Program & Abstract Book - EPFL Latsis Symposium 2009

EPFL Latsis Symposium 2009: Understanding Violence
P-30
84
February 11-13 2009
ne u r a l c o r r e l a t e s o f a b n o r m a l
a g g r e s s i o n f o l l o w i n g p e r i p u b e r t a l s t r e s s
in r a t s
Marquez, Cristina 1 ; Vaucher, Angélique 1 ; Sonnay, Aliénor 1 ;
Sigmund, Coralie 1 ; Marquis, Julien 2 ; Groner, Anna Claire 2 ;
Sandi, Carmen 1
1 Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland;
2 Laboratory of Virology and Genetics, School of Life Science,
Ecole Polytechnique Fédérale de Lausanne, Lausanne,
Switzerland
Early life stress in humans enhances the risk for psychopathologies, including
excessive aggression and violence. Adolescence is an important
maturation phase during which critical neurodevelopmental events occur
in brain regions associated with motivation, emotion and cognition. It is
also a relevant period for developing social competences required for adult
life. In rodents, stress can induce long-lasting changes in emotional and
neuroendocrine responsiveness to stress that can be associated with several
psychopathologies. Here we examine behavioral and molecular consequences
of exposure to stress during the peripubertal period. Male Wistar
rats were subchronically exposed to stress (predator odour and open elevated
spaces) during peripuberty (7 days of stress across the P28-P42
period). The long term effects of peripubertal stress were examined when
animals were 3 months-old. Peripuberty-stressed animals displayed increased
anxiety and aggressive behaviors. In the resident-intruder test,
peripuberty-stressed rats attacked more the vulnerable parts of their opponent
and showed a lack of inhibitory control of their behavior (continued
attacking despite clear signals of submission). In order to elucidate the
mechanisms involved in this model of abnormal aggression, we studied
(i) basal brain energy metabolism using 14C-2deoxyglucose autoradiography,
(ii) the pattern of activation of different brain areas after an aggressive
encounter (resident-intruder test) using c-fos immunohistochemistry,
(iii) the levels of expression of the serotonin transporter using qPCR.
Peripuberty-stressed animals showed an increased basal metabolism in
amygdala and bed nucleus of stria terminalis, both areas related to anxiety,
and an increase in the basal expression of the serotonin transporter
in the prefrontal cortex. The aggressive animals showed increase in c-fos
expression in medial amygdala and a lower activation of the medial orbitofrontal
cortex, after the resident-intruder test. Our findings highlight the
relevance of this peripubertal stress model to investigate the neurobiological
correlates of abnormal aggression and confirm the serotonergic system
and the interactions between amygdala and prefrontal cortex as key elements
in the understanding of violence.