0001, η2 = 0.62),
with higher performance of the subjects in the treatment
groups (M = 1878.34) than controls (M = 1237.67) (Figure
3a), indicating that subjects in treatment conditions were
less depressive than those in the control conditions.
3.3.2. Immobility
A signicant eect of L. barbarum treatment was found
for immobility (F (1,24) = 37.45, P = 0.0001, η2 = 0.61).
e subjects in the treatment groups (M = 0.78) were
less immobile than controls (M = 1.51) (Figure 3b). is
means that the subjects in treatment conditions were less
depressive than those in control conditions.
3.3.3. Mobility
A signicant eect of treatment was found for mobility (F
(1,24) = 26.56, P = 0.0001, η2 = 0.53) with higher mobility
of the subjects in the treatment groups (M = 3.78) than the
controls (M = 2.91) (Figure 3c).
3.3.4. Velocity
A signicant eect of sex was found for velocity (F (1,50) =
8.52, P = 0.005, η2 = 0.15), with a higher velocity of females
(M = 455.91) than males (M = 506.45). e main eect of
treatment was signicant on velocity (F (1,50) = 4.05, P =
0.05, η2 = 0.08), with a higher mean of the subjects in the
treatment groups (M = 448.22) than controls (M = 414.13)
(Figure 3d).
3.5. Water maze measurements
3.5.1. Immobility
An interaction eect between sex and L. barbarum
treatment was signicant (F (1,50) = 4.06, P = 0.05, η2
= 0.8). As can be seen, females were less immobile in
treatment conditions (M = 0.099) than control conditions
(M = 0.221), but males were more immobile in treatment
conditions (M = 0.123) than control conditions (M =
0.040) (Figure 4a).
3.5.2. Velocity in the water maze
e main eect of sex was signicant on velocity (F (1,50)
= 4.40, P = 0.04, η2 = 0.08). Males (M = 1679.65) showed
more velocity than females (M = 1515.39). e main eect
of treatment was signicant on velocity in the open eld
(F (1, 50) = 8.88, P = 0.004, η2 = 0.15). e subjects in the
treatment groups (M = 1714.18) were faster than controls
(M = 1480.85) (Figure 4b).
3.6. Correlation analysis
Analyses were conducted in terms of velocity since it was
a common parameter for all behaviors and free from all
situational constraints. Concerning control conditions,
velocity scores in the elevated plus maze were positively
highly correlated with those in the open eld test (r =
0.50, P < 0.01). ese scores in the elevated plus maze
and open eld test were not signicantly correlated with
those for depression (r = 0.24, P > 0.05 and r = –0.15, P
> 0.05, respectively). However, the scores in the elevated
plus maze and open eld test were signicantly negatively
correlated with those for spatial learning (r = –0.39, P <
0.05 and r = –0.56, P < 0.01, respectively). Moreover, the
scores for depression were negatively correlated with those
for spatial learning (r = –0.38, P < 0.05).
As for the treatment condition (i.e. methanol extract
of L. barbarum), velocity scores in the elevated plus maze
were not correlated with those in the open eld test (r =
0.15, P > 0.01). ese scores in the elevated plus maze
were signicantly correlated with those for depression (r
= 0.44, P < 0.01), whereas the scores in the open eld were
not correlated with those for depression (r = –0.19, P >
PEHLİVAN KARAKAŞ et al. / Turk J Biol
768
0.05). e scores in the elevated plus maze and open eld
test were also not signicantly correlated with those for
spatial learning (r = 0.30, P > 0.05 and r = 0.09, P > 0.05).
Moreover, the scores for depression were not signicantly
correlated with those for spatial learning (r = –0.21, P >
0.05) in the treatment condition.
4. Discussion
4.1. Anxiety-like behaviors
In the open eld test (Pyter and Nelson, 2006; Benabid et
al., 2008), L. barbarum was found to reduce anxiety in this
study. Specically, our ndings showed that the subjects
treated with L. barbarum traveled greater distances in
the open eld, spent more time at the edge of the open
eld, spent more time at the center of the open eld,
less frequently entered the edge of the open eld, more
frequently entered the center of the open eld, showed
more mobility, and showed more velocity than those in
control conditions. In the elevated plus maze (Dawson
and Tricklebank, 1995), L. barbarum also reduced anxiety.
Specically, the subjects receiving L. barbarum spent more
time in the open arms, spent less time in the closed arms,
were more mobile, and more frequently entered the closed
arms than the controls.
Taken together, the ndings of the present study show
that in both the open eld and the elevated plus maze
L. barbarum reduced anxiety. is nding is consistent
with previous research indicating that LBP-standardized
juice reduced levels of anxiety (Amagase and Nance,
2008). ese ndings can be explained from at least
three perspectives. First, since the methanol extract of L.
barbarum included polysaccharide, this polysaccharide
may increase the level of serotonin or melatonin, which
in turn may decrease anxiety. e evidence for this comes
MOB
Mobility (min)
0
1
2
3
4
5
aa
bb
male
control treatment
control treatment
female
TDT
b
Total distance traveled (cm)
0
500
1000
1500
2000
2500
control treatment control treatment
male female
a
a
b
b
VEL
d
Velocity (cm/min)
0
100
200
300
400
500
600
male
control treatment
control treatment
female
a
a
b
c
IT
Immobility time (min)
0.0
0.5
1.0
1.5
2.0
2.5
male
control treatment
control treatment
female
aa
bb
a
c
Figure 3. (a) Total distance traveled in the Porsolt test (TDT), (b) immobility (IT), (c) mobility (MOB), and (d) velocity (VEL) in
the forced swim test are represented for forced swim test (Porsolt) measurements. Right striated bar represents rats exposed to the
methanol extract of L. barbarum (n = 14); dotted striated bar represents control conditions (n = 14). a, b: mean values with the
same letters above columns are not signicantly dierent (P > 0.05).
PEHLİVAN KARAKAŞ et al. / Turk J Biol
769
from previous studies indicating that melatonin (Karakas
et al., 2011) and serotonin (Parks et al., 1998; Sarnyai et
al., 2000) decrease anxiety levels. Second, polysaccharide
may stimulate the dendrite patterns in the hippocampus.
ere is strong evidence that polysaccharides enhance the
network of dendrites in the hippocampus (Zhang et al.,
2012) that is closely related to emotions such as anxiety
and prevented hippocampal volume reduction (Gao et al.,
2014). ird, β-carotene, one of the important components
of L. barbarum, may decrease anxiety levels. ere is
some evidence for the benecial eects of β-carotene in
decreasing anxiety and increasing memory (Song and Xu,
2013). Future studies should compare the eects of LBPs
with those of polysaccharides and β-carotene on anxiety-
like behaviors and spatial memory.
In the current research a signicant interaction eect
between sex and L. barbarum treatment on anxiety indicated
that females outperformed males in both the open eld and
elevated plus maze. For instance, we found that females
benetted from the methanol extract of L. barbarum more
than males in terms of total entrances to closed arms and
total entrances to open arms. is outcome may be due
to two factors: selectivity and estradiol eects. According
to the selectivity hypothesis, females tend to process all
information in the environment, whereas males tend to
focus on only what is most important in the environment
(Meyers-Levy, 1989). Searching for all information may be
dicult for females. e methanol extract of L. barbarum
may facilitate information processing and thereby may
lower the level of anxiety. Second, estradiol level of females
may contribute to low levels of anxiety. Even though there
is no direct support for this, studies on spatial learning
showed that varied estradiol levels may dierently aect
the learning performance of female Wistar rats (Wide at
al., 2004; Daniel, 2006). Future studies should examine the
eects of estradiol levels in females with dierent levels of
the methanol extract of L. barbarum.
4.2. Depression-like symptoms
We evaluated the depressive-like responses (learned
helplessness) of the subjects in a forced swim test (Porsolt
et al., 1977) and found that the subjects receiving L.
barbarum were less depressive than the controls.
is outcome was in line with previous research
ndings (Zhang et al., 2012) that demonstrated that LBP
treatment signicantly decreased the immobility time
of stressed rats in a forced swimming test. Zhang et al.
(2012) explained this outcome from the view that LBP
may stimulate dendrite patterns in the hippocampus.
We also speculate that this outcome may be due to the
increase in levels of melatonin or serotonin, which are the
two important neurotransmitters in reducing depression
levels. Another plausible factor may be the increased level
of energy metabolism (Coskun et al., 2012). e methanol
extract of L. barbarum may increase glucose levels of
blood, which in turn leads to high energy metabolism. We
observed that subjects exposed to the methanol extract of
L. barbarum were more mobile controls.
4.3. Spatial memory performance
In this experiment the behaviors related to spatial memory
(i.e. time to nd the platform, time spent in the correct
quadrant, entrance frequencies to the correct and other
quadrants, mobility, and velocity) were measured by the
Morris water maze (Hooge and De Deyn, 2001), in which
an animal tries to nd a hidden platform 2 cm below the
water.
In the present study it was found that in the Morris
water maze the subjects receiving L. barbarum showed
IMOB
Immobility
0.00
0.05
0.10
0.15
0.20
0.25
0.30
control treatment
male
female
control treatment
a
ab
ab
b
VEL
Velocity (cm/min)
0
500
1000
1500
2000
2500
control treatment
male female
control treatment
aa
a
b
ab
Figure 4. (a) Immobility (IMOB) and Velocity (VEL) in water maze are represented for water maze measurements. Right striated
bar represents exposured the methanol extract of L. barbarum (n = 14); Dotted striated bar represents control condition (n = 14).
a, b, c mean-values with the same letters above columns are not signicantly dierent (P > 0.05).
PEHLİVAN KARAKAŞ et al. / Turk J Biol
770
more velocity and were less immobilized among females but
more immobilized among males than in control condition.
is means that the methanol extract of L. barbarum is
more benecial to spatial learning than control conditions
and females are better at spatial memory than males.
e nding that the methanol extract of L. barbarum is
benecial to spatial learning is consistent with a recent
nding (Chen et al., 2014) of some benecial eects of
LBPs on learning and memory in rats. In line with this
nding, this research also demonstrated that the methanol
extract of L. barbarum increases spatial learning memory,
especially for females. is eect may be modulated by
the hippocampus. Research demonstrated that LBPs
enhanced cell proliferation in the hippocampus. It is well
known that the hippocampus may play an important role
in searching and navigating in the environment (Ekstrom
et al., 2003). e second nding, that females are better at
spatial memory than males, is also consistent with previous
research ndings indicating that females are better at
recognizing tasks than males (Sutclie et al., 2007).
Correlational analyses showed a signicant positive
relationship between the elevated maze and open eld and
a negative relationship between these anxiety measures
with spatial learning, as well as a negative relationship
between depression and spatial learning in control
conditions. is clearly provides evidence for the fact that
the methanol extract of L. barbarum plays an important role
as an eective agent in eliminating signicant relationships
among anxiety, depression, and spatial learning. We also
found that the relationship between the elevated plus maze
and depression was stronger in treatment conditions than
in controls. is may suggest
that velocity in the elevated
plus maze can be transferred to that in the Porsolt test via
the methanol extract of L. barbarum. is outcome may be
due to closed and narrow spaces in both tests. e methanol
extract of L. barbarum may be more time-resistant in
closed and narrow areas than open and wider areas.
Obviously, future studies are needed for the investigation
of underlying reasons for this strong relationship.
In conclusion, the present experiment provides, for
the rst time, evidence for the benecial eect of the
methanol extract of L. barbarum on low levels of anxiety
and depression-like behaviors. is study also makes
a contribution to the understanding of the interaction
eect between treatment and sex, indicating that females
seem to benet from the methanol extract of L. barbarum
more than males in terms of anxiety and depression-like
behaviors as well as spatial learning behavior.
Future studies should include a research paradigm
in which secondary metabolites such as polysaccharides,
polyphenols, and β-carotene can be separated and isolated
from the crude methanol extract of L. barbarum to
better understand the underlying mechanism of its role
in aective and learning behaviors. In conclusion, the
ndings of this study suggest that the methanol extract of
L. barbarum decreases the level of anxiety and depression-
like behaviors and increases spatial learning behavior in
Wistar albino rats and that females benet from it more
than males in terms of these behaviors.
Acknowledgment
e rst author thanks her husband, Assoc Prof Dr Alper
Karakaş, for all of his support.
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