The study investigated the antidepressant effects of low doses of amisulpride, an atypical antipsychotic drug, using a forced swim test on mice. Mice were injected with either 0.1 mg/kg or 1.0 mg/kg of amisulpride or a saline solution and observed during a 6-minute forced swim. The time spent immobile was measured but neither dose of amisulpride showed a significant decrease in immobility time compared to the saline control group, failing to replicate previous research. While other studies have found evidence that low doses of amisulpride increase dopamine and have an antidepressant effect, this study was unable to demonstrate that using the forced swim test

1. Investigating the Antidepressant Properties of Low Dose Amisulpride
in the Forced Swim Test
A.G. Grant, E.S. Sola, K.A. Webster, and J.H. Porter
Introduction
 Amisulpride, a benzamide derivative, is a second generation
(atypical) antipsychotic drug. Atypical antipsychotics block
receptors in the dopamine pathways, similar to their typical
antipsychotic counterpoints, but atypicals have been shown to not
cause extrapyramidal motor side effects. The selective binding
profile of amisulpride separates it from other antipsychotic drugs
because it primarily targets dopamine D2 and D3 receptors and
serotonin 5-HT 2B and 5-HT7 receptors and acts as a functional
antagonist. Amisulpride also elicits a presynaptic receptor response
and, at low doses like those used in the present study, the drug has
been shown to increase dopamine concentrations in the brain. This
presynaptic effect is what is believed to cause the antidepressant
effects at low doses.
 The purpose of the present study was to examine the antidepressant
like effect of low dose amisulpride in C57BL/6 mice. The animals
were tested using 0.1 mg/kg and 1.0 mg/kg amisulpride that was
injected subcutaneously 45 minutes before the start of the test. The
study used a forced swim test model which has strong face validity
when measuring the amount of time each animal spends mobile
versus immobile. The initial dose of 0.1 mg/kg was based off of a
study conducted by Abbas, et al. 2009. We hypothesized that we
would be able to replicate the results of the Abbas study by finding
a decreased amount of time spent immobile in the mice that were
injected with low dose amisulpride.
Overview
The C57BL/6 mice (n=18) were housed in individual cages.
The animals were subcutaneously injected with either a drug or
saline solution 45 minutes before the test began and the treatment
condition of the animal was kept blind to the individuals conducting
the study.
A clear plastic cylinder (45cm tall, 21cm wide) was filled to a 30 cm
line with water between 22-25 degrees Celsius.
The animals were individually placed in the cylinder filled with
water that did not permit them to touch the bottom and they were
forced to swim for 6 minutes. The session was recorded on a
portable camera connected to a tripod. After the session the animals
were dried and placed in a warming chamber.
Water was emptied and refilled between sessions to avoid olfactory
cues.
After the test four independent raters that were kept blind to the
treatment of the animal and scored the video footage from the last
four minutes of the recording. Immobility was defined as time spent
only making movements required to stay afloat. Figure 1
Inter-rater reliability of 80% or higher was required for all scorers
and it is believed that the drug elicits an antidepressant effect if the
amount of time the mice with a drug treatment spent immobile is less
than that of the animals injected with a saline solution.
Results
Discussion & Conclusions
 Two trials were conducted for the forced swim study at two
different doses. Figures 2 to the left shows the data from the
first trial comparing the time spent immobile between
amisulpride 0.1 and vehicle. The data did not show a
significant change in time spent immobile between the two
treatments. For the second trial a slightly higher dose of
amisulpride 1.0 compared to vehicle was used, see Figure 3,
and this dose did not show a difference in time spent
immobile either. Neither of our trials replicated the data found
by Abbas, et. Al which means we did not find antidepressant
properties in our testing of low doses of amisulpride. The
study used three separate scorers for the video data of the
mice. There needed to be an 80% inter-rater reliability score
in order for the data to be considered and if the raters were
unable to come to numbers in that range then that animal’s
data was removed
FIG. 1
Abbas, A., & al, e. (2009). Amisulpride is a potent 5-HT7 antagonist:
relevance for antidepressant action in vivo. Psychopharmacology.
Li, Y., & al., e. (2015). Dopamine D2/D3 but not dopamine D1
receptors are involved in the rapid antidepressant-like effects of
ketamines in the forced swim test. Behavioural Brain Research,
100-105.
Thank you to Dr. Joseph Porter for being my faculty mentor, and Kevin
Webster, Erik Sola, and Charlotte Cooper for helping conduct the study
and score the data.
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FIG. 3
Acknowledgments
Bibliography
FIG. 2
 While past research has found amisulpride to have an
antidepressant effect at low doses due to the drug’s effect on
presynaptic dopamine D2 and D3 receptors that increases
the dopamine concentration in the brain, the present study
was unable to replicate these results. The present study
used a forced swim test which is designed so that, if a drug
were to have antidepressant effects, the time the animal
spends immobile should be decreased in an animal in a drug
state. Other studies, such as the one conducted by Li, et al.
found that dopamine D2 and D3 receptors are responsible
for the antidepressant properties of ketamine in the forced
swim study they conducted. This would lead us to believe
that amisulpride may still have antidepressant properties
even though our study did not show that. Further studies
focusing on the antidepressant properties of amisulpride
could use other behavioral tasks of depressive-like behavior
( i.e. Tail-Suspension test) and could try using lower doses
since low dose amisulpride is what is used to treat
dysthymia.