Neurobiopsychologische Analyse des Angstverhaltens im Modell der Ratte: Auswirkung serotonerger Manipulationen
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Philipps-Universität Marburg
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Abstract
The aim of this dissertation is a more in-depth examination of the psychological and neurochemical relation between anxiety and the neurotransmitter serotonin (5-hydroxytryptamine, 5HT). Despite the existence of already comprehensive literature, the role of 5HT in anxiety is not absolutely clear. Behavioral results of studies working with 5HT-lesions have been inconsistent (Griebel 1995, Menard & Treit 1999). A possible reason could be the fact that most studies use general lesions of 5HT although 5HT-projections are widely branched (Feldman et al. 1997) and different 5HT-receptors (Lesch et al. 2003, Hennig & Netter 2005) modulate anxiety in a different way (Deakin & Graeff 1991, Graeff et al. 1997). There are also individual variations of anxiety in rats (Schwarting et al. 1998) which again could affect 5HT-manipulations.
These largely unconsidered aspects form the core of the three studies performed within this dissertation, and thus looking for individual differences or the role of 5HT in the ventral striatum. The behavior of rats was tested after 5HT-manipulation with the toxin 5,7-dihydroxytryptamin (5,7-DHT), the potential toxic 3,4-methylenedioxymethamphetamin (MDMA) and the 5HT2C-antagonist RS102221. An injection of 5,7-DHT into the ventral striatum lead to a lesion of 5HT in the anterior forebrain (striatum and frontal cortex). Different reuptake inhibitors were needed to protect the dopaminergic system. Other studys working with aimed injections of 5HT-toxins often neglect to analyze other brain regions or other neurotransmitters and underrate the degree of destruction. Here, the reduced 5HT-level in the anteroir forebrain yielded moderate anxiogenic effets in the elevated plus-maze (EPM) and in the open field (OF). Also, there were lesion effects on aversively motivated ultrasonic vocalization (USV). An injection of the 5HT2C-antagonist RS102221 into the ventral striatum did not affect anxiety in the OF. This result suggests that the anxiogenic effects shown in the aforementioned lesion study can possibly be tracked back to other 5HT-receptors or extrastriatal lesion of 5HT. The study of long lasting effects of MDMA, considering individual differences in anxiety, shows that MDMA has subject-dependent effects. The behavior in the EPM, OF and in the exploration of a novel object was effected only in the low anxiety subjects.
Together, an injection of the toxin 5,7-DHT in a specific brain region can lead to a global lesion and therefore other areas and neurotransmitters should always be studied as well. Further, there are different effects of 5HT-manipulation in different individuals. So animals should be studied regarding their individual disposition, for example in anxiety, before performing a test. Also, it is to advise not only to test the behavior visible to humans, but to also test the rats’ USV.
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Created: 2007Issued: 2008-02-20Updated: 2011-08-10
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Fachbereich Psychologie
Publisher
Philipps-Universität Marburg
Language
ger
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DoctoralThesis
Keywords
Plus-mazePlus-LabyrinthBehaviourWistar-ratCorpus striatumEctasyAnxietySerotoninVerhaltenPrefrontal cortex
DFG-subjects
EcstasyAngstCorpus striatumPräfrontaler CortexSerotoninWistar-Ratte
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150
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Ludwig, Verena (133936090): Neurobiopsychologische Analyse des Angstverhaltens im Modell der Ratte: Auswirkung serotonerger Manipulationen. : Philipps-Universität Marburg 2008-02-20. DOI: https://doi.org/10.17192/z2008.0075.
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This item has been published with the following license: In Copyright