The Journal of Neuroscience, April 1, 1998, 18(7):2667-2672
Behavioral and Neurobiological Consequences of Social Subjugation
during Puberty in Golden Hamsters
Yvon
Delville,
Richard H.
Melloni Jr, and
Craig F.
Ferris
Neuropsychiatric Sciences Program, Psychiatry Department,
University of Massachusetts Medical Center, Worcester, Massachusetts
01655
In golden hamsters, offensive aggression is facilitated by
vasopressin and inhibited by serotonin. We tested whether these neurotransmitter systems respond to modifications resulting from the
stress of threat and attack (i.e., social subjugation) during puberty.
Male golden hamsters were weaned at postnatal day 25 (P25), exposed
daily to aggressive adults from P28 to P42, and tested for offensive
aggression as young adults (P45). The results showed a
context-dependent alteration in aggressive behavior. Subjugated animals
were more likely to attack younger and weaker intruders than
nonsubjugated controls. Conversely, subjugated animals were less likely
to attack animals of similar size and age. After testing, the animals
were killed, and their brains were collected to determine whether these
behavioral changes are underlined by changes in the vasopressin and
serotonin systems. Social subjugation resulted in a 50% decrease in
vasopressin levels within the anterior hypothalamus, a site involved in
the regulation of aggression. Furthermore, whereas the density of
vasopressin-immunoreactive fibers within the area was not significantly
altered in subjugated animals, the number of serotonin-immunoreactive
varicosities within the anterior hypothalamus and lateral septum was
20% higher in subjugated animals than in their controls. These results
establish puberty as a developmental period sensitive to environmental
stressors. Furthermore, the results show that changes in the
vasopressin and serotonin systems can correlate with behavioral
alterations, supporting the role of these two neurotransmitters in the
regulation of aggression.
Key words:
aggression; vasopressin; serotonin; hypothalamus; development; adolescence
Copyright © 1998 Society for Neuroscience 0270-6474/98/1872667-06$05.00/0