Measuring Behavior 2005: Beiderbeck et al.

Differences in aggression in male Wistar rats are accompanied by distinct arginine-vasopressin release patterns within the lateral septum

D.I. Beiderbeck, I.D. Neumann and A.H. Veenema

Department of Behavioral Neuroendocrinology, Institute of Zoology, University of Regensburg, Regensburg, Germany

Aggressive and violent behaviors are a major health problem in human society. However, animal models studying aggressive behavior and underlying neurobiological mechanisms are limited. Therefore, we studied differences in aggressive behavior in male Wistar rats genetically selected for high (HAB) and low (LAB) anxiety-related behavior, and in nonselected (NAB) Wistar rats. Using the resident-intruder paradigm, we found that LAB rats had a shorter attack latency and displayed significantly higher levels of offensive aggression – in particular lateral threat, clinch, and offensive upright - in comparison to HAB and NAB rats, which did not differ in aggressive behavior. We further measured arginine-vasopressin (AVP) release within the lateral septum in these males during an aggressive encounter using intracerebral microdialysis, as AVP released within this limbic brain region is thought to play a role in the regulation of aggression. The high level of aggression displayed by LAB residents was accompanied by a significant decrease in AVP release within the septum compared to baseline AVP release, while local AVP release in non-aggressive HAB residents rather tended to increase during the resident-intruder test. In contrast, in aggressive NAB rats, AVP release within the septum was increased, while in non-aggressive NAB rats local AVP release remained unchanged. Thus, male offensive aggression, as tested with a resident-intruder paradigm, is dependent on the innate level of emotionality, and is associated with a change in the release of AVP within the lateral septum. Further research is required to study the causal involvement of AVP-mediated effects in male aggressive behavior. Supported by VolkswagenStiftung (IDN) and Bayerische Forschungsstiftung (AV).

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.