Emotional and Anxiety Assessments in CNS Disorders - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 247

1.2.3. Notes

The light/dark test is limited by its ability to yield false-positive
results if the compound increases locomotor activity. Preliminary
screening of locomotor activity by open fi eld is necessary and suf-
fi cient to reduce false-positive result ( 8 ).

The social interaction test, as the fi rst animal model to test anxiety,
was developed by File and Hyde in 1978 ( 9 ). This test uses etho-
logically relevant sources of anxiety to eliminate introduction of
aversive or appetitive conditions, such as food/water deprivation,
electric shock, and open/high place. Four conditions are used in
social interaction test: low light, familiar environment (LF); low
light, unfamiliar environment (LU); high light, familiar environment
(HF); high light, unfamiliar environment (HU). LF generates the
lowest level of anxiety and is appropriate to test anxiogenic effect.
HU generates the highest level of anxiety and is used to test anxiolytic
effect. An increase in the social interaction, without an increase
in locomotor activity, indicates an anxiolytic effect. In contrast, a
decrease in the social interaction indicates an anxiogenic effect.

1.3. The Social
Interaction Test

A 60 × 60-cm wooden box with 35-cm-high walls is placed in a
quiet room illuminated with either high light (300 LUX) or low
light (30 LUX) depending on the anxiolytic or anxiogenic effect
the experimenters want to test. Infrared photocells are mounted in
the walls 4.5 and 12.5 cm from the fl oor. Video camera is mounted
vertically above the box.

1.3.1. Materials
and Equipment

Social interaction test is performed between pairs of rodents that
are either singly housed or group housed. Group-housed rodents
are normally singly housed for 4-7 days before test because social
isolation reliably increases the social interaction time ( 10 ). The weight
difference of rodents assigned to test partners should be less than
5 g. The pairs of rodents are randomly allocated to same drug
treatment. For rodents with intracranial infusion or lesions, the
procedure should be modifi ed to test operated rodents with an
unoperated, untreated partner and score only the social interaction
initiated by the treated rodents. Isolated rodents are habituated in
the testing cage for 30 min prior to testing. For rodents allocated
to familiar test conditions, each rodent should be placed singly in
the test box for 5-10 min on 2 consecutive days. On day 3, the pair
of rodents is placed into the test box for 10 min. The test session is
recorded and social interaction is scored later. The defi ned social
interaction includes the following: sniffi ng, grooming the partner,
wrestling, and climbing on or under the other partner. It is also
important to score other behaviors, such as aggressiveness, fearfulness,
social activity, and locomotion. Mean time of social interaction in
different groups is statistically analyzed by unpaired student's t -test
(two groups) or one-way ANOVA (multiple groups). A sample
result showed that diazepam at the dose of 0.1 mg/kg and (-)-nicotine

1.3.2. Methods