Emotional and Anxiety Assessments in CNS Disorders - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 245

overhead lights, which produce consistent illumination within the
rooms (2,800 lumens each). Pilot studies are required to determine
the most appropriate illumination level. The EPM apparatus should
be placed in the central of room so that four arms are equally
illuminated. Rodents should be hand handled by the same experi-
menter before the test. EPM is thoroughly cleaned by 70% ethanol
and dried before each use to avoid odor interference. Rodents are
placed in the central of the EPM facing open arm. Initially facing
open arm or closed arm would result in different results. Rodents
freely explore the arms for 5 min. The number of arm entries and
the amount of time spent in the open and closed arm are scored by
either single highly trained observers or by video-tracking system.
An arm entry is counted when all four paws of the rodent are on
the arm. The advantage of video-tracking system is to avoid the
subjective score by the observer. For the laboratory without video-
tracking system as it is expensive, it is recommended to score by
the experimenter who does not know the treatment of rodents.
At the end of a 5-min test, remove the rodent from EPM and place
into a transport cage and back to home cage outside the room.
EPM results can be analyzed by one-way between-subjects ANOVAs
to determine the effects of treatment and is followed by post hoc
test, such as Newman-Keuls and Tukey's, if signifi cant main effect
is obtained. Typically, analysis of variance is used to analyze the
effects of following measures: open arm entries, closed arm entries,
time spent in open arm, and time spent in closed arm. The ratio of
open arm and closed arm entries and time is usually to be calcu-
lated and analyzed to avoid the individual difference in the rodent
motor activity. The sample result showed that ( 5 ) diazepam, as a
positive control, signifi cantly increased time spending in open arm
and open arm entries. Rolipram, a PDE4 inhibitor, increased the
percentages of both entries into and time spent in the open arms,
suggesting that rolipram has anxiolytic-like effect in EPM test.

Although the use of guinea pigs, gerbils, and wide mice in the
EPM has been validated, it is still particularly valuable to use rats
and mice in the EPM because the method is highly validated, appa-
ratus are commercially available, and the animals are affordable.
Animal strains, age, sex, and estrous cycle should be considered
when setting up an EPM test. Pilot studies should be carried out to
establish a steady open arm time/entries baseline for the particular
animal. For example, female rodents have inconsistent results in
EPM due to the fl uctuation of estrogen and/or progesterone level.
Ovariectomy surgery is recommended to remove ovaries to avoid
the interference of endogenous hormones. The following problems
during the EPM test should be noticed. Rodents fall off the open
arm. Although it is not frequently happened, rodent should be
put back to the open arm and continue to test when it falls off.
The experimenter should make a note and this rodent should be

1.1.3. Notes