[Abstract Title]. - Society for Neuroscience

Poster
281. Stress and the Brain: Early Life Experience I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 281.15/NN29
Topic: E.06.e. Early life experience
Support: NIH Grant DA10886
Title: Conditioned place aversion and 22-kHz distress vocalizations in socially subjugated male
rats
Authors: R. J. BROWN, A. R. LUMIA, R. L. CUNNINGHAM, K. A. FRAHM, *M. Y.
MCGINNIS;
Dept Pharmacol, UTHSCSA, San Antonio, TX
Abstract: The early experience of social subjugation (SS) results in negative behavioral
consequences in adulthood. In the present study, we wanted to determine if exposure to cues
previously associated with SS elicits a behavioral response in subjugated rats. The importance of
odor, the presence of a subjugator, and the home cage environment were examined. Specifically,
we hypothesized that odors and environmental cues associated with SS would induce a
conditioned place aversion and elicit 22-kHz ultrasonic distress vocalizations. Gonadally intact,
Long-Evans male rats were divided into two groups: SS and controls. SS involved exposure to an
aggressive, adult male for 10 min every other day over an 18-day period. On postnatal day 38
(P38), SS rats underwent subjugation in the presence of lemon odor. Controls were placed in a
novel cage with lemon odor. On alternate days both groups were exposed to a novel cage with
almond odor. Beginning on P59, behavioral tests were performed in two different settings: a
conditioned place preference (CPP) apparatus and the home cage (HC) of a subjugating male.
CPP tests were used to determine if SS rats developed a conditioned place aversion to either the
odor or to the presence of the subjugator. The first test was performed in a 3-chambered CPP
apparatus with lemon odor in one chamber, almond odor in the other, and no odor in the middle
chamber. The amount of time spent in each chamber was recorded. The second CPP test was
performed with a subjugating male placed behind a partition in one side chamber while the other
two chambers were empty. HC tests were used to examine the importance of the subjugation
environment. These tests involved exposure to the HC alone, the HC with the SS-paired odor,
and the HC with the subjugator placed behind a partition. 22-kHz vocalizations were recorded
using a bat detector. In the CPP tests, SS rats spent less time with lemon and more time with
almond compared to controls, though this was not significant. SS animals spent significantly less
time in the chamber containing the subjugator than in the other two chambers combined, while
controls did not. In the HC tests, SS rats only vocalized when the subjugator was present.
Controls did not emit 22-kHz vocalizations in any HC test condition. The results from CPP and
HC tests suggest that the physical presence of a subjugating male is the most salient cue.
Although the presentation of an SS-paired odor may be sufficient to induce a conditioned place