Objectives: To study effects of willughbela cochinchinensis (WC) on learning and memory deficits in experimental animals. Subjects and methods: 50 Swiss mice were randomly separated into 5 experimental groups, 10 mice for each group.
Trang 1AMELIORATION OF LEARNING AND MEMORY DEFICITS
BY WILLUGHBEIA COCHINCHINENSIS IN MICE
Nguyen Thi Hoa*; Le Van Quan*; Can Van Mao* SUMMARY
Objectives: To study effects of willughbela cochinchinensis (WC) on learning and memory deficits in experimental animals Subjects and methods: 50 Swiss mice were randomly separated into 5 experimental groups, 10 mice for each group Group 1: mice were intraperitoneally (i.p) injected and orally (p.o) administered saline at dose 0.1 mL/10 g; group 2: mice were injected i.p 1.5 mg/kg scopolamin and p.o 0.1 mL/10 g saline; group 3, group 4 and group 5: mice were injected i.p 1.5 mg/kg scopolamin and p.o 100 mg/kg, 150 mg/kg and 200 mg/kg WC, respectively 60 minutes after drug injections, animals performed a passive avoidance test which includes two phases: training phase: animals were placed in the light compartment and if they moved to the dark compartment, they were given electrical foot shocks for 3 seconds; test phase: animals were also placed in the light compartment but they were not given any electrical foot shocks at the dark compartment Results: In test phase, mean latency
to entry dark compartment in group 2 was shorter than that in group 1 and the latencies in group
4 and 5 were longer than that in group 2 Conclusion: Our results provided an evidence for
effective treatment of WC in memory deficits animal model
* Keyword: Willughbela cochinchinensis; Learning and memory deficits; Mice
INTRODUCTION
Alzheimer’s disease (AD) accounts for
60 - 80% of cases of dementia in older
people [1] Mechanism of AD has been
suggested to be involved in
neurodegeneration and formations of
plaques and neurofibrillary tangles in
brains which cause atrophied cortex and
enlarged ventricles [2] Following these
damages in brains, patients with AD
develop deficits in memory, recognition
and behavioral controlling [3] If they don’t
receive any treatments, these disorders
will be worse and seriously affect to their
life as well as their families
Up to date, there is no effective special treatments for AD and patients with AD must receive treatments in all their life Furthermore, in some cases, effects of drugs on AD treatments are limited Thus, development of new drugs and natural plants for effective treatments of AD are necessary
It has indicated that dementia in patients with AD relates to disorders in cholinergic systems Thus, they used scopolamin, cholinergic receptor antagonist, to induce
a animal model of AD WC or “Gui do” has been used in Vietnamese traditional medicines used for treatment of dementia
* Vietnam Military Medical University
Corresponding author: Can Van Mao (canvanmao2011@gmail.com)
Date received: 10/06/2017 Date accepted: 10/08/2017
Trang 2as well as diarrhea, heartburn, and
subcutaneous abscess and as a diuretic
Our preliminary screening study revealed
that methanolic extracts derived from the
wood of W cochinchinensis exhibit AChE
(acetylcholinesterase) and BChE
(butyrylcholinesterase) strong inhibited
activities which are main mechanism of
actions of drugs for treatments of AD [4]
To provide basics for using WC to treat
AD in humans, we conducted the present
study with the aims: To investigate effects
of WC on deficits in learning and memory
in experimental animals
SUBJECTS AND METHODS
1 Subjects
50 Swiss mice (150 - 250 g body
weight) were used in the present study
Animals were housed in individual cages,
maintained in controlled temperature and
12h light/dark cycles with free access to
water and food The present study was
conducted at Department of Physiology,
Vietnam Military Medical University All
procedures were performed in
accordance with the Animal Center
Guidelines for the Care and Use of
Laboratory Animals at the Vietnam
Military Medical University
* Materials:
WC was isolated by Department of
Pharmacy, Hochiminh City University of
Medicine and Pharmacy and was
supplied in power form WC power was
dissolved in saline using a magnetic
stirrer
2 Methods
* Animal grouping and drug treatments:
Animals were separated randomly into
5 experimental groups, 10 mice for each group Group 1 (control group): mice were
ip and p.o treated saline; group 2 (scopolamin group): mice were i.p treated scopolamin 1.5 mg/kg and p.o treated saline at 0.1 mL/10 g; group 3, group 4 and group 5 (WC groups): mice were i.p injected scopolamin 1.5 mg/kg and p.o
WC 100 mg/kg, 150 mg/kg and 200 mg/kg, respectively WC and saline were orally administered at 60 minutes and scopolamin and saline were i.p injected at
30 minutes before the behavioral task
* Passive avoidance test:
Animals were required to perform passive avoidance test, which includes two phases:
- Training phase: was conducted at
60 minute after WC treatments on the first day Passive avoidance box (Ugo Basile) was a chamber which contained
2 compartments: light one and dark one
There was a wall with a door to separate
these compartments (fig.1) The mice
were placed in light compartment and explore freely for 30 minutes Then, the door was raised to allow the mice to enter the dark compartment When the mice entered the dark compartment, the door was closed and an electronic foot shock was delivered for 3 seconds If mice didn’t entered the dark compartment within
300 seconds, mice were captured and placed inside the dark compartment and a foot shock was delivered for 3 seconds
Trang 3Figure 1: Apparatus of passive avoidance test
- Test phase: were conducted on the
second day Mice were placed in the light
compartment and the door was raised In
the test phase, when mice entered the
dark compartment, no foot shock was
delivered Mice’s behaviors were recorded
for 300 seconds by using a digital video
system If animals didn’t enter the dark
compartment, entry latencies were
measured as 300 seconds and the trials
were over
* Research indicators:
In the present study, we analyzed
some research indicators, follow as:
- Latencies from beginning of trials to entrance into the dark compartment Units were measured as seconds (s) In the present study, entry latencies were analyzed
in the training phase and the test phase
- Average speeds, units were measures
as meter/second (m/s)
* Data analyses:
Entry latencies and average speeds were analyzed by one-way analysis of variance (ANOVA) followed by the Tukey’s post-hoc test for multiple comparisons, using SPSS 19.0 Results were considered
to be statistically significant at p < 0.05 All results were expressed as mean ± SEM
RESULTS
1 Differences in entry latencies in the training phase
Figure 2: Entry latencies in training phase
Trang 4Figure 2 showed mean entry latencies of experimental groups in the training phase One way ANOVA indicated that there were no significant differences in entry latencies between experimental groups in the training phase (p > 0.05)
2 Differences in entry latencies in the test phase
Figure 3: Entry latencies in test phase
Figure 3 showed differences in entry latencies between experimental groups in the test phase One way ANOVA indicated there was a significant main effects of experimental group [F(4.49) = 4.949; p = 0.002] Post hoc test indicated that mean entry latency in the scopolamin group was significantly shorter than this in the control group (Tukey test, p < 0.05) Contrarily, entry latencies in WC 150 mg/kg WC 200 mg/kg treated groups were significantly longer than that in the scopolamin treated group (p < 0.001)
3 Differences in average speeds
Figure 4: Average speeds in experimental groups
Trang 5Figure 4 showed differences in average
speeds between experimental groups
One way ANOVA indicated that there was
a significant difference in average speeds
between experimental groups [F(4.49)
= 2.991, p = 0.029] Post hoc test
indicated that mean average speed was
significantly higher than that in the control
group (Tukey test, p < 0.05) After WC
treatments, mean average speeds in the
WC 150 mg/kg group and WC 200 mg/kg
group were significantly lower than that in
the scopolamin group (p < 0.05)
DISCUSSION
Passive avoidance test is used widely
to evaluate learning and memory in
rodents [5] Thus, this behavioral test is
appropriate for the aim of our study In the
present study, in the training phase, mice
had no experience with dangerous events
(foot shocks) in the dark compartment
Thus, mice had tendencies to move to the
dark compartment because of their
nocturnal life These reasons induced,
there was no significant difference in entry
latencies between experimental groups
In the test phase, learning and memory
abilities of animals were expressed When
animals had these better abilities, they
would recognize that when they moved to
the dark compartment, they were received
foot shocks Thus, the longer entry latencies
they present, the better learning and
memory abilities of animals they have In
the present study, scopolamin induced
deficits in learning and memory abilities of
animals expressed by differences in entry
latencies between the control group and
scopolamin group Entry latencies of
scopolamin treated mice were shorter
than these of saline treated mice These results are consisted with previous studies [6, 7] Interestingly, in the present study,
we found that after WC treatments, there were a significant increases in entry latencies of animals treated by WC at doses 150 mg/kg and 200 mg/kg, in compared to that of animals treated by scopolamin These results indicated that
WC ameliorated scopolamin-induced disorders in learning and memory in experimental animals
Furthermore, in the present study, we also found that scopolamin induced hyperactivities in experimental animals These results are consistent with effects
of scopolamin to inhibit acetylcholinesterase enzyme [8] and also with hyperactivities
of patients with AD caused by disorders in activities of the cholinergic system [9] Interestingly, WC treatments also reduced locomotordisorders of experimental animals The present’s results provided a important base for us to conduct next steps to apply WC for treatments of diseases relating to deficits In learning and memory, such as Alzheimer’s disease
CONCLUSION
In the present study, we demonstrated that WC reduced disorders in learning and memory as well as locomotion in experimental animals:
- In the test phase of passive avoidance test, WC at doses 150 mg/kg and 200 mg/kg increased entry latencies
in animals with scopolamin-induced deficits in learning and memory
- WC at the same doses decreased average speeds of animals with scopolamin- induced hyperactivities
Trang 6ACKNOWLEDGEMENTS
This work was supported by Grant
106-YS.05-2013.24 from Vietnam’s
National Foundation for Science and
Technology Development (NAFOSTED)
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