Behavioral phenotyping of oxytocin deficient mice exposed to acute shaker
stress
M. Mach1,2, M. Morris1, M. Dubovicky2,
E. Ujhazy2 and J.B. Lucot1
1Department of
Pharmacology/Toxicology School of Medicine, Wright State University, Dayton,OH,
USA
2Laboratory of Teratology Institute of Experimental Pharmacology,
Slovak Academy of Sciences, Bratislava, Slovakia
When the targeted gene is not expressed in the brain, the behavioral
phenotype of the mutant mice may reveal genetic mechanisms underlying
normal behavior and may increase our knowledge of genetic factors in neuropsychiatric
disorders. Reliable phenotyping methods are of great importance in understanding
the influence of genetic or pharmacological interference on a complex
organism. Therefore, it is necessary to develop behavioral tests that
enable to obtain a differential, and thus a reliable image of the phenotype
of an animal. Oxytocin (OT) is a stress-responsive hormone which has behavioral
actions, including antidepressive, sedative and anxiolytic effects. Behavioral
performance assessment was conducted after acute shaker stress in male
and female OT knockout (OT -/-) and wild type (OT +/+). A standard battery
of behavioral tests using Hamilton-Kinder measuring system was used including
measuring anxiety (elevated plus maze), locomotor activity (open field
test) and sensorimotor function (acoustic startle response and pre-pulse
inhibition). Moreover, the plasma corticosterone level was established
after the stress. Stress significantly impaired all measures observed
in the open field test. However, the decrease in basic and fine movements
in male OT -/- was significantly lower than in OT +/+ (p<0.001) and
the total time spent in the periphery tended to be higher in OT -/- (p<0.09).
The elevated plus maze showed a decrease in basic movements after stress
with a greater decrement in OT -/- males. Stress also increased total
time in the closed arms for both genders and genotypes. Acoustic startle
response and pre-pulse inhibition were not altered by stress, genotype
or gender. We conclude:
- There is a gender specific role for OT in the behavioral response
to stress.
- OT attenuates the locomotor response to stress in males.
This work was funded by USA Department of Defense contract # DAMD
17-00-C-0020 and supported by the grant VEGA 2/5052/25 Bratislava, Slovakia.
Paper presented
at Measuring Behavior 2005
, 5th International Conference on Methods and Techniques
in Behavioral Research, 30 August - 2 September 2005, Wageningen, The
Netherlands.
© 2005 Noldus
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