Abstracts - Deutsche Zoologische Gesellschaft

Behavioral Biology Posters 109P BB.9 - ENAnxiety-like behaviour and its modulation by winner and loser experience in adultwildtype and serotonin transporter knockout miceFriederike Jansen, Lars Lewejohann, Norbert SachserAbteilung für Verhaltensbiologie, Universität MünsterIn serotonergic neurotransmission the serotonin transporter (5-HTT) plays a key-role by regulatingthe re-uptake of the messenger molecule from the synaptic cleft. Humans, who experience stressfullife events, develop anxiety-disorders and depression more frequently when showing a reduced5-HTT expression. To further analyse these gene x environment interaction 5-HTT knockout micewere used as an animal model. The study examined if a genetic disposition for the development ofanxiety-like behaviour in 5-HTT knockout mice can be modulated by environmental influences inadulthood. To create positive or negative life experiences, Resident-Intruder tests were performedfrom which the mice of the genotypes 5-HTT+/+, 5-HTT+/- and 5-HTT-/- could emanate as winnersor losers. After the encounters anxiety-like and explorative behaviour were measured in testsfor anxiety-like behaviour. A general comparison of the three genotypes revealed a higher rate ofanxiety-like behaviour in 5-HTT-/- mice. After repeated confrontation with a conspecific, winnersas well as losers showed increased anxiety-like and decreased explorative behaviour. Only for individualswith negative life experiences (losing) a dependency of genotype was detected, in such amanner that 5-HTT-/- mice exhibited the highest ratio of anxiety-like behaviour and the lowest levelof exploration. This study proves an interdependence of genotype, social experience and anxiety-likebehaviour exists in adult 5-HTT knockout mice.P BB.10 - ENThe effects of olfactory stimulation in early-life on anxiety-like behaviour in wildtypeand serotonin transporter knockout mice in adulthoodRebecca Heiming, Lars Lewejohann, Norbert SachserAbteilung für Verhaltensbiologie, Westfälische Wilhelms-Universität MünsterDepression and anxiety disorders in humans are known to be influenced by the expression rate of theserotonin transporter (5-HTT). Following adverse life events, the risk to suffer from depression is increasedin humans with a low 5-HTT expression. The aim of this study was to elucidate the effect ofadverse early life events on anxiety-like behaviour in 5-HTT knockout mice, expressing either noneor a reduced amount of 5-HTT proteins. Animals were confronted with adverse early life events byrepeatedly exposing pregnant and lactating 5-HTT females to the olfactory cues of unfamiliar adultmales, i.e. small amounts of male bedding. The stimuli signal the danger of infant killing and simulatea threatening environment for a female and her young. Starting on postnatal day 50 the offspringwere examined in a battery of tests for anxiety-like behaviour such as the elevated-plus-maze anddark-light test. Homozygous 5-HTT knockout mice showed an increased anxiety-like behaviourcompared to heterozygous and wildtype animals, confirming previous results. Furthermore the appliedtreatment enhanced the anxiety-related behaviour in the offspring, especially in homozygousand heterozygous serotonin transporter knockout mice, which seemed to be more susceptible toadverse early life events than wildtypes. We conclude that the degree of anxiety-like behaviour inadulthood results from an interaction of genetic predisposition to anxiety and adverse events in earlyphases of life.